NISTIR 6520

BEES 2.0

Building for Environmental and Economic Sustainability

Technical Manual and User Guide

Barbara C. Lippiatt

With Support From:

U.S. Environmental Protection Agency

Office of Pollution Prevention and Toxics

and

U.S. Department of Housing and Urban Development

Partnership for Advancing Technology in Housing

NISTIR 6520

BEES 2.0

Building for Environmental and Economic Sustainability

Technical Manual and User Guide

Barbara C. Lippiatt

Office of Applied Economics

Building and Fire Research Laboratory

National Institute of Standards and Technology

Gaithersburg, MD 20899-8603

June 2000

With Support From:

U.S. Department of Commerce

William M. Daley, Secretary

Technology Administration

Dr. Cheryl L. Shavers, Under Secretary of

Commerce for Technology

National Institute of Standards and

Technology

Raymond G. Kammer, Director

U.S. Environmental Protection Agency

Carol M. Browner, Administrator

Office of Pollution Prevention and

Toxics

William H. Sanders, III, Director

U.S. Department of Housing and Urban

Development

Andrew M. Cuomo, Secretary

Partnership for Advancing Technology

in Housing

Elizabeth J. Burdock, Director

iii

Abstract

The BEES (Building for Environmental and Economic Sustainability) version 2.0 software

implements a rational, systematic technique for selecting environmentally and economically

balanced building products. The technique is based on consensus standards and designed to be

practical, flexible, and transparent. The Windows-based decision support software, aimed at

designers, builders, and product manufacturers, includes actual environmental and economic

performance data for 65 building products across a range of functional applications. BEES

measures the environmental performance of building products using the environmental life-cycle

assessment approach specified in ISO 14040 standards. All stages in the life of a product are

analyzed: raw material acquisition, manufacture, transportation, installation, use, and waste

management. Economic performance is measured using the American Society for Testing and

Materials (ASTM) standard life-cycle cost method (E 917), which covers the costs of initial

investment, replacement, operation, maintenance and repair, and disposal. Environmental and

economic performance are combined into an overall performance measure using the ASTM

standard for Multiattribute Decision Analysis (E 1765). For the entire BEES analysis, building

products are defined and classified based on the ASTM standard classification for building

elements known as UNIFORMAT II (E 1557).

Key words: Building products, economic performance, environmental performance, green

buildings, life cycle assessment, life-cycle costing, multiattribute decision analysis, sustainable

development

Disclaimer

The United States Department of Commerce and NIST do not endorse any particular brand,

product, or service. The enclosed information is provided for comparing generic, U.S. industryaverage product classes only and no representations are made as to the quality or fitness of any

specific manufacturer's product. Users shall not in any way say or imply that the information

obtained from BEES is an endorsement of any particular product, service, or brand.

The BEES tool bears no warranty, neither express nor implied. NIST does not assume legal liability

nor responsibility for a User's utilization of BEES. NO WARRANTIES AS TO ANY MATTER

WHATSOEVER ARE MADE BY NIST, INCLUDING NO WARRANTY OF

MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
iv

Acknowledgments

The BEES tool could not have been completed without the help of others. Thanks are due the

NIST Building and Fire Research Laboratory (BFRL) for its support of this work from its

inception. The U.S. Environmental Protection Agency (EPA), Pollution Prevention Division also

deserves thanks for its continued support. Deserving special thanks is the BEES environmental

data contracting team of Environmental Strategies and Solutions and Ecobalance, Inc., for its

superb data development, documentation, and technical support. The author is grateful to the

EPA Framework for Responsible Environmental Decisionmaking team, led by Mary Ann Curran

of the EPA Sustainable Technology Division, for recommending methodology improvements that

have been incorporated into BEES 2.0. Thanks are also due Sarah Bretz and her colleagues from

Lawrence Berkeley National Laboratory for providing the Energy Star “Cool Roof” data used to

analyze BEES roof covering alternatives. Also deserving special thanks are the 60 BEES 2.0 Beta

Testers for their time spent reviewing the BEES 2.0 Beta version and their comments leading to

many improvements. The author is particularly grateful for the key cooperation and support

offered by a wide variety of industry associations and manufacturers with products represented in

BEES. Their cooperation exceeded all expectations, and led to improvements in the underlying

BEES performance data. The comments of NIST BFRL colleagues Hunter Fanney, Harold Marshall,

Stephen Weber, and Mark Ehlen inspired many improvements. Special thanks are due Amy Boyles for

helping test, document, and review BEES 2.0. Thanks are also due Cathy Linthicum for her wonderful

secretarial support.

Copyright Information

This software was developed at the National Institute of Standards and Technology by employees of

the Federal Government in the course of their official duties. Pursuant to title 17 Section 105 of the

United States Code this software is not subject to copyright protection and is in the public domain.

We would appreciate acknowledgement if the software is used.
v

Getting Started

System Requirements

BEES runs on Windows 95, Windows 98, Windows 2000, and Windows NT personal computers

with a 486 or higher microprocessor, 32 Mb or more of RAM, and at least 31 Mb of available

disk space. At least one printer must be installed

Installing BEES

From Download Site. Once you've completed the BEES registration form, click Submit, and then

click bees20.exe to download the self-extracting file. If prompted during the download, choose to

save the file to disk. Once downloaded, from Windows Explorer double click on the file to begin

the self-extraction process. Choose to unzip the file to a new folder. Once unzipped, from

Windows Explorer double click on the file SETUP.EXE in your new folder to begin the selfexplanatory BEES 2.0 installation process. During installation, you will need to choose a

directory to install BEES 2.0; you must choose a directory different from the one that contains the

setup file (SETUP.EXE). Once installation is complete, you are ready to run BEES 2.0 from

your program group BEES.

From CD-ROM. Install BEES by inserting the compact disc into your CD-ROM drive and

running the BEES setup program, SETUP.EXE. Follow on-screen installation instructions. Once

installation is complete, you are ready to run BEES 2.0 from your program group BEES.

Running BEES

First time BEES users may find it useful to read the BEES Tutorial, found in section 4 of this

report. The BEES Tutorial is a printed version of the BEES on-line help system, with step-by-step

instructions for running the software. The tutorial also includes illustrations of the screen displays.

Alternatively, first-time users may choose to double-click on the help icon installed in the BEES

program group at installation for an electronic version of the help system.

While running the BEES software, context-sensitive help is often available from the BEES Main

Menu. Context-sensitive help is also available through Help buttons on many of the BEES

windows.
vi

Contents

Abstract .................................................................................................................................. iii

Acknowledgments................................................................................................................... iv

Getting Started......................................................................................................................... v

Contents.................................................................................................................................. vi

List of Tables........................................................................................................................ viii

List of Figures.......................................................................................................................... x

1. Background and Introduction ...............................................................................................1

2. The BEES Model.................................................................................................................3

2.1 Environmental Performance..........................................................................................4

2.1.1 Goal and Scope Definition...................................................................................4

2.1.2 Inventory Analysis...............................................................................................6

2.1.3 Impact Assessment..............................................................................................8

2.1.4 Interpretation .................................................................................................... 27

2.2 Economic Performance .............................................................................................. 32

2.3 Overall Performance................................................................................................... 34

2.4 Limitations................................................................................................................. 34

3. BEES Product Data ........................................................................................................... 39

3.1 Portland Cement Concrete Slabs, Walls, Beams, and Columns (BEES Codes A1030,

A2020, B1011, B1012)............................................................................................... 39

3.2 Roof and Wall Sheathing Alternatives (B1020, B2015).............................................. 45

3.2.1 Oriented Strand Board Sheathing (B1020A, B2015A)........................................ 45

3.2.2 Plywood Sheathing (B1020B, B2015B)............................................................. 48

3.3 Exterior Wall Finish Alternatives (B2011)................................................................... 51

3.3.1 Brick and Mortar (B2011A) .............................................................................. 51

3.3.2 Stucco (B2011B)............................................................................................... 53

3.3.3 Aluminum Siding (B2011C)............................................................................... 56

3.3.4 Cedar Siding (B2011D)..................................................................................... 57

3.3.5 Vinyl Siding (B2011E) ...................................................................................... 58

3.4 Wall and Ceiling Insulation Alternatives (B2012, B3012)............................................ 60

3.4.1 Blown Cellulose Insulation (B2012A, B3012A)................................................. 60

3.4.2 Fiberglass Batt Insulation (B2012B, B2012C, B2012E, B3012B)...................... 63

3.4.3 Blown Fiberglass Insulation (B3012D) .............................................................. 66

3.4.4 Blown Mineral Wool Insulation (B2012D, B3012C).......................................... 68

3.5 Framing Alternatives ( B2013).................................................................................... 71
vii

3.5.1 Steel Framing (B2013A).................................................................................... 71

3.5.2 Wood Framing (B2013B).................................................................................. 73

3.6 Roof Covering Alternatives (B3011)........................................................................... 75

3.6.1 Asphalt Shingles (B3011A)................................................................................ 75

3.6.2 Clay Tile (B3011B) ........................................................................................... 78

3.6.3 Fiber Cement Shingles (B3011C)....................................................................... 81

3.7 Interior Finishes (C3012)............................................................................................ 83

3.7.1 Paints – General Information ............................................................................. 83

3.7.2 Virgin Latex Interior Paint (C3012A) ................................................................ 84

3.7.3 Recycled Latex Interior Paint (C3012B) ............................................................ 86

3.8 Floor Covering Alternatives (C3020).......................................................................... 87

3.8.1 Ceramic Tile with Recycled Windshield Glass (C3020A) ................................... 87

3.8.2 Linoleum Flooring (C30202) ............................................................................. 89

3.8.3 Vinyl Composition Tile (C3020C) ..................................................................... 92

3.8.4 Composite Marble Tile (C3020D)...................................................................... 94

3.8.5 Terrazzo (C3020E)............................................................................................ 96

3.8.6 Carpeting – General Information........................................................................ 98

3.8.7 Wool Carpet (C3020G,C3020J,C3020M,C3020P) .......................................... 100

3.8.8 Nylon Carpet (C3020F,C3020I,C3020L,C3020O)........................................... 104

3.8.9 Recycled Polyester Carpet (C3020H,C3020K,C3020N,C3020Q).................... 106

3.9 Parking Lot and Driveway Paving Alternatives (G2022,G2031)................................ 108

3.9.1 Concrete Paving (G2022A, G2022B, G2022C, G2031A, G2031B, G2031C) .. 108

3.9.2 Asphalt Parking Lot Paving with GSB88 Asphalt Emulsion Maintenance

(G2022D) ................................................................................................................ 110

3.9.3 Asphalt Parking Lot Paving with Asphalt Cement Maintenance (G2022E)....... 112

3.9.4 Asphalt Driveway Paving with Sealer Maintenance (G2031D) ......................... 114

4. BEES Tutorial.................................................................................................................. 117

4.1 Setting Parameters.................................................................................................... 117

4.2 Defining Alternatives................................................................................................ 120

4.3 Viewing Results........................................................................................................ 122

4.4 Browsing Environmental and Economic Performance Data ....................................... 123

5. Future Directions.............................................................................................................. 133

Appendix A. BEES Computational Algorithms.................................................................... 134

A.1 Environmental Performance ................................................................................... 134

A.2 Economic Performance ........................................................................................... 135

A.3 Overall Performance ............................................................................................... 135

References............................................................................................................................ 136
viii

List of Tables

Table 2.1 BEES Global Warming Potential Equivalency Factors................................................ 12

Table 2.2 BEES Acidification Potential Equivalency Factors..................................................... 13

Table 2.3 BEES Eutrophication Potential Equivalency Factors.................................................. 14

Table 2.4 BEES Natural Resource Depletion Equivalency Factors............................................. 16

Table 2.5 Densities of BEES Building Products......................................................................... 17

Table 2.6 Volatile Organic Compound Emissions for BEES Floor Coverings............................. 18

Table 2.7 BEES Indoor Air Performance Scores for Floor Covering Products........................... 19

Table 2.8 BEES Ozone Depletion Potential Equivalency Factors............................................... 22

Table 2.9 Sampling of BEES Maximum Incremental Reactivity Equivalency Factors................. 24

Table 2.10 Sampling of Ecological Toxicity Potential Equivalency Factors................................ 26

Table 2.11 Sampling of Human Toxicity Potential Equivalency Factors..................................... 27

Table 2.12 Pairwise Comparison Values for Deriving Impact Category Importance Weights...... 29

Table 2.13 Relative Importance Weights based on Science Advisory Board Study..................... 29

Table 2.14 U.S. Rankings for Current and Future Consequences by Impact Category................ 30

Table 2.15 Relative Importance Weights based on Harvard University study.............................. 31

Table 3.1 Concrete Constituent Quantities by Compressive Strength of Concrete ...................... 42

Table 3.2 Energy Requirements for Portland Cement Manufacturing ......................................... 43

Table 3.3 BEES Life-Cycle Cost Data Specifications and Codes for Concrete Products............. 44

Table 3.4 Oriented Strand Board Sheathing Constituents........................................................... 46

Table 3.5 Oriented Strand Board Manufacturing Emissions....................................................... 47

Table 3.6 Plywood Constituents................................................................................................ 49

Table 3.7 Plywood Manufacturing Emissions............................................................................. 50

Table 3.8 Energy Requirements for Brick Manufacturing........................................................... 52

Table 3.9 Masonry Cement Constituents ................................................................................... 53

Table 3.10 Stucco Constituents................................................................................................. 54

Table 3.11 Energy Requirements for Masonry Cement Manufacturing....................................... 55

Table 3.12 Density of Stucco by Type ....................................................................................... 55

Table 3.13 Aluminum Siding Constituents................................................................................. 56

Table 3.14 Energy Requirements for Cedar Siding Manufacture ................................................ 58

Table 3.15 Hogfuel Emissions................................................................................................... 58

Table 3.16 Vinyl Siding Constituents......................................................................................... 60

Table 3.17 Blown Cellulose Mass by Application ...................................................................... 61

Table 3.18 Blown Cellulose Insulation Constituents................................................................... 61

Table 3.19 Fiberglass Batt Mass by Application......................................................................... 64

Table 3.20 Fiberglass Batt Constituents..................................................................................... 65

Table 3.21 Energy Requirements for Fiberglass Batt Insulation Manufacturing .......................... 65

Table 3.22 Blown Fiberglass Mass............................................................................................. 67

Table 3.23 Blown Fiberglass Constituents ................................................................................. 67

Table 3.24 Energy Requirements for Fiberglass Insulation Manufacturing.................................. 68

Table 3.25 Blown Mineral Wool Constituents ........................................................................... 69

Table 3.26 Energy Requirements for Mineral Wool Insulation Manufacturing............................ 70

Table 3.27 Energy Requirements for Lumber Manufacture ........................................................ 74
ix

Table 3.28 Hogfuel Emissions................................................................................................... 74

Table 3.29 Asphalt Shingle Constituents.................................................................................... 76

Table 3.30 Seven Kg (15 lb) Roofing Felt Constituents ............................................................. 76

Table 3.31 Fourteen Kg (30 lb) Roofing Felt Constituents......................................................... 78

Table 3.32 Fiber Cement Shingle Constituents........................................................................... 81

Table 3.33 Characteristics of BEES Paints and Primer............................................................... 84

Table 3.34 Virgin Latex Paint and Primer Constituents.............................................................. 85

Table 3.35 Market Shares of Resins........................................................................................... 85

Table 3.36 Components of Paint Resins..................................................................................... 85

Table 3.37 Ceramic Tile with Recycled Glass Constituents........................................................ 87

Table 3.38 Energy Requirements for Ceramic Tile with Recycled Glass Manufacturing.............. 88

Table 3.39 Linoleum Constituents............................................................................................. 89

Table 3.40 Energy Requirements for Cork Flour Production...................................................... 91

Table 3.41 Energy Requirements for Linoleum Manufacturing................................................... 91

Table 3.42 Linoleum Raw Materials Transportation................................................................... 91

Table 3.43 Vinyl Composition Tile Constituents........................................................................ 93

Table 3.44 Energy Requirements for Vinyl Composition Tile Manufacturing ............................. 93

Table 3.45 Composite Marble Tile Constituents ........................................................................ 94

Table 3.46 Energy Requirements for Composite Marble Tile Manufacturing.............................. 95

Table 3.47 Terrazzo Constituents.............................................................................................. 96

Table 3.48 Energy Requirements for Carpet Manufacturing..................................................... 100

Table 3.49 Carpet Installation Parameters................................................................................ 100

Table 3.50 Wool Carpet Constituents...................................................................................... 101

Table 3.51 Raw Wool Material Flows ..................................................................................... 102

Table 3.52 Raw Wool Constituents ......................................................................................... 102

Table 3.53 Wool Yarn Production Requirements..................................................................... 103

Table 3.54 Wool Transportation.............................................................................................. 103

Table 3.55 Nylon Carpet Constituents..................................................................................... 104

Table 3.56 Nylon Yarn Production Requirements.................................................................... 105

Table 3.57 Recycled Polyester Carpet Constituents ................................................................. 106

Table 3.58 Recycled PET Yarn Production Requirements........................................................ 107

Table 3.59 Raw Materials for Asphalt Base Layer ................................................................... 111

Table 3.60 Energy Requirements for Asphalt Paving with GSB88 Emulsion Maintenance...... 1123

Table 3.61 Raw Materials for Asphalt Cement Maintenance .................................................... 113

Table 3.62 Energy Requirements for Asphalt Cement Maintenance.......................................... 114

Table 3.63 Raw Materials for Driveway Sealer........................................................................ 115

Table 3.64 Energy Requirements for Asphalt Sealer Maintenance............................................ 116

Table 4.1 BEES Products Keyed to Environmental and Economic Performance Data Codes ... 131
x

List of Figures

Figure 2.1 Decision Criteria for Setting Product System Boundaries............................................5

Figure 2.2 BEES Inventory Data Categories................................................................................7

Figure 2.3 BEES Study Periods For Measuring Building Product Environmental And Economic

Performance............................................................................................................. 33

Figure 2.4 Deriving the BEES Overall Performance Score......................................................... 36

Figure 3.1 Portland Cement Concrete Without Fly Ash Flow Chart ........................................... 41

Figure 3.2 Portland Cement Concrete With Fly Ash or Slag Flow Chart .................................... 42

Figure 3.3 Oriented Strand Board Flow Chart ........................................................................... 46

Figure 3.4 Plywood Sheathing Flow Chart................................................................................. 49

Figure 3.5 Brick and Mortar Flow Chart.................................................................................... 51

Figure 3.6 Stucco (Type C) Flow Chart..................................................................................... 54

Figure 3.7 Stucco (Type MS) Flow Chart.................................................................................. 54

Figure 3.8 Aluminum Siding Flow Chart.................................................................................... 56

Figure 3.9 Cedar Siding Flow Chart .......................................................................................... 57

Figure 3.10 Vinyl Siding Flow Chart ......................................................................................... 59

Figure 3.11 Blown Cellulose Insulation Flow Chart................................................................... 61

Figure 3.12 Fiberglass Batt Insulation Flow Chart ..................................................................... 64

Figure 3.13 Blown Fiberglass Insulation Flow Chart.................................................................. 67

Figure 3.14 Blown Mineral Wool Insulation Flow Chart............................................................ 69

Figure 3.15 Steel Framing Flow Chart....................................................................................... 72

Figure 3.16 Wood Framing Flow Chart ..................................................................................... 74

Figure 3.17 Asphalt Shingles Flow Chart................................................................................... 76

Figure 3.18 Clay Tile Flow Chart .............................................................................................. 79

Figure 3.19 Fiber Cement Shingles Flow Chart.......................................................................... 81

Figure 3.20 Virgin Latex Interior Paint Flow Chart.................................................................... 84

Figure 3.21 Recycled Latex Interior Paint Flow Chart ............................................................... 86

Figure 3.22 Ceramic Tile with Recycled Glass Flow Chart......................................................... 88

Figure 3.23 Linoleum Flow Chart.............................................................................................. 90

Figure 3.24 Vinyl Composition Tile Flow Chart......................................................................... 93

Figure 3.25 Composite Marble Tile Flow Chart......................................................................... 95

Figure 3.26 Epoxy Terrazzo Flow Chart.................................................................................... 97

Figure 3.27 Wool Carpet Flow Chart....................................................................................... 101

Figure 3.28 Wool Fiber Production ......................................................................................... 102

Figure 3.29 Nylon Carpet Flow Chart...................................................................................... 105

Figure 3.30 Recycled Polyester Carpet Flow Chart.................................................................. 107

Figure 3.31 Handling and Reclamation of PET ........................................................................ 107

Figure 3.32 Concrete Paving Flow Chart................................................................................. 109

Figure 3.33 Asphalt with GSB88 Emulsion Maintenance Flow Chart....................................... 111

Figure 3.34 Asphalt with Asphalt Cement Maintenance Flow Chart......................................... 113

Figure 3.35 Asphalt with Sealer Maintenance Flow Chart........................................................ 115

Figure 4.1 Setting Analysis Parameters.................................................................................... 118

Figure 4.2 Viewing Impact Category Weights ......................................................................... 119

Figure 4.3 Entering User-Defined Weights .............................................................................. 119
xi

Figure 4.4 Selecting Building Element for BEES Analysis ....................................................... 120

Figure 4.5 Selecting Building Product Alternatives.................................................................. 121

Figure 4.6 Setting Transportation Parameters.......................................................................... 122

Figure 4.8 Viewing BEES Overall Performance Results........................................................... 125

Figure 4.9 Viewing BEES Environmental Performance Results ............................................... 125

 Figure 4.10 Viewing BEES Economic Performance Results ................................................... 126

Figure 4.11 Viewing BEES Summary Table ............................................................................ 126

Figure 4.12 Viewing BEES Environmental Impact Category Performance Results by Life-Cycle

Stage.................................................................................................................... 127

Figure 4.13 Viewing BEES Environmental Impact Category Performance Results Contributing by

Flow..................................................................................................................... 128

Figure 4.14 Viewing BEES Embodied Energy Results............................................................. 129

Figure 4.15 A Sampling of BEES “All Tables In One” Display ................................................ 130
xii
1

1. Background and Introduction

Buildings significantly alter the environment. According to Worldwatch Institute,1 building

construction consumes 40 % of the raw stone, gravel, and sand used globally each year,

and 25 % of the virgin wood. Buildings also account for 40 % of the energy and 16 % of

the water used annually worldwide. In the United States, about as much construction and

demolition waste is produced as municipal garbage. Unhealthy indoor air is found in 30 %

of new and renovated buildings worldwide.

Negative environmental impacts arise from building construction and renovation. For

example, raw materials extraction can lead to resource depletion and biological diversity

losses. Building product manufacture and transport consumes energy, generating

emissions linked to global warming, acid rain, and smog. Landfill problems may arise from

waste generation. Poor indoor air quality may lower worker productivity and adversely

affect human health.

Selecting environmentally preferable building products is one way to reduce these negative

environmental impacts. However, while 93 % of U.S. consumers worry about their

home’s environmental impact, only 18 % are willing to pay more to reduce the impact,

according to a survey of 3,600 consumers in 9 U.S. metropolitan areas.2 Thus,

environmental performance must be balanced against economic performance. Even the

most environmentally conscious building product manufacturer or designer will ultimately

weigh environmental benefits against economic costs. To satisfy their customers,

manufacturers and designers need to develop and select building products with an

attractive balance of environmental and economic performance.

Identifying environmentally and economically balanced building products is no easy task.

Today, the green building decisionmaking process is based on little structure and even less

credible, scientific data. There is a great deal of interesting green building information

available, so that in many respects we know what to say about green buildings. However,

we still do not know how to synthesize the available information so that we know what to

do in a way that is transparent, defensible, and environmentally sound.

In this spirit, the U.S. National Institute of Standards and Technology (NIST) Green

Buildings Program began the Building for Environmental and Economic Sustainability

(BEES) project in 1994. The purpose of BEES is to develop and implement a systematic

methodology for selecting building products that achieve the most appropriate balance

 

1

 D.M. Roodman and N. Lenssen, A Building Revolution: How Ecology and Health Concerns are

Transforming Construction, Worldwatch Paper 124, Worldwatch Institute, Washington, DC, March 1995.

2

 1995 Home Shoppers survey cited in Minneapolis Star Tribune, 11/16/96, p H4 (article by Jim

Buchta). According to another survey, Japanese consumers are willing to pay up to 25 % more for

environmentally friendly products (Maurice Strong, Chairman, Earth Council Institute, “Closing Day

Engineering and Construction for Sustainable Development in the 21st Century,

Washington, DC, February 4-8, 1996, p 54)
2

between environmental and economic performance based on the decision maker’s values.

The methodology is based on consensus standards and is designed to be practical, flexible,

and transparent. The BEES model is implemented in publicly available decision-support

software, complete with actual environmental and economic performance data for a

number of building products. The intended result is a cost-effective reduction in buildingrelated contributions to environmental problems.

In 1997, the U.S. Environmental Protection Agency’s (EPA) Environmentally Preferable

Purchasing (EPP) Program also began supporting the development of BEES. The EPP

program is charged with carrying out Executive Order 13101, Greening the Government

Through Waste Prevention, Recycling, and Federal Acquisition, which directs Executive

agencies to reduce the environmental burdens associated with the $200 billion in products

and services they purchase each year, including building products. Over the next several

years, BEES will be further developed as a tool to assist the Federal procurement

community in carrying out the mandate of Executive Order 13101.

In 1999, the U.S. Department of Housing and Urban Development's (HUD) Partnership

for Advancing Technology in Housing (PATH) Program began supporting the

development of BEES data for residential building products. This year, PATH is

supporting an effort to explore the technical and economic feasibility together with the

most suitable framework for a residential version of BEES. This work is based on input

from homebuilders, residential designers, and product suppliers. The purpose is to

provide a useful tool for the residential sector.
3

2. The BEES Model

The BEES methodology takes a multidimensional, life-cycle approach. That is, it

considers multiple environmental and economic impacts over the entire life of the building

product. Considering multiple impacts and life-cycle stages is necessary because product

selection decisions based on single impacts or stages could obscure others that might

cause equal or greater damage. In other words, a multidimensional, life-cycle approach is

necessary for a comprehensive, balanced analysis.

It is relatively straightforward to select products based on minimum life-cycle economic

impacts because building products are bought and sold in the marketplace. But how do we

include life-cycle environmental impacts in our purchase decisions? Environmental impacts

such as global warming, water pollution, and resource depletion are for the most part

economic externalities. That is, their costs are not reflected in the market prices of the

products that generated the impacts. Moreover, even if there were a mandate today to

include environmental “costs” in market prices, it would be nearly impossible to do so due

to difficulties in assessing these impacts in economic terms. How do you put a price on

clean air and clean water? What is the value of human life? Economists have debated these

questions for decades, and consensus does not appear likely.

While environmental performance cannot be measured on a monetary scale, it can be

quantified using the evolving, multi-disciplinary approach known as environmental lifecycle assessment (LCA). The BEES methodology measures environmental performance

using an LCA approach, following guidance in the International Standards Organization

14040 series of standards for LCA.3 Economic performance is separately measured using

the American Society for Testing and Materials (ASTM) standard life-cycle cost (LCC)

approach. These two performance measures are then synthesized into an overall

performance measure using the ASTM standard for Multiattribute Decision Analysis.4 For

the entire BEES analysis, building products are defined and classified based on

UNIFORMAT II, the ASTM standard classification for building elements.5

 

3

 International Standards Organization, Environmental Management--Life-Cycle Assessment--

Principles and Framework, International Standard 14040, 1997; ISO Environmental Management--LifeCycle Assessment—Goal and Scope Definition and Inventory Anslysis, International Standard 14041,

1998; and ISO Environmental Management--Life-Cycle Assessment—Life Cycle Impact Assessment,

International Standard 14042, 2000.

4

 American Society for Testing and Materials, Standard Practice for Applying the Analytic Hierarchy

Process to Multiattribute Decision Analysis of Investments Related to Buildings and Building Systems,

ASTM Designation E 1765-98, West Conshohocken, PA, 1998.

5

 American Society for Testing and Materials, Standard Classification for Building Elements and

Related Sitework--UNIFORMAT II, ASTM Designation E 1557-97, West Conshohocken, PA, September

1997.
4

2.1 Environmental Performance

Environmental life-cycle assessment is a “cradle-to-grave,” systems approach for

measuring environmental performance. The approach is based on the belief that all stages

in the life of a product generate environmental impacts and must therefore be analyzed,

including raw materials acquisition, product manufacture, transportation, installation,

operation and maintenance, and ultimately recycling and waste management. An analysis

that excludes any of these stages is limited because it ignores the full range of upstream

and downstream impacts of stage-specific processes.

The strength of environmental life-cycle assessment is its comprehensive, multidimensional scope. Many green building claims and strategies are now based on a single

life-cycle stage or a single environmental impact. A product is claimed to be green simply

because it has recycled content, or claimed not to be green because it emits volatile

organic compounds (VOCs) during its installation and use. These single-attribute claims

may be misleading because they ignore the possibility that other life-cycle stages, or other

environmental impacts, may yield offsetting impacts. For example, the recycled content

product may have a high embodied energy content, leading to resource depletion, global

warming, and acid rain impacts during the raw materials acquisition, manufacturing, and

transportation life-cycle stages. LCA thus broadens the environmental discussion by

accounting for shifts of environmental problems from one life-cycle stage to another, or

one environmental medium (land, air, water) to another. The benefit of the LCA approach

is in implementing a trade-off analysis to achieve a genuine reduction in overall

environmental impact, rather than a simple shift of impact.

The general LCA methodology involves four steps.6 The goal and scope definition step

spells out the purpose of the study and its breadth and depth. The inventory analysis step

identifies and quantifies the environmental inputs and outputs associated with a product

over its entire life cycle. Environmental inputs include water, energy, land, and other

resources; outputs include releases to air, land, and water. However, it is not these inputs

and outputs, or inventory flows, that are of primary interest. We are more interested in

their consequences, or impacts on the environment. Thus, the next LCA step, impact

assessment, characterizes these inventory flows in relation to a set of environmental

impacts. For example, the impact assessment step might relate carbon dioxide emissions, a

flow, to global warming, an impact. Finally, the interpretation step combines the

environmental impacts in accordance with the goals of the LCA study.

2.1.1 Goal and Scope Definition

The goal of the BEES LCA is to generate relative environmental performance scores for

building product alternatives based on U.S. average data. These will be combined with

 

6

 International Standards Organization, Environmental Management--Life-Cycle Assessment--

Principles and Framework, Draft International Standard 14040, 1996.
5

relative, U.S. average economic scores to help the building community select

environmentally and economically balanced building products.

The scoping phase of any LCA involves defining the boundaries of the product system

under study. The manufacture of any product involves a number of unit processes (e.g.,

ethylene production for input to the manufacture of the styrene-butadiene bonding agent

for stucco walls). Each unit process involves many inventory flows, some of which

themselves involve other, subsidiary unit processes. The first product system boundary

determines which unit processes are included in the LCA. In the BEES system, the

boundary-setting rule consists of a set of three decision criteria. For each candidate unit

process, mass and energy contributions to the product system are the primary decision

criteria. In some cases, cost contribution is used as a third criterion.7 Together, these

criteria provide a robust screening process, as illustrated in Figure 2.1, showing how five

ancillary materials (e.g., limestone used in portland cement manufacturing) are selected

from a list of nine candidate materials for inclusion in the LCA. A material must have a

large contribution to at least one decision criterion to be selected. The weight criterion

selects materials A, B, and C; the energy criterion adds material E; and cost flags material

I. As a result, the unit processes for producing ancillary materials A, B, C, E, and I are

included in the system boundaries.

Ancillary

Material Weight Energy

Cost

 (as a flag

when

necessary)

Included in

system

boundaries

A Yes

B Yes

C Yes

D No

E Yes

F No

G No

H No

I Yes

negligible contribution

small contribution

large contribution

Figure 2.1 Decision Criteria for Setting Product System Boundaries

The second product system boundary determines which inventory flows are tracked for inbounds unit processes. Quantification of all inventory flows is not practical for the

following reasons:

 

7

 While a large cost contribution does not directly indicate a significant environmental impact, it may

indicate scarce natural resources or numerous subsidiary unit processes potentially involving high energy

consumption.
6

• An ever-expanding number of inventory flows can be tracked. For instance, including

the U.S. Environmental Protection Agency’s Toxic Release Inventory (TRI) data

would result in tracking approximately 200 inventory flows arising from polypropylene

production alone. Similarly, including radionucleide emissions generated from

electricity production would result in tracking more than 150 flows. Managing such

large inventory flow lists adds to the complexity, and thus the cost, of carrying out and

interpreting the LCA.

• Attention should be given in the inventory analysis step to collecting data that will be

useful in the next LCA step, impact assessment. By restricting the inventory data

collection to the flows actually needed in the subsequent impact assessment, a more

focused, higher quality LCA can be carried out.

Therefore, in the BEES model, a focused, cost-effective set of inventory flows is tracked,

reflecting flows that will actually be needed in the subsequent impact assessment step.

Defining the unit of comparison is another important task in the goal and scoping phase of

LCA. The basis for all units of comparison is the functional unit, defined so that the

products compared are true substitutes for one another. In the BEES model, the functional

unit for most building products is 0.09 m2 (1 ft2) of product service for 50 years.8,9

Therefore, for example, the functional unit for the BEES roof covering alternatives is

covering 0.09 m

2

 (1 ft2) of roof surface for 50 years. The functional unit provides the

critical reference point to which all inventory flows are scaled.

Scoping also involves setting data requirements. Data requirements for the BEES study

include:

• Geographic coverage: The data are U.S. average data.

• Time period covered: The data are a combination of data collected specifically for

BEES within the last 6 years, and data from the well-known Ecobalance LCA

database created in 1990.10 Most of the Ecobalance data are updated annually. No

data older than 1990 are used.

• Technology covered: When possible, the most representative technology is studied.

Where data for the most representative technology are not available, an aggregated

result is used based on the U.S. average technology for that industry.

2.1.2 Inventory Analysis

 

8

 All product alternatives are assumed to meet minimum technical performance requirements (e.g.,

acoustic and fire performance).

9

 The functional unit for concrete products except concrete paving is 0.76 cubic meters (1 cubic yard)

of product service for 50 years.

10 Ecobalance, Inc., DEAMTM 3.0: Data for Environmental Analysis and Management, Bethesda, MD,

1999.
7

Inventory analysis entails quantifying the inventory flows for a product system. Inventory

flows include inputs of water, energy, and raw materials, and releases to air, land, and

water. Data categories are used to group inventory flows in LCAs. For example, in the

BEES model, flows such as aldehydes, ammonia, and sulfur oxides are grouped under the

air emissions data category. Figure 2.2 shows the categories under which data are grouped

in the BEES system. Refer to the BEES environmental performance data files, accessible

through the BEES software, for a detailed listing of approximately 400 inventory flow

items included in BEES.

Unit

Process

Other Releases

Releases to Land

Water Effluents

Air Emissions

Water

Energy

Raw Materials

Intermediate Material

or Final Product

Figure 2.2 BEES Inventory Data Categories

A number of approaches may be used to collect inventory data for LCAs. These range

from:11

• Unit process- and facility-specific: collect data from a particular process within a given

facility that are not combined in any way

• Composite: collect data from the same process combined across locations

• Aggregated: collect data combining more than one process

• Industry-average: collect data derived from a representative sample of locations

believed to statistically describe the typical process across technologies

• Generic: collect data whose representatives may be unknown but which are

qualitatively descriptive of a process

Since the goal of the BEES LCA is to generate U.S. average results, data are primarily

collected using the industry-average approach. Data collection is done under contract with

 

11 U.S. Environmental Protection Agency, Office of Research and Development, Life Cycle

Assessment: Inventory Guidelines and Principles, EPA/600/R-92/245, February 1993.
8

Environmental Strategies and Solutions (ESS) and Ecobalance, Inc., using the Ecobalance

LCA database covering more than 6,000 industrial processes gathered from actual site and

literature searches from more than 15 countries. Where necessary, the data are adjusted to

be representative of U.S. operations and conditions. Approximately 90 % of the data

come directly from industry sources, with about 10 % coming from generic literature and

published reports. The generic data include inventory flows for electricity production

from the average United States grid, and for selected raw material mining operations (e.g.,

limestone, sand, and clay mining operations). In addition, ESS and Ecobalance gathered

additional LCA data to fill data gaps for the BEES products. Assumptions regarding the

unit processes for each building product are verified through experts in the appropriate

industry to assure the data are correctly incorporated in BEES.

2.1.3 Impact Assessment

The impact assessment step of LCA quantifies the potential contribution of a product’s

inventory flows to a range of environmental impacts. There are several well-known LCA

impact assessment approaches.

Direct Use of Inventories. In the most straightforward approach to LCA, the impact

assessment step is skipped, and the life cycle inventory results are used as-is in the final

interpretation step to help identify opportunities for pollution prevention or increases in

material and energy efficiency for processes within the life cycle. However, this approach

in effect gives the same weight to all inventory flows (e.g., to the reduction of carbon

dioxide emissions and to the reduction of lead emissions). For most impacts, equal

weighting of flows is unrealistic.

Critical Volumes (Switzerland). The "weighted loads" approach, better known as the

Swiss critical volume approach, was the first method proposed for aggregating inventory

flow data.12 The critical volume for a substance is a function of its load and its legal limit.

Its load is the total quantity of the flow per unit of the product. Critical volumes can be

defined for air and water, and in principle also for soil and groundwater, providing there

are legal limit values available.

This approach has the advantage that long lists of inventory flows, especially for air and

water, can be aggregated by summing the critical volumes for the individual flows within

the medium being considered--air, water, or soil. However, the critical volume approach is

rarely used today due to the following disadvantages of using legal limit values:

 

12 K. Habersatter, Ecobalance of Packaging Materials - State of 1990, Swiss Federal Office of

Environment, Forests, and Landscape, Bern, Switzerland, February 1991, and Bundesamt fur

Umweltschutz, Oekobilanzen von Packstoffen, Schriftenreihe Umweltschutz 24, Bern, Switzerland, 1984.
9

• Legal limit values are available only for certain chemicals and pollutants. Long-term

global effects such as global warming are excluded since there are no legal limits for

the chemicals involved.

• Legal limit values often differ from country to country, and their basis is far from being

purely scientific. Socioeconomic factors, technical limitations (for example, analytical

detection limits), and the feasibility of supervision and control are also taken into

account when arriving at legal limits.

Ecological Scarcity (Switzerland). A more general approach has been developed by the

Swiss Federal Office of Environment, Forests, and Landscape.13 With this approach, "EcoPoints" are calculated for a product, using the "Eco-Factor" determined for each inventory

flow. Eco-Factors are based on current annual flows relative to target maximum annual

flows for the geographic area considered. The Eco-Points for all inventory flows are

added together to give one single, final score.

The concept used in this approach is appealing but has the following difficulties:

• It is valid only in a specific geographical area.

• Estimating annual and target flows can be a difficult and time-consuming exercise.

• The scientific calculation of environmental impacts is combined with political and

subjective judgment, or valuation. The preferred approach is to separate the science

from the valuation.

Environmental Priorities System (Sweden). The Environmental Priority Strategies in

Product Design System, the EPS System, was developed by the Swedish Environmental

Research Institute.14 It takes an economic approach to assessing environmental impacts.

The basis for the evaluation is the Environmental Load Unit, which corresponds to the

willingness to pay 1 European Currency Unit. The final result of the EPS system is a single

number summarizing all environmental impacts, based on:

• Society's judgment of the importance of each environmental impact.

• The intensity and frequency of the impact.

• Location and timing of the impact.

• The contribution of each flow to the impact in question.

• The cost of decreasing each inventory flow by one weight unit.

 

13 Ahbe S. Braunschweig A., and R. Muller-Wenk, Methodik fur Oekobilanzen auf der bases

Okologischer Optimierung, Schriftenreihn Umwelt 133, Swiss Federal Office of Environment, Forests,

and Landscape, October 1990.

14 Steen B., and S-O Ryding, The EPS Enviro-Accounting Method, IVL Report, Swedish

Environmental Research Institute, Goteborg, Sweden, 1992.
10

The EPS system combines indices of ecological, sociological, and economic effects to give

a total effect index for each flow. The total effect index is multiplied by the amount of the

flow to give the "environmental load unit." Although this methodology is popular in

Sweden, its use is criticized due to its lack of transparency and the quantity and quality of

the model’s underlying assumptions.

Classification/Characterization. The classification/characterization approach to impact

assessment was developed within the Society for Environmental Toxicology and

Chemistry (SETAC). It involves a two-step process:15,16,17

• Classification of inventory flows that contribute to specific environmental impacts. For

example, greenhouse gases such as carbon dioxide, methane, and nitrous oxide are

classified as contributing to global warming.

• Characterization of the potential contribution of each classified inventory flow to the

corresponding environmental impact. This results in a set of indices, one for each

impact, that is obtained by weighting each classified inventory flow by its relative

contribution to the impact. For instance, the Global Warming Potential index is

derived by expressing each contributing inventory flow in terms of its equivalent

amount of carbon dioxide.

The BEES model uses this classification/characterization approach because it enjoys some

general consensus among LCA practitioners and scientists.18 The following global and

regional impacts are assessed using the classification/characterization approach: Global

Warming Potential, Acidification Potential, Eutrophication Potential, and Natural

Resource Depletion. Indoor Air Quality and Solid Waste impacts are also included in

BEES, for a total of six impacts for most BEES products.

As part of its Framework for Responsible Environmental Decisionmaking project, EPA

confirmed the validity of the six impacts included in BEES 1.0. In addition, EPA

suggested that four additional impacts be pilot tested in BEES 2.0: Smog, Ecological

Toxicity, Human Toxicity, and Ozone Depletion.19 For a select group of products,

BEES 2.0 also assesses Smog and in some cases Ecological Toxicity, Human

Toxicity, and Ozone Depletion as well. These “expanded impact” products are

identified in table 4.1. Note that the data and science underlying measurement of

these four impacts are less certain than for the original six BEES impacts. The

classification/characterization method does not offer the same degree of relevance for all

environmental impacts. For global and regional effects (e.g., global warming and

 

15 SETAC-Europe, Life Cycle Assessment, B. DeSmet, et al. (eds), 1992.

16 SETAC, A Conceptual Framework for Life Cycle Impact Assessment, J. Fava, et al. (eds), 1993.

17 SETAC, Guidelines for Life Cycle Assessment: A “Code of Practice,” F. Consoli, et al. (eds), 1993.

18 SETAC, Life-Cycle Impact Assessment: The State-of-the-Art, J. Owens, et al. (eds), 1997.

19 U.S. EPA, Framework for Responsible Environmental Decisionmaking (FRED): Using Life Cycle

Assessment to Evaluate Preferability of Products, by Science Applications International Corporation,

Research Triangle Institute, and EcoSense, Inc, Draft Report, 1999.
11

acidification) the method may result in an accurate description of the potential impact. For

impacts dependent upon local conditions (e.g., smog, ecological toxicity, and human

toxicity) it may result in an oversimplification of the actual impacts because the indices are

not tailored to localities.

If the BEES user has important knowledge about other potential environmental impacts, it

should be brought into the interpretation of the BEES results. The ten BEES impacts are

discussed below.

Global Warming Potential. The Earth absorbs radiation from the Sun, mainly at the

surface. This energy is then redistributed by the atmosphere and ocean and re-radiated to

space at longer wavelengths. Some of the thermal radiation is absorbed by “greenhouse”

gases in the atmosphere, principally water vapor, but also carbon dioxide, methane, the

chlorofluorocarbons, and ozone. The absorbed energy is re-radiated in all directions,

downwards as well as upwards, such that the radiation that is eventually lost to space is

from higher, colder levels in the atmosphere. The result is that the surface loses less heat

to space than it would in the absence of the greenhouse gases and consequently stays

warmer than it would be otherwise. This phenomenon, which acts rather like a ‘blanket’

around the Earth, is known as the greenhouse effect.

The greenhouse effect is a natural phenomenon. The environmental issue is the increase

in the greenhouse effect due to emissions generated by humankind. The resulting general

increase in temperature can alter atmospheric and oceanic temperatures, which can

potentially lead to alteration of circulation and weather patterns. A rise in sea level is also

predicted due to thermal expansion of the oceans and melting of polar ice sheets. Global

Warming Potentials, or GWPs, have been developed to measure the increase.

Several models have been developed to calculate GWPs. The Intergovernmental Panel on

Climate Change (IPCC) has compiled a list of "provisional best estimates" for GWPs,

based on the expert judgment of scientists worldwide. 20 Because of its broad support,

this list has been used in the BEES model.

A single index, expressed in grams of carbon dioxide per functional unit of product, is

derived to measure the quantity of carbon dioxide with the same potential for global

warming:

global warming index = Σi wi x GWPi, where

 

20 International Panel on Climate Change (IPCC), IPCC Second Assessment—Climate Change 1995: A

Report of the Intergovernmental Panel on Climate Change, 1996.
12

wi = weight (in grams) of inventory flow i, and

GWPi = grams of carbon dioxide with the same heat trapping potential as one

gram of inventory flow i, as listed in Table 2.1.

Table 2.1 BEES Global Warming Potential Equivalency Factors

Flow (i)

GWPI

(CO2-equivalents)

Carbon dioxide 1

Methane 24

Nitrous oxide 360

Acidification. Acidifying compounds may in a gaseous state either dissolve in water or

fix on solid particles. They reach ecosystems through dissolution in rain or wet

deposition. Acidification affects trees, soil, buildings, animals, and humans. The two

compounds principally involved in acidification are sulfur and nitrogen compounds. Their

principal human source is fossil fuel and biomass combustion. Other compounds released

by human sources, such as hydrogen chloride and ammonia, also contribute to

acidification.

An index for potential acid deposition onto the soil and in water can be developed by

analogy with the global warming potential, with hydrogen as the reference substance. The

result is a single index for potential acidification (in grams of hydrogen per functional unit

of product), representing the quantity of hydrogen emissions with the same potential

acidifying effect:

acidification index = ΣI wi * APi, where

wi = weight (in grams) of inventory flow i, and

APi = grams of hydrogen with the same potential acidifying effect as one gram of

inventory flow i, as listed in Table 2.2.21

 

21 CML, Environmental Life Cycle Assessment of Products: Background, Leiden, The Netherlands,

October 1992.
13

Table 2.2 BEES Acidification Potential Equivalency Factors

Flow (i)

API

(HydrogenEquivalents)

Sulfur oxides 0.031

Nitrogen oxides 0.022

Ammonia 0.059

Hydrogen Fluoride 0.050

Hydrogen Chloride 0.027

Eutrophication Potential. Eutrophication is the addition of mineral nutrients to the soil or

water. In both media, the addition of large quantities of mineral nutrients, such as nitrogen

and phosphorous, results in generally undesirable shifts in the number of species in

ecosystems and a reduction in ecological diversity. In water, it tends to increase algae

growth, which can lead to lack of oxygen and therefore death of species like fish.

An index for potential eutrophication can be developed by analogy with the global

warming potential, with phosphate ions as the reference substance. The result is a single

index for potential eutrophication (in grams of phosphate ions per functional unit of

product), representing the quantity of phosphate ions with the same potential nutrifying

effect:

eutrophication index = Σi wi x EPi, where

wi = weight (in grams) of inventory flow i, and

EPi = grams of phosphate ions with the same potential nutrifying effect as one

grams of inventory flow i, as listed in Table 2.3.22

Natural Resource Depletion. Natural resource depletion can be defined as the decreasing

availability of natural resources. The resources considered in this impact are fossil and

mineral resources. It is important to recognize that this impact addresses only the

depletion aspect of resource extraction, not the fact that the extraction itself may

generate impacts. Extraction impacts, such as methane emissions from coal mining, are

addressed in other impacts, such as global warming.

 

22 CML, 1992.
14

Table 2.3 BEES Eutrophication Potential Equivalency Factors

Flow (i)

EPi

(phosphateequivalents)

Phosphates 1.00

Nitrogen Oxides 0.13

Ammonia 0.42

Nitrogenous Matter 0.42

Nitrates 0.10

Phosphorous 3.06

Chemical Oxygen Demand 0.02

Some experts believe resource depletion is fully accounted for in market prices. That is,

market price mechanisms are believed to take care of the scarcity issue, price being a

measure of the level of depletion of a resource and the value society places on that

depletion. However, price is influenced by many factors other than resource supply, such

as resource demand and non-perfect markets (e.g., monopolies and subsidies).

Furthermore, resource depletion is at the heart of the sustainability debate. Thus, in the

BEES model, resource depletion is explicitly accounted for in the LCA impact

assessment.

To assess resource depletion, the amount of reserves of a resource, or resource base,

needs to be determined. For mineral resources, the reserve base is defined as follows:

The reserve base encompasses those parts of the resources that have a

reasonable potential for becoming economically available within planning

horizons beyond those that assume proven technology and current

economics. It includes those resources that are currently economic,

marginally economic, and subeconomic.23

Reserve base quantities used in the BEES model are listed in Table 2.4.

Once reserves are established, an equivalency factor can be derived for each resource that

will relate its inventory flow with the depletion of the resource. The equivalency factor

addresses how long a given resource will continue to be available at current extraction

levels, as well as the size of the reserve. Using equivalency factors, a single index is

produced for natural resource depletion:

 

23U.S. Department of the Interior, Bureau of Mines, Mineral Commodity Summary, 1994.
15

Depletion Index = i

i

2

i

i

i

i i i

*w

(reserve )

production *w

reserve *years

1

∑ = ∑

where:

reservei = reserves (in kg) for natural resource i (the larger the reserve, the smaller

the equivalency factor)

yearsi = years of remaining use for natural resource i (the longer available, the

smaller the equivalency factor)

productioni = annual production (in kg/year) for natural resource i

wi = the weight (in kg) of the inventory flow for resource i

The BEES natural resource depletion equivalency factors are shown in the last column of

Table 2.4.

Solid Waste. Solid waste is an inventory outflow of the building products included in the

BEES system. The BEES inventory analysis tracks the weight of non-recyclable solid

waste resulting from the installation, replacement, and disposal of each building product

over the 50-year study period. Equivalency factors have not been developed to consider

the ultimate fate of the non-recyclable solid waste (e.g., landfill leachate, gas or incinerator

emissions, and ash). Thus, the Direct Use of Inventories Approach, described at the

beginning of this subsection, is used, with solid waste volume representing the solid waste

impact of the product. Solid waste volume (in m3, or ft3, of waste per functional unit of

product) is derived as follows:

solid waste volume = (Σi wi ) / density,

where:

wi = weight (in kg) of non-recyclable solid waste inventory flow i, and

density = density of the product (in kg/0.0283 m3, or kg/ ft3), as listed in Table 2.5.

Indoor Air Quality. Indoor air quality impacts are not included in traditional life-cycle

impact assessments. Most LCAs conducted to date have been applied to relatively shortlived, non-building products (e.g., paper versus plastic bags), for which indoor air quality

impacts are not an important issue. However, the indoor air performance of building

products is of particular concern to the building community and should be explicitly

considered in any building product LCA.

Ideally, equivalency factors would be available for indoor air pollutants as they are for

global warming gases. However, there is little scientific consensus about the relative

contributions of pollutants to indoor air performance. In the absence of equivalency
16

Table 2.4 BEES Natural Resource Depletion Equivalency Factors

Inventory Flow Units Source of Data

Annual

Production

(kg/yr)

(1)

Reserve Base

(kg)

(2)

Years of Remaining

Use

(3)=(2)/(1)

Equivalency

Factor

(4)=

1/[(2)*(3)]

Oil (in ground) kg of oil World Energy Council

1995

3.2 E+12 2.4 E+14 75 5.6 E-17

Natural Gas (in ground) kg of natural gas World Energy Council

1995

2.0 E+12 1.3 E+14 66 1.2 E-16

Coal (in ground) kg of coal World Energy Council

1995

4.5 E+12 3.0 E+15 666 5.0 E-19

Bauxite (Al2O3.2 H2O, ore) dry kg of bauxite US Bureau of Mines 1996 1.1 E+11 2.8 E+13 257 1.4 E-16

Cadmium (Cd, ore) kg of Cd content US Bureau of Mines 1996 2.0 E+07 9.7 E+08 49 2.1 E-11

Copper (Cu, ore) kg of Cu content US Bureau of Mines 1996 9.8 E+09 6.1 E+11 62 2.6 E-14

Gold (Au, ore) kg of Au content US Bureau of Mines 1996 2.2 E+06 6.1 E+07 28 5.9 E-10

Iron (Fe, ore) kg of Fe content US Bureau of Mines 1996 4.3 E+11 1.0 E+14 231 4.3 E-17

Lead (Pb, ore) kg of Pb content US Bureau of Mines 1996 2.8 E+09 1.2 E+11 43 1.9 E-13

Manganese (Mn, ore) kg of Mn content US Bureau of Mines 1996 7.3 E+09 5.0 E+12 685 2.9 E-16

Mercury (Hg, ore) kg of Hg content US Bureau of Mines 1996 3.1 E+06 2.4 E+08 77 5.4 E-11

Nickel (Ni, ore) kg of Ni content US Bureau of Mines 1996 9.2 E+08 1.1 E+11 120 7.6 E-14

Phosphate Rock (in ground) kg of rock US Bureau of Mines 1996 1.4 E+11 3.4 E+13 248 1.2 E-16

Potash (K2O, in ground) kg of K2O equivalent US Bureau of Mines 1996 2.6 E+10 1.7 E+13 649 9.1 E-17

Silver (Ag, ore) kg of Ag content US Bureau of Mines 1996 1.4 E+07 4.2 E+08 30 7.9 E-11

Tin (Sn, ore) kg of Sn content US Bureau of Mines 1996 1.8 E+08 1.0 E+10 56 1.8 E-12

Uranium (U, ore) kg of U content World Energy Council

1995

3.3 E+07 1.3 E+10 412 1.8 E-13

Zinc (Zn, ore) kg of Zn content US Bureau of Mines 1996 7.1 E+09 3.3 E+11 47 6.5 E-14

Due to abundant resources, the depletion index has been set to zero for the following resources: Clay (in ground), Dolomite (CaCO3MgCO3, in ground), Feldspar (ore), Gypsum (ore), Kaolin (Al2O3.2SiO2.2H2O, ore), Limestone (in

ground), Sand (in ground), Sodium Chloride (NaCl, in ground or in sea). Note that local shortages of these resources may exist. Local shortages are translated into higher transportation distances and therefore higher emissions, but they have

no impact on the depletion factor.
17

Table 2.5 Densities of BEES Building Products

Product

Density

kg/0.0283m3 (lb/ft3)

All Concrete Products 66 (145)

All Asphalt Products 66 (145)

Roof and Wall Sheathing

 - Oriented Strand Board 18 (38)

 - Plywood 13 (28)

Exterior Wall Finishes

 - Brick 60 (132)

 - Stucco 55 (121)

 - Cedar Siding 17 (37)

 - Aluminum Siding 76 (168)

 - PVC Siding 39 (87)

Interior Wall Finishes

 - Recycled Latex Paint 36 (80)

 - Virgin Latex Paint 36 (80)

Batt Insulation

 - R-11 Fiberglass 0.23 (0.5)

 - R-13 Fiberglass 0.36 (0.8)

 - R-15 Fiberglass 0.68 (1.5)

 - R-30 Fiberglass 0.23 (0.5)

Blown Insulation

 - R-13 Cellulose 0.73 (1.6)

 - R-30 Cellulose 0.73 (1.6)

 - R-12 Mineral Wool 0.98 (2.2)

 - R-30 Mineral Wool 0.98 (2.2)

 - R-30 Fiberglass 0.35 (0.75)

Roof Coverings

 - Asphalt Shingles 89 (196)

 - Clay Tile 60 (132)

 - Fiber Cement Shingles 44 (97)

Framing

 - Steel 224 (493)

 - Wood 13 (29)

Floor Coverings

 - Ceramic Tile 61 (134)

 - Linoleum 33 (73)

 - Vinyl Composition Tile 59 (130)

 - Composite Marble Tile 73 (161)

 - Terrazzo 72 (159)

 - Tile Carpet 6.3 (14)

 - Broadloom Carpet 6.2 (14)

factors, a product’s total volatile organic compound (VOC) emissions are often used as a

measure of its indoor air performance. Note that total VOCs equally weights the contributions of

the individual compounds that make up the measure. Further, reliance on VOC emissions alone
18

may be misleading if other indoor air contaminants, such as particulates and aerosols, are also

present.

Indoor air quality should be considered for the following building elements currently covered in

BEES: floor coverings, interior wall finishes, wall and roof sheathing, and wall and ceiling

insulation. Other BEES building elements are primarily exterior or inert interior elements for

which indoor air quality is not an issue.

Floor Coverings. BEES currently includes 17 floor covering products. Data for two components

of their indoor air performance are considered—total VOC emissions from the products

themselves and indoor air performance for their installation adhesives.

Recognizing the inherent limitations in using total VOCs to assess indoor air quality performance,

and in the absence of more scientific data, estimates of total VOC emissions from the floor

covering products are used as a proxy for their indoor air performance. Ceramic tile, composite

marble tile, and terrazzo are inert and emit no VOCs.24 Total VOCs for all other BEES floor

coverings are shown in Table 2.6.

Table 2.6 Volatile Organic Compound Emissions for BEES Floor Coverings

Floor Covering

Total Volatile Organic

Compound Emissions

(Mg/m2/h at 24 h)

Linoleum 1.667

Vinyl Composition

Tilea,b

0.155

Carpet c 0.500

a Averages for three linoleum and two VCT emissions tests conducted in a test chamber designed in accordance with ASTM

 D5116-90 at Air Quality Sciences Laboratory, Atlanta, Georgia, 1991-1992.

b Note that vinyl composition tile has substantially lower polyvinylchloride (PVC) and plasticizer content than vinyl sheet

 flooring and thus emits lower levels of VOCs. Some vinyl sheet flooring may emit higher levels of VOCs than linoleum.

c Carpet and Rug Institute (CRI) emissions standard for green labelling. Seventy-five percent of carpets tested meet these

 standards.

The second component of the BEES indoor air assessment for floor coverings is indoor air

performance for their installation adhesives. Linoleum, vinyl composition tile, and carpets installed

with traditional synthetic adhesives are assumed to be installed using a styrene-butadiene adhesive,

and ceramic tile with recycled glass and composite marble tile using a styrene-butadiene cement

mortar. Carpets installed with a low-VOC styrene-butadiene adhesive are assumed to have 17 %

 

24 American Institute of Architects, Environmental Resource Guide, Ceramic Tile Material Report, p. 1, and

Terrazzo Material Report, p. 1, 1996.
19

the emissions of an equivalent quantity of traditional styrene-butadiene adhesive.25 Assuming

indoor air impacts are proportional to the amount of styrene-butadiene used per functional unit

(as quantified in the BEES environmental performance data files), styrene-butadiene usage may be

used as a proxy for indoor air performance as follows:

• linoleum—0.00878 kg/m2 (0.00079 kg/ft2)

• vinyl composition tile—0.00878 kg/m2 (0.00079 kg/ft2)

• ceramic tile with recycled windshield glass—0.00311 kg/m2 (0.00028 kg/ft2)

• composite marble tile—0.00311 kg/m2 (0.00028 kg/ft2)

• terrazzo—no installation adhesives

• wool broadloom carpet—1.30932 kg/m2 (0.12164 kg/ft2) traditional/ 0.22260 kg/m2 (0.02068

kg/ft2) low-VOC

• nylon broadloom carpet—3.27320 kg/m2 (0.30409 kg/ft2) traditional/ 0.55650 kg/m2

(0.05170 kg/ft2 low-VOC)

• PET broadloom carpet—3.27320 kg/m2 (0.30409 kg/ft2) traditional/ 0.55650 kg/m2 (0.05170

kg/ft2) low-VOC

• wool carpet tile—0.24779 kg/m2 (0.02302 kg/ft2) traditional/ 0.04209 kg/m2 (0.00391 kg/ft2)

low-VOC

• nylon carpet tile—0.61946 kg/m2 (0.05755 kg/ft2) traditional/ 0.10527 kg/m2 (0.00978 kg/ft2)

low-VOC

• PET carpet tile—0.61946 kg/m2 (0.05755 kg/ft2) traditional/ 0.10527 kg/m2 (0.00978 kg/ft2)

low-VOC

To assess overall indoor air performance for BEES floor coverings, each product’s performance

data for product emissions and installation adhesives are normalized by dividing by the

corresponding performance value for the worst performing product, then averaged across

performance categories as shown in Table 2.7. By taking the simple average, each performance

category is weighted equally.

Table 2.7 BEES Indoor Air Performance Scores for Floor Covering Products

Normalized Indoor Air Performance Score

Floor Covering Product

Emissions

Installation

Adhesives Average

Ceramic Tile w/

Glass

0 0.09 0.05

Linoleum 100.00 0.26 50.13

Vinyl Composition

Tile

15.94 0.26 8.10

Composite Marble

Tile

0 0.09 0.05

Terrazzo 0 0 0

 

25 Based on data reported in Environmental Building News, Vol. 3, No. 6, November/December 1994, p 4.
20

Wool Broadloom 44.52 40.00 42.26

Wool Broadloom &

Low-VOC

44.52 6.80 25.66

Nylon Broadloom 44.52 100.00 72.26

Nylon Broadloom &

Low-VOC

44.52 17.00 30.76

PET Broadloom 44.52 100.00 72.26

PET Broadloom &

Low-VOC

44.52 17.0 30.76

Wool Tile 44.52 7.57 26.05

Wool Tile &

Low-VOC

44.52 1.29 22.91

Nylon Tile 44.52 18.92 31.72

Nylon Tile &

Low-VOC

44.52 3.22 23.87

PET Tile 44.52 18.92 31.72

PET Tile/Low-VOC 44.52 3.22 23.87

Interior Wall Finishes. BEES evaluates indoor air performance for interior wall finishes based on

total VOC emissions. Total VOCs for virgin latex paint are estimated to be 100 g/L, and for

recycled latex paint 125 g/L.26 Both paints are initially applied by priming followed by two coats

of paint. For both, one coat is reapplied every 4 years over the 50-year use phase. Based on these

figures, virgin latex paint will emit 13.46 g of VOCs per 0.09 m2 (1 ft2) over 50 years of use, and

recycled latex paint 16.58 g of VOCs per 0.09 m2 (1 ft2) over 50 years. These flows are directly

used to assess indoor air performance for the two interior wall finishes.

Note that due to limitations of indoor air science, the BEES indoor air performance scores

for floor coverings and interior wall finishes are based on heuristics. If the BEES user has

better knowledge, or simply wishes to test the effect on overall results of changes in relative

indoor air performance, these scores may be changed by editing the “total” and “use” columns of

the “Indoor Air” rows of the BEES environmental performance data files.

Wall and Roof Sheathing. Indoor air quality is a concern for many wood products due to their

formaldehyde emissions. Formaldehyde is thought to affect human health, especially for people

with chemical sensitivity. Composite wood products using urea-formaldehyde adhesives have

higher formaldehyde emissions than those using phenol-formaldehyde adhesives, and different

composite wood products have different levels of emissions. Composite wood products include

particleboard, insulation board, medium density fiberboard, oriented strand board (OSB),

hardboard, and softwood and hardwood plywood.

BEES assumes formaldehyde emissions is the only significant indoor air concern for wood

products. BEES currently analyzes two composite wood products—OSB and softwood plywood.

Most OSB is now made using a methylene diphenylisocyanate (MDI) binder, which is the binder

 

26 Based on data reported in Environmental Building News, Vol. 8, No. 2, February 1999, pp 12,18.
21

BEES uses in modeling OSB environmental performance. OSB using an MDI binder emits no

formaldehyde other than the insignificant amount naturally occurring in the wood itself.27

Softwood plywood also has extremely low formaldehyde emissions because it uses phenolformaldehyde binders and because it is used primarily on the exterior shell of buildings.28 Thus,

neither of the two composite wood products as modeled in BEES are thought to significantly

affect indoor air quality.

Wall and Ceiling Insulation. Indoor air quality is also discussed in the context of insulation

products. The main issues are the health impacts of fibers, hazardous chemicals, and particles

released from some insulation products. These releases are the only insulation-related indoor air

issues addressed in BEES.

As a result of its listing by the International Agency for Research on Cancer as a “possible

carcinogen,” fiberglass products are now required to have cancer warning labels. The fiberglass

industry has responded by developing fiberglass products that reduce the amount of loose fibers

escaping into the air. For cellulose products, there are claims that fire retardant chemicals and

respirable particles are hazardous to human health. Mineral wool is sometimes claimed to emit

fibers and chemicals that could be health irritants. For all these products, however, there should be

little or no health risks to building occupants if they are installed in accordance with

manufacturer’s recommendations. Assuming proper installation, then, none of these products as

modeled in BEES are thought to significantly affect indoor air quality.29

Ozone Depletion (assessed for a limited number of BEES products as described in this

section under Classification/Characterization). The ozone layer is present in the stratosphere

and acts as a filter absorbing harmful short wave ultraviolet light while allowing longer

wavelengths to pass through. A thinning of the ozone layer allows more harmful short wave

radiation to reach the Earth’s surface, potentially causing changes to ecosystems as flora and

fauna have varying abilities to cope with it. There may also be adverse effects on agricultural

productivity. Effects on man can include increased skin cancer rates (particularly fatal

melanomas) and eye cataracts, as well as suppression of the immune system. Another problem is

the uncertain effect on the climate.

Since the late 1970s, a thinning of the ozone layer over the Antarctic has been observed during

the Spring, which amounts to 80 % to 98 % removal of this layer (the ozone ‘hole’). This "hole"

over the Antarctic is created due to the unique chemistry present over the Poles. Under certain

conditions chlorine and bromine (from chlorofluorocarbons—CFCs--and other sources) undergo

complex reactions which result in ozone depletion.

 

27 Alex Wilson and Nadav Malin, “The IAQ Challenge: Protecting the Indoor Environment,” Environmental

Building News, Vol. 5, No. 3, May/June 1996, p 15.

28 American Institute of Architects, Environmental Resource Guide, Plywood Material Report, May 1996.

29 Alex Wilson, “Insulation Materials: Environmental Comparisons,” Environmental Building News, Vol. 4,

No. 1, pp.15-16
22

A single index, expressed in grams of CFC-11 per functional unit of product, is derived to

measure the quantity of CFC-11 with the same potential ozone depleting effect: 30

Ozone Depletion index = ∑i ODPi x mi, where

mi = mass (in grams) of inventory flow i, and ODPi = grams of CFC-11 with the same

ozone depleting potential as one gram of inventory flow i, as listed in table 2.8.

Table 2.8 BEES Ozone Depletion Potential Equivalency Factors

Flow

Chemical

Formula

ODP

(CFC-11 equivalents)

Methyl Bromide CH3Br 0.37

Carbon Tetrachloride CCl4 1.2

CFC 11 CFCl3 1

CFC 113 CF2ClCFCl2 0.9

CFC 114 CF2ClCF2Cl 0.85

CFC 115 CF3CF2Cl 0.4

CFC 12 CCl2F2 0.82

Halon 1201 CHF2Br 1.4

Halon 1202 CF2Br2 1.25

Halon 1211 CF2ClBr 5.1

Halon 1301 CF3Br 12

Halon 2311 CF3CHBrCl 0.14

Halon 2401 CHF2CF2Br 0.25

Halon 2402 CF2ClBr 7

HCFC 123 CHCl2CF3 0.012

HCFC 124 CHClFCF3 0.026

HCFC 141b CFCl2CH3 0.086

HCFC 142b CF2ClCH3 0.043

HCFC 22 CHF2Cl 0.034

HCFC 225ca C3HF5Cl2 0.017

HCFC 225cb C3HF5Cl2 0.017

Methyl Chloroform, HC140aCH3CCl3 0.11

This method is limited by the following factors:

1. The Ozone Depletion Potentials upon which the assessment method is based are subject to

considerable uncertainty and regular modification.

2. Greenhouse gases can affect the level of ozone directly through chemical reactions or

indirectly by contributing to global warming. At present, the influence of this factor is not

incorporated due to the complex nature of the reactions involved.

 

30 World Meteorological Organization (WMO), Scientific assessment of ozone depletion, 1991. Updated with

World Meteorological Organization (WMO), Scientific Assessment of Ozone Depletion: 1998, Report 44 (Global

Ozone Research and Monitoring Project).
23

3. Concentrations of trace gases such as nitrogen oxides affect atmospheric levels of the

hydroxyl radical (OH), which in turn can affect the atmospheric lifetime of hydrogenated

halocarbons. This process can influence future ozone depletion rates. Thus, ozone depletion

rates may vary with time.

4. ODPs are defined at steady state, and therefore do not represent transient effects. In reality,

shorter-lived halocarbons will reach a "steady state" ability to destroy ozone before longerlived compounds. ODPs are based on annually averaged global changes in ozone, which do

not take into account the chemical reactions involving a change in state which occur

specifically at the Poles. Consequently, ODP-derived concentrations tend to understate the

damage to the ozone caused by the presence of chlorine and bromine in the atmosphere.

Smog Formation (assessed for a limited number of BEES products as described in this

section under Classification/Characterization). Under certain climatic conditions, air emissions

from industry and transportation can be trapped at ground level, where they react with sunlight to

produce photochemical smog. One of the components of smog is ozone, which is not emitted

directly, but rather produced through the interactions of volatile organic compounds (VOCs) and

oxides of nitrogen (NOx).

While NOx availability ultimately limits the production of ozone, the reactivity of the VOC

determines the rate at which ozone is produced. Thus, when attempting to quantify smog

potential, not only must the reactivity of the VOC be considered, but also the environmental

conditions (e.g., NOx concentration).

There are a number of difficulties inherent in calculating VOC reactivities, not the least of which is

the non-linear nature of the reactions that produce photochemical smog. This is typified by the

properties of NOx, which can either form ozone or inhibit its formation, depending on the overall

environmental conditions. Additionally, scientists are still not certain of the exact mechanism

underlying ozone formation.

One method that is used to quantify the ozone production potential of various VOCs is based on

the incremental reactivity (IR) scale.31 This scale gives factors for VOCs that indicate the change

in ozone caused by adding a small amount of the compound to the emissions, divided by the

amount added. The resulting factor is generally expressed in moles of ozone formed per gram of

VOC emitted. For the reasons stated above, there are limits to the accuracy of the calculated IR

factors. All the same, government bodies have generally accepted them.32

The US Environmental Protection Agency ranks volatile organic compounds as being either

‘negligibly reactive’ or ‘reactive’. These rankings are used for regulatory control purposes and

 

31 William P. Carter, "Development of Ozone Reactivity Scales for Volatile Organic Compounds", Journal of

the Air & Waste Management Association, Vol. 44, July 1994, pp. 881-899

32 Dr. Basil Dimitriades, a Senior Scientific Advisor at the Atmospheric Processes Research Division of the US

EPA, stated that while the use of incremental reactivity (IR) factors is not officially sanctioned, when IR data are

presented in reports, they are accepted as being accurate (August 26, 1997). Bart Croes of the California Air

Resources Board (CARB) indicated that MIR factors were specifically used to develop legislation for California

(August 26, 1997).
24

are based on the reactivity of a compound. Compounds with incremental reactivities less than

that for ethane are considered ‘negligibly reactive’.33 This is not to say that these compounds

don’t form ozone, they do; they simply produce ozone in small enough amounts that their effect

on overall ozone formation is considered to be inconsequential.

The Maximum Incremental Reactivity (MIR) index is calculated to measure smog formation

potential as follows:

MIR = ∑i mi x MIRi, where

mi = mass (in grams) of inventory flow i, and MIRi = Maximum Incremental Reactivity for

inventory flow i.

A partial listing of the 53 flows used in this calculation are shown in Table 2.9.

Table 2.9 Sampling of BEES Maximum Incremental Reactivity Equivalency Factors

Substance Chemical Formula

MIR

(Maximum Incremental Reactivity)

1-Butanol C4H10O 3.324

2-Methyl 1-Butene C5H10 5.543

Acetaldehyde CH3CHO 6.322

Benzene C6H6 0.601

Methyl Bromide CH3Br 0.015

1-Butene CH3CH2CHCH2 10.68

Carbon Monoxide CO 0.061

Cyclopentadiene C5H6 12.51

Dibutyl Ether C6H14O 2.809

1,3-Dimethyl Cyclohexane C8H16 2.586

Ethane C2H6 0.299

Ethyl Acetylene C4H6 11.08

Formaldehyde CH2O 7.009

Glyoxal C2H2O2 2.209

Heptane C7H16 1.045

Isobutyl Alcohol (CH3)2CHCH2OH 2.332

Methane CH4 0.016

Methyl Cyclopentane C6H12 3.444

Methyl Glyoxal C3H4O2 14.32

1-Nonene C9H18 3.06

3-Octene C8H16 7.528

2-Pentene CH3CH2(CH)2CH3 11.79

Styrene C6H5CHCH2 2.28

Toluene C6H5CH3 3.154

Trimethyl Amine (CH3)3N 6.699

 

33 The incremental reactivity for ethane has been estimated to be 0.299 grams ozone per gram VOC.
25

n-Undecane C11H24 0.619

Vinyl Acetate C4H6O2 6.96

m-Xylene C6H4(CH3)2 8.82

Ecological Toxicity (assessed for a limited number of BEES products as described in this

section under Classification/Characterization). Ecological toxicity impacts were not included

in BEES 1.0. However, several approaches for ranking chemicals according to relative hazard

have been developed in recent years, in support of waste minimization and pollution

prevention34,35,36 and the Clean Air Act,37 which are potentially applicable in an LCA context.

Research Triangle Institute (RTI) developed the method described below and used in BEES 2.0

after reviewing these sources.

The RTI method includes measurements of relative hazard (toxicity factors or benchmarks) and

environmental fate and transport (persistence and biomagnification factors). The approach

involves the following steps:

1. Screen inventory data by identifying chemical-specific inventory flows or general

inventory flows that can be represented by a chemical-specific surrogate, and

eliminate those that are within 15 % of one another.

2. Identify aquatic and terrestrial benchmarks for both acute and chronic toxicity.

3. Assign chemicals a default benchmark if data are missing. The geometric mean of

the available benchmarks is used as the default.

4. Normalize benchmarks within each category based on the geometric mean.

5. Select the maximum normalized benchmark as the toxicity factor.

6. Identify persistence factors for pertinent environmental media.

7. Identify biomagnification factors.

8. Multiply toxicity, persistence, and biomagnification factors for each inventory flow

within each environmental medium for the TPB score.

9. Multiply TPB scores by the inventory mass per functional unit.

10. Sum factors to derive the total terrestrial and aquatic ecological toxicity impact

indicator (ETI).

11. Determine the percentage of each ETI relative to the total ETI and select inventory

flows contributing 0.1 % or more.

12. Compare inventory impacts to total US emissions to determine relative

significance.

 

34 United States Environmental Protection Agency. Waste Minimization Prioritization Tool, Beta Test Version

1.0: User’s Guide and System Documentation, Draft, EPA 530-R-97-019, Office of Solid Waste, Office of

Pollution Prevention and Toxics, Washington, DC, 1997.

35 United States Environmental Protection Agency. Chemical Hazard Evaluation for Management Strategies, A

Method for Ranking and Scoring Chemicals by Potential Human Health and Environmental Impacts, EPA/600/R94/177, Office of Research and Development, Washington, DC., 1994.

36 Research Triangle Institute. A Multimedia Waste Reduction Management System for the State of North

Carolina, Final Report, Prepared for the North Carolina Department of Health, Environment, and Natural

Resources, Pollution Prevention Program, April, 1993.

37 United States Environmental Protection Agency. Technical Background Document to Support Rulemaking

Pursuant to the Clean Air Act - Section 112(g), Ranking of Pollutants with Respect to Hazard to Human Health,

EPA-450/3-92-010, Office of Air Quality Planning and Standards, Research Triangle Park, NC, 1994.
26

Table 2.10 gives examples of the 152 RTI ecological toxicity potential equivalency factors used in

BEES to evaluate ecological toxicity for a handful of building products.

Table 2.10 Sampling of Ecological Toxicity Potential Equivalency Factors

Flow (i)

Ecotoxicity

(grams

equivalent

Ecotoxicity)

Hydrocarbons 21.90

Nitrogen Oxides 7.30

Carbon Monoxide 7.30

Dioxins 20.2x108

Hydrogen Chloride 10.95

Human Toxicity (assessed for a limited number of BEES products as described in this

section under Classification/Characterization). One approach to developing human toxicity

indicators has been reported by the U.S EPA in Framework for Responsible Environmental

Decision Making (FRED).38 The FRED approach is based on the belief that industrial systems

often release substances into the environment which can have toxic effects on human beings. In

order for actual effects to occur, exposure to the substance must occur, the substance must be

assimilated, and the received dose to the individual must exceed the body’s ability to detoxify it.

There are many potential toxic effects from exposure to industrial and natural substances, ranging

from transient irritation to permanent disability and even death. Some substances have a wide

range of different effects, and different individuals have a widely varying tolerance to different

substances. Finally, of the millions of industrial chemicals, very few have been subjected to

toxicological evaluation. All these factors make assessments of the human toxicity potential of

given substances difficult at best. When evaluated on a life-cycle basis, evaluating their impact is

even more problematic.

Nevertheless, because human toxicity is a real and important environmental issue, the FRED LCA

system incorporated an indicator based on the recommendation of the International Life Sciences

Institute (ILSI), which suggested that all life-cycle human toxicity indicators be based on “No

Observable adverse Effect Levels” (NOELs) and “Lowest Observable Effect Levels” (LOELs).

In other words, toxicity indicators are based on concentrations or doses of chemicals tested on

humans or laboratory animals that caused no effect or minimal effect. Generally, the lower the

NOEL or LOEL, the more toxic the chemical. This approach has been incorporated into the

 

38 U.S. EPA, Framework for Responsible Environmental Decisionmaking (FRED): Using Life Cycle Assessment

to Evaluate Preferability of Products, Draft Report, by Science Applications International Corporation, Research

Triangle Institute, and EcoSense, Inc, 1999.
27

Environmental Defense Fund (EDF) Scorecard developed in conjunction with University of

California at Berkeley. The FRED methodology used the Environmental Defense Fund (EDF)

Scorecard as an indicator of human toxicity. This indicator consists of a pair of measures, one for

carcinogenic and one for non-carcinogenic effects:

Carcinogenic Effects Index = ∑ i wi x TEPi, where

wi = weight of inventory flow i per functional unit of product, and

TEPi = Toxic Equivalency Potential, estimated as the weight of benzene with the same

potential cancer-causing effect as a unit weight of inventory flow i.

Non-Carcinogenic Effects Index = ∑ i wi x TEPi, where

wi = weight of inventory flow i per functional unit of product, and

TEPi = Toxic Equivalency Potential, estimated as the weight of toluene with the same

potential toxic effect as a unit weight of inventory flow i.

Toxic Equivalency Potentials (TEPs) for some of the 174 BEES inventory flows used in this

calculation are given in Table 2.11. In BEES, the human toxicity impact score is computed by

weighting equally the normalized carcinogenic and non-carcinogenic effects indices.

Table 2.11 Sampling of Human Toxicity Potential Equivalency Factors

Flow to Air

TEP(carcinogens)

weight Benzene/

weight substance

TEP (non-carcinogens)

weight Toluene/

weight substance

Ammonia 0 3.2

Benzene 1 17

Formaldehyde 0.003 7

Lead 15 1,300,000

Phenolics 0 0.045

Flow to Water

TEP(carcinogens)

weight Benzene/

weight substance

TEP (non-carcinogens)

weight Toluene/

weight substance

Ammonia

(NH4 +, NH3 as N) 0 0.041

Benzene 0.99 11

Phenols 0 0.0038

2.1.4 Interpretation

At the LCA interpretation step, the impact assessment results are combined. Few products are

likely to dominate competing products in all BEES impact categories. Rather, one product may

out-perform the competition relative to natural resource depletion and solid waste, fall short
28

relative to global warming and acidification, and fall somewhere in the middle relative to indoor

air quality and eutrophication. To compare the overall environmental performance of competing

products, the performance measures for all impact categories may be synthesized. Note that in

BEES 2.0, synthesis of impact measures is optional.

Synthesizing the impact category performance measures involves combining apples and oranges.

Global warming potential is expressed in carbon dioxide equivalents, acidification in hydrogen

equivalents, eutrophication in phosphate equivalents, and so on. How can the diverse measures of

impact category performance be combined into a meaningful measure of overall environmental

performance? The most appropriate technique is Multiattribute Decision Analysis (MADA).

MADA problems are characterized by tradeoffs between apples and oranges, as is the case with

the BEES impact assessment results. The BEES system follows the ASTM standard for

conducting MADA evaluations of building-related investments.39

MADA first places all impact categories on the same scale by normalizing them. Within an impact

category, each product’s performance measure can be normalized by dividing by the highest

measure for that category, as in the BEES model. All performance measures are thus translated to

the same, dimensionless, relative scale from 0 to 100, with the worst performing product in each

category assigned the highest possible normalized score of 100. Refer to Appendix A for the

BEES environmental performance computational algorithms.

MADA then weights each impact category by its relative importance to overall environmental

performance. In the BEES software, the set of importance weights is selected by the user. Several

derived, alternative weight sets are provided as guidance, and may either be used directly or as a

starting point for developing user-defined weights. The alternative weights sets are based on an

EPA Science Advisory Board study, a Harvard University study, and a set of equal weights,

representing a spectrum of ways in which people value various aspects of the environment.

EPA Science Advisory Board study. In 1990, EPA’s Science Advisory Board (SAB) developed

lists of the relative importance of various environmental impacts to help EPA best allocate its

resources. The following criteria were used to develop the lists:

• The spatial scale of the impact

• The severity of the hazard

• The degree of exposure

• The penalty for being wrong

Nine of the ten BEES impact categories were among the SAB lists of relative importance:40

• Relatively High-Risk Problems: global warming, indoor air quality, ecological toxicity, human

toxicity, ozone depletion, smog

 

39 American Society for Testing and Materials, Standard Practice for Applying the Analytic Hierarchy Process

to Multiattribute Decision Analysis of Investments Related to Buildings and Building Systems, ASTM Designation

E 1765-95, West Conshohocken, PA, 1995.

40 United States Environmental Protection Agency, Science Advisory Board, Reducing Risk: Setting Priorities

and Stretegies for Environmental Protection, SAB-EC-90-021, Washington, D.C., September 1990, pp 13-14.
29

• Relatively Medium-Risk Problems: acidification, eutrophication

• Relatively Low-Risk Problems: solid waste41

The SAB did not explicitly consider natural resource depletion as an impact. For this exercise,

natural resource depletion is assumed to be a relatively medium-risk problem, based on other

relative importance lists.42

Verbal importance rankings, such as “relatively high-risk,” may be translated into numerical

importance weights by following guidance provided by a MADA method known as the Analytic

Hierarchy Process (AHP).43 The AHP methodology suggests the following numerical comparison

scale:

1 Two impacts contribute equally to the objective (in this case environmental performance)

3 Experience and judgment slightly favor one impact over another

5 Experience and judgment strongly favor one impact over another

7 One impact is favored very strongly over another, its dominance demonstrated in practice

9 The evidence favoring one impact over another is of the highest possible order of

affirmation

2,4,6,8 When compromise between values of 1, 3, 5, 7, and 9, is needed.

Through an AHP process known as pairwise comparison, numerical comparison values are

assigned to each possible pair of environmental impacts. Relative importance weights can then be

derived by computing the normalized eigenvector of the largest eigenvalue of the matrix of

pairwise comparison values. Tables 2.12 and 2.13 list the pairwise comparison values assigned to

the SAB verbal importance rankings, and the resulting importance weights computed for the

BEES impacts, respectively.

Table 2.12 Pairwise Comparison Values for Deriving Impact Category Importance Weights

Verbal Importance Comparison Pairwise Comparison Value

High vs. Medium 2

Medium vs. Low 2

High vs. Low 4

Table 2.13 Relative Importance Weights based on Science Advisory Board Study

Relative Importance Weight ( %)

Impact Category 6 Impacts 7 Impactsa10 Impactsa

Global Warming 27 21 13

Acidification 13 11 6

 

41 The SAB report classifies solid waste under its low-risk groundwater pollution category (SAB, Reducing Risk,

Appendix A, pp 10-15).

42 See, for example, Hal Levin, “Best Sustainable Indoor Air Quality Practices in Commercial Buildings,” Third

International Green Building Conference and Exposition--1996, NIST Special Publication 908, Gaithersburg, MD,

November 1996, p 148.

43 Thomas L. Saaty, MultiCriteria Decision Making: The Analytic Hierarchy Process--Planning, Priority

Setting, Resource Allocation, University of Pittssburgh, 1988.
30

Eutrophication 13 11 6

Natural Resource Depletion 13 11 6

Indoor Air Quality 27 21 13

Solid Waste 7 4 4

Smog 21 13

Ecological Toxicity 13

Human Toxicity 13

Ozone Depletion 13

aThis set of expanded impacts is available for a limited number of BEES products, as identified in Table 4.1.

Harvard University Study. In 1992, an extensive study was conducted at Harvard University to

establish the relative importance of environmental impacts.44 The study developed separate

assessments for the United States, The Netherlands, India, and Kenya. In addition, separate

assessments were made for “current consequences” and “future consequences” in each country.

For current consequences, more importance is placed on impacts of prime concern today. Future

consequences places more importance on impacts that are expected to become significantly worse

in the next 25 years.

Nine of the ten BEES impact categories were among the studied impacts. Table 2.14 shows the

current and future consequence rankings assigned to these impacts in the United States. The study

did not explicitly consider solid waste as an impact. For this exercise, solid waste is assumed to

rank low for both current and future consequences, based on other relative importance lists.45

Verbal importance rankings from the Harvard study are translated into numerical, relative

importance weights using the same, AHP-based numerical comparison scale and pairwise

Table 2.14 U.S. Rankings for Current and Future Consequences by Impact Category

Impact Category Current Consequences Future Consequences

Global Warming Low High

Acidification High Low

Eutrophication Medium Medium

Natural Resource Depletiona Medium Medium-Low

Indoor Air Quality Medium Low

Smog High Low

Ecological Toxicity Medium-Low Medium-Low

Human Toxicity Medium-Low Medium-Low

Ozone Depletion Low High

aAverage of consequences for hazards contributing to natural resource depletion.

 

44 Vicki Norberg-Bohm et al, International Comparisons of Environmental Hazards: Development and

Evaluation of a Method for Linking Environmental Data with the Strategic Debate Management Priorities for Risk

Management, Center for Science & International Affairs, John F. Kennedy School of Government, Harvard

University, October 1992.

45 See, for example, Hal Levin, “Best Sustainable Indoor Air Quality Practices in Commercial Buildings,” p

148. As in the SAB report, solid waste is classified under groundwater pollution.
31

comparison process described above for the SAB study. Sets of relative importance weights are

derived for current and future consequences, and then combined by weighing future consequences

as twice as important as current consequences.46 Table 2.15 lists the resulting importance weights

for the ten BEES impacts. The combined importance weight set is offered as an option in the

BEES software. However the BEES user is free to use the current or future consequence weight

sets by entering these weights under the user-defined software option.

Table 2.15 Relative Importance Weights based on Harvard University study

Relative Importance Weight Set

Current

( %)

Future

( %)

Combined

( %)

Impact Category 6 7

a

10a6 7

a

10a

6 7

a

10a

Global Warming 8 6 5 38 35 22 28 25 16

Acidification 33 25 19 10 9 6 17 15 10

Eutrophication 16 12 9 19 18 11 18 16 10

Natural Resource Depletion 16 12 9 14 13 8 15 13 9

Indoor Air Quality 16 12 9 10 9 6 12 10 7

Solid Waste 11 8 7 9 8 5 10 8 6

Smog 25 19 7 5 13 10

Ecological Toxicity 9 8 8

Human Toxicity 9 9 9

Ozone Depletion 5 20 15

aThis set of expanded impacts is available for a limited number of BEES products, as identified in table 4.1.

 

46 The Harvard study ranks impacts “high” in future consequences if the current level of impact is expected to

double in severity over the next 25 years based on a “business as usual” scenario. Vicki Norberg-Bohm,

International Comparisons of Environmental Hazards, pp 11-12.
32

2.2 Economic Performance

Measuring the economic performance of building products is more straightforward than

measuring environmental performance. Published economic performance data are readily

available, and there are well-established ASTM standard methods for conducting economic

performance evaluations. First cost data are collected from the R.S. Means publication, 2000

Building Construction Cost Data, and future cost data are based on data published by Whitestone

Research in The Whitestone Building Maintenance and Repair Cost Reference 1999,

supplemented by industry interviews. The most appropriate method for measuring the economic

performance of building products is the life-cycle cost (LCC) method. BEES follows the ASTM

standard method for life-cycle costing of building-related investments.47

It is important to distinguish between the time periods used to measure environmental

performance and economic performance. These time periods are different. Recall that in

environmental LCA, the time period begins with raw material acquisition and ends with product

end-of-life. Economic performance, on the other hand, is evaluated over a fixed period (known as

the study period) that begins with the purchase and installation of the product, and ends at some

point in the future that does not necessarily correspond with product end-of-life.

Economic performance is evaluated beginning at product purchase and installation because this is

when out-of-pocket costs begin to be incurred, and investment decisions are made based upon

out-of-pocket costs. The study period ends at a fixed date in the future. For a private investor, its

length is set at the period of product or facility ownership. For society as a whole, the study

period length is often set at the useful life of the longest-lived product alternative. However, when

all alternatives have very long lives, (e.g., more than 50 years), a shorter study period may be

selected for three reasons:

• Technological obsolescence becomes an issue

• Data become too uncertain

• The farther in the future, the less important the costs

In the BEES model, economic performance is measured over a 50 year study period, as shown in

Figure 2.3. This study period is selected to reflect a reasonable period of time over which to

evaluate economic performance for society as a whole. The same 50 year period is used to

evaluate all products, even if they have different useful lives. This is one of the strengths of the

LCC method. It adjusts for the fact that different products have different useful lives when

evaluating them over the same study period.

For consistency, the BEES model evaluates the use stage of environmental performance over the

same 50 year study period. Product replacements over this 50 year period are accounted for in

the environmental performance score, and end-of-life solid waste is prorated to year 50 for

products with partial lives remaining after the 50 year period.

 

47American Society for Testing and Materials, Standard Practice for Measuring Life-Cycle Costs of Buildings

and Building Systems, ASTM Designation E 917-94, West Conshohocken, PA, March 1994.
33

The LCC method sums over the study period all relevant costs associated with a product.

Alternative products for the same function, say floor covering, can then be compared on the basis

of their LCCs to determine which is the least cost means of providing that function over the study

period. Categories of cost typically include costs for purchase, installation, maintenance, repair,

and replacement. A negative cost item is the residual value. The residual value is the product

value remaining at the end of the study period. In the BEES model, the residual value is computed

by prorating the purchase and installation cost over the product life remaining beyond the 50 year

period.48

Site Selection

and

Preparation

Construction

and Outfitting

Operation

and Use

Renovation

or Demolition

Product

Manufacture

Raw

Materials

Acquisition

ENVIRONMENTAL

STUDY PERIOD

50 Year Use Stage

ECONOMIC STUDY PERIOD

50 years

FACILITY LIFE CYCLE

Figure 2.3 BEES Study Periods For Measuring Building Product Environmental And

Economic Performance

The LCC method accounts for the time value of money by using a discount rate to convert all

future costs to their equivalent present value. Refer to Appendix A for the BEES economic

performance computational algorithm showing the discounting technique.

Future costs must be expressed in terms consistent with the discount rate used. There are two

approaches. First, a real discount rate may be used with constant-dollar (e.g., 2000) costs. Real

discount rates reflect the portion of the time value of money attributable to the real earning power

of money over time and not to general price inflation. Even if all future costs are expressed in

constant 2000 dollars, they must be discounted to reflect this portion of the time-value of money.

Second, a market discount rate may be used with current-dollar amounts (e.g., actual future

prices). Market discount rates reflect the time value of money stemming from both inflation and

the real earning power of money over time. When applied properly, both approaches yield the

 

48 For example, a product with a 40-year life that costs $10 per 0.09 square meters ($10 per square foot) to

install would have a residual value of $7.50 in year 50, considering replacement in year 40.
34

same LCC results. The BEES model computes LCCs using constant 2000 dollars and a real

discount rate. As a default, the BEES tool uses a real rate of 4.2 %, the 2000 rate mandated by

the U.S. Office of Management and Budget (OMB) for most Federal projects.49

2.3 Overall Performance

The BEES overall performance score combines the environmental and economic results into a

single score, as illustrated in Figure 2.4. To combine them, the two results must first be placed on

a common basis. The environmental performance score reflects relative environmental

performance, or how much better or worse products perform with respect to one another. The

economic performance score, the LCC, reflects absolute performance, regardless of the set of

alternatives under analysis. Before combining the two, the life-cycle cost is converted to the same,

relative basis as the environmental score by dividing by the highest-life-cycle cost alternative.

Then the environmental and economic performance scores are combined into an overall score by

weighting environmental and economic performance by their relative importance values. Overall

scores are thereby placed on a scale from 0 to 100; if a product performs worst with respect to all

environmental impacts and has the highest life-cycle cost, it would receive the worst possible

overall score of 100. The BEES user specifies the relative importance weights used to combine

environmental and economic performance scores and may test the sensitivity of the overall scores

to different sets of relative importance weights. Refer to Appendix A for the BEES overall

performance computational algorithm.

2.4 Limitations

Properly interpreting the BEES scores requires placing them in perspective. There are inherent

limits to applying U.S. industry-average LCA and LCC results and in comparing building products

outside the design context.

The BEES LCA and LCC approaches produce U.S. average performance results for generic

product alternatives. The BEES results do not apply to products manufactured in other countries

where manufacturing and agricultural practices, fuel mixes, environmental regulations,

transportation distances, and labor and material markets may differ.50 Furthermore, all products

in an industry-average, generic product group, such as vinyl composition tile floor covering, are

not created equal. Product composition, manufacturing methods, fuel mixes, transportation

practices, useful lives, and cost can all vary for individual products in a generic product group.

Thus, the BEES results for the generic product group do not necessarily represent the

performance of an individual product.

 

49 Office of Management and Budget (OMB) Circular A-94, Guidelines and Discount Rates for Benefit-Cost

Analysis of Federal Programs, Washington, DC, October 27, 1992 and OMB Circular A-94, Appendix C,

February 2000.

50 Since most linoleum manufacturing takes place in Europe, linoleum is modeled based on European

manufacturing practices, fuel mixes, and environmental regulations. However, the BEES linoleum results are only

applicable to linoleum imported into the United States because transport from Europe to the United States is built

into the BEES linoleum data.
35

The BEES LCA uses selected inventory flows converted to selected local, regional, and global

environmental impacts to assess environmental performance. Those inventory flows which

currently do not have scientifically proven or quantifiable impacts on the environment are

excluded, such as mineral extraction and wood harvesting which are qualitatively thought to lead

to loss of habitat and an accompanying loss of biodiversity. Ecological toxicity, human toxicity,

ozone depletion, and smog impacts are included in BEES 2.0 for a select set of products (see

table 4.1), but the science and data underlying their measurement are less certain. Finally, since

BEES develops U.S. average results, some local impacts such as resource scarcity (e.g., water

scarcity) are excluded even though the science is proven and quantification is possible. If the

BEES user has important knowledge about these or other potential environmental impacts, it

should be brought into the interpretation of the BEES results.

During the interpretation step of the BEES LCA, environmental impacts are optionally combined

into a single environmental performance score using relative importance weights. These weights

necessarily incorporate values and subjectivity. BEES users should routinely test the effects on the

environmental performance scores of changes in the set of importance weights.

The BEES environmental scores do not represent absolute environmental damage. Rather, they

represent proportional differences in damage, or relative damage, among competing alternatives.

Consequently, the environmental performance score for a given product alternative can change if

one or more competing alternatives are added to or removed from the set of alternatives under

consideration. In rare instances, rank reversal, or a reordering of scores, is possible. Finally, since

they are relative performance scores, no conclusions may be drawn by comparing scores across

building elements. That is, if exterior wall finish Product A has an environmental performance

score of 60, and roof covering Product D has an environmental performance score of 40, Product

D does not necessarily perform better than Product A (keeping in mind that lower performance

scores are better). The same limitation relative to comparing environmental performance scores

across building elements, of course, applies to comparing overall performance scores across

elements.

There are inherent limits to comparing product alternatives without reference to the whole

building design context. First, it may overlook important environmental and cost interactions

among building elements. For example, the useful life of one building element (e.g., floor

coverings), which influences both its environmental and economic performance scores, may

depend on the selection of related building elements (e.g., subflooring). There is no substitute for

good building design.

Environmental and economic performance are but two attributes of building product performance.

The BEES model assumes that competing product alternatives all meet minimum
36

Figure 2.4 Deriving the BEES Overall Performance Score

Global Warming

Acid Rain

Eutrophification

Resource Depletion

Indoor Air Quality

Solid Waste

Environmental

Performance

Score

Economic

Performance

Score

Overall

Score

First Cost

Future Costs

Carbon Dioxide

 Methane

Nitrous Oxide

Smog

Ozone Depletion

Ecological Toxicity

Human Toxicity
37

technical performance requirements.51 However, there may be significant differences in technical

performance, such as acoustical performance, fire performance, or aesthetics, which may

outweigh environmental and economic considerations.

 

51 Environmental and economic performance results for wall insulation, roof coverings and concrete beams and

columns do consider technical performance differences. For wall insulation and roof coverings, BEES accounts for

differential heating and cooling energy use. For concrete beams and columns, BEES accounts for different

compressive strengths.
38
39

3. BEES Product Data

The BEES model uses the ASTM standard classification system, UNIFORMAT II,52 to organize

comparable building products into groups. The ASTM standard classifies building components

into a three-level hierarchy: major group elements (e.g., substructure, shell, interiors), group

elements (e.g., foundations, roofing, interior finishes), and individual elements (e.g., slab on grade,

roof coverings, floor finishes). Elements are defined such that each performs a given function,

regardless of design specifications or materials used. The UNIFORMAT II classification system is

well suited to the BEES environmental and economic performance methodologies, which define

comparable products as those that fulfill the same basic function. The BEES model uses the

UNIFORMAT II classification of individual elements, the third level of the hierarchy, as the point

of departure for selecting functional applications for BEES product comparisons.

3.1 Portland Cement Concrete Slabs, Walls, Beams, and Columns (BEES

Codes A1030, A2020, B1011, B1012)

Portland cement concrete, typically referred to as “concrete,” is a mixture of portland cement (a

fine powder), water, fine aggregate such as sand or finely crushed rock, and coarse aggregate

such as gravel or crushed rock. The mixture creates a semi-fluid material that forms a rock-like

material when it hardens. Note that the terms “cement” and “concrete” are often used

interchangeably, yet cement is actually only one of several concrete constituents.

Concrete is specified for different building elements by its compressive strength measured 28 days

after casting. Concretes with greater compressive strengths generally contain more cement. While

the compressive strength of concrete mixtures can range from 0.69 MPa to 138 MPa (100 psi to

20,000 psi), concrete for residential slabs and basements often has a compressive strength of 21

MPa (3000 psi) or less, and concrete for structural applications such as beams and columns often

have compressive strengths of 28 MPa or 34 MPa (4000 psi or 5000 psi). Thus, concrete mixes

modeled in the BEES software are limited to compressive strengths of 21 MPa, 28 MPa, and 34

MPa (3000 psi, 4000 psi, and 5000 psi).

To reduce cost, heat generation, and the environmental burden of concrete, ground granulated

blast furnace slag (referred to as GGBFS or “slag”) or fly ash may be substituted for a portion of

the portland cement in the concrete mix. Fly ash is a waste material that results from burning coal

to produce electricity. Slag is a waste material that is a result of steel production. When used in

concrete, slag and fly ash are cementitious materials that can act in a similar manner as cement by

facilitating compressive strength development.

BEES performance data apply to four building elements: 21 MPa (3000 psi) Slabs on Grade and

Basement Walls; and 28 MPa or 34 MPa (4000 psi or 5000 psi) Beams and Columns. For each

 

52 American Society for Testing and Materials, Standard Classification for Building Elements and Related

Sitework--UNIFORMAT II, ASTM Designation E 1557-96, West Conshohocken, PA, 1996.
40

building element, concrete alternatives with 100 % cement (no fly ash or slag), 15 %, and 20 %

fly ash content (by weight of cement), and 20 %, 35 %, and 50 % slag content (by weight of

cement) may be compared. While life-cycle costs differ among building elements, the

environmental performance for a given slag or fly ash content and compressive strength rating is

the same. The detailed environmental performance data for all concrete products except concrete

paving53 may be viewed by opening the following files under the File/Open menu item in the

BEES software:

• A1030A.DBF—Concrete without supplementary cementitious materials

• A1030B.DBF—15 % Fly Ash Content Concrete

• A1030C.DBF—20 % Fly Ash Content Concrete

• Α1030D.DBF—20 % Slag Content Concrete

• Α1030Ε.DBF—35 % Slag Content Concrete

• Α1030F.DBF—50 % Slag Content Concrete

Within each of these six environmental performance data files, there are three complete sets of

environmental performance data corresponding to compressive strength ratings of 21 MPa, 28

MPa, and 34 MPa (3000 psi, 4000 psi, and 5000 psi).

BEES environmental performance data for concrete products are from the Portland Cement

Association LCA database. This subsection incorporates extensive documentation provided by the

Portland Cement Association for incorporating their LCA data into BEES.54

BEES comparisons for slabs, basement walls, beams, and columns are limited to concrete

products. Thus, for these building elements, the environmental performance data for all concrete

mixes could be modeled from “cradle-to-ready-mix plant gate” rather than from “cradle-to-grave”

as for all other BEES products. That is, environmental flows for transportation from the readymix plant to the building site, installation (including concrete forms, reinforcing steel, welded wire

fabric, and wire mesh), and end of life are ignored. This modeling change does not affect

environmental performance results since BEES assesses relative environmental performance

within a given building element, and there will be no environmental performance differences based

on fly ash or slag content for the ignored life-cycle stages.

Figures 3.1 and 3.2 show the elements of concrete production with and without slag or fly ash.

Raw Materials. Table 3.1 shows quantities of concrete constituents for the three compressive

strengths modeled. Other materials that are sometimes added, such as silica fume and chemical

admixtures, are not considered. Typically, fly ash or slag are an equal replacement for cement.

Quantities of constituent materials used in an actual project may vary.

 

53 The environmental performance of concrete paving products is discussed later in this section.

54 Portland Cement Association, Data Transmittal for Incorporation of Slag Containing Concrete Mixes into

Version 2.0 of the BEES Software, PCA R&D Serial No. 2168a, PCA Project 94-04, prepared by Construction

Technology Laboratories, Inc. and JAN Consultants, May 2000; and Portland Cement Association, Concrete

Products Life Cycle Inventory (LCI) Data Set for Incorporation into the NIST BEES Model, PCA R&D Serial No.

2168, PCA Project 94-04a, prepared by Michael Nisbet, JAN Consultants, 1998.
41

Portland Cement. Cement plants are located throughout North America at locations with

adequate supplies of raw materials. Major raw materials for cement manufacture include

Functional Unit

of Concrete

Without

 Fly Ash

Ready-Mix

Plant

Operations

Material

Transportation

Portland

Cement

Production

Fine

Aggregate

Production

Coarse

Aggregate

Production

 Figure 3.1 Portland Cement Concrete Without Fly Ash Flow Chart

limestone, cement rock/marl, shale, and clay. These raw materials contain various proportions of

calcium oxide, silicon dioxide, aluminum oxide, and iron oxide, with oxide content varying widely

across North America. Since portland cement must contain the appropriate proportion of these

oxides, the mixture of the major raw materials and minor ingredients (as required) varies among

cement plants. BEES data for cement manufacture is based on the average raw material mix and

oxide content for all U.S. cement plants for an ASTM C150 Type I/II cement, the most

commonly used cement in North America. The average raw materials for U.S. cement include

limestone, cement rock/marl, shale, clay, bottom ash, fly ash, foundry sand, sand, and iron/iron

ore.

In the manufacturing process, major raw materials are blended with minor ingredients, as

required, and processed at high temperatures in a cement kiln to form an intermediate material

known as clinker. Gypsum is interground with clinker to form portland cement. Gypsum content

is assumed to be added at 5.15 % (by weight) of portland cement.

Aggregate. Aggregate is a general term that describes a filler material in concrete. Aggregate

generally provides 60 % to 75 % of the concrete volume. Typically, aggregate consists of a
42

Functional Unit

of

Concrete With

Fly Ash

Ready-Mix

Plant

Operations

Material

Transportation

Portland

Cement

Production

Fly Ash

or Slag

Fine

Aggregate

Production

Coarse

Aggregate

Production

Figure 3.2 Portland Cement Concrete With Fly Ash or Slag Flow Chart

Table 3.1 Concrete Constituent Quantities by Compressive Strength of Concrete

Constituent Weight

in kg per m3

(lb/ yd3)

Concrete

Constituent

21 MPa

(3000 psi )

28 MPa

(4000 psi)

34 MPa

(5000 psi)

Cement and Fly Ash or

Slag

223 (376) 279 (470) 335 (564)

Coarse Aggregate 1127 (1900) 1187 (2000) 1187 (2000)

Fine Aggregate 831 (1400) 771 (1300) 712 (1200)

Water 141 (237) 141 (237) 141 (237)

mixture of coarse and fine rocks. Aggregate is either mined or manufactured. Sand and gravel are

examples of mined aggregate. These materials are dug or dredged from a pit, river bottom, or

lake bottom and require little or no processing. Crushed rock is an example of manufactured

aggregate. Crushed rock is produced by crushing and screening quarry rock, boulders, or largesized gravel. Approximately half of the coarse aggregate used in the United States is crushed

rock.

Fly Ash. Fly ash is a waste material that results from burning coal to produce electricity. In LCA

terms, fly ash is an environmental outflow of coal combustion, and an environmental inflow of

concrete production. As in most LCAs, this waste product is assumed to be an environmentally
43

“free” input material.55 However, transport of the fly ash to the ready mix plant is included.

Slag. Slag is a waste material, which is a result of the production of steel. Similar to fly ash, slag

is an environmental outflow of steel production and an environmental inflow of concrete

production. Therefore, slag is considered to be an environmentally “free” input material.55 Unlike

fly ash, slag must be processed prior to inclusion in concrete. Processing consists of quenching

and granulating at the steel mill, transport to the grinding facility, and finish grinding.

Transportation to the ready mix plant is included.

Energy Requirements: Portland Cement. Portland cement is manufactured using one of four

processes: wet process, dry process, preheater, or preheater/precalciner. The wet process is the

oldest and uses the most energy due to the energy required to evaporate the water. New cement

manufacturing plants are being constructed, and older plants converted, to use the more energy

efficient preheater or preheater/precalciner processes. As of 1995, the mix of production

processes was 30 % wet, 27 % dry, 19 % preheater, and 24 % preheater/precalciner. Table 3.2

presents U.S. industry-average energy use by process and fuel type, and, for all processes

combined, average energy use weighted by the 1996 process mix. Note that the production of

waste fuels is assumed to be free of any environmental burdens to portland cement production

(LCA dictates that waste fuel production burdens be allocated to the product whose manufacture

generated the waste fuels).

Table 3.2 Energy Requirements for Portland Cement Manufacturing

Cement Manufacturing Process*

Fuel Use Wet

( %)

Dry

( %)

Preheater (

%)

Precalciner

( %)

Weighted

Average

( %)

 Coal 49 45 67 60 54

 Petroleum Coke 18 31 6 8 17

 Natural Gas 9 8 10 16 11

 Liquid Fuels** 1 1 2 1 1

 Wastes 16 6 4 3 8

 Electricity 7 9 12 12 10

 All Fuels: 100 100 100 100 100

Total Energy in kJ/kg

of cement (Btu/lb)

6838 (2940) 6117 (2630) 4885 (2100) 4699 (2020) 5745 (2470)

* Cement constitutes only 10 to 15 % by weight of concrete’s total mass.

** Liquid fuels include gasoline, middle distillates, residual oil, and liquefied petroleum gas

Aggregate. In BEES, coarse and fine aggregate are assumed to be crushed rock, which tends to

slightly overestimate the energy use of aggregate production. Production energy for both coarse

 

55 The environmental burdens associated with waste products are typically allocated to the products generating

the waste.
44

and fine aggregate is assumed to be 155 kJ/kg of aggregate (66.8 Btu/lb).

Fly Ash. Fly ash is a waste material with no production energy burdens.

Slag. Similar to fly ash, slag is a waste material and therefore does not include energy burdens

associated with steel production. Because slag requires processing prior to incorporation into

concrete, the energy use for granulation and grinding are included. Production energy is assumed

to be 465 kJ/kg of slag (200 Btu/lb).

Round-trip distances for transport of concrete raw materials to the ready mix plant are assumed to

be 97 km (60 mi) for portland cement and fly ash, 216 km (134 mi) for slag, and 80 km (50 mi)

for aggregate. The method of transport is truck, consuming 1.18 kJ/kg*km (0.818 Btu/lb*mi).

Concrete. In BEES, concrete is assumed to be produced in a central ready-mix operation. Energy

use in the batch plant includes electricity and fuel used for heating and mobile equipment. Average

energy use is assumed to be 247 MJ/m3 of concrete (0.179 MBtu/yd3, or about 45 Btu/lb of

concrete).

Emissions. Emissions for concrete raw materials are from the Portland Cement Association

cement LCA database. Emissions include particulate matter, carbon dioxide (CO2), carbon

monoxide (CO), sulfur oxides (SOx), nitrogen oxides (NOx), total hydrocarbons, and hydrogen

chloride (HCl). Emissions vary for the eighteen different mixtures of compressive strength and fly

ash or slag content as shown in the concrete environmental performance data files.

Cost. The detailed life-cycle cost data for concrete products may be viewed by opening the file

LCCOSTS.DBF under the File/Open menu item in the BEES software. Life-cycle cost data

include first cost data (purchase and installation costs) and future cost data (cost and frequency of

replacement, and where appropriate and data are available, of operation, maintenance, and repair).

Costs are listed under the BEES codes listed in Table 3.3. First cost data are collected from the

R.S. Means publication, 2000 Building Construction Cost Data, and future cost data are based on

data published by Whitestone Research in The Whitestone Building Maintenance and Repair Cost

Reference 1999, supplemented by industry interviews.

Table 3.3 BEES Life-Cycle Cost Data Specifications and Codes for Concrete Products

Concrete Product Specification BEES Code

0 % Fly Ash Content Slab on Grade 10.2cm-15.2cm (4"-6") thick A1030,A0

15 % Fly Ash Content Slab on Grade 10.2cm-15.2cm (4"-6") thick A1030,B0

20 % Fly Ash Content Slab on Grade 10.2cm-15.2cm (4"-6") thick A1030,C0

0 % Fly Ash Content Basement Wall 20.3-38.1cm (8"-15") thick A2020,A0

15 % Fly Ash Content Basement Wall 20.3-38.1cm (8"-15") thick A2020,B0

20 % Fly Ash Content Basement Wall 20.3-38.1cm (8"-15") thick A2020,C0

0 % Fly Ash Content Beams 3.0-7.6 m (10'-25') span B1011,A0

15 % Fly Ash Content Beams 3.0-7.6 m (10'-25') span B1011,B0

20 % Fly Ash Content Beams 3.0-7.6 m (10'-25') span B1011,C0

0 % Fly Ash Content Columns 40.6-61.0cm (16"-24") diameter B1012,A0
45

15 % Fly Ash Content Columns 40.6-61.0cm (16"-24") diameter B1012,B0

20 % Fly Ash Content Columns 40.6-61.0cm (16"-24") diameter B1012,C0

3.2 Roof and Wall Sheathing Alternatives (B1020, B2015)

3.2.1 Oriented Strand Board Sheathing (B1020A, B2015A)

Oriented strand board (OSB) is made from strands of low density wood. A wax, primarily a

petroleum-based wax, is used to bind the strands. Resins, mainly phenolic resin with some

Methylene Diphenyl Isocyanate (MDI) resin, are also used as a binder material in making most

OSB. For the BEES system, 1.1 cm (7/16 in) thick OSB boards are studied. The flow diagram in

Figure 3.3 shows the major elements of oriented strand board production.

BEES performance data are provided for both roof and wall sheathing. Life-cycle costs differ for

the two applications, while the environmental performance data are assumed to be the same. The

detailed environmental performance data for OSB roof and wall sheathing may be viewed by

opening the file B1020A.DBF under the File/Open menu item in the BEES software.

Raw Materials. Energy use for timber production is based on studies by Forintek and Procter &

Gamble.56 The average energy use reported is 200 MJ per 907 kg (95 Btu/lb) of greenwood

produced, assumed to be in the form of diesel fuel for tractors. Tailpipe emissions from tractors

and emissions associated with production of diesel fuel are included based on the Ecobalance

LCA database.

BEES also accounts for the absorption of carbon dioxide by trees. The “uptake” of carbon

dioxide during the growth of timber is assumed to be 1.74 kg of carbon dioxide per kg of

greenwood harvested. The volume of wood harvested is based on an average density of 500

kg/m3 (31 lb/ft3), with aspen at 450 kg/m3 (28 lb/ft3) and Southern yellow pine at 550 kg/m3 (34

lb/ft3).

Transportation of Raw Materials to Manufacturing Plant. For transportation of raw materials

to the manufacturing plant, BEES assumes truck transportation of 161 km (100 mi) for wood

timber and truck transportation of 322 km (200 mi) for both the resins and the wax. The tailpipe

 

56 Ash, Knoblock, and Peters, Energy Analysis of Energy from the Forest Options, ENFOR Project P-59, 1990; B.

N. Johnson, “Inventory of Land Management Inputs for Producing Absorbent Fiber for Diapers: A Comparison of

Forest Products Journal, vol 44, no. 6, 1994.
46

Installation Waste

Manufacturing Electricity

Production

Timber

Production Resin Production

Petroleum

Wax

Production

Transportation

(truck)

161 km (100 mi)

Transportation

(truck)

322 km (200 mi)

Transportation

(truck)

322 km (200 mi)

Transportation

(50% rail/50% truck)

161-805-1609 km sensitivity

(100-500-1000 mi)

Figure 3.3 Oriented Strand Board Flow Chart

emissions from the trucks and the emissions from producing the fuel used in the trucks are taken

into account based on the Ecobalance database.

Manufacturing. The components and energy requirements for OSB manufacturing are based on a

study performed by the United States Department of Agriculture (USDA).57 Table 3.4 shows the

constituents of OSB production.

Table 3.4 Oriented Strand Board Sheathing Constituents

Component Input

(kg/kg product)

In Final Product

(kg/kg)

In Final

Product ( %)

Wood 1.365 0.967 96.7

Resin 0.023 0.023 2.3

Wax 0.010 0.010 1.0

Total: 1.398 1 100

There is no waste from the OSB manufacturing process. All the input resin (mainly phenolic resin

with some Methylene Diphenyl Isocyanate (MDI) resin) and the wax are assumed to go into the

final product and the excess wood material is assumed to be burned on site for fuel.

The energy for the OSB manufacturing process is generated from burning the wood waste and

from purchased electricity. The amount of electricity used is assumed to be 612 MJ/kg (263.2

 

57Spelter H, Wang R, and Ince P, Economic Feasibility of Products from Inland West Small-Diameter Timber,

United States Department of Agriculture, Forest Service ( May 1996).
47

Btu/lb) of OSB produced.

The emissions from the OSB manufacturing process are based on a Forintek Canada Corporation

Study, as reported in Table 3.5.58 Since these emissions are assumed to be from combustion of the

wood residue and any volatile organic compound (VOC) emissions from drying the OSB, the

carbon dioxide (CO2) emissions are all assumed to be biomass-based. VOC emissions are reduced

by 30 % to account for process improvements over time. Electricity production emissions are

based on a standard US electricity grid.

Table 3.5 Oriented Strand Board Manufacturing Emissions

Emission

Value

(per oven dry tonne of OSB)

Carbon Dioxide 488 kg (1076 lb)

Carbon Monoxide 91 g (3.2 oz)

Methane 43 g (1.5 oz)

Nitrous Oxides 685 g (24.2 oz)

Sulfur Dioxide 159 g (5.6 oz)

Volatile Organic

Compounds 161 g (5.7 oz)

Particulates 502 g (17.7 oz)

The resin used in OSB production is assumed to be 80 % phenolic resin and 20 % Methylene

Diphenyl Isocyanate. Data representing the production of both resins are derived from the

Ecobalance database.

The wax used in the production of OSB is assumed to be petroleum wax. Production of the

petroleum wax is based on the Ecobalance database and includes the extraction, transportation,

and refining of crude oil into petroleum wax.

Transportation from Manufacturing to Use. Transportation of OSB to the building site is

modeled as a variable of the BEES system, with equal portions by truck and rail. Emissions

associated with the combustion of fuel in the train and truck engines are included as are the

emissions associated with producing the fuel, both based on the Ecobalance database.

Installation: Installation waste with a mass fraction of 0.015 is assumed.

Cost. Installation costs for OSB sheathing vary by application. The detailed life-cycle cost data for

this product may be viewed by opening the file LCCOSTS.DBF under the File/Open menu item in

the BEES software. Its costs are listed under the following codes:

• B1020,A0—Oriented Strand Board Roof Sheathing

 

58 Forintek Canada Corporation, Building Materials in the Context of Sustainable Development: Raw Material

Balances, Energy Profiles and Environmental Unit Factor Estimates for Structural Wood Products, March 1993, p

27.
48

• B2015,A0—Oriented Strand Board Wall Sheathing

Life-cycle cost data include first cost data (purchase and installation costs) and future cost data

(cost and frequency of replacement, and where appropriate and data are available, of operation,

maintenance, and repair). First cost data are collected from the R.S. Means publication, 2000

Building Construction Cost Data, and future cost data are based on data published by Whitestone

Research in The Whitestone Building Maintenance and Repair Cost Reference 1999,

supplemented by industry interviews.

3.2.2 Plywood Sheathing (B1020B, B2015B)

Plywood sheathing is made from lower density wood. Phenol formaldehyde is used in the

manufacturing process. For the BEES system, 1.3 cm (1/2 in) thick plywood boards are studied.

The flow diagram shown in Figure 3.4 shows the major elements of plywood sheathing

production.

BEES performance data are provided for both roof and wall sheathing. Life-cycle costs differ for

the two applications, while the environmental performance data are assumed to be the same. The

detailed environmental performance data for plywood roof and wall sheathing may be viewed by

opening the file B1020B.DBF under the File/Open menu item in the BEES software.

Raw Materials. BEES accounts for energy use during timber production. Energy use was based

on studies by Forintek and Procter & Gamble.59 The average energy use reported was 200 MJ

per 907 kg (95 Btu/lb) of greenwood produced, assumed to be in the form of diesel fuel for

tractors. Tailpipe emissions from tractors and emissions associated with production of diesel fuel

are included based on the Ecobalance LCA database.

BEES also accounts for the absorption of carbon dioxide by trees. The “uptake” of carbon

dioxide during the growth of timber is assumed to be 1.74 kg of carbon dioxide per kilogram of

greenwood harvested. The volume of wood harvested is based on an average density of 600

kg/m3 (37.5 lb/ ft3).

Transportation of Raw Materials to Manufacturing Plant. For transportation of raw materials

to the manufacturing plant, BEES assumes truck transportation of 161 km (100 mi) for wood

timber and truck transportation of 322 km (200 mi) for the resin. The tailpipe emissions from the

trucks and the emissions from producing the fuel used in the trucks are taken into account based

on the Ecobalance database.

 

59 Ash, Knoblock, and Peters, Energy Analysis of Energy from the Forest Options, ENFOR Project P-59, 1990; B.

N. Johnson, “Inventory of Land Management Inputs for Producing Absorbent Fiber for Diapers: A Comparison of

Cotton and Softwood Land Management,” Forest Products Journal, vol 44, no. 6, 1994.
49

Installation Waste

Transportation

(50% rail/50% truck)

161-805-1609 km sensitivity

(100-500-1000 mi)

Manufacturing Electricity

Production

Timber

Production

Phenol

Formaldehyde

Production

Transportation

(truck)

161 km (100 mi)

Transportation

(truck)

322 km (200 mi)

Figure 3.4 Plywood Sheathing Flow Chart

Manufacturing. The components and energy requirements for plywood manufacturing are based

on a Forintek Canada Corporation study60. Table 3.6 shows the constituents of plywood

production.

Table 3.6 Plywood Constituents

Constituent

Input

(kg/kg product)

In Final Product

(kg/kg)

In Final

Product ( %)

Wood 1.51 0.899 89.9

Resin 0.101 0.101 10.1

Total: 1.611 1 100

There is no waste from the plywood manufacturing process. All the input resin, phenol

formaldehyde, is assumed to go into the final product and the residual wood material in the form

of bark and wasted veneers is assumed to be burned on site for fuel (except for some waste

veneer’s cores, which are normally sold for landscaping timber or converted into chips for pulp).

The energy for the plywood manufacturing process is generated from burning the wood waste and

from purchased electricity. The amount of electricity used is based on the Forintek study and is

assumed to be 351 MJ per oven dry tonne (151 Btu/lb) of plywood produced. Electricity

production emissions are based on a standard U.S. electricity grid. The emissions from the

 

60 Forintek Canada Corporation, Building Materials in the Context of Sustainable Development: Raw Material

Balances, Energy Profiles and Environmental Unit Factor Estimates for Structural Wood Products, March 1993,

pp 20-24.
50

plywood manufacturing process are based on the Forintek Canada Corporation study, as reported

in Table 3.7.

Table 3.7 Plywood Manufacturing Emissions

Emission

Amount

(per oven dry tonne of plywood)

Carbon Dioxide 500 kg (1102.3 lb)

Carbon Monoxide 112 g (3.95 oz)

Methane 35 g (1.2 oz)

Nitrous Oxides 668 g (23.6 oz)

Sulfur Dioxide 30 g (1.1 oz)

Volatile Organic

Compounds 408 g (14.4 oz)

Particulates 699 g (24.7 oz)

Since emissions are assumed to be from combustion of the wood residue and any VOC emissions

from drying the plywood, CO2 emissions are all assumed to be biomass-based.

The glue used in bonding plywood consists of phenolic resin in liquid form combined with

extender (dry fibers) assumed to be caustic soda. Data for the production of this glue are based

on the Ecobalance database.

Transportation from Manufacturing to Use. Transportation of plywood to the building site is

modeled as a variable of the BEES system, with equal portions by truck and rail. Emissions

associated with the combustion of fuel in the train and truck engines are included as are the

emissions associated with producing the fuel, both based on the Ecobalance database.

Installation. Installation waste with a mass fraction of 0.015 is assumed.

Cost. Installation costs for plywood vary by application. The detailed life-cycle cost data for this

product may be viewed by opening the file LCCOSTS.DBF under the File/Open menu item in the

BEES software. Its costs are listed under the following codes:

• B1020,B0—Plywood Roof Sheathing

• B2015,B0—Plywood Wall Sheathing

Life-cycle cost data include first cost data (purchase and installation costs) and future cost data

(cost and frequency of replacement, and where appropriate and data are available, of operation,

maintenance, and repair). First cost data are collected from the R.S. Means publication, 2000

Building Construction Cost Data, and future cost data are based on data published by Whitestone

Research in The Whitestone Building Maintenance and Repair Cost Reference 1999,

supplemented by industry interviews.
51

3.3 Exterior Wall Finish Alternatives (B2011)

3.3.1 Brick and Mortar (B2011A)

Brick is a masonry unit of clay or shale, formed into a rectangular shape while plastic, then burned

or fired in a kiln. Mortar is used to bond the bricks into a single unit. Facing brick is used on

exterior walls for an attractive appearance.

For the BEES system, solid, fired clay facing brick (10 cm x 6.8 cm x 20 cm, or 4 in x 2-2/3 in x 8

in) and Type N mortar are studied. The flow diagram shown in Figure 3.5 shows the major

elements of clay facing brick and mortar production. The detailed environmental performance data

for this product may be viewed by opening the file B2011A.DBF under the File/Open menu item

in the BEES software.

Functional Unit of

Brick and Mortar

Exterior Wall

Brick

Production

Train

Transport

(Brick only)

Truck

Transport

(Brick only)

Mortar

Production

Electricity

Production

Clay Mining Fuel Oil

Production

Coal

Production

Sawdust

Production

Natural

Gas

Production

Diesel Fuel

Production

Electricity

Production

Truck

Transport

(Raw Matl's)

Electricity

Production

Gasoline

Production

Sand

Mining

Masonry

Cement

Production

Brick and Mortar

End-of-Life

Figure 3.5 Brick and Mortar Flow Chart

Raw Materials. Production of the raw materials for brick and mortar are based on the Ecobalance

LCA database. Type N mortar consists of 1 part (by volume) masonry cement, 3 parts sand,61 and

6.3 L (1.67 gal) of water. Masonry cement is modeled based on the assumptions outlined below

for stucco exterior walls.

 

61 Based on ASTM Specification C 270-96.
52

Energy Required. The energy requirements for brick production (drying and firing) are listed in

Table 3.8. The production of the different types of fuel is based on the Ecobalance LCA database.

Table 3.8 Energy Requirements for Brick Manufacturing

Fuel Use Manufacturing Energy

Total Fossil Fuel 2.88 MJ/kg (1,238 Btu/lb)

 % Coal 9.6 %

 % Natural Gas* 71.9 %

 % Fuel Oil 7.8 %

 % Wood 10.8 %

* Includes Propane

The mix of brick manufacturing technologies is 73 % tunnel kiln technology and 27 % periodic

kiln technology.

The mortar is assumed to be mixed in a 5.9 kW (8 hp), gasoline powered mixer with a flow rate

of 0.25 m3 (9 ft3) of mortar per hour, running for five minutes.

Emissions. Emissions are based on AP-4262 data for emissions from brick manufacturing for each

manufacturing technology and type of fuel burned.

Transportation. Transportation of the raw materials to the brick manufacturing facility is not

taken into account (often manufacturing facilities are located close to mines). However,

transportation to the building site is modeled as a variable. Bricks are assumed to be transported

by truck and train (86 % and 14 %, respectively) to the building site. The BEES user can select

from among three travel distances.

Use. The density of brick is assumed to be 2.95 kg (6.5 lb) per brick. The density of the Type N

mortar is assumed to be 2002 kg/m3 (125 lb/ft3). A brick wall is assumed to be 80 % brick and 20

% mortar by surface area.

End-Of-Life. The brick wall is assumed to have a useful life of 100 years. Seventy-five percent

of the bricks are assumed to be recycled after the 100 year use.

Cost. The detailed life-cycle cost data for this product may be viewed by opening the file

LCCOSTS.DBF under the File/Open menu item in the BEES software. Its costs are listed under

BEES code B2011, product code 10. Life-cycle cost data include first cost data (purchase and

installation costs) and future cost data (cost and frequency of replacement, and where appropriate

and data are available, of operation, maintenance, and repair). First cost data are collected from

the R.S. Means publication, 2000 Building Construction Cost Data, and future cost data are

based on data published by Whitestone Research in The Whitestone Building Maintenance and

Repair Cost Reference 1999, supplemented by industry interviews.

 

62 United States Environmental Protection Agency, Clearinghouse for Inventories and Emission Factors, Version

6.0, EPA 454/C-98-005, Emission Factor and Inventory Group, October 1998.
53

3.3.2 Stucco (B2011B)

Stucco is cement plaster used to cover exterior wall surfaces. For the BEES system, three coats

of stucco (two base coats and one finish coat) are studied. A layer of bonding agent, polyvinyl

acetate, is assumed to be applied between the wall and the first layer of base coat stucco.

Figures 3.6 and 3.7 show the elements of stucco production from both portland cement (for a

base coat Type C plaster, finish coat Type F plaster) and masonry cement (for a base coat Type

MS plaster, finish coat Type F plaster). Since both cements are commonly used for stucco

exterior walls, LCA data for both portland cement and masonry cement stucco were collected and

then averaged for use in the BEES system.

The detailed environmental performance data for stucco exterior walls may be viewed by opening

the file B2011B.DBF under the File/Open menu item in the BEES software.

Raw Materials. The raw material consumption for masonry cement is based on Type N masonry

cement as shown in Table 3.9.

Table 3.9 Masonry Cement Constituents

Masonry Cement Constituent Physical Weight

( %)

Portland Cement Clinker 50

Limestone 47.5

Gypsum 2.4

Production of these raw materials is based on the Ecobalance LCA database.

Stucco consists of the raw materials listed in Table 3.10.63

The coat of bonding agent is assumed to be 0.15 mm (0.006 in) thick. The bonding agent is

polyvinyl acetate.

Production of sand, lime, and polyvinyl acetate is based on the Ecobalance database.

Energy Requirements. The energy requirements for masonry cement production are shown in

Table 3.11.

 

63 Based on ASTM Specification C 926-94.
54

Functional Unit

of Stucco

Exterior Wall

Stucco (Type F)

Production

Truck

Transport

(Raw Matl's)

Electricity

Production

Gasoline

Production

Sand

Mining

Portland

Cement

Production

Hydrated

Lime

Production

Electricity

Production

Stucco

Truck

Transport

(Raw Matl's)

Electricity

Production

Gasoline

Production

Sand

Mining

Portland

Cement

Production

Hydrated

Lime

Production

Electricity

Production

Stucco (Type C)

Production

Bonding Agent

Production

Electricity

Production

Oxygen

Production

Acetic acid

Production

Ethylene

Production

Electricity

Production

End-of-Life

Figure 3.6 Stucco (Type C) Flow Chart

Functional Unit of

Stucco

Exterior Wall

Stucco (Type F)

Production

Truck

Transport

(Raw Matl's)

Electricity

Production

Gasoline

Production

Sand

Mining

Masonry

Cement

Production

Stucco

Truck

Transport

(Raw Matl's)

Electricity

Production

Gasoline

Production

Sand

Mining

Masonry

Cement

Production

Stucco (Type MS)

Production

Bonding Agent

Production

Electricity

Production

Oxygen

Production

Acetic acid

Production

Ethylene

Production

Electricity

Production

End-of-Life

Figure 3.7 Stucco (Type MS) Flow Chart

Table 3.10 Stucco Constituents

Cementitious Materials (parts by volume) Sand

Type of Stucco Portland

Cement

Masonry

Cement

Lime per volume of

cementitious mat’l

Base Coat C 1 0.5 3.75
55

Finish Coat F 1 1.125 2.25

Base Coat MS 1 3.75

Finish Coat FMS 1 2.25

Table 3.11 Energy Requirements for Masonry Cement Manufacturing

Fuel Use Manufacturing Energy

Total Fossil Fuel 2.72 MJ/kg (1169 Btu/lb)

 % Coal 84

 % Natural Gas 7

 % Fuel Oil 1

 % Wastes 8

Total Electricity 0.30 MJ/kg (129 Btu/lb)

These percentages are based on average fuel use in portland cement manufacturing.

Stucco is assumed to be mixed in an 5.9 kW (8 hp), gasoline powered mixer with a flow rate of

0.25 m3 (9 ft3) of stucco per hour, running for five minutes.

Emissions. Emissions for masonry cement production are based on AP-42 data for controlled

emissions from cement manufacturing. Clinker is assumed to be produced in a wet process kiln.

Transportation. Transportation distance to the building site is modeled as a variable.

Use. The thickness of the three layers of stucco is assumed to be 1.6 cm (5/8 in) each. The

densities of the different types of stucco are shown in Table 3.12.

Table 3.12 Density of Stucco by Type

Type of Stucco

Density

kg/0.0283m3 (lb/ ft3)

Base Coat C 51.79 (114.18)

Finish Coat F 55.78 (122.97)

Base Coat MS 53.97 (118.98)

Finish Coat FMS 61.55 (135.69)

Cost. The detailed life-cycle cost data for this product may be viewed by opening the file

LCCOSTS.DBF under the File/Open menu item in the BEES software. Its costs are listed under

BEES code B2011, product code 20. Life-cycle cost data include first cost data (purchase and

installation costs) and future cost data (cost and frequency of replacement, and where appropriate

and data are available, of operation, maintenance, and repair). First cost data are collected from

the R.S. Means publication, 2000 Building Construction Cost Data, and future cost data are

based on data published by Whitestone Research in The Whitestone Building Maintenance and

Repair Cost Reference 1999, supplemented by industry interviews.
56

3.3.3 Aluminum Siding (B2011C)

Aluminum siding is a commonly-used exterior wall cladding. Aluminum siding is very attractive

for its weight and durability, weighing less and lasting longer than traditional wood and vinyl

siding. The manufacture of any aluminum product consists of many steps – crude oil production,

distillation and desalting, hydrotreating of crude oil, salt mining, caustic soda manufacturing,

limestone mining, lime manufacture, bauxite mining, alumina production, coal mining, coke

production, aluminum smelting, and ingot casting. For the BEES system, 0.061 cm (0.024 in)

thick, 20 cm (8 in) wide horizontal siding, is studied. The aluminum siding is assumed to be

fastened with aluminum nails 41 cm (16 in) on center. The flow diagram in Figure 3.8 shows the

major elements of aluminum siding production.

Functional Unit of

Aluminum Siding

Truck

Transport

Aluminum Nail

Production

PVC

Production

Aluminum Siding

Production

Aluminum

Sheet

Production

Figure 3.8 Aluminum Siding Flow Chart

Raw Materials. There are a number of aluminum siding products on the market, each with

different proprietary ingredients. The product studied for the BEES system is manufactured as an

aluminum sheet with a Polyvinyl Chloride (PVC) thermoset topcoat. Table 3.13 presents the

major constituents of aluminum siding. Production requirements for these constituents are based

on the Ecobalance LCA database.

Table 3.13 Aluminum Siding Constituents

Constituent Percent Weight %

Aluminum Sheet 99

PVC Topcoat 1

Transportation. Transport of PVC from its production site to the aluminum siding manufacturing

plant is taken into account. Transportation of manufactured aluminum siding by heavy-duty truck
57

to the building site is modeled as a variable of the BEES system. Emissions associated with the

combustion of fuel in the truck engines are included, as are the emissions associated with fuel

production, both based on the Ecobalance LCA database.

Use. Installation waste with a mass fraction of 0.05 is assumed.

3.3.4 Cedar Siding (B2011D)

Cedar wood is ideal for exterior siding because it is a lightweight, low-density material that

provides adequate weatherproofing. It also provides an attractive exterior wall finish. As with

most wood products, cedar siding production consist of three major steps. First, roundwood is

harvested from logging camps. Second, logs are sent to sawmills and planing mills where the logs

are washed, debarked, and sawed into planks. The planks are edged, trimmed, and dried in a kiln.

The dried planks are then planed and the lumber sent to a final trimming operation. Third, lumber

from the sawmill is shaped into fabricated, milled wood products.

For the BEES system, beveled cedar siding 1.3 cm (1⁄2 in) thick and 15 cm (6 in) wide is studied.

Cedar siding is assumed to be installed with galvanized nails 41 cm (16 in) on center and finished

with one coat of primer and two coats of stain. Stain is reapplied every ten years. The flow

diagram in Figure 3.9 shows the major elements of cedar siding production.

Functional Unit of

Cedar Siding

Truck

Transport

Galvanized Nail

Production

Cedar

Wood

Harvesting

Wood Stain

Production

Cedar Wood

Siding Production

Wood Primer

Production

Electricity

Production

Figure 3.9 Cedar Siding Flow Chart

Raw Materials. Production data for cedar wood is derived from the Ecobalance LCA database.

Energy Requirements. The energy requirements for cedar siding manufacture are approximately
58

5.6 MJ/kg (2,413 Btu/lb) of cedar siding produced.64 Table 3.14 shows the breakdown by fuel

type. BEES data for production and combustion of the natural gas, heavy fuel oil, and liquid

petroleum fuels used for cedar siding production are based on the Ecobalance database.

Table 3.14 Energy Requirements for Cedar Siding Manufacture

Fuel Use65 Manufacturing Energy

Total Fossil Fuel 5.6 MJ/kg (2,413 Btu/lb)

 % Natural Gas 39.8

 % Heavy Fuel Oil 4.1

 % Liquid Petroleum Gas 4.1

 % Hogfuel 52

Emissions. The hogfuel emissions from the cedar sawmill are listed in Table 3.15.

Table 3.15 Hogfuel Emissions66

Emission Amount

g/MJ wood burned (oz/kWh)

Carbon Dioxide (CO2) 81.5 (10.35)

Carbon Monoxide (CO) 0.011 (0.0014)

Methane (CH4) 0.008 (0.001)

Nitrogen Oxides (NOX) 0.110 (0.014)

Sulfur Oxides (SOX) 0.0002 (0.000025)

Volatile Organic Compounds (VOC) 0.039 (0.005)

Particulates 0.708 (0.09)

Transportation. Since sawmills are typically located close to the forested area, transportation of

raw materials to the sawmill is not taken into account. Transport of primer and stain to the

manufacturing plant is included. Transport of cedar siding by truck to the building site is modeled

as a variable of BEES. Emissions associated with the combustion of fuel in the truck engine are

included, as are the emissions associated with producing the fuel. Both sets of emissions data are

based on the Ecobalance database.

Use. The density of cedar siding at 12 % moisture content is assumed to be 449 kg/ m3 (28 lb/

ft3). At installation, 5 % waste is assumed.

3.3.5 Vinyl Siding (B2011E)

 

64 Building Materials in the Context of Sustainable Development – Raw Material Balances, Energy Profiles and

Environmental Unit Factor Estimates for Structural Wood Products, March 1993.

65 Excluding electricity

66 Building Materials in the Context of Sustainable Development – Raw Material Balances, Energy Profiles and

Environmental Unit Factor Estimates for Structural Wood Products, op cit.
59

Vinyl siding is attractive for its low maintenance, and cost. Durability under exposure to a wide

variety of weather conditions is another key attraction. Like all plastic materials, vinyl results from

a series of processing steps that convert hydrocarbon-based raw materials (petroleum, natural gas,

or coal) into polymers. The vinyl polymer is based in part on hydrocarbon feedstocks: ethylene

obtained by processing natural gas or petroleum. The other part of the vinyl polymer is based on

the natural element chlorine. Inherent in the vinyl manufacturing process is the ability to

formulate products of virtually any color with any number of performance qualities--including

ultraviolet light stabilization, impact resistance, and flexibility--in virtually any size, shape, or

thickness.

Vinyl siding is manufactured in a wide variety of profiles, colors, and thickness’ to meet different

market applications. For the BEES system, 0.11 cm (0.0428 in) thick, 23 cm (9 in) wide

horizontal vinyl siding installed with galvanized nail fasteners is studied. The fasteners are

assumed to be placed 41 cm (16 in) on center. Figure 3.10 shows the major steps for vinyl siding

production.

Functional Unit of

PVC Siding

Truck

Transport

Galvanized Nail

Production

PVC

Production

PVC Siding

Production

Titanium

Dioxide

Production

Truck

Transport

(Raw Matl's)

Figure 3.10 Vinyl Siding Flow Chart

Raw Materials. Polyvinyl chloride (PVC) is the main component in the manufacture of vinyl

siding. Titanium dioxide (TiO2) is a chemical additive that is used in the siding as a pigment or

bleaching agent. Table 3.16 presents the proportions of PVC and titanium dioxide in the siding

studied. Data representing the production of raw materials for vinyl siding are based on the

Ecobalance database.
60

Table 3.16 Vinyl Siding Constituents

Constituent Percent by Weight ( %)

Polyvinyl Chloride (PVC) 80

Titanium Dioxide (TiO2) 20

Transportation. Transportation of raw materials to the manufacturing plant is taken into account.

Transportation of the manufactured siding to the building site by heavy-duty truck is modeled as a

variable of BEES. Emissions associated with the combustion of fuel in the truck engine are

included, as are emissions associated with fuel production. Emissions data are derived from the

Ecobalance database.

Use. At installation, 5 % of the product is lost to waste.

3.4 Wall and Ceiling Insulation Alternatives (B2012, B3012)

3.4.1 Blown Cellulose Insulation (B2012A, B3012A)

Blown cellulose insulation is produced primarily from post-consumer wood pulp (newspapers),

typically accounting for roughly 80 % of the insulation by weight. Cellulose insulation is treated

with fire retardant. Ammonium sulfate, borates, and boric acid are used most commonly and

account for the other 20 % of the cellulose insulation by weight. The flow diagram shown in

Figure 3.11 shows the elements of blown cellulose insulation production.

BEES performance data are provided for thermal resistance values of R-13 for a wall application

and R-30 for a ceiling application. The amount of cellulose insulation material used per functional

unit is shown in Table 3.17, based on information from the Cellulose Insulation Manufacturers

Association (CIMA).

The detailed environmental performance data files for this product may be viewed by opening the

following files under the File/Open menu item in the BEES software:

• B2012A.DBF—R-13 Blown Cellulose Wall Insulation

• B3012A.DBF—R-30 Blown Cellulose Ceiling Insulation

•

Transportation of Raw Materials to Manufacturing. Transport of raw materials to the

manufacturing plant is taken into account, assuming truck transportation of 161 km (100 mi) for

wastepaper and truck transportation of 322 km (200 mi) for both the ammonium sulfate and the

boric acid. The tailpipe emissions from the trucks and the emissions from producing the fuel used

in the trucks are based on the Ecobalance database.

Manufacturing. The constituents for cellulose insulation manufacture are based on information

from CIMA, as shown in Table 3.18.
61

Installation Waste

Transportation

(truck)

80-322-483 km sensitivity

(50-200-300 mi)

Manufacturing Electricity

Production

Ammonium Sulfate

Production

Boric Acid

Production

Transportation

(truck)

161 km (100 mi)

Transportation

(truck)

322 km (200 mi)

Transportation

(truck)

322 km (200 mi)

wastepaper

Diesel Fuel

Production &

Use in Installation

Figure 3.11 Blown Cellulose Insulation Flow Chart

Table 3.17 Blown Cellulose Mass by Application

Application Thickness

cm (in)

Density

kg/m3 (lb/ft3)

Mass per Functional Unit

kg/m2 (oz/ft2)

Wall (R-13) 8.9 (3.5) 25.6 (1.6) 2.26 (7.41)

Ceiling (R-30) 20.6 (8.1) 25.6 (1.6) 5.27 (17.28)

Table 3.18 Blown Cellulose Insulation Constituents

Constituent

Input

(kg/kg product) In Final Product ( %)

Wastepaper 0.80 80

Ammonium Sulfate 0.155 15.5

Boric Acid 0.045 4.5

Total: 1.0 100

There are no wastes or water effluents from the manufacturing process. Manufacturing energy is
62

assumed to come from purchased electricity. The amount of electricity used is based on CIMA

data and a requirement of 0.35 MJ per kg (150 Btu per lb) of cellulose insulation produced.

Electricity production emissions are based on the Ecobalance database and a standard U.S.

electricity grid.

The only burdens for production of wastepaper are those associated with collection and

transportation of wastepaper to the manufacturing facility.

Ammonium sulfate is assumed to be produced as a co-product of caprolactam production. The

materials and energy used by the process are based on the Ecobalance database.

The boric acid used in the manufacture of cellulose insulation is assumed to be produced from

borax. Production of boric acid is based on the Ecobalance database.

Transportation from Manufacturing to Use. Transport of cellulose insulation to the building

site by truck is modeled as a variable of BEES, based on a range of likely distances (80 km, 322

km, and 483 km, or 50 mi, 200 mi, and 300 mi) provided by CIMA. Emissions associated with

combustion of fuel in the truck engine are included as are the emissions associated with producing

the fuel. Emissions data are derived from the Ecobalance database.

Since it is assumed that all three insulation materials studied (cellulose, fiberglass, and mineral

wool) have similar packaging requirements, no packaging burdens are taken into account.

Installation. At installation, 5 % of the product is lost to waste. The energy required for blowing

the insulation is included, assuming the insulation is blown at a rate of 1134 kg (2,500 lb) per hour

using energy provided by a diesel truck. BEES accounts for emissions associated with burning

diesel fuel in a reciprocating engine, as well as emissions associated with producing the diesel fuel.

Use. It is important to consider thermal performance differences when assessing environmental

and economic performance for insulation product alternatives. Thermal performance affects

building heating and cooling loads, which in turn affect energy-related LCA inventory flows and

building energy costs over the 50 year use stage. Since alternatives for ceiling insulation all have

R-30 thermal resistance values, thermal performance differences are at issue only for the wall

insulation alternatives.

For wall insulation, thermal performance differences are separately assessed for 14 U.S. cities

spread across a wide range of climate and fuel cost zones, and for electricity, distillate oil, and

natural gas heating fuel types (electricity is assumed for all cooling). When selecting wall

insulation alternatives for analysis, the BEES user selects the U.S. city closest to the building

location and the building heating fuel type, so that thermal performance differences may be

customized to these important contributors to building energy use. A NIST study of the economic

efficiency of energy conservation measures (including insulation), tailored to these cities and fuel

types, is used to estimate 50 year heating and cooling requirements per functional unit of
63

insulation.67 BEES environmental performance results account for the energy-related inventory

flows resulting from these energy requirements. To account for the 50 year energy requirements

in BEES economic performance results, 1997 fuel prices by State68 and U.S. Department of

Energy fuel price projections over the next 30 years69 are used to compute the present value cost

of operational energy per functional unit for each alternative R-value.

Cost. Installation costs for blown cellulose insulation vary by application. The detailed life-cycle

cost data for this product may be viewed by opening the file LCCOSTS.DBF under the File/Open

menu item in the BEES software. Its costs are listed under the following codes:

• B2012,A0—R-13 Blown Cellulose Wall Insulation

• B3012,A0—R-30 Blown Cellulose Ceiling Insulation

Life-cycle cost data include first cost data (purchase and installation costs) and future cost data

(cost and frequency of replacement, and where appropriate and data are available, of operation,

maintenance, and repair). Operational energy costs for wall insulation (discussed above under

“Use”) are found in the file USEECON.DBF. All other future cost data are based on data

published by Whitestone Research in The Whitestone Building Maintenance and Repair Cost

Reference 1999, supplemented by industry interviews. First cost data are collected from the R.S.

Means publication, 2000 Building Construction Cost Data.

3.4.2 Fiberglass Batt Insulation (B2012B, B2012C, B2012E, B3012B)

Fiberglass batt insulation is made by forming spun-glass fibers into batts. Using a rotary process,

molten glass is poured into a rapidly spinning disc that has thousands of fine holes in its rim.

Centrifugal force extrudes the molten glass through the holes, creating the glass fibers. The fibers

are made thinner by jets, air, or steam and are immediately coated with a binder and/or de-dusting

agent. The material is then cured in ovens and formed into batts. The flow diagram in Figure 3.12

shows the elements of fiberglass batt insulation production.

BEES performance data are provided for thermal resistance values of R-11, R-13, and R-15 for a

wall application, and R-30 for a ceiling application. The amount of fiberglass insulation material

used per functional unit is shown in Table 3.19. The detailed environmental performance data for

this product may be viewed by opening the following files under the File/Open menu item in the

BEES software:

 

67 Stephen R. Petersen, Economics and Energy Conservation in the Design of New Single-Family Housing,

NBSIR 81-2380, National Bureau of Standards, Washington, D.C., 1981.

68 Therese K. Stovall, Supporting Documentation for the 1997 Revision to the DOE Insulation Fact Sheet,

ORNL-6907, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 1997.

69 Sieglinde K. Fuller, Energy Price Indices and Discount Factors for Life-Cycle Cost Analysis—April 1997,

NISTIR 85-3273-12, National Institute of Standards and Technology, 1997. The year 30 DoE cost esclation factor

is assumed to hold for years 31-50.
64

Installation Waste

Transportation

(truck)

80-322-483 km sensitivity

(50-200-300 mi)

Fiberglass

Insulation

Manufacturing

Electricity

Production

Sand

Production

Borax

Production

Transportation

(truck)

402 km (250 mi)

Transportation

(truck)

 161 km (100 mi)

Transportation

(train)

805 km (500 mi)

Glass Cullet

Natural Gas

Production

Glass Fiber

Production

Limestone

Production

Transportation

(truck)

161 km (100 mi)

Phenol

Formaldehyde

Production

Transportation

(truck)

322 km (200 mi)

Figure 3.12 Fiberglass Batt Insulation Flow Chart

• B2012B.DBF—R-11 Fiberglass Batt Wall Insulation

• B2012E.DBF—R-13 Fiberglass Batt Wall Insulation

• B2012C.DBF—R-15 Fiberglass Batt Wall Insulation

• B3012B.DBF—R-30 Fiberglass Batt Ceiling Insulation

Table 3.19 Fiberglass Batt Mass by Application

Application

Thickness

cm (in)

Density

kg/m3

 (lb/ft3)

Mass per Functional Unit

kg/m2

 (oz/ft2)

Wall--R-11 8.9 (3.5) 8.0 (0.5) 0.71 (2.33)

Wall--R-13 8.9 (3.5) 12.8 (0.8) 1.18 (3.88)

Wall--R-15 8.9 (3.5) 24.0 (1.5) 2.15 (7.05)

Ceiling--R-30 22.9 (9.0) 8.0 (0.5) 1.83 (6.0)

Raw Materials. Fiberglass batts are composed of the materials listed in Table 3.20. Production

requirements for these materials are based on the Ecobalance LCA database.
65

Table 3.20 Fiberglass Batt Constituents

Constituent Physical Weight (

%)

Borax 6.9

Glass Cullet 6.2

Limestone 50

Phenol Formaldehyde 5.9

Sand 31

Fiberglass batt production involves the energy requirements as listed in Table 3.21.

Table 3.21 Energy Requirements for Fiberglass Batt Insulation Manufacturing

Fuel Use Manufacturing Energy

Electricity 0.13 MJ/kg fiberglass (56 Btu/lb)

Natural Gas 6 MJ/kg fiberglass (2,580 Btu/lb)

Emissions. Emissions associated with fiberglass batt insulation manufacture are based on AP-42

data for the glass fiber manufacturing industry.

Use. It is important to consider thermal performance differences when assessing environmental

and economic performance for insulation product alternatives. Thermal performance affects

building heating and cooling loads, which in turn affect energy-related LCA inventory flows and

building energy costs over the 50 year use stage. Since alternatives for ceiling insulation all have

R-30 R-values, thermal performance differences are at issue only for the wall insulation

alternatives.

For wall insulation, thermal performance differences are separately assessed for 14 U.S. cities

spread across a wide range of climate and fuel cost zones, and for electricity, distillate oil, and

natural gas heating fuel types (electricity is assumed for all cooling). When selecting wall

insulation alternatives for analysis, the BEES user selects the U.S. city closest to the building

location and the building heating fuel type, so that thermal performance differences may be

customized to these important contributors to building energy use. A NIST study of the economic

efficiency of energy conservation measures (including insulation), tailored to these cities and fuel

types, is used to estimate 50 year heating and cooling requirements per functional unit of

insulation.70 BEES environmental performance results account for the energy-related inventory

flows resulting from these energy requirements. To account for the 50 year energy requirements

in BEES economic performance results, 1997 fuel prices by State71 and U.S. Department of

 

70 Stephen R. Petersen, Economics and Energy Conservation in the Design of New Single-Family Housing,

NBSIR 81-2380, National Bureau of Standards, Washington, D.C., 1981.

71 Therese K. Stovall, Supporting Documentation for the 1997 Revision to the DOE Insulation Fact Sheet,

ORNL-6907, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 1997.
66

Energy fuel price projections over the next 30 years72 are used to compute the present value cost

of operational energy per functional unit for each R-value.

When installing fiberglass batt insulation, approximately 2 % of the product is lost to waste.

Although fiberglass insulation reuse or recycling is feasible, very little occurs now. Most

fiberglass insulation waste is currently disposed of in landfills.

Cost. Purchase and installation costs for fiberglass batt insulation vary by R-value and application.

The detailed life-cycle cost data for this product may be viewed by opening the file

LCCOSTS.DBF under the File/Open menu item in the BEES software. Its costs are listed under

the following codes:

• B2012,B0—R-11 Fiberglass Batt Wall Insulation

• B2012,E0—R-13 Fiberglass Batt Wall Insulation

• B2012,C0—R-15 Fiberglass Batt Wall Insulation

• B3012,B0—R-30 Fiberglass Batt Ceiling Insulation

Life-cycle cost data include first cost data (purchase and installation costs) and future cost data

(cost and frequency of replacement, and where appropriate and data are available, of operation,

maintenance, and repair). Operational energy costs for wall insulation (discussed above under

“Use”) are found in the file USEECON.DBF. All other future cost data are based on data

published by Whitestone Research in The Whitestone Building Maintenance and Repair Cost

Reference 1999, supplemented by industry interviews. First cost data are collected from the R.S.

Means publication, 2000 Building Construction Cost Data.

3.4.3 Blown Fiberglass Insulation (B3012D)

Blown fiberglass insulation is made by forming spun-glass fibers using the same method as for

batts but leaving the insulation loose. Using a rotary process, molten glass is poured into a rapidly

spinning disc that has thousands of fine holes in its rim. Centrifugal force extrudes the molten

glass through the holes, creating the glass fibers. The fibers are made thinner by jets, air, or steam

and are immediately coated with a binder and/or de-dusting agent

.

The flow diagram in Figure 3.13 shows the elements of blown fiberglass insulation production.

BEES performance data are provided for a thermal resistance value of R-30 for a ceiling

application. The amount of fiberglass insulation material used per functional unit is shown in

Table 3.22. The detailed environmental performance data for blown fiberglass insulation may be

viewed by opening the file B3012D.DBF under the File/Open menu item in the BEES software.

 

72 Sieglinde K. Fuller, Energy Price Indices and Discount Factors for Life-Cycle Cost Analysis—April 1997,

NISTIR 85-3273-12, National Institute of Standards and Technology, 1997. The year 30 DoE cost esclation factor

is assumed to hold for years 31-50.
67

Installation Waste

Transportation

(truck)

80-322-483 km sensitivity

(50-200-300 mi)

Fiberglass

Insulation

Manufacturing

Electricity

Production

Sand

Production

Borax

Production

Transportation

(truck)

402 km (250 mi)

Transportation

(truck)

161 km (100 mi)

Transportation

(train)

805 km (500 mi)

Glass Cullet

Natural Gas

Production

Glass Fiber

Production

Limestone

Production

Transportation

(truck)

161 km (100 mi)

Phenol

Formaldehyde

Production

Transportation

(truck)

322 km (200 mi)

Diesel Fuel

Production &

Use in Installation

Figure 3.13 Blown Fiberglass Insulation Flow Chart

Table 3.22 Blown Fiberglass Mass

Application

Thickness

cm (in)

Density

kg/m3 (lb/ft3)

Mass per Functional Unit

kg/m2 (oz/ft2)

Ceiling (R-30) 22.9 (9.0) 12.0 (0.75) 2.8 (9.17)

Raw Materials. Blown fiberglass is composed of the materials listed in Table 3.23.

Table 3.23 Blown Fiberglass Constituents

Constituent Physical Weight ( %)

Borax 6.9

Glass Cullet 6.2

Limestone 50

Phenol Formaldehyde 5.9

Sand 31

Production requirements for fiberglass insulation constituents are based on the Ecobalance LCA

database.

Fiberglass production involves the energy requirements as listed in Table 3.24.
68

Table 3.24 Energy Requirements for Fiberglass Insulation Manufacturing

Fuel Use Manufacturing Energy

Electricity 0.13 MJ/kg fiberglass (56 Btu/lb)

Natural Gas 6 MJ/kg fiberglass (2,580 Btu/lb)

Emissions. Emissions associated with fiberglass insulation manufacture are based on AP-42 data

for the glass fiber manufacturing industry.

Use. It is important to recognize thermal performance differences when assessing environmental

and economic performance for insulation product alternatives. Thermal performance affects

building heating and cooling loads, which in turn affect energy-related LCA inventory flows and

building energy costs over the 50 year use stage. However, since alternatives for ceiling insulation

all have R-30 R-values, there are no thermal performance differences for this application.

When installing blown fiberglass insulation, approximately 5 % of the product is lost to waste.

Although fiberglass insulation reuse or recycling is feasible, very little occurs now. Most

fiberglass insulation waste is currently disposed of in landfills. Energy for blowing the insulation is

included, based on a 18 kW (25 hp) diesel engine blowing 1134 kg (2,500 lb) of fiberglass

insulation per hour.

Cost. The detailed life-cycle cost data for this product may be viewed by opening the file

LCCOSTS.DBF under the File/Open menu item in the BEES software. Its costs are listed under

BEES code B3012,D0. Life-cycle cost data include first cost data (purchase and installation

costs) and future cost data (cost and frequency of replacement, and where appropriate and data

are available, of operation, maintenance, and repair). All other future cost data are based on data

published by Whitestone Research in The Whitestone Building Maintenance and Repair Cost

Reference 1999, supplemented by industry interviews. First cost data are collected from the R.S.

Means publication, 2000 Building Construction Cost Data.

3.4.4 Blown Mineral Wool Insulation (B2012D, B3012C)

Blown mineral wool insulation is made by spinning fibers from natural rock (rock wool) or iron

ore blast furnace slag (slag wool). Rock wool and slag wool are manufactured by melting the

constituent raw materials in a cupola. A molten stream is created and poured onto a rapidly

spinning wheel or wheels. The viscous molten material adheres to the wheels and the centrifugal

force throws droplets of melt away from the wheels, forming fibers. The fibers are then collected

and cleaned to remove non-fibrous material. During the process a phenol formaldehyde binder

and/or a de-dusting agent are applied to reduce free, airborne wool during application. The flow

diagram in Figure 3.14 shows the elements of blown mineral wool insulation production.
69

Installation Waste

Transportation

(truck)

80-322-483 km sensitivity

(50-200-300 mi)

Mineral Wool

Insulation

Manufacturing

Electricity

Production

Diabase Rock

Production

Transportation

(truck)

161 km (100 mi)

Transportation

(truck)

161 km (100 mi)

Iron Slag

Coke

Production

Phenol

Formaldehyde

Production

Transportation

(truck)

322 km (200 mi)

Diesel Fuel

Production &

Use in Installation

Figure 3.14 Blown Mineral Wool Insulation Flow Chart

BEES performance data are provided for a thermal resistance value of R-12 for a wall application,

and R-30 for a ceiling application. The detailed environmental performance data for blown

mineral wool insulation may be viewed by opening the following files under the File/Open menu

item in the BEES software:

• B2012D.DBF—R-12 Blown Mineral Wool Wall Insulation

• B3012C.DBF—R-30 Blown Mineral Wool Ceiling Insulation

Raw Materials. Mineral wool insulation is composed of the materials listed in Table 3.25.

Production requirements for the mineral wool constituents are based on the Ecobalance LCA

database.

Table 3.25 Blown Mineral Wool Constituents

Mineral Wool Constituents Physical Weight ( %)

Phenol Formaldehyde 2.5

Iron-ore slag (North American) 78

Diabase/basalt 20

Mineral wool production involves the energy requirements listed in Table 3.26.

Emissions. Emissions associated with mineral wool insulation production are based on AP-42

data for the mineral wool manufacturing industry.
70

Table 3.26 Energy Requirements for Mineral Wool Insulation Manufacturing

Fuel Use Manufacturing Energy

Electricity 1.0 MJ/kg (430 Btu/lb)

Coke 6.38 MJ/kg (2,743 Btu/lb)

Use. It is important to consider thermal performance differences when assessing environmental

and economic performance for insulation product alternatives. Thermal performance affects

building heating and cooling loads, which in turn affect energy-related LCA inventory flows and

building energy costs over the 50 year use stage. Since alternatives for ceiling insulation all have

R-30 R-values, thermal performance differences are at issue only for wall insulation alternatives.

For wall insulation, thermal performance differences are separately assessed for 14 U.S. cities

spread across a wide range of climate and fuel cost zones, and for electricity, distillate oil, and

natural gas heating fuel types (electricity is assumed for all cooling). When selecting wall

insulation alternatives for analysis, the BEES user selects the U.S. city closest to the building

location and the building heating fuel type, so that thermal performance differences may be

customized to these important contributors to building energy use. A NIST study of the economic

efficiency of energy conservation measures (including insulation), tailored to these cities and fuel

types, is used to estimate 50 year heating and cooling requirements per functional unit of

insulation.73 BEES environmental performance results account for the energy-related inventory

flows resulting from these energy requirements. To account for the 50 year energy requirements

in BEES economic performance results, 1997 fuel prices by State74 and U.S. Department of

Energy fuel price projections over the next 30 years75 are used to compute the present value cost

of operational energy per functional unit for each R-value.

Mineral wool insulation is typically blown into place. It is assumed to be blown at a rate of 1134

kg/h (2,500 lb/h) with a 25 horsepower diesel engine. During installation, 5 % of the product is

lost to waste.

Cost. Purchase and installation costs for blown mineral wool insulation vary by application. The

detailed life-cycle cost data for this product may be viewed by opening the file LCCOSTS.DBF

under the File/Open menu item in the BEES software. Its costs are listed under the following

codes:

• B2012,D0—R-12 Blown Mineral Wool Wall Insulation

• B3012,C0—R-30 Blown Mineral Wool Ceiling Insulation

Life-cycle cost data include first cost data (purchase and installation costs) and future cost data

(cost and frequency of replacement, and where appropriate and data are available, of operation,

 

73 Stephen R. Petersen, Economics and Energy Conservation in the Design of New Single-Family Housing,

NBSIR 81-2380, National Bureau of Standards, Washington, D.C., 1981.

74 Therese K. Stovall, Supporting Documentation for the 1997 Revision to the DOE Insulation Fact Sheet,

ORNL-6907, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 1997.

75 Sieglinde K. Fuller, Energy Price Indices and Discount Factors for Life-Cycle Cost Analysis—April 1997,

NISTIR 85-3273-12, National Institute of Standards and Technology, 1997. The year 30 DoE cost escalation factor

is assumed to hold for years 31-50.
71

maintenance, and repair). Operational energy costs for wall insulation (discussed above under

“Use”) are found in the file USEECON.DBF. All other future cost data are based on data

published by Whitestone Research in The Whitestone Building Maintenance and Repair Cost

Reference 1999, supplemented by industry interviews. First cost data are collected from the R.S.

Means publication, 2000 Building Construction Cost Data.

3.5 Framing Alternatives ( B2013)

3.5.1 Steel Framing (B2013A)

Steel is an important construction framing material. Steel is made from iron, which in turn is made

from iron ore, coal, and limestone in the presence of oxygen. The steel-making process includes

the processing of iron ore, coal, and limestone prior to a blast furnace operation, which makes the

raw material, iron. Other materials used in steel manufacturing processes include nickel,

manganese, chromium, and zinc, as well as various lubricating oils, cleaning solvents, acids, and

alkalines.

Cold-formed steel framing is manufactured from blanks sheared from sheets that are cut from

coils or plates, or by roll-forming cold or hot-rolled coils or sheets. Both these forming

operations are done at ambient temperatures. Light-gauge steel shapes are formed from flatrolled 12- to 20-gauge carbon steel as either single bent shapes or bent shapes welded together.

Two basic types of steel framing, nailable and nonnailable, are available in both punched and solid

forms. Zinc chromate primer, galvanized, and painted finishes are available. Steel stud and joist

systems have been adopted as an alternative to wood and masonry systems in most types of

construction. Steel framing is also used extensively for interior partitions because it is fireresistant, easy to erect, and makes installation of utilities more convenient. Light-gauge steel

framing can be installed directly at the construction site or it can be prefabricated off- or on-site.

The assembly process relies on a number of accessories usually made of steel, such as bridging,

bolts, nuts, screws, and anchors, as well as devices for fastening units together, such as clips and

nails.

In recent years, structural steel has increasingly been used for framing systems due to its fire

resistance and high strength-to-weight ratio. For the BEES system, 18-gauge (1.1 mm, or 0.0428

in thick) steel studs and tracks are evaluated. Tracks are sized to fit the studs. Self-tapping steel

screws, used as fasteners for the steel studs, are included. Figure 3.15 shows the elements of steel

framing production. The detailed environmental performance data for this product may be viewed

by opening the file B2013A.DBF under the File/Open menu item in the BEES software:

Raw Materials. Production of the raw materials necessary for steel stud manufacture is based on

data from the American Iron and Steel Institute (AISI). Four North American steel companies

provided primary data for the production of hot-rolled coil, while data for cold-rolled steel and
72

Steel Stud

Production

Steel Screw

Production

Functional Unit of

Steel Framing

Truck

Transport

Figure 3.15 Steel Framing Flow Chart

hot dip galvanized steel came from three sites. Further primary data was collected for some

upstream processes, such as iron ore mining and lime production. Secondary data were obtained

from LCA databases and literature. The steel is assumed to be made of steel produced from the

Basic Oxygen Furnace (BOF) process, which includes roughly 20 % recycled material.

Fasteners are produced largely from recycled material, and are produced primarily in Electric Arc

Furnaces (EAF). European data are used for the production of steel fasteners76.

Energy Requirements. Energy requirements for producing steel are based on the European data

source listed above, combined with upstream U.S. energy production models in the Ecobalance

LCA database.

Emissions. Emissions for steel stud and self-tapping screw production are based on the

Ecobalance LCA database.

Transportation. Transport of steel raw materials to the manufacturing plant is included.

Transport of steel framing by heavy-duty truck to the building site is a variable of the BEES

model. Emissions associated with the combustion of fuel in the truck engine and with production

of the fuel are included, based on the Ecobalance database.

Use. Use of steel framing for exterior walls without a thermal break such as rigid foam may

increase thermal insulation requirements or otherwise adversely affect building thermal

performance. While this interdependency of building elements is not accounted for in BEES 2.0, it

will be considered in the future as the BEES system moves beyond building products to building

systems and components.

Cost. The detailed life-cycle cost data for this product may be viewed by opening the file

LCCOSTS.DBF under the File/Open menu item in the BEES software. Its costs are listed under

BEES code B2013, product code A0. Life-cycle cost data include first cost data (purchase and

installation costs) and future cost data (cost and frequency of replacement, and where appropriate

and data are available, of operation, maintenance, and repair). First cost data are collected from

the R.S. Means publication, 2000 Building Construction Cost Data, and future cost data are

 

76 Swiss Federal Office of Environment, Forests and Landscape (FOEFL or BUWAL), Environmental Series

No. 250.
73

based on data published by Whitestone Research in The Whitestone Building Maintenance and

Repair Cost Reference 1999, supplemented by industry interviews.

3.5.2 Wood Framing (B2013B)

Wood framing is the most common structural system used for non-load-bearing and load-bearing

interior walls, and includes lumber, constructed truss products, and specific applications of treated

lumber. Floor framing consists of a system of sills, girders, subflooring, and joists or floor trusses

that provide support for floor loads and walls. There are two types of interior partitions: bearing

partitions, which support floors, ceilings, or roofs, and nonbearing partitions, which carry only

their own weight. The sole plate and the top plate frame the wall structure of vertical studs, and

sheathing or diagonal bracing ensures lateral stability. In general, dimensions for framing lumber

are given in nominal inches (i.e., 2 x 4 x 6). Framing lumber must be properly grade-marked to be

acceptable under the major building codes. Such grade marks identify the grade, species or

species group, seasoning condition at time of manufacture, producing mill, and the grading ruleswriting agency.

Wood studs are produced in a sawmill, where harvested wood is debarked and sawn into specific

dimensions. The lumber is then dried in a controlled environment until the desired moisture

content (between 12 % and 19 %) is reached. It is possible to treat framing lumber with

preservatives in order to guard against insect attack, or to shield against surface moisture which

might cause fungal decay.

The functional unit of comparison for BEES framing alternatives is 1 ft2 of load bearing wall

framing for 50 years. Preservative-treated pine wood studs, 5.08 cm x 10.16 cm (2 in x 4 in), with

a moisture content of 12 % are studied. The preservative is assumed to be Type C Chromated

Copper Arsenate (CCA), a common water-borne preservative used in the treatment of wood

products. Galvanized nails used to fasten the studs together to form the wall framing are also

studied. The flow diagram shown in Figure 3.16 shows the major elements of wood stud

production. The detailed environmental performance data for this product may be viewed by

opening the file B2013B.DBF under the File/Open menu item in the BEES software.

Raw Materials. For BEES, data were collected for the harvested trees used to produce the

lumber necessary for framing load-bearing walls. Production of the other raw materials--steel for

nails and chromated copper arsenate for preservative--is based on data from the Ecobalance LCA

database.

Energy Requirements. The energy requirements for lumber manufacture are shown in Table

3.27. The energy is assumed to come primarily from burning wood waste. Other fuel sources,

including natural gas and petroleum, are also used.
74

Wood Stud

Production

Galvanized Nail

Production

Timber

Harvesting

Preservative

Production

Heavy Fuel Oil

Production

Natural Gas

Production

Liquid

Petroleum Gas

Production

Functional Unit of

Framing

Truck

Transport

Hogfuel

Production

Figure 3.16 Wood Framing Flow Chart

Table 3.27 Energy Requirements for Lumber Manufacture77

Fuel Usea

Manufacturing Energy

MJ/kg (Btu/lb)

Total Fossil Fuel 5.6 (2,413)

 % Natural Gas 39.8

 % Heavy Fuel Oil 4.1

 % Liquid Petroleum Gas 4.1

 % Hogfuel 52

 aExcluding electricity

Emissions. The emissions from the lumber manufacturing process are shown in Table 3.28.

Table 3.28 Hogfuel Emissions78

Emission

Amount

g/MJ Wood burned (oz/kWh)

Carbon Dioxide (CO2) 81.5 (10.35)

Carbon Monoxide (CO) 0.011 (0.0014)

Methane (CH4) 0.008 (0.001)

Nitrogen Oxides (NOX) 0.110 (0.014)

Sulfur Oxides (SOX) 0.0002 (0.000025)

Volatile Organic Compounds (VOC) 0.039 (0.005)

Particulates 0.708 (0.09)

 

77 Forintek Canada Corporation, Building Materials in the Context of Sustainable Development – Raw Material

Balances, Energy Profiles and Environmental Unit Factor Estimates for Structural Wood Products, March 1993.

78 Forintek Canada Corporation, op cit.
75

Transportation. Since sawmills are often located close to tree harvesting areas, the

transportation of lumber to the sawmill is not taken into account. However, truck transportation

of 322 km (200 mi) is assumed for the preservative. The tailpipe emissions from the truck engine

and the emissions that result from the production of the fuel used in the truck are taken into

account based on the Ecobalance database. Transportation of framing lumber by heavy-duty

truck to the construction site is a variable of the BEES model.

Use. The density of pine at 12 % moisture content (seasoned wood) is assumed to be 449 kg/m3

(28 lb/ft3). Retention of CCA in lumber is assumed to be 6.4 kg/m3 (0.40 lb/ft3). It is assumed

that wood studs are placed 41 cm (16 in) on center and are fastened with galvanized steel nails.

At installation, 5 % of the product is lost to waste.

Cost. The detailed life-cycle cost data for this product may be viewed by opening the file

LCCOSTS.DBF under the File/Open menu item in the BEES software. Its costs are listed under

BEES code B2013, product code B0. Life-cycle cost data include first cost data (purchase and

installation costs) and future cost data (cost and frequency of replacement, and where appropriate

and data are available, of operation, maintenance, and repair). First cost data are collected from

the R.S. Means publication, 2000 Building Construction Cost Data, and future cost data are

based on data published by Whitestone Research in The Whitestone Building Maintenance and

Repair Cost Reference 1999, supplemented by industry interviews.

3.6 Roof Covering Alternatives (B3011)

3.6.1 Asphalt Shingles (B3011A)

Asphalt shingles are commonly made from fiberglass mats filled with asphalt, then coated on the

exposed side with mineral granules for both a decorative finish and a wearing layer. Asphalt

shingles are nailed over roofing felt onto sheathing.

For BEES, a roof covering of asphalt shingles with a 20 year life, roofing felt, and galvanized

nails is analyzed. The flow diagram shown in Figure 3.17 shows the elements of asphalt shingle

production. The detailed environmental performance data for this product may be viewed by

opening the file B3011A.DBF under the File/Open menu item in the BEES software.

Filler is assumed to be 50 % dolomite and 50 % limestone. Granules production is modeled as

rock mining and grinding. Production requirements for the asphalt shingle constituents are based

on the Ecobalance LCA database.

Seven kg (fifteen lb) felt consists of asphalt and organic felt as listed in Table 3.30. The organic

felt is assumed to consist of 50 % recycled cardboard and 50 % wood chips. The production of

these materials, and the asphalt, is based on the Ecobalance LCA database.

Energy Requirements. The energy requirement for asphalt shingle production is assumed to be
76

Functional Unit

of

Asphalt Shingles

Galvanized

Nail Production

Truck

Transport

Asphalt

Shingle

Production

Granules

Production

Fiberglass

Production

Limestone

Production

Truck

Transport

(Raw Matl's)

Train

Transport

(Raw Matl's)

Asphalt

Production

Dolomite

Production

#15 Felt

Production

Asphalt

Production

Cardboard

Production

Woodchips

Production

Figure 3.17 Asphalt Shingles Flow Chart

33 MJ/m2 of natural gas (2,843 Btu/ft2) of shingles.

Raw Materials. Asphalt shingles are composed of the materials listed in Table 3.29.

Table 3.29 Asphalt Shingle Constituents

Asphalt Shingle Constituents Physical Weight

Asphalt 1.9 kg/m2 (40 lb/square)

Filler 4.2 kg/ m2 (86 lb/square)

Fiberglass 0.2 kg/ m2 (4 lb/square)

Granules 3.7 kg/ m2 (75 lb/square)

Table 3.30 Seven Kg (15 lb) Roofing Felt Constituents

7 kg (15 lb)

Felt Constituents Physical Weight

Asphalt 0.5 kg/ m2 (9.6 lb/square)

Organic Felt 0.3 kg/ m2 (5.4 lb/square)

Total: 0.8 kg/ m2 (15 lb/square)

Emissions. Emissions associated with manufacturing asphalt shingles and roofing felt are taken

into account based on AP-42 data for asphalt shingle and saturated felt processing.

Transportation. Transport of the asphalt shingle raw materials is taken into account. The

distance transported is assumed to be 402 km (250 mi) for all of the components. Asphalt is

assumed to be transported by truck, train, and pipeline in equal proportions. Dolomite, limestone,

and granules are assumed to be transported by truck and train in equal proportions. Fiberglass is

assumed to be transported by truck.
77

Transport of the raw materials for roofing felt is also taken into account. The distance

transported is assumed to be 402 km (250 mi) for all of the components. Asphalt is assumed to

be transported by truck, train, and pipeline in equal proportions, while the cardboard and wood

chips are assumed to be transported by truck.

Transport of the shingles, roofing felt, and nails to the building site is a variable of the BEES

system.

Use. It is important to consider solar reflectivity differences among roof coverings of different

materials and colors when assessing the environmental and economic performance of roof

covering alternatives. “Cool” roofs reflect and emit solar radiation well, and thus stay cooler in

the sun than less reflective, less emissive materials. The cool temperature results in building-scale

cooling energy savings ranging from 2 % to 60 %.79 A much less significant rise in building

heating energy costs also occurs. BEES accounts for solar reflectivity performance in computing

energy-related LCA inventory flows and building energy costs over the 50 year use stage for roof

covering products.

For roof coverings, thermal performance differences are separately assessed for 16 U.S. cities

spread across a range of Sunbelt climate and fuel cost zones. When selecting roof covering

alternatives for use in Sunbelt climates,80 the BEES user chooses 1) the roof covering material and

color, 2) the U.S. Sunbelt climate city closest to the building location, 3) the building type (new

or existing), 4) its heating and cooling system (electric air-source heat pump or gas

furnace/central air conditioning heating and cooling systems), and 5) its duct placement

(uninsulated attic ducts or ducts in the conditioned space), so that thermal performance

differences may be customized to these important contributors to building energy use. Energy use

data provided to the National Institute of Standards and Technology by Lawrence Berkeley

National Laboratory (and which LBL developed for the U.S. EPA Energy Star Roof Products

program), tailored to these five parameters, are used to estimate 50 year heating and cooling

requirements per functional unit of roof covering.81 BEES environmental performance results

account for the energy-related inventory flows resulting from these energy requirements (stored in

USEFLOWS.DBF), and BEES economic performance results account for the present value cost

resulting from these energy requirements (stored in USEECON.DBF).

Asphalt shingle and roofing felt installation is assumed to require 47 nails/ m2 (440 nails/square).

Installation waste from scrap is estimated at 5 % of the installed weight. At 20 years, new shingles

are installed over the existing shingles. At 40 years, both layers of roof covering are removed

before installing replacement shingles.

 

79 Memorandum from Sarah Bretz/Lawrence Berkeley National Laboratory to Barbara Lippiatt/National

Institute of Standards and Technology, 12/18/98.

80 In cold climates, the amount of roof insulation is more important to thermal performance than the color of the

roof covering.

81 LBL data were developed for BEES by LBL’s Sarah Bretz, based on Konopacki and Akbari, Simulated

Impact of Roof Surface Solar Absorptance, Attic, and Duct Insulation on Cooling and Heating Energy Use in

Single-Family New Residential Buildings, LBNL-41834, Lawrence Berkeley National Laboratory, Berkeley, CA,

1998, and on Parker et al., “Measured and Simulated Performance of Reflective Roofing Systems in Residential

ASHRAE Transactions, SF-98-6-2, Vol. 104, 1998, p. 1.
78

Cost. The detailed life-cycle cost data for this product may be viewed by opening the file

LCCOSTS.DBF under the File/Open menu item in the BEES software. Its costs are listed under

BEES code B3011, product code A0. Life-cycle cost data include first cost data (purchase and

installation costs) and future cost data (cost and frequency of replacement, and where appropriate

and data are available, of operation, maintenance, and repair). Operational energy costs for roof

coverings in U.S. Sunbelt climates (discussed above under “Use”) are found in the file

USEECON.DBF. First cost data are collected from the R.S. Means publication, 2000 Building

Construction Cost Data, and other future cost data are based on data published by Whitestone

Research in The Whitestone Building Maintenance and Repair Cost Reference 1999,

supplemented by industry interviews.

3.6.2 Clay Tile (B3011B)

Clay tiles are made by shaping and firing clay. The most commonly used clay tile is the red

Spanish tile. For the BEES system, a roof covering of 70 year red Spanish clay tiles, roofing felt,

and nails is studied. Due to the weight of the tile and its relatively long useful life, 14 kg (30 lb)

felt and copper nails are used. The flow diagram shown in Figure 3.18 shows the elements of clay

tile production. The detailed environmental performance data for this product may be viewed by

opening the file B3011B.DBF under the File/Open menu item in the BEES software.

Raw Materials. The weight of the clay tile studied is 381 kg (840 lb) per square, requiring 171

pieces of tile. Production of the clay is based on the Ecobalance LCA database.

Fourteen kg (30 lb) felt consists of asphalt and organic felt as listed in Table 3.31. The organic

felt is assumed to consist of 50 % recycled cardboard and 50 % wood chips. The production of

these materials, and the asphalt, is based on the Ecobalance LCA database.

Table 3.31 Fourteen Kg (30 lb) Roofing Felt Constituents

14 kg (30 lb)

Felt Constituents Physical Weight

Asphalt 0.9 kg/m2

 (19.2 lb/square)

Organic Felt 0.5 kg/ m2 (10.8 lb/square)

Total: 1.4 kg/ m2 (30 lb/square)
79

Functional Unit

 of Clay Tile Roofing

Galvanized

Nail

Production

Truck

Transport

Clay Tile

Production

Truck

Transport

(Raw Matl's)

Clay Tiles

Clay

Production

#30 Felt

Production

Asphalt

Production

Cardboard

Production

Woodchips

Production

Train

Transport

(Raw Matl's)

Copper Nail

Production

Figure 3.18 Clay Tile Flow Chart

Energy Requirements. The energy required to fire clay tile is 6.3 MJ per kg (2,708 Btu per lb) of

clay tile. The fuel type is natural gas.

Emissions. Emissions associated with natural gas combustion are based on AP-42 emission

factors.

Transportation. Transport of the clay raw material is taken into account. The distance

transported is assumed to be 402 km (250 mi) for the clay by train and truck. Transport of the

raw materials for roofing felt is also taken into account. The distance transported is assumed to

be 402 km (250 mi) for all of the components. Asphalt is assumed to be transported by truck,

train, and pipeline in equal proportions, while the cardboard and wood chips are assumed to be

transported by truck. Transport of the tiles to the building site is a variable of the BEES model.

Use. It is important to consider solar reflectivity differences among roof coverings of different

materials and colors when assessing the environmental and economic performance of roof

covering alternatives. “Cool” roofs reflect and emit solar radiation well, and thus stay cooler in

the sun than less reflective, less emissive materials. The cool temperature results in building-scale

cooling energy savings ranging from 2 % to 60 %.82 A much less significant rise in building

heating energy costs also occurs. BEES accounts for solar reflectivity performance in computing

energy-related LCA inventory flows and building energy costs over the 50 year use stage for roof

covering products.

 

82 Memorandum from Sarah Bretz/Lawrence Berkeley National Laboratory to Barbara Lippiatt/National

Institute of Standards and Technology, 12/18/98.
80

For roof coverings, thermal performance differences are separately assessed for 16 U.S. cities

spread across a range of Sunbelt climate and fuel cost zones. When selecting roof covering

alternatives for use in Sunbelt climates, 83 the BEES user chooses 1) the roof covering material

and color, 2) the U.S. Sunbelt climate city closest to the building location, 3) the building type

(new or existing), 4) its heating and cooling system (electric air-source heat pump or gas

furnace/central air conditioning heating and cooling systems), and 5) its duct placement

(uninsulated attic ducts or ducts in the conditioned space), so that thermal performance

differences may be customized to these important contributors to building energy use. Energy use

data provided to the National Institute of Standards and Technology by Lawrence Berkeley

National Laboratory (and which LBL developed for the U.S. EPA Energy Star Roof Products

program), tailored to these five parameters, are used to estimate 50 year heating and cooling

requirements per functional unit of roof covering.84 BEES environmental performance results

account for the energy-related inventory flows resulting from these energy requirements (stored in

USEFLOWS.DBF), and BEES economic performance results account for the present value cost

resulting from these energy requirements (stored in USEECON.DBF).

Clay tile roofing is assumed to require two layers of 14 kg (30 lb) roofing felt, 13 galvanized

nails/m2 (120/square) for underlayment, and 37 copper nails/m2 (342/square) for the tile (2 copper

nails/tile). Installation waste from scrap is estimated at 5 % of the installed weight. One-fourth of

the tiles are replaced after 20 years, and another one-fourth at 40 years. All tiles are replaced at 70

years.

Cost. The detailed life-cycle cost data for this product may be viewed by opening the file

LCCOSTS.DBF under the File/Open menu item in the BEES software. Its costs are listed under

BEES code B3011, product code B0. Life-cycle cost data include first cost data (purchase and

installation costs) and future cost data (cost and frequency of replacement, and where appropriate

and data are available, of operation, maintenance, and repair). Operational energy costs for roof

coverings in U.S. Sunbelt climates (discussed above under “Use”) are found in the file

USEECON.DBF. First cost data are collected from the R.S. Means publication, 2000 Building

Construction Cost Data, and other future cost data are based on data published by Whitestone

Research in The Whitestone Building Maintenance and Repair Cost Reference 1999,

supplemented by industry interviews.

 

83 In cold climates, the amount of roof insulation is more important to thermal performance than the color of the

roof covering.

84 LBL data were developed for BEES by LBL’s Sarah Bretz, based on Konopacki and Akbari, Simulated

Impact of Roof Surface Solar Absorptance, Attic, and Duct Insulation on Cooling and Heating Energy Use in

Single-Family New Residential Buildings, LBNL-41834, Lawrence Berkeley National Laboratory, Berkeley, CA,

1998, and on Parker et al., “Measured and Simulated Performance of Reflective Roofing Systems in Residential

ASHRAE Transactions, SF-98-6-2, Vol. 104, 1998, p. 1.
81

3.6.3 Fiber Cement Shingles (B3011C)

In the past, fiber cement shingles were manufactured using asbestos fibers. Now asbestos fibers

have been replaced with cellulose fibers. For the BEES study, a 45 year fiber cement shingle

consisting of cement, sand, and cellulose fibers is studied. Roofing felt and galvanized nails are

used for installation. The flow diagram shown in Figure 3.19 shows the elements of fiber cement

shingle production. The detailed environmental performance data for this product may be viewed

by opening the file B3011C.DBF under the File/Open menu item in the BEES software.

Raw Materials. Fiber cement shingles are composed of the materials listed in Table 3.32. The

filler is sand, and the organic fiber is wood chips. The weight of fiber cement shingles is assumed

to be 16 kg/m2 (325 lb/square), based on 36 cm x 76 cm x 0.4 cm (14 in x 30 in x 5/32 in) size

shingles.

Functional Unit of

Fiber Cement Shingles

Galvanized

Nail Production

Truck

Transport

Fiber Cement

Shingle

Production

Woodchips

Production

Truck

Transport

(Raw Matl's)

Portland

Cement

Production

Sand

Production

#30 Felt

Production

Asphalt

Production

Cardboard

Production

Woodchips

Production

Figure 3.19 Fiber Cement Shingles Flow Chart

Table 3.32 Fiber Cement Shingle Constituents

Fiber Cement Shingle

Constituents

Physical Weight

( %)

Portland Cement 90

Filler 5

Organic Fiber 5

Portland cement production requirements are identical to those noted above for a stucco exterior

wall finish. Fourteen kg (30 lb) roofing felt is modeled as noted above for clay tile roofing.

Production requirements for the raw materials is based on the Ecobalance LCA database.
82

Energy Requirements. The energy requirements for fiber cement shingle production are assumed

to be 33 MJ/m2 of natural gas and 11 MJ/m2 of electricity (2843 Btu/ft2 of natural gas and 948

Btu/ft2 of electricity) of shingle.

Transportation. Transport of the raw materials is taken into account. The distance over which all

materials are transported is assumed to be 402 km (250 mi). Shingle materials are assumed to be

transported by truck. For roofing felt, asphalt is assumed to be transported by truck, train, and

pipeline in equal proportions, while the cardboard and wood chips are assumed to be transported

by truck.

Transport of the shingles to the building site is a variable of the BEES model.

Use. It is important to consider solar reflectivity differences among roof coverings of different

materials and colors when assessing the environmental and economic performance of roof

covering alternatives. “Cool” roofs reflect and emit solar radiation well, and thus stay cooler in

the sun than less reflective, less emissive materials. The cool temperature results in building-scale

cooling energy savings ranging from 2 % to 60 %.85 A much less significant rise in building

heating energy costs also occurs. BEES accounts for solar reflectivity performance in computing

energy-related LCA inventory flows and building energy costs over the 50 year use stage for roof

covering products.

For roof coverings, thermal performance differences are separately assessed for 16 U.S. cities

spread across a range of Sunbelt climate and fuel cost zones. When selecting roof covering

alternatives for use in Sunbelt climates, 86 the BEES user chooses 1) the roof covering material

and color, 2) the U.S. Sunbelt climate city closest to the building location, 3) the building type

(new or existing), 4) its heating and cooling system (electric air-source heat pump or gas

furnace/central air conditioning heating and cooling systems), and 5) its duct placement

(uninsulated attic ducts or ducts in the conditioned space), so that thermal performance

differences may be customized to these important contributors to building energy use. Energy use

data provided to the National Institute of Standards and Technology by Lawrence Berkeley

National Laboratory (and which LBL developed for the U.S. EPA Energy Star Roof Products

program), tailored to these five parameters, are used to estimate 50 year heating and cooling

requirements per functional unit of roof covering.87 BEES environmental performance results

account for the energy-related inventory flows resulting from these energy requirements (stored in

USEFLOWS.DBF), and BEES economic performance results account for the present value cost

resulting from these energy requirements (stored in USEECON.DBF).

 

85 Memorandum from Sarah Bretz/Lawrence Berkeley National Laboratory to Barbara Lippiatt/National

Institute of Standards and Technology, 12/18/98.

86 In cold climates, the amount of roof insulation is more important to thermal performance than the color of the

roof covering.

87 LBL data were developed for BEES by LBL’s Sarah Bretz, based on Konopacki and Akbari, Simulated

Impact of Roof Surface Solar Absorptance, Attic, and Duct Insulation on Cooling and Heating Energy Use in

Single-Family New Residential Buildings, LBNL-41834, Lawrence Berkeley National Laboratory, Berkeley, CA,

1998, and on Parker et al., “Measured and Simulated Performance of Reflective Roofing Systems in Residential

ASHRAE Transactions, SF-98-6-2, Vol. 104, 1998, p. 1.
83

Fiber cement shingle roofing requires one layer of 14 kg (30 lb) felt underlayment, 13 nails/m2

(120 nails/square) for the underlayment, and 32 nails/m2 (300 nails/square) for the shingles.

Installation waste from scrap is estimated at 5 % of the installed weight. Fiber cement roofing is

assumed to have a useful life of 45 years.

Cost. The detailed life-cycle cost data for this product may be viewed by opening the file

LCCOSTS.DBF under the File/Open menu item in the BEES software. Its costs are listed under

BEES code B3011, product code C0. Life-cycle cost data include first cost data (purchase and

installation costs) and future cost data (cost and frequency of replacement, and where appropriate

and data are available, of operation, maintenance, and repair). Operational energy costs for roof

coverings in U.S. Sunbelt climates (discussed above under “Use”) are found in the file

USEECON.DBF. First cost data are collected from the R.S. Means publication, 2000 Building

Construction Cost Data, and other future cost data are based on data published by Whitestone

Research in The Whitestone Building Maintenance and Repair Cost Reference 1999,

supplemented by industry interviews.

3.7 Interior Finishes (C3012)

3.7.1 Paints – General Information

Conventional paints are generally classified into two basic categories: water-based (in which the

solvent is water) and oil-based (in which the solvent is an organic liquid, usually derived from

petrochemicals). Oil-based paints are sometimes referred to as solvent-based. Paints essentially

consist of a resin or binder, pigments, and a carrier in which these are dissolved or suspended.

Once the paint is applied to a surface, the carrier evaporates, leaving behind a solid coating. In

oil-based paints the carrier is a solvent consisting of volatile organic compounds (VOCs), which

can adversely affect indoor air quality and the environment. As a result, government regulations

and consumer demand are forcing continuing changes in paint formulations. These changes have

led to formulations containing more paint solids and less solvent, and a shift away from oil-based

paints to waterborne or latex paints.

Paint manufacture essentially consists of combining the ingredients, less some of the solvent, in a

steel mixing vessel. In some cases the mixing is followed by a grinding operation to break up the

dry ingredients, which tend to clump during mixing. Finally, additional solvents or other liquids

are added to achieve final viscosity, and supplemental tinting is added. The paint is then strained,

put into cans, and packaged for shipping.

Because they do not use solvents as the primary carrier, latex paints emit far fewer volatile

organic compounds (VOCs) upon application. They also do not require solvents for cleaning of

the tools and equipment. Water with a coalescing agent is the carrier for latex paints. The

coalescing agent is typically a glycol or glycol ether. The binder is synthetic latex made from

polyvinyl acetate and/or acrylic polymers and copolymers. Titanium dioxide is the primary

pigment used to impart hiding properties in white or light-colored paints. A range of pigment

extenders may be added. Other additives include surfactants, defoamers, preservatives, and
84

fungicides.

BEES considers two latex-based paint alternatives, virgin latex paint and latex paint with a 35 %

recycled content. The two alternatives are applied the same way. The surface to be painted is first

primed and then painted with two coats of paint. One coat of paint is then applied every 4 years.

The characteristics of both the paint and the primer are displayed in Table 3.33.

Table 3.33 Characteristics of BEES Paints and Primer

Characteristic Primer Paint (recycled or virgin)

Spread rate of the coat m2/L

(ft2/gal)

7.4 (300) 8.6 (350)

Density of product kg/L (lb/gal) 1.26 (10.5) 1.28 (10.7)

3.7.2 Virgin Latex Interior Paint (C3012A)

Major virgin latex paint constituents are resins (binder), titanium dioxide (pigment), limestone

(extender), and water (thinner), which are mixed together until they form an emulsion. Figure

3.20 displays the system under study for virgin latex paint.

Truck Transport Functional Unit of

Virgin Latex Interior Paint

Truck Transport

(Raw Matl's)

Virgin Latex

Interior Paint Mfg

Resin Mfg

Titanium

Oxide Mfg Limestone

Quarrying

Truck Transport

(Raw Matl's) Primer Mfg

Resin Mfg

Titanium

Oxide Mfg Limestone

Quarrying

Figure 3.20 Virgin Latex Interior Paint Flow Chart

Raw Materials. The average composition of the virgin latex paint/primer system modeled in

BEES is listed in Table 3.34.
85

Table 3.34 Virgin Latex Paint and Primer Constituents

Constituent

Paint

(Weight %)

Primer

(Weight %)

Resin 25 25

Titanium dioxide 12.5 7.5

Limestone 12.5 7.5

Water 50 60

Table 3.35 displays the market shares for the resins used for interior latex paint and primer.

Table 3.35 Market Shares of Resins

Resin type Market share ( %)

Vinyl Acrylic 40

Polyvinyl Acetate 40

Styrene Acrylic 20

Table 3.36 shows the components of the three types of resin as modeled in BEES. The production

of the monomers used in the resins is based on the Ecobalance LCA database.

Table 3.36 Components of Paint Resins

Resin Type Components

Vinyl Acrylic Vinyl acetate (50 %)

Butyl acrylate (50 %)

Polyvinyl Acetate Vinyl acetate (100 %)

Styrene Acrylic Styrene (50 %)

Butyl acrylate (50 %)

Emissions. Emissions associated with paint manufacturing, such as particulates to the air, are

based on AP-42 emission factors.

Transportation. Truck transportation of raw materials to the paint manufacturing site is assumed

to average 402 km (250 mi) for titanium dioxide and limestone, and 80 km (50 mi) for the resins.

Use. Refer to Section 2.1.3, Impact Assessment, for a discussion of indoor air quality scoring for

paints.

Cost. The detailed life-cycle cost data for this product may be viewed by opening the file

LCCOSTS.DBF under the File/Open menu item in the BEES software. Its costs are listed under

BEES code C3012, product code A0. Life-cycle cost data include first cost data (purchase and

installation costs) and future cost data (cost and frequency of replacement, and where appropriate

and data are available, of operation, maintenance, and repair). First cost data are collected from

the R.S. Means publication, 2000 Building Construction Cost Data, and future cost data are

based on data published by Whitestone Research in The Whitestone Building Maintenance and

Repair Cost Reference 1999, supplemented by industry interviews.
86

3.7.3 Recycled Latex Interior Paint (C3012B)

Figure 3.21 displays the BEES flow chart for recycled latex paint.

Truck Transport Functional Unit of

Recycled Latex Interior Paint

Truck Transport

(Raw Matl's) Primer Mfg

Resin Mfg

Titanium

Oxide Mfg Limestone

Quarrying

Truck Transport

(Raw Matl's)

Recycled Latex

Interior Paint Mfg

Transport

of recycled

paint

Truck Transport

(Raw Matl's)

Virgin Latex

Interior Paint Mfg

Resin Mfg

Titanium

Oxide Mfg Limestone

Quarrying

Figure 3.21 Recycled Latex Interior Paint Flow Chart

Raw Materials. The latex paint under study has a 65 % recycled content, or a 35 % content of

virgin materials. The recycled content of the paint consists of leftover paint that is collected. After

being pre-sorted at the collection site, recycled paints are sorted again at the "re-manufacturing"

site. It is assumed that 10 % of the collected paint imported to the "re-manufacturing" site must

be discarded (paint contaminated with texture material such as sand). The recycled paint is

environmentally “free”, but its transportation to the paint manufacturing site is taken into account.

The virgin materials in the recycled paint consist of either virgin paint ingredients (resin, titanium

dioxide, and limestone) or virgin paint as a whole.
87

Transportation. Transport of collected paint from the collection point to the re-manufacturing

site is assumed to average 80 km (50 mi) by truck.

Emissions. Emissions associated with paint manufacturing, such as particulates to the air, are

based on AP-42 emission factors.

Use. Refer to Section 2.1.3, Impact Assessment, for a discussion of indoor air quality scoring for

paints.

Cost. The detailed life-cycle cost data for this product may be viewed by opening the file

LCCOSTS.DBF under the File/Open menu item in the BEES software. Its costs are listed under

BEES code C3012, product code B0. Life-cycle cost data include first cost data (purchase and

installation costs) and future cost data (cost and frequency of replacement, and where appropriate

and data are available, of operation, maintenance, and repair). First cost data are collected from

the R.S. Means publication, 2000 Building Construction Cost Data, and future cost data are

based on data published by Whitestone Research in The Whitestone Building Maintenance and

Repair Cost Reference 1999, supplemented by industry interviews.

3.8 Floor Covering Alternatives (C3020)

3.8.1 Ceramic Tile with Recycled Windshield Glass (C3020A)

Ceramic tile flooring consists of clay, or a mixture of clay and other ceramic materials, which is

baked in a kiln to a permanent hardness. To improve environmental performance, recycled

windshield glass can be added to the ceramic mix. For the BEES system, 50 year ceramic tile with

75 % recycled windshield glass content, installed using a latex-cement mortar, is studied. The

flow diagram shown in Figure 3.22 shows the elements of ceramic tile with recycled glass

production. The detailed environmental performance data for this product may be viewed by

opening the file C3020A.DBF under the File/Open menu item in the BEES software.

Raw Materials. For a 15 cm x 15 cm x 1.3 cm (6 in x 6 in x 1⁄2 in) ceramic tile with 75 % recycled

glass content, clay and glass are found in the quantities listed in Table 3.37.

Table 3.37 Ceramic Tile with Recycled Glass Constituents

Ceramic Tile w/ Recycled

Glass Constituents Physical Weight

Recycled Glass 475.5 g (17 oz)

Clay 156.9 g (6 oz)

Total: 632.4 g (23 oz)
88

Functional Unit of

Ceramic Tile w/

Recycled Glass

Flooring

Ceramic Tile

Production

Truck

Transport

Mortar

Production

Electricity

Production

Clay Mining Fuel Oil

Production

Coal

Production

Sawdust

Production

Natural

Gas

Production

Diesel Fuel

Production

Electricity

Production

Truck

Transport

(Raw Matl's)

Electricity

Production

Gasoline

Production

Sand

Mining

Portland

Cement

Production

Ceramic Tile w/ Recycled Glass

Recycled

Glass

StyreneButadiene

Production

Styrene

Production

Butadiene

Production

Truck

Transport

Figure 3.22 Ceramic Tile with Recycled Glass Flow Chart

Production requirements for clay are based on the Ecobalance LCA database. The recycled

windshield glass material is environmentally “free.” Burdens associated with glass production

should be allocated to the product with the first use of the glass (vehicle windshields). The

transportation of the glass to the tile facility and the processing of the glass are taken into

account.

The production of mortar (1 part portland cement, 5 parts sand) and styrene-butadiene are based

on the Ecobalance LCA database.

Energy Requirements. The energy requirements for the drying and firing processes of ceramic

tile production are listed in Table 3.38.

Table 3.38 Energy Requirements for Ceramic Tile with Recycled Glass Manufacturing

Fuel Use

Manufacturing

Energy

Total Fossil Fuel 4.19 MJ/kg (1,801 Btu/lb)

 % Coal 9.6

 % Natural Gas* 71.9

 % Fuel Oil 7.8

 % Wood 10.8

* Includes Propane

Emissions. Emissions associated with fuel combustion for tile manufacturing are based on AP-42

emission factors.

Use. Installation of ceramic tile is assumed to require a layer of latex-mortar approximately 1.3

cm (1/2 in) thick. The relatively small amount of latex-mortar between tiles is not included.
89

Ceramic tile with recycled glass is assumed to have a useful life of 50 years.

Refer to section 2.1.3 for indoor air performance assumptions for this product.

Cost. The detailed life-cycle cost data for this product may be viewed by opening the file

LCCOSTS.DBF under the File/Open menu item in the BEES software. Its costs are listed under

BEES code C3020, product code A0. Life-cycle cost data include first cost data (purchase and

installation costs) and future cost data (cost and frequency of replacement, and where appropriate

and data are available, of operation, maintenance, and repair). First cost data are collected from

the R.S. Means publication, 2000 Building Construction Cost Data, and future cost data are

based on data published by Whitestone Research in The Whitestone Building Maintenance and

Repair Cost Reference 1999, supplemented by industry interviews.

3.8.2 Linoleum Flooring (C30202)

Linoleum is a resilient, organic-based floor covering consisting of a backing covered with a thick

wearing surface. For the BEES system, a 2.5 mm (0.098 in) sheet linoleum, manufactured in

Europe, and with a jute backing and an acrylic lacquer finish coat is studied. A styrene-butadiene

adhesive is included for installation. The flow diagram shown in Figure 3.23 shows the elements

of linoleum flooring production. The detailed environmental performance data for this product

may be viewed by opening the file C3020B.DBF under the File/Open menu item in the BEES

software.

Raw Materials. Table 3.39 lists the constituents of 2.5 mm (98 mil) linoleum and their

proportions.

Table 3.39 Linoleum Constituents

Constituent Physical Weight ( %)*Physical Weight

linseed oil 23.3 670 g/m2 (2.2 oz/ft2)

pine rosin 7.8 224 g/m2 (0.7oz/ft2)

limestone 17.7 509 g/m2 (1.7 oz/ft2)

wood flour 30.5 877 g/m2 (2.9 oz/ft2)

cork flour 5.0 144 g/m2 (0.5 oz/ft2)

pigment 4.4 127 g/m2 (0.4 oz/ft2)

backing (jute) 10.9 313 g/m2 (1.0 oz/ft2)

acrylic lacquer 0.35 10 g/m2 (0.03 oz/ft2)

Total: 100.0 2874 g/m2 (9.4 oz/ft2)

*

Jonsson Asa, Anne-Marie Tillman, and Torbjorn Svensson, Life-Cycle Assessment of Flooring Materials, Chalmers

University of Technology, Sweden, 1995.
90

Functional Unit of

Linoleum

Flooring

StyreneButadiene

Production

Ship

Transport

(Linoleum)

Truck

Transport

Linoleum

Production

Electricity

Production

Styrene

Production

Sawdust

Production

Natural

Gas

Production

Electricity

Production

Truck

Transport

(Raw Matl's)

Linoleum

Butadiene

Production

Train

Transport

(Raw Matl's)

Ship

Transport

(Raw Matl's)

Acrylic

Lacquer

Production

Linseed Oil

Production

TiO2

Production

Limestone

Production

Electricity

Production

Cork

Production

Electricity

Production

End-of-Life

Figure 3.23 Linoleum Flow Chart

The cultivation of linseed is based on a United States agricultural model which estimates soil

erosion and fertilizer run-off, 88 with the following inputs: 89

• Fertilizer: 35 kg nitrogen fertilizer per 10,000 m2 (31 lb/acre), 17 kg phosphorous fertilizer

per hectare (15 lb/acre), and 14 kg potassium fertilizer per 10,000 m2 (12 lb/acre)

• Pesticides: 0.5 kg active compounds per hectare (0.4 lb/acre), with 20 % lost to air

• Diesel farm tractor: 0.65 MJ per kg (279 Btu per lb) linseed

• Linseed yield: 600 kg/10,000 m2 (536 lb/acre)

The production of the fertilizers and pesticides is based on the Ecobalance LCA database. The

cultivation of pine trees for pine rosin is based on Ecobalance LCA data for cultivated forestry,

with inventory flows allocated between pine rosin and its coproduct, turpentine. The production

of limestone is based on Ecobalance data for open pit limestone quarrying and processing. Wood

flour is sawdust produced as a coproduct of wood processing. Its production is based on the

Ecobalance LCA database. Cork flour is a coproduct of wine cork production. Cork tree

cultivation is not included but the processing of the cork is included as shown below. Heavy

metal pigments are used in linoleum production. Production of these pigments are modeled based

on the production of titanium dioxide pigment. Jute used in linoleum manufacturing is mostly

grown in India and Bangladesh. Its production is based on the Ecobalance LCA database. The

production of acrylic lacquer is based on the Ecobalance LCA database.

 

88 Ecobalance, Sheehan, J. et al., Life Cycle Inventory of Biodiesel and Petroleum Diesel for Use in an Urban Bus,

NREL/SR-580-24089, prepared for USDA and U.S DoE, May 1998.

89Potting Jose and Kornelis Blok, Life-cycle Assessment of Four Types of Floor Covering, Utrecht University,

The Netherlands, 1994.
91

Energy Requirements. Energy requirements for linseed oil production include fuel oil and steam,

and are allocated on a mass basis between linseed oil (34 %) and linseed cake (66 %). Allocation

is necessary because linseed cake is a co-product of linseed oil production whose energy

requirements should not be included in the BEES data.

Cork Flour production involves the energy requirements as listed in Table 3.40.

Table 3.40 Energy Requirements for Cork Flour Production

Cork Product Electricity Use

Cork Bark 0.06 MJ/kg (26 Btu/lb)

Ground Cork 1.62 MJ/kg (696 Btu/lb)

Linoleum production involves the energy requirements as listed in Table 3.41.

Table 3.41 Energy Requirements for Linoleum Manufacturing

Fuel Use Manufacturing Energy

Electricity 2.3 MJ/kg (989 Btu/lb)

Natural Gas 5.2 MJ/kg (2,235 Btu/lb)

Emissions. Tractor emissions for linseed cultivation are based on the Ecobalance LCA database.

The emissions associated with linseed oil production are allocated on a mass basis between oil (34

%) and cake (66 %).

Since most linoleum manufacturing takes place in Europe, it is assumed to be a European product

in the BEES model. European linoleum manufacturing results in the following air emissions in

addition to those from the energy use:

• Volatile Organic Compounds: 1.6 g/kg (0.025 oz/lb)

• Solvents: 0.94 g/kg (0.015 oz/lb)

• Particulates: 0.23 g/kg (0.004 oz/lb)

Transportation. Transport of linoleum raw materials from point of origin to a European

manufacturing location is shown in Table 3.42.90

Table 3.42 Linoleum Raw Materials Transportation

Raw Material Distance Mode of Transport

linseed oil 4,350 km (2,703 mi)

1,500 km (932 mi)

Ocean Freighter

Train

pine rosin 2,000 km (1,243 mi) Ocean Freighter

limestone 800 km (497 mi) Train

wood flour 600 km (373 mi) Train

cork flour 2,000 km (1,243 mi) Ocean Freighter

 

90 Life-Cycle Assessment of Flooring Materials, Jonsson Asa, Anne-Marie Tillman, & Torbjorn Svensson,

Chalmers University of Technology, Sweden, 1995.
92

pigment 500 km (311 mi) Diesel Truck

backing (jute) 10,000 km (6,214 mi) Ocean Freighter

acrylic lacquer 500 km (311 mi) Diesel Truck

Transport of the finished product from Europe to the United States is included. Transport of the

finished product from the point of U.S. entry to the building site is a variable of the BEES model.

Use. The installation of linoleum requires a styrene-butadiene adhesive. Linoleum flooring has a

useful life of 18 years.

Refer to section 2.1.3 for indoor air performance assumptions for this product.

Cost. The detailed life-cycle cost data for this product may be viewed by opening the file

LCCOSTS.DBF under the File/Open menu item in the BEES software. Its costs are listed under

BEES code C3020, product code B0. Life-cycle cost data include first cost data (purchase and

installation costs) and future cost data (cost and frequency of replacement, and where appropriate

and data are available, of operation, maintenance, and repair). First cost data are collected from

the R.S. Means publication, 2000 Building Construction Cost Data, and future cost data are

based on data published by Whitestone Research in The Whitestone Building Maintenance and

Repair Cost Reference 1999, supplemented by industry interviews.

3.8.3 Vinyl Composition Tile (C3020C)

Vinyl composition tile is a resilient floor covering. Relative to the other types of vinyl flooring

(vinyl sheet flooring and vinyl tile), vinyl composition tile contains a high proportion of inorganic

filler. For the BEES study, vinyl composition tile is modeled with a composition of limestone,

plasticizer, and a copolymer of vinyl chloride-vinyl acetate. A layer of styrene-butadiene adhesive

is used during installation. Figure 3.24 shows the elements of vinyl composition tile production.

The detailed environmental performance data for this product may be viewed by opening the file

C3020C.DBF under the File/Open menu item in the BEES software.

Raw Materials. Table 3.43 lists the constituents of 30 cm x 30 cm x 0.3 cm (12 in x 12 in x 1/8

in) vinyl composition tile and their proportions. A finish coat of acrylic latex is applied to the vinyl

composition tile at manufacture. The thickness of the finish coat is assumed to be 0.025 mm

(0.98 mils). The production of these raw materials, and the styrene-butadiene adhesive, is based

on the Ecobalance LCA database.
93

Vinyl Composition Tile

Electricity

Production

Oxygen

Production

Acetic acid

Production

Ethylene

Production

Electricity

Production

Functional Unit of

Vinyl Comp Tile

StyreneButadiene

Production

Truck

Transport

Vinyl

Composition

Tile

 Production

Electricity

Production

Styrene

Production

Fuel Oil

Production

Butadiene

Production

Acrylic

Lacquer

Production

Plasticizer

Production

Limestone

Production

Electricity

Production

PVC

Production

Polyvinyl

Acetate

Production

Fuel Oil

Production

Electricity

Production

Electricity

Production

Electricity

Production

End-of-Life

Figure 3.24 Vinyl Composition Tile Flow Chart

Table 3.43 Vinyl Composition Tile Constituents

Constituent Physical Weight ( %)

Limestone 84

Vinyl resins:

 10 % vinyl acetate / 90 % vinyl chloride 12

Plasticizer: bis(2-ethylhexyl) phthalate 4

Energy Requirements. Energy requirements for the manufacturing process (mixing,

folding/calendaring, finish coating, and die cutting) are listed in Table 3.44.

Table 3.44 Energy Requirements for Vinyl Composition Tile Manufacturing

Fuel Use

Manufacturing

Energy

Electricity 1.36 MJ / kg (585 Btu/lb)

Natural Gas 0.85 MJ / kg (365 Btu/lb)

Emissions. Emissions associated with the manufacturing process arise from the combustion of

fuel oil and are based on AP-42 emission factors.

Use. Installing vinyl composition tile requires a layer of styrene-butadiene adhesive 0.0025 mm
94

(0.10 mils) thick. The life of the flooring is assumed to be 18 years.

Refer to section 2.1.3 for indoor air performance assumptions for this product.

Cost. The detailed life-cycle cost data for this product may be viewed by opening the file

LCCOSTS.DBF under the File/Open menu item in the BEES software. Its costs are listed under

BEES code C3020, product code C0. Life-cycle cost data include first cost data (purchase and

installation costs) and future cost data (cost and frequency of replacement, and where appropriate

and data are available, of operation, maintenance, and repair). First cost data are collected from

the R.S. Means publication, 2000 Building Construction Cost Data, and future cost data are

based on data published by Whitestone Research in The Whitestone Building Maintenance and

Repair Cost Reference 1999, supplemented by industry interviews.

3.8.4 Composite Marble Tile (C3020D)

Composite marble tile is a type of composition flooring. It is a mixture of polyester resin and

matrix filler that is colored for marble effect and poured into a mold. The mold is then vibrated to

release air and level the matrix. After curing and shrinkage the part is removed from the mold,

trimmed, and polished if necessary. For the BEES system, a 30 cm x 30 cm x 0.95 cm (12 in x 12

in x 3/8 in) tile, installed using a latex-cement mortar, is studied. The flow diagram in Figure 3.25

shows the elements of composite marble tile production. The detailed environmental performance

data for this product may be viewed by opening the file C3020D.DBF under the File/Open menu

item in the BEES software.

Raw Materials Table 3.45 gives the constituents involved in the production of the marble matrix

and their proportions. It is assumed there is no loss of weight during casting.

Table 3.45 Composite Marble Tile Constituents

Constituent Physical Weight

( %)

Resin 23.1

Filler 75.2

Catalyst (MEKP) 0.2

Pigment (TiO2) 1.5

The resin percentage is an average based on data from four sources ranging from 19 % to 26 %

resin content. The remainder of the matrix is composed of filler, catalyst, and pigment. The filler

is the largest portion of the matrix. Since calcium carbonate is the typical filler used for U.S.

composite marble tile production, it is the assumed filler material in the BEES model. The filler is

composed of coarse and fine particles with a ratio of two parts coarse to one part fine. Filler

production involves the mining and grinding of calcium carbonate.
95

Composite Marble Tile

Electricity

Production

Functional Unit of

Composite Marble

Tile

Resin

Production

Truck

Transport

Pigment

 Production

Electricity

Production

Electricity

Production

End-of-Life

Filler

production

Composite Marble

Tile Production

Catalyst

 Production

Electricity

Production

Truck Transport

(Raw Materials)

Mortar

Production

Styrene-Butadiene

Production

Portland

Cement

Production

Sand Mining Gasoline

Production

Styrene

Production

Butadiene

Production

Electricity

Production

Figure 3.25 Composite Marble Tile Flow Chart

Resin is the second-most important ingredient used for the marble matrix. It is an unsaturated

polyester resin cross-linked with styrene monomer. The styrene content is assumed to range from

35 % to 55 %.

The main catalyst used in the United States for the marble matrix is Methyl Ethyl Ketone Peroxide

(MEKP). This catalyst is used as a solvent in the mixture of resin and filler, so is consumed in the

process. Its amount is assumed to be about 1 % of the resin content, or 0.235 % of the total

marble matrix.

A colorant may be used if necessary. The quantity depends on the color required. The colorant is

usually added to the mixture before all the filler has been mixed. For the BEES study, titanium

dioxide at 1 % to 2 % is assumed.

Energy Requirements. Electricity is the only energy consumed in producing and casting the

resin-filler mixture for composite marble tile. Table 3.46 shows electricity use for composite

marble tile manufacturing.

Table 3.46 Energy Requirements for Composite Marble Tile Manufacturing

Fuel Use Manufacturing Energy

Electricity 0.047 MJ/kg (20.25 Btu/lb)

Emissions. The chief emission from composite marble tile manufacturing is fugitive styrene,
96

which arises from the resin constituent and is assumed to be 2 % of the resin input. There could

be some emissions from the solvent, but most manufacturers now use water-based solvents, which

do not release any pollutants.

Use. Installing composite marble tile requires a sub-floor of a compatible type, such as concrete.

A layer of mortar is used at 2.26 kg/0.09 m2 (4.98 lb/ft2), assuming a 1.3 cm (1/2 in) thick layer.

It is assumed that composite marble tile has a useful life of 75 years.

Cost. The detailed life-cycle cost data for this product may be viewed by opening the file

LCCOSTS.DBF under the File/Open menu item in the BEES software. Its costs are listed under

BEES code C3020, product code D0. Life-cycle cost data include first cost data (purchase and

installation costs) and future cost data (cost and frequency of replacement, and where appropriate

and data are available, of operation, maintenance, and repair). First cost data are collected from

the R.S. Means publication, 2000 Building Construction Cost Data, and future cost data are

based on data published by Whitestone Research in The Whitestone Building Maintenance and

Repair Cost Reference 1999, supplemented by industry interviews.

3.8.5 Terrazzo (C3020E)

Epoxy terrazzo is a type of composition flooring. It contains a high proportion of inorganic filler

(principally marble dust and chips), a pigment for aesthetic purposes, and epoxy resin. The

materials are mixed and installed directly on site and, when dry, are carefully polished. Figure

3.26 shows the elements of terrazzo flooring production. The detailed environmental

performance data for this product may be viewed by opening the file C3020E.DBF under the

File/Open menu item in the BEES software.

Raw Materials Table 3.47 lists the constituents of epoxy terrazzo and their proportions.

Table 3.47 Terrazzo Constituents

Terrazzo Constituents Physical Weight ( %)

marble dust 22

epoxy resin 77

pigment (titanium dioxide) 1

The finished floor is assumed to be 9.5 mm (3/8 in) thick. Typical amounts of raw materials used

are as follows: 1.5 kg (3.3 lb) of marble dust and 0.23 kg (0.5 lb) of marble chips per 0.09 m2 (1

ft2), 3.8 L (1 gal) of epoxy resin to cover 0.8 m2 (8.5 ft2) of surface, and depending on customer

selection, from 1 % to 15 % of the total content is pigment.

The production of these raw materials, including the quarrying of marble, is based on the

Ecobalance LCA database. Note that because marble dust is assumed to be a coproduct rather

than a waste byproduct of marble production, a portion of the burdens of marble quarrying is

allocated to marble dust production.
97

Transportation Functional Unit of Epoxy Terrazzo

Terrazzo

Terrazzo

Manufacturing (raw

materials)

Marble Dust &

Chips

Epoxy Resin

Pigments

Energy

Energy Terrazzo

Installation

Energy

Energy

Energy

Figure 3.26 Epoxy Terrazzo Flow Chart

Energy Requirements. The energy requirements for the on-site "manufacturing" process involve

mixing in an 8hp gasoline-powered mixer (a 0.25 m3, or 9 ft3 mixer running for 5 min).

Emissions. Emissions associated with the mixing process arise from the combustion of gasoline

and are based on AP-42 emission factors.

Use. Installing epoxy terrazzo requires a sub-floor of a compatible type, such as concrete. It is

assumed that epoxy terrazzo flooring has a useful life of 75 years.

Cost. The detailed life-cycle cost data for this product may be viewed by opening the file

LCCOSTS.DBF under the File/Open menu item in the BEES software. Its costs are listed under

BEES code C3020, product code E0. Life-cycle cost data include first cost data (purchase and

installation costs) and future cost data (cost and frequency of replacement, and where appropriate

and data are available, of operation, maintenance, and repair). First cost data are collected from

the R.S. Means publication, 2000 Building Construction Cost Data, and future cost data are

based on data published by Whitestone Research in The Whitestone Building Maintenance and

Repair Cost Reference 1999, supplemented by industry interviews.
98

3.8.6 Carpeting – General Information

Carpets are composed of a facing and a backing, which are attached during manufacture. Before

assembly, most carpets fibers are dyed. Adhesives are typically used for commercial installations.

Each of these components is discussed in turn, followed by a discussion of the manufacturing

process.

Carpet facing. Carpets are manufactured from a variety of fibers, usually nylon, polyester, olefin,

or wool.

Carpet dyes. Dyes are applied to textile fibers in a number of ways, depending on the properties

of the fiber, the dye, and the final product. The types of dyes used include inorganic, moralized

organic, acid, dispersed, premetallized, and chrome dyes.

Carpet backing.

• Primary backing – usually made of either woven slit-film polypropylene or synthetic

nonwoven polyester or polyester/nylon.

• Secondary backing – usually a woven or nonwoven fabric reinforcement laminated to the back

of tufted carpeting (often with a styrene butadiene latex adhesive) to enhance dimensional

stability, strength, stretch resistance, lie-flat stiffness, and handling. Most secondary backings

are woven jute, woven polypropylene, or nonwoven polypropylene, although some

manufacturers use propylene-polyethylene and polyvinyl chloride backings. The term

“secondary backing” is sometimes used in a broader sense to include an attached cushion and

other polymeric back coatings. Because secondary backing is visible in finished carpeting

(while primary backing is concealed under the pile yarn), most dealers and installers refer to

the secondary backing simply as “backing”.

Carpet adhesives. Two types of carpet adhesive comprise most of the commercial market – latex

and pressure sensitive adhesives. Low-VOC styrene butadiene latex adhesives are thought to be

an environmentally-friendly adhesive alternative.

Carpet manufacture and fabrication. Carpet manufacture consists of a number of steps,

including formation of the synthetic fibers; dyeing of the fibers; and construction, treatment, and

finishing of the carpet.

• Forming synthetic fibers – nylon, olefin, and polyester are all thermoplastic, melt-spun

synthetic fibers. Synthetic fibers are extruded and solidify as they cool. Post-treatments

generally enhance the physical properties of the fiber. The bundle of fibers is then put through

a crimping or texturizing process, after which it is either chopped into staple fiber or wound

into bulk continuous filament yarn. The yarn may be heat-set to improve its ability to

withstand the stresses of dyeing, finishing, and traffic wear. Heat-setting is performed either

by the autoclave method, in which batches of the yarn are treated with pressurized steam, or

the continuous method, in which the yarn is heat-set in an ongoing manner.
99

• Dyeing fibers – polymer, fiber, or yarn can be dyed before carpet is manufactured by applying

the color through one of several processes:

1. Solution dyeing – involves adding color pigments to the molten polymer prior to

extrusion;

2. Stock dyeing – cut staple fiber is packed into a large kettle after which dye liquid is

forced through the fibers continuously as the temperature is increased. This process is

often used to dye wool fiber;

3. Package dyeing – yarn is wound onto a special perforated cone; or

4. Space dyeing – involves knitting plain circular-knit tubing, which is then printed with

dyestuffs in a multicolored pattern, steamed, washed, extracted, dried, and then

unraveled and rewound into cones.

• Construction, treatment and finishing techniques – several different techniques are used to

attach yarn to the carpet backing. Tufting is by far the most widespread, with weaving,

knitting, fusion bonding, and custom tufting also in use.

1. Tufting – the yarn is stitched through a fabric backing, creating a loop called a tuft;

2. Weaving – carpet looms weave colored pile yarns and backing yarns into a carpet,

which then gets a back coating, usually of latex, for stability;

3. Knitting – carpet knitting machines produce facing and backing simultaneously, with

three sets of needles to loop pile yarn, backing yarn, and stitching yarn together;

4. Fusion bonding – the yarn is embedded between two parallel sheets of adhesive-coated

backing, and the sheets are slit, forming two pieces of cut pile carpet; and

5. Custom tufting – special designs are created using motorized hand tools called singlehanded tufters and pass machines.

Commercial-grade carpet for medium traffic is evaluated for the BEES system. Two applications

are studied: broadloom and carpet tile. The tufting manufacturing process is assumed for all

carpet alternatives. Three face fiber materials are studied: wool, nylon, and recycled polyester

(from soft drink PET bottles). The primary backing for all carpets is comprised of a plastic

compound into which the face yarn is inserted by tufting needles. Also, a coating is applied to the

back of the carpet to secure the face yarns to the primary backing. As carpet manufacturing and

installation are assumed to be similar for the three face fiber options, the corresponding modeling

is displayed only once in this general carpet information section.

Energy Requirements. Table 3.48 displays the energy requirements for tufting carpet. 91

 

91 J. Potting and K. Blok, Life Cycle Assessment of Four Types of Floor Covering , Utrecht University, The

Netherlands, 1994.
100

Table 3.48 Energy Requirements for Carpet Manufacturing

Fuel Type Manufacturing Energy

Electricity 1.80 MJ/m2 (0.046 kW*h/ft2)

Natural gas 8.2 MJ/m2 (0.21 kW*h /ft2)

Emissions. Emissions associated with fuel combustion for carpet manufacture are based on AP42 emission factors.

Use. Glue is typically used for commercial carpet installations. Two glue alternatives are

evaluated: traditional latex glue and low-VOC latex glue. Details on these carpet installation

parameters are given in Table 3.49.

Table 3.49 Carpet Installation Parameters

Parameter Broadloom Tile92

Glue application

 (applies to both

traditional and lowVOC glues)

2 layers:93

• one full layer of glue, spread rate of

1.77 m2/L (8 yd2/gal)

• spots of glue (10 % of full spread

of glue with spread rate of 4.42

m

2

/L, or 20 yd2/gal)

1 layer at 8.8 square

m

2

/L (40 yd2/gal)

Cutting waste 5.7 % 2 %

Data for production of the traditional and low-VOC glues are based on the Ecobalance LCA

database.

3.8.7 Wool Carpet (C3020G,C3020J,C3020M,C3020P)

A 1.13 kg (40 oz) wool carpet with a 25 year life is included in BEES. Figure 3.27 displays the

system under study for wool carpet manufacture. The detailed environmental performance data

for this product may be viewed by opening the following files under the File/Open menu item in

the BEES software:

• C3020G.DBF — Wool Carpet Tile with Traditional Glue

• C3020J.DBF — Wool Carpet Tile with Low-VOC Glue

• C3020M.DBF — Wool Broadloom Carpet with Traditional Glue

• C3020P.DBF — Wool Broadloom Carpet with Low-VOC Glue

 

92 Note that wool carpet tile is not currently manufactured on industrial lines.

93 Spread rates for glue as recommended by the Carpet and Rug Institute.
101

Truck Transport Functional Unit of

Wool Carpet

Glue

Manufacturing

(traditional or lowVOC)

Truck

Transport

(Raw Matl's)

Truck Transport

(Raw Matl's)

Wool Carpet

Manufacturing

Wool Fiber

Mfg

Primary

Backing

Mfg

(PP or

PVC)

Coating

Mfg

Styrene

Butadiene

Production

Filler

Production

Synthetic

Glue Mfg

Figure 3.27 Wool Carpet Flow Chart

Raw materials. Table 3.50 lists the constituents of wool carpet and their amounts.

Table 3.50 Wool Carpet Constituents

Constituent Material

Amount

g/m2 (oz/ft2)

Face fiber Wool 1400 (4.59)

Backing Polypropylene for

broadloom,

PVC for tile

130 (0.43)

Styrene butadiene latex 950 (3.11), including 710 g

(25.04 oz) of limestone as a

filler

The production of the plastic compound for backing, either polypropylene or PVC, and the

production of the styrene butadiene latex are based on the Ecobalance LCA database.

The wool fiber is produced in New Zealand, following the major production steps displayed in

Figure 3.28.
102

Food

Production

Sheep

Raising

and

Shearing

Wool

Scouring

Wool

Drying,

Dyeing,

Blending

Fertilizer

 Production

Wool

Carding

and

Spinning

Figure 3.28 Wool Fiber Production

The material flows included for the production of raw wool are displayed in Table 3.51. 94

Table 3.51 Raw Wool Material Flows

Flow Amount

Inputs:

 - Nitrogen supply (ammonium nitrate) 29 g of nitrogen/kg raw wool (0.46 oz/lb)

 - Phosphate supply (P2O5) 770 g of P2O5/kg raw wool (12.32 oz/lb)

Outputs:

 - Raw wool 5.5 kg (12.13 lb) of raw wool / 8 month period

 - Methane emissions (enteric

fermentation)

8.8 kg (19.4 lb) / head / year

aAverage of data reported in two sources: International Panel on Climate Change for methane, 1993, reports 9.62

kg/head/y and AP-42, Table 14-4-2, gives 8 kg/head/yr.

The fertilizer inputs correspond to the production of food for the sheep. Fertilizer production is

based on the Ecobalance LCA database.

Raw wool is greasy and carries debris that needs to be washed off in a process called “scouring.”

The amount of washed wool per kg of raw wool is 80 %, as shown in Table 3.52 along with other

raw wool constituents.

Table 3.52 Raw Wool Constituents

Constituent Weight ( %)

Clean fiber (ready to be carded and spun) 80

Grease 6

Suint salts 6

Dirt 8

Grease is recovered at an average recovery rate of 40 %.95 The scoured fiber is then dried,

carded, and spun. Table 3.53 lists the main inflows and outflows for the production of wool yarn

from raw wool. 96 The data for raw wool processing are from the Wool Research Organisation of

New Zealand (WRONZ).

 

94 J.Potting and K.Blok, Life Cycle Assessment of Four Types of Floor Covering, Utrecht University, The

Netherlands, 1994.

95 The non-recovered grease exits the system (e.g., as sludge from water effluent treatment).

96 These requirements also include processes such as dyeing and blending which take place at this stage.
103

Table 3.53 Wool Yarn Production Requirements

Flow Amount

Input:

 - Natural Gas 4.3 MJ/kg (1849 Btu/lb)

 - Electricity 0.56 MJ/kg (241 Btu/lb)

 - Lubricant 0.05 kg/kg (0.05 oz/oz)

 - Water 30 L/kg (3.59 gal/lb)

Output:

 - Wool yarn (taking into account material

losses through drying, carding, and

spinning)

0.75 kg/kg (0.75 oz/oz)

-Water emissions corresponding to scouring:

 BOD

 COD

3.3 g/kg (0.053 oz/lb)

9.3 g/kg (0.15 oz/lb)

Most of the required energy is used at the scouring step. As grease is a co-product of the scouring

process, a mass-based allocation is used to determine how much of the energy entering this

process is actually due to the production of washed wool alone.97 One-fourth of the required

energy (about 1MJ, or 948 Btu) is used for drying.98 Energy requirements with regard to wool

carding and spinning are negligible. Water consumption is assumed to be 20 L/kg to 40 L/kg (2.4

gal/lb to 4.8 gal/lb) of greasy wool. Lubricant is added for blending, carding, and spinning. Some

lubricant is incorporated into the wool.

Transportation. Backing and coating raw materials are assumed to travel 402 km (250 mi) to the

carpet manufacturing plant. Wool yarn comes from New Zealand. Table 3.54 displays the

transportation modes and distances the wool travels before being used in the tufting process.

Table 3.54 Wool Transportation

Mode of Transportation Distance

Sea Freighter 11112 km (6,000 nautical miles)

Truck 805 km (500 mi)

Use. Refer to section 2.1.3 for indoor air performance assumptions for this product.

Cost. Purchase and installation costs for wool carpet vary by application (broadloom or tile) and

glue type (traditional or low-VOC). The detailed life-cycle cost data may be viewed by opening

the file LCCOSTS.DBF under the File/Open menu item in the BEES software. Costs are listed

under the following codes

• C3020, G0—Wool Carpet Tile with Traditional Glue

 

97 This allocation is also applied to the non-energy flows for this process.

98 Including dyeing and blending.
104

• C3020, J0—Wool Carpet Tile with Low-VOC Glue

• C3020, M0—Wool Broadloom Carpet with Traditional Glue

• C3020, P0—Wool Broadloom Carpet with Low-VOC Glue

Life-cycle cost data include first cost data (purchase and installation costs) and future cost data

(cost and frequency of replacement, and where appropriate and data are available, of operation,

maintenance, and repair). First cost data are collected from the R.S. Means publication, 2000

Building Construction Cost Data, and future cost data are based on data published by Whitestone

Research in The Whitestone Building Maintenance and Repair Cost Reference 1999,

supplemented by industry interviews.

3.8.8 Nylon Carpet (C3020F,C3020I,C3020L,C3020O)

A 0.68 kg (24 oz) nylon carpet with an 11 year life is included in BEES. Figure 3.29 displays the

system under study for nylon carpet manufacture. The detailed environmental performance data

for this product may be viewed by opening the following files under the File/Open menu item in

the BEES software:

• C3020F.DBF—Nylon Carpet Tile with Traditional Glue

• C3020I.DBF—Nylon Carpet Tile with Low-VOC Glue

• C3020L.DBF—Nylon Broadloom Carpet with Traditional Glue

• C3020O.DBF—Nylon Broadloom Carpet with Low-VOC Glue

Raw Materials. Table 3.55 lists the constituents of nylon carpet and their amounts.

Table 3.55 Nylon Carpet Constituents

Constituent Material Amount

g/m2 (oz/ft2)

Face fiber Nylon 6,6 810 (2.65)

Backing Polypropylene for

broadloom,

PVC for tile

130 (0.43)

Styrene butadiene latex 930 (3.05), including 710 g

(25.04 oz) of limestone as a filler

The production of the plastic compound for backing (either polypropylene or PVC), the styrene

butadiene latex, and the nylon fiber are based on the Ecobalance LCA database.

The spinning of nylon fiber is based on melt extrusion, for which the Association of Plastic

Manufacturers in Europe (APME) is the data source for energy requirements and AP-42 the data

source for emissions. The inputs and outputs of the nylon yarn manufacturing process are

displayed in Table 3.56.
105

Truck Transport Functional Unit of

Nylon Carpet

Glue

Manufacturing

(traditional or

low-VOC)

Truck

Transport

(Raw Matl's)

Truck Transport

(Raw Matl's)

Nylon Carpet

Manufacturing

Nylon Fiber

Mfg

Primary

Backing

Mfg

(PP or

PVC)

Coating

Mfg

Styrene

Butadiene

Production

Filler

Production

Synthetic

Glue Mfg

Figure 3.29 Nylon Carpet Flow Chart

Table 3.56 Nylon Yarn Production Requirements

Flow Amount

Input:

 - Electricity 1.8 MJ/kg (774 Btu/lb)

 - Fuel Oil 0.7 MJ/kg (301 Btu/lb)

 - Natural gas 0.2 MJ/kg (86 Btu/lb)

Output (emissions to the air):

 - Hydrocarbons except methane 2.3 g/kg (0.037 oz/lb)

 - Particulates 0.6 g/kg (0.0096 oz/lb)

Transportation. Transport of raw materials to the carpet manufacturing plant is assumed to

require 402 km (250 mi) by truck.

Use. Refer to section 2.1.3 for indoor air performance assumptions for this product.

Cost. Purchase and installation costs for nylon carpet vary by application (broadloom or tile) and

glue type (traditional or low-VOC). The detailed life-cycle cost data may be viewed by opening

the file LCCOSTS.DBF under the File/Open menu item in the BEES software. Costs are listed

under the following codes:
106

• C3020,F0—Nylon Carpet Tile with Traditional Glue

• C3020,I0—Nylon Carpet Tile with Low-VOC Glue

• C3020,L0—Nylon Broadloom Carpet with Traditional Glue

• C3020,O0—Nylon Broadloom Carpet with Low-VOC Glue

Life-cycle cost data include first cost data (purchase and installation costs) and future cost data

(cost and frequency of replacement, and where appropriate and data are available, of operation,

maintenance, and repair). First cost data are collected from the R.S. Means publication, 2000

Building Construction Cost Data, and future cost data are based on data published by Whitestone

Research in The Whitestone Building Maintenance and Repair Cost Reference 1999,

supplemented by industry interviews.

3.8.9 Recycled Polyester Carpet (C3020H,C3020K,C3020N,C3020Q)

A 0.68 kg (24 oz) carpet with polyester fiber recycled from soft drink bottles (PET) and with an 8

year life is included in BEES. Figure 3.30 displays the system under study for recycled polyester

carpet manufacture. The detailed environmental performance data for this product may be viewed

by opening the following files under the File/Open menu item in the BEES software:

• C3020H.DBF—Recycled Polyester Carpet Tile with Traditional Glue

• C3020K.DBF— Recycled Polyester Carpet Tile with Low-VOC Glue

• C3020N.DBF—Recycled Polyester Broadloom Carpet with Traditional Glue

• C3020Q.DBF—Recycled Polyester Broadloom Carpet with Low-VOC Glue

Raw materials. Table 3.57 lists the constituents of recycled polyester carpet and their amounts.

Table 3.57 Recycled Polyester Carpet Constituents

Constituent Material Amount

g/m2 (oz/ft2)

Face fiber Recycled PET 810 (2.65)

Backing Polypropylene for

broadloom,

PVC for tile

130 (0.43)

Styrene butadiene latex 930 (3.05), including 710 g

(25.04 oz) of limestone as a filler

The production of the plastic compound for backing (either polypropylene or PVC), the styrene

butadiene latex, and the recycled PET fiber are based on the Ecobalance LCA database. The

recycling of PET is modeled as shown in Figure 3.31.
107

Truck Transport Functional Unit of

Recycled PET Carpet

Glue

Manufacturing

(traditional or

low-VOC)

Truck

Transport

(Raw Matl's)

Truck Transport

(Raw Matl's)

Recycled PET

Carpet

Manufacturing

Recycled

PET

Fiber Mfg

Primary

Backing

Mfg

(PP or

PVC)

Coating

Mfg

Styrene

Butadiene

Production

Filler

Production

Synthetic

Glue Mfg

Figure 3.30 Recycled Polyester Carpet Flow Chart

PET Sorting

and Baling collected PET bottles PET Shredding TruckTransport recycled PET

Figure 3.31 Handling and Reclamation of PET

The spinning of the PET fiber is based on melt extrusion, for which the Association of Plastic

Manufacturers in Europe (APME) is the data source for energy requirements and AP-42 the data

source for emissions. The inputs and outputs of the recycled PET yarn manufacturing process are

displayed in Table 3.58.

Table 3.58 Recycled PET Yarn Production Requirements

Flow Amount

Input:

 - Electricity 1.8 MJ/kg (774 Btu/lb)

 - Fuel Oil 0.7 MJ/kg (301 Btu/lb)

 - Natural Gas 0.2 MJ/kg (86 Btu/lb)
108

Output (emissions to the air):

 - Hydrocarbons except methane 0.05 g/kg (0.0008 oz/lb)

 - Particulates 0.03 g/kg (0.00048 oz/lb)

Transportation. Transport of raw materials to the carpet manufacturing plant is assumed to

require 402 km (250 mi) by truck. Another 274 km (170 mi) is added for transport of the recycled

PET from the materials recovery facility to the recycled yarn processing site.

Use. Refer to section 2.1.3 for indoor air performance assumptions for this product.

Cost. Purchase and installation costs for recycled PET carpet vary by application (broadloom or

tile) and glue type (traditional or low-VOC). The detailed life-cycle cost data may be viewed by

opening the file LCCOSTS.DBF under the File/Open menu item in the BEES software. Costs are

listed under the following codes:

• C3020,H0—Recycled Polyester Carpet Tile with Traditional Glue

• C3020,K0— Recycled Polyester Carpet Tile with Low-VOC Glue

• C3020,N0—Recycled Polyester Broadloom Carpet with Traditional Glue

• C3020,Q0—Recycled Polyester Broadloom Carpet with Low-VOC Glue

Life-cycle cost data include first cost data (purchase and installation costs) and future cost data

(cost and frequency of replacement, and where appropriate and data are available, of operation,

maintenance, and repair). First cost data are collected from the R.S. Means publication, 2000

Building Construction Cost Data, and future cost data are based on data published by Whitestone

Research in The Whitestone Building Maintenance and Repair Cost Reference 1999,

supplemented by industry interviews.

3.9 Parking Lot and Driveway Paving Alternatives (G2022,G2031)

3.9.1 Concrete Paving (G2022A, G2022B, G2022C, G2031A, G2031B, G2031C)

For the BEES system, concrete paving consists of a 15 cm (6 in) layer of concrete poured over a

20 cm (8 in) base layer of crushed stone. The three concrete paving alternatives have varying

degrees of fly ash in the portland cement (0 %, 15 %, and 20 % fly ash). Section 3.1 describes

the production of concrete. For the paving alternatives, a compressive strength of 21 MPa (3000

psi) is used. The flow diagram shown in Figure 3.32 shows the elements of concrete paving. The

detailed environmental performance data for concrete paving may be viewed by opening the

following files under the File/Open menu item in the BEES software:

• G2022A.DBF—0 % Fly Ash Content Concrete

• G2022B.DBF—15 % Fly Ash Content Concrete

• G2022C.DBF—20 % Fly Ash Content Concrete
109

Installation Waste

Transportation

(truck)

80-322-483 km sensitivity

(50-200-300 mi)

Concrete

Coarse

Aggregate

Production

Stone Base

Production

Fine

Aggregate

Production

Fly Ash

Transport

Portland

Cement

Production

Figure 3.32 Concrete Paving Flow Chart

Raw Materials. The materials required to produce concrete are given in Section 3.1.

The amount of material used per functional unit (0.09 m2, or 1 ft2of paving for 50 years) is 32.9

kg (72.5 lb) of concrete and 33.3 kg (73.3 lb) of crushed stone.

Energy Requirements. The energy requirements for concrete production are outlined in Section

3.1. The energy required for site preparation and placement of crushed stone is 0.7 MJ/ ft2 of

paving, and the energy required for concrete placement is included in transportation to the site.

Emissions. Emissions associated with the manufacture of concrete are based on primary data

from the portland cement industry as described in Section 3.1. In addition, for the concrete

paving option, upstream emissions data for the production of fuels and electricity are added to the

industry emissions data.

Transportation. Transport of raw materials is taken into account. Transport of the concrete to

the building site is a variable of the BEES model.

Use. A light-colored paving material, such as concrete, will contribute less to the “urban heat

island” effect than a dark-colored paving material, such as asphalt. These differences are not

accounted for in BEES, but should be factored into interpretation of the results.

Cost. The detailed life-cycle cost data for concrete paving may be viewed by opening the file

LCCOSTS.DBF under the File/Open menu item in the BEES software. Costs are listed under the
110

following codes:

• G2022,A0—0 % Fly Ash Content Concrete Parking Lot Paving

• G2022,B0—15 % Fly Ash Content Concrete Parking Lot Paving

• G2022,C0—20 % Fly Ash Content Concrete Parking Lot Paving

• G2031,A0—0 % Fly Ash Content Concrete Driveways

• G2031,B0—15 % Fly Ash Content Concrete Driveways

• G2031,C0—20 % Fly Ash Content Concrete Driveways

Life-cycle cost data include first cost data (purchase and installation costs) and future cost data

(cost and frequency of replacement, and where appropriate and data are available, of operation,

maintenance, and repair). First cost data are collected from the R.S. Means publication, 2000

Building Construction Cost Data, and future cost data are based on data published by Whitestone

Research in The Whitestone Building Maintenance and Repair Cost Reference 1999,

supplemented by industry interviews.

3.9.2 Asphalt Parking Lot Paving with GSB88 Asphalt Emulsion Maintenance (G2022D)

For the BEES system, asphalt parking lot paving consists of a 22 cm (8.75 in) thick layer of

asphalt (a 6 cm , or 2.5 in, wearing course over a 16 cm, or 6.25, in binder course) over a 20 cm

(8 in) layer of crushed stone with maintenance over 50 years.99 The GSB88 Emulsified SealerBinder produced by Asphalt Systems, Inc. of Salt Lake City, Utah is one of two maintenance

alternatives studied. GSB88 Emulsifier Sealer-Binder is a high-resin-content emulsifier made from

naturally occurring asphalt. This maintenance product is applied to the base asphalt every four

years to prevent oxidation and cracking. The flow diagram in Figure 3.33 shows the elements of

asphalt paving with GSB88 emulsion maintenance. The detailed environmental performance data

for this product may be viewed by opening the file G2022D.DBF under the File/Open menu item

in the BEES software.

Raw Materials. The materials required to produce the asphalt layer are shown in Table 3.59. The

production of the raw materials required for the pavement and the emulsifier is based on the

Ecobalance database.

The amount of material used per functional unit (0.09 m2, or 1 ft2 of paving for 50 years) is 48 kg

(106 lb) of asphalt , 33.3 kg (73.3 lb) of crushed stone, and 12 installments of the GSB88

emulsion maintenance at 0.374 kg (0.82 lb) each (for a total of 4.48 kg, or 9.8 lb of GSB88

 

99 While the combined asphalt binder and wearing course is thicker than commonly used, BEES asphalt paving

specifications are structurally equivalent to those for BEES concrete paving to which it is compared. Equivalent

thicknesses provided by Scott Tarr, Construction Technology Laboratories, Inc., May 2000 and based on American

Association of State Highway and Transportation Officials (AASHTO) design equations.
111

Installation Waste

Transportation

(truck)

80-322-483 km sensitivity

(50-200-300 mi)

Diesel Fuel

Production &

Use in Installation

Base Layer

Hot Mix

Asphalt Tack Coat

Asphalt

Production

Gravel

Production

Diesel Fuel

Production

Natural Gas

Production

HCl

Production

Emulsifier

Production

Asphalt

Production

Asphalt

Emulsion

HCl

Production

Emulsifier

Production

Asphalt

Production

Gilsonite

Production

Sand

Production

Detergent

Production

Light Fuel Oil

Production

Stone Base

Production

Figure 3.33 Asphalt with GSB88 Emulsion Maintenance Flow Chart

Table 3.59 Raw Materials for Asphalt Base Layer

Constituent

Percent of

Base Layer

(by weight)

Percent of

Component

(by weight)

 - Hot Mix Asphalt (binder course) 71.4

 - Gravel 95

 - Asphalt 5

 - Hot Mix Asphalt (wearing course) 28.5

 - Gravel 94

 - Asphalt 6

 - Tack Coat 0.1

 - Asphalt 66

 - Water 33

 - Emulsifier 1.1

 - HCl 0.2

asphalt emulsion maintenance over 50 years).

Energy Requirements. The energy requirements for producing the base layer’s hot mix asphalt,

for installing the base layer, and for applying the GSB88 emulsion maintenance are listed in Table

3.60.
112

Table 3.60 Energy Requirements for Asphalt Paving with GSB88 Emulsion Maintenance

Fuel Use Energy Use

Hot Mix Asphalt Production:

 - Diesel 0.017 MJ/kg (7.3 Btu/lb)

 - Natural Gas 0.29 MJ/kg (124.7 Btu/lb)

Site Prep. and Stone Base Placement

- Diesel 0.7 MJ/ ft2

Asphalt (binder course) Installation:

 - Diesel 0.96 MJ/ ft2

Asphalt (wearing course) Installation:

 - Diesel 0.48 MJ/ ft2

Emulsion Maintenance:

 - Diesel 0.000945 MJ/ ft2

Emissions. Emissions associated with the manufacture of hot mix asphalt are based on U.S. EPA

AP-42 emission factors. Emissions from the production of the upstream materials and energy

carriers are from the Ecobalance database.

Transportation. Transport of the raw materials is taken into account. Transport of asphalt to the

building site is a variable of the BEES model.

Cost. The detailed life-cycle cost data for this product may be viewed by opening the file

LCCOSTS.DBF under the File/Open menu item in the BEES software. Its costs are listed under

BEES code G2022, product code D0. Life-cycle cost data include first cost data (purchase and

installation costs) and future cost data (cost and frequency of replacement, and where appropriate

and data are available, of operation, maintenance, and repair). First cost data are collected from

the R.S. Means publication, 2000 Building Construction Cost Data, and future cost data are

based on data published by Whitestone Research in The Whitestone Building Maintenance and

Repair Cost Reference 1999, supplemented by industry interviews.

3.9.3 Asphalt Parking Lot Paving with Asphalt Cement Maintenance (G2022E)

For the BEES system, asphalt parking lot paving consists of a 22 cm (8.75 in) thick layer of

asphalt (a 6 cm , or 2.5 in, wearing course over a 16 cm, or 6.25, in binder course) over a 20 cm

(8 in) layer of crushed stone with maintenance over 50 years.100 Asphalt cement maintenance is

one of two maintenance alternatives studied. Asphalt cement maintenance involves milling the

existing 6 cm (2.5 in) asphalt wearing course then topping with a fresh 6 cm (2.5 in) layer of

asphalt cement every 8 years. The flow diagram shown in Figure 3.34 shows the elements of

asphalt paving with asphalt cement maintenance. The detailed environmental performance data

 

100 While the combined asphalt binder and wearing course is thicker than commonly used, BEES asphalt paving

specifications are structurally equivalent to those for BEES concrete paving to which it is compared. Equivalent

thicknesses provided by Scott Tarr, Construction Technology Laboratories, Inc., May 2000 and based on American

Association of State Highway and Transportation Officials (AASHTO) design equations.
113

for this product may be viewed by opening the file G2022E.DBF under the File/Open menu item

in the BEES software.

Installation Waste

Transportation

(truck)

80-322-483 km sensitivity

(50-200-300 mi)

Diesel Fuel

Production &

Use in Installation

Base Layer

Hot Mix

Asphalt Tack Coat

Asphalt

Production

Gravel

Production

Diesel Fuel

Production

Natural Gas

Production

HCl

Production

Emulsifier

Production

Asphalt

Production

Asphalt

Cement

Hot Mix

Asphalt Tack Coat

Asphalt

Production

Gravel

Production

Diesel Fuel

Production

Natural Gas

Production

HCl

Production

Emulsifier

Production

Asphalt

Production

Stone Base

Production

Figure 3.34 Asphalt with Asphalt Cement Maintenance Flow Chart

Raw Materials. The materials required to produce the asphalt base layer are identical to those

given in the previous section. The materials required to produce the asphalt cement maintenance

product are shown in Table 3.61.

The production of the raw materials required for both the pavement and its maintenance is based

on the Ecobalance database.

Table 3.61 Raw Materials for Asphalt Cement Maintenance

Constituent

Percent of

Base Layer

(by weight)

Percent of

Component

(by weight)

Asphalt Cement:

 - Hot Mix Asphalt 99.4

 - Gravel 95

 - Asphalt 5

 - Tack Coat 0.6

 - Asphalt 66

 - Water 33

 - Emulsifier 1.1

 - HCl 0.2
114

The amount of material used per functional unit (0.09 m2, or 1 ft2 of paving for 50 years) is 48 kg

(106 lb) of asphalt, 33.3 kg (73.3 lb) of crushed stone, and 6 installments of the asphalt cement

maintenance at 13.7 kg (30.3 lb) each (for a total of 82.4 kg, or 181.8 lb of asphalt cement

maintenance over 50 years).

Energy Requirements. The energy requirements for producing and installing the original layer

of hot mix asphalt over a crushed stone base are shown in Table 3.60. The energy requirements

for the asphalt cement maintenance are listed in Table 3.62.

Table 3.62 Energy Requirements for Asphalt Cement Maintenance

Fuel Use Energy

Diesel 0.72 MJ/ ft2

Emissions. Emissions associated with the manufacture of hot mix asphalt are based on U.S. EPA

AP-42 emission factors. Emissions from the production of the upstream materials and energy

carriers are from the Ecobalance database.

Transportation. Transport of the raw materials is taken into account. Transport of asphalt to the

building site is a variable of the BEES model.

Cost. The detailed life-cycle cost data for this product may be viewed by opening the file

LCCOSTS.DBF under the File/Open menu item in the BEES software. Its costs are listed under

BEES code G2022, product code E0. Life-cycle cost data include first cost data (purchase and

installation costs) and future cost data (cost and frequency of replacement, and where appropriate

and data are available, of operation, maintenance, and repair). First cost data are collected from

the R.S. Means publication, 2000 Building Construction Cost Data, and future cost data are

based on data published by Whitestone Research in The Whitestone Building Maintenance and

Repair Cost Reference 1999, supplemented by industry interviews.

3.9.4 Asphalt Driveway Paving with Sealer Maintenance (G2031D)

For the BEES system, asphalt driveway paving consists of a 22 cm (8.75 in) thick layer of asphalt

(a 6 cm , or 2.5 in, wearing course over a 16 cm, or 6.25, in binder course) over a 20 cm (8 in)

layer of crushed stone with maintenance over 50 years.101 Asphalt driveway sealer maintenance

involves adding a coat of sealer every 4 years. The flow diagram shown in Figure 3.35 shows the

elements of asphalt paving with sealer maintenance. The detailed environmental performance data

for this product may be viewed by opening the file G2031D.DBF under the File/Open menu item

in the BEES software.

 

101 While the combined asphalt binder and wearing course is thicker than commonly used, BEES asphalt paving

specifications are structurally equivalent to those for BEES concrete paving to which it is compared. Equivalent

thicknesses provided by Scott Tarr, Construction Technology Laboratories, Inc., May 2000 and based on American

Association of State Highway and Transportation Officials (AASHTO) design equations.
115

Installation Waste

Transportation

(truck)

80-322-483 km sensitivity

(50-200-300 mi)

Diesel Fuel

Production &

Use in Installation

Base Layer

Hot Mix

Asphalt Tack Coat

Asphalt

Production

Gravel

Production

Diesel Fuel

Production

Natural Gas

Production

HCl

Production

Emulsifier

Production

Asphalt

Production

Driveway

Sealer

Emulsifier

Production

Asphalt

Production

Acrylic Resin

Production

Detergent

Production

Ammonia

Production

Stone Base

Production

Figure 3.35 Asphalt with Sealer Maintenance Flow Chart

Raw Materials. The materials required to produce the asphalt base layer are identical to those

shown in the section above, Asphalt Parking Lot Paving with Asphalt Emulsion Maintenance.

The materials required to produce the driveway sealer are shown in Table 3.63.

Table 3.63 Raw Materials for Driveway Sealer

Constituent

Percent of Sealer

(by weight)

 - Asphalt 47.5

 - Water 39.6

 - Acrylic Resin 11

 - Detergent 0.6

 - Emulsifier 0.6

 - Ammonia 0.1

The production of the raw materials required for both the asphalt base layer and the sealer are

based on the Ecobalance database.

The amount of material used per functional unit (0.09 m2, or 1 ft2 of paving for 50 years) is 48 kg

(106 lb) of asphalt, 33.3 kg (73.3 lb) of crushed stone, and 12 installments of the driveway sealer

maintenance at 0.054 kg (0.12 lb) each (for a total of 0.65 kg, or 1.4 lb of driveway sealer

maintenance over 50 years).
116

Energy Requirements. The energy requirements for producing and installing the base layer’s hot

mix asphalt are listed in Table 3.60. The energy required for installing the asphalt sealer is shown

in Table 3.64.

Table 3.64 Energy Requirements for Asphalt Sealer Maintenance

Fuel Use Energy

Diesel 0.000945 MJ/ ft2

Emissions. Emissions associated with the manufacture of hot mix asphalt are based on U.S. EPA

AP-42 emission factors. Emissions from the production of the upstream materials and energy

carriers are from the Ecobalance database.

Transportation. Transport of the raw materials is taken into account. Transport of the asphalt to

the building site is a variable of the BEES model.

Cost. The detailed life-cycle cost data for this product may be viewed by opening the file

LCCOSTS.DBF under the File/Open menu item in the BEES software. Its costs are listed under

BEES code G2031, product code D0. Life-cycle cost data include first cost data (purchase and

installation costs) and future cost data (cost and frequency of replacement, and where appropriate

and data are available, of operation, maintenance, and repair). First cost data are collected from

the R.S. Means publication, 2000 Building Construction Cost Data, and future cost data are

based on data published by Whitestone Research in The Whitestone Building Maintenance and

Repair Cost Reference 1999, supplemented by industry interviews.
117

4. BEES Tutorial

To balance the environmental and economic performance of building products, follow three main

steps:

1. Set your study parameters to customize key assumptions

2. Define the alternative building products for comparison. BEES results may be

computed once alternatives are defined.

3. View the BEES results to compare the overall environmental/economic

performance balance for your alternatives.

4.1 Setting Parameters

Select Analysis/Set Parameters from the BEES Main Menu to set your study parameters. A

window listing these parameters appears, as shown in Figure 4.1. Move around this window by

pressing the Tab key.

BEES uses importance weights to combine environmental and economic performance measures

into a single performance score. If you prefer not to weight the environmental and economic

performance measures, select the “no weighting” option. In this case, BEES will compute and

display only disaggregated performance results.

Assuming you have chosen to weight BEES results, you are asked to enter your relative

preference weights for environmental versus economic performance. These values must sum to

100. Enter a value between 0 and 100 for environmental performance reflecting your percentage

weighting. For example, if environmental performance is all-important, enter a value of 100. The

corresponding economic preference weight is automatically computed. Next you are asked to

select your relative preference weights for the environmental impact categories included in the

BEES environmental performance score: Global Warming Potential, Acidification Potential,

Eutrophication Potential, Natural Resource Depletion, Indoor Air Quality, and Solid Waste. (For

a select group of products, BEES 2.0 also includes Ecological Toxicity, Human Toxicity, Ozone

Depletion, and Smog. These “expanded impact” products are identified in Table 4.1.) You are

presented with four sets of alternative weights. You may choose to define your own set of

weights, or select a built-in weight set derived from an EPA Scientific Advisory Board study, a

Harvard University study, or a set of equal weights. Press View Weights to display the impact

category weights for all four weight sets, as shown in Figure 4.2. If you select the user-defined

weight set, you will be asked to enter weights for all impacts, as shown in Figure 4.3. These

weights must sum to 100.
118

Figure 4.1 Setting Analysis Parameters
119

Figure 4.2 Viewing Impact Category Weights

Figure 4.3 Entering User-Defined Weights
120

Finally, enter the real (excluding inflation) discount rate for converting future building product

costs to their equivalent present value. All future costs are converted to their equivalent present

values when computing life-cycle costs. Life-cycle costs form the basis of the economic

performance scores. The higher the discount rate, the less important to you are future building

product costs such as repair and replacement costs. The maximum value allowed is 20 %. A

discount rate of 20 % would value each dollar spent 50 years hence as only $0.0001 in present

value terms. The 2000 rate mandated by the U.S. Office of Management and Budget for most

Federal projects, 4.2 %, is provided as a default value.102

4.2 Defining Alternatives

Figure 4.4 Selecting Building Element for BEES Analysis

Select Analysis/Define Alternatives from the Main Menu to select the alternative building

products you want to compare. A window appears as in Figure 4.4.

Selecting alternatives is a two-step process.

1. Select the building element for which you want to compare alternatives.

Building elements are organized using the hierarchical structure of the ASTM

 

102 Office of Management and Budget (OMB) Circular A-94, Guidelines and Discount Rates for Benefit-Cost

Analysis of Federal Programs, Washington, DC, October 27, 1992 and OMB Circular A-94, Appendix C,

February 2000.
121

standard UNIFORMAT II classification system.103 Click on the down arrows

to display the complete lists of available choices at each level of the hierarchy.

BEES 2.0 contains environmental and economic performance data for 65

products across 15 building elements: slabs on grade, basement walls, beams,

columns, roof sheathing, exterior wall finishes, wall insulation, wall sheathing,

framing, roof coverings, ceiling insulation, interior wall finishes, floor

coverings, parking lot paving, and driveways. Press Ok to select the choice in

view.

2. Once you have selected the building element, you are presented with a window

of product alternatives available for BEES scoring, such as in Figure 4.5.

Select an alternative with a mouse click. You must select at least two

alternatives. After selecting each alternative, you will be presented with a

window, such as in Figure 4.6, asking for the assumed distance for transporting

the product from the manufacturing plant to your building site.104

Figure 4.5 Selecting Building Product Alternatives

 

103 American Society for Testing and Materials, Standard Classification for Building Elements and Related

Sitework--UNIFORMAT II, ASTM Designation E 1557-96, West Conshohocken, PA, 1996.

104 If you have chosen the wall insulation element, you will first be asked for parameter values so that heating

and cooling energy use over the 50-year study period can be properly estimated. If you have chosen roof coverings

and installation will be in a U.S. Sunbelt climate, you will be asked for parameter values that will permit

accounting of 50-year heating and cooling energy use based on roof covering color. If you have chosen concrete

beams or columns, you will be asked for assumed compressive strength.
122

Figure 4.6 Setting Transportation Parameters

If you have already set your study parameters, press Compute BEES Results to compute and

display the BEES environmental and economic performance results.

4.3 Viewing Results

Once you have set your study parameters, defined your product alternatives, and computed BEES

results, BEES displays the window for selecting BEES reports illustrated in Figure 4.7. By

default, the three summary graphs shown in Figures 4.8, 4.9, and 4.10 are selected for display or

printing. For all BEES graphs, the larger the value, the worse the performance. Also, all BEES

graphs are stacked bar graphs, meaning the height of each bar represents a summary performance

score consisting of contributing scores represented as its stacked bars.

1. The Overall Performance Results graph displays the weighted environmental

and economic performance scores and their sum, the overall performance

score. If you chose not to weight, this graph is not available.

2. The Environmental Performance Results graph displays the weighted

environmental impact category scores and their sum, the environmental

performance score. On this graph, if an alternative performs worst with respect

to all environmental impact categories, it receives a score of 100, the worst

possible score. If you chose not to weight, this graph is not available.

3. The Economic Performance Results graph displays the initial cost, discounted

future costs and their sum, the life-cycle cost.
123

BEES results are derived by using the BEES methodology to combine the BEES environmental

and economic performance data using your study parameters. The methodology is described in

section 2. The detailed BEES environmental and economic performance data, documented in

section 3, may be browsed by selecting File/Open from the Main Menu.

From the window for selecting BEES reports, you may choose to display a summary table

showing the derivation of summary scores, graphs depicting results by life-cycle stage and by

contributing flow for each environmental impact category, graphs depicting embodied energy

performance, and an All Tables in One option reporting detailed results in tabular form. Figures

4.11 through 4.15 illustrate each of these options105.

To compare BEES results based on different parameter settings, either bring the summary table in

focus and select Analysis/Set Parameters from the Main Menu, or press the Change Parameters

button on the summary table. Change your parameters, and press Ok. You may now display

reports based on your new parameters. You may find it convenient to view reports with different

parameter settings side-by-side by selecting Window/Tile from the Main Menu. Note that

parameter settings are displayed on the table corresponding to each graph.

4.4 Browsing Environmental and Economic Performance Data

The BEES environmental and economic performance data may be browsed by selecting File/Open

from the Main Menu. Environmental data files are specific to products, while there is a single

economic data file, LCCOSTS.DBF, with cost data for all products. As explained in section 3,

some environmental data files map to a product in more than one application, while the economic

data vary for each application. Table 4.1 lists the products by environmental data file name (all

with the .DBF extension) and by code number within the economic performance data file

LCCOSTS.DBF. Table 4.1 also indicates the number of environmental impacts available for

scoring for each product.106

The environmental performance data files are similarly structured, with 3 simulations in each. The

first column in all these files, “Xport,” shows compressive strength (in MPa) for concrete

products except concrete paving, or transportation distance from manufacture to use (in miles) for

all other products. All files contain 3 sets of inventory data corresponding to the 3 simulations.

For each simulation, the environmental performance data file lists a number of environmental

flows. Flows marked “(r)” are raw materials inputs, “(a)” air emissions, “(ar)”

 

105 Detailed results for the Indoor Air Quality impact are not reported because this impact is evaluated

differently for each relevant building element. Refer to section 2.1.3 for detailed Indoor Air Quality results, and

look for summary Indoor Air Quality scores in the BEES summary reports.

106 Since floor coverings includes a mixture of six- and ten-impact products, if a six-impact product is selected

for BEES analysis together with a ten-impact product, both will be scored based on six impacts. Thus, linoleum

and vinyl composition tile may be scored based on ten impacts only by selecting these products alone.
124

Figure 4.7 Selecting BEES Reports

radioactive air emissions, “(w)” water effluents, “(wr)” radioactive water effluents, “(s)” releases

to soil, and “E” energy usage. All quantities for concrete products except paving concrete are

given per 0.76 m3 (1 yd3) of concrete over 50 years of use, and for all other building products,

including concrete paving, per 0.09 m2 (1 ft2) of product over 50 years of use. The column labeled

“Total” is the primary data column, giving total flow amounts. Next are columns giving flow

amounts for each product component, followed by columns giving flow amounts for each lifecycle stage. The product component columns sum to the total column, as do the life-cycle stage

columns. The Iaindex column is for internal BEES use.

The economic performance data file LCCOSTS.DBF lists for each cost the year of occurrence

(counting from year 0) and amount (in 2000 dollars) per 0.76 m3 (1 yd3) for concrete products
125

Figure 4.8 Viewing BEES Overall Performance Results

Figure 4.9 Viewing BEES Environmental Performance Results
126

 Figure 4.10 Viewing BEES Economic Performance Results

Figure 4.11 Viewing BEES Summary Table
127

Figure 4.12 Viewing BEES Environmental Impact Category Performance Results by LifeCycle Stage
128

Figure 4.13 Viewing BEES Environmental Impact Category Performance Results

Contributing by Flow
129

Figure 4.14 Viewing BEES Embodied Energy Results
130

Figure 4.15 A Sampling of BEES “All Tables In One” Display
131

Table 4.1 BEES Products Keyed to Environmental and Economic Performance Data Codes

Individual Element BEES Product

Number

Impacts

Environmental Data File

Name

Economic Data

Code

Slab on Grade 100 % Cement Content Concrete 6 A1030A A1030,A0

Slab on Grade 15 % Fly Ash Content Concrete 6 A1030B A1030,B0

Slab on Grade 20 % Fly Ash Content Concrete 6 A1030C A1030,C0

Slab on Grade 20 % Slag Content Concrete 6 A1030D A1030,D0

Slab on Grade 35 % Slag Content Concrete 6 A1030E A1030,E0

Slab on Grade 50 % Slag Content Concrete 6 A1030F A1030,F0

Basement Walls 100 % Cement Content Concrete 6 A1030A A2020,A0

Basement Walls 15 % Fly Ash Content Concrete 6 A1030B A2020,B0

Basement Walls 20 % Fly Ash Content Concrete 6 A1030C A2020,C0

Basement Walls 20 % Slag Content Concrete 6 A1030D A2020,D0

Basement Walls 35 % Slag Content Concrete 6 A1030E A2020,E0

Basement Walls 50 % Slag Content Concrete 6 A1030F A2020,F0

Beams 100 % Cement Content Concrete 6 A1030A B1011,A0

Beams 15 % Fly Ash Content Concrete 6 A1030B B1011,B0

Beams 20 % Fly Ash Content Concrete 6 A1030C B1011,C0

Beams 20 % Slag Content Concrete 6 A1030D B1011,D0

Beams 35 % Slag Content Concrete 6 A1030E B1011,E0

Beams 50 % Slag Content Concrete 6 A1030F B1011,F0

Columns 100 % Cement Content Concrete 6 A1030A B1012,A0

Columns 15 % Fly Ash Content Concrete 6 A1030B B1012,B0

Columns 20 % Fly Ash Content Concrete 6 A1030C B1012,C0

Columns 20 % Slag Content Concrete 6 A1030D B1012,D0

Columns 35 % Slag Content Concrete 6 A1030E B1012,E0

Columns 50 % Slag Content Concrete 6 A1030F B1012,F0

Roof Sheathing Oriented Strand Board 6 B1020A B1020,A0

Roof Sheathing Plywood 6 B1020B B1020,B0

Exterior Wall Finishes Brick & Mortar 6 B2011A B2011,A0

Exterior Wall Finishes Stucco 6 B2011B B2011,B0

Exterior Wall Finishes Aluminum Siding 6 B2011C B2011,C0

Exterior Wall Finishes Cedar Siding 6 B2011D B2011,D0

Exterior Wall Finishes Vinyl Siding 6 B2011E B2011,E0

Wall Insulation R-13 Blown Cellulose 6 B2012A B2012,A0

Wall Insulation R-11 Fiberglass Batt 6 B2012B B2012,B0

Wall Insulating R-15 Fiberglass Batt 6 B2012C B2012,C0

Wall Insulation R-12 Blown Mineral Wool 6 B2012D B2012,D0

Wall Insulation R-13 Fiberglass Batt 6 B2012E B2012,E0

Framing Steel 6 B2013A B2013,A0

Framing Wood 6 B2013B B2013,B0

Wall Sheathing Oriented Strand Board 6 B1020A B2015,A0

Wall Sheathing Plywood 6 B1020B B2015,B0

Roof Coverings Asphalt Shingle 6 B3011A B3011,A0

Roof Coverings Clay Tile 6 B3011B B3011,B0

Roof Coverings Fiber Cement Shingle 6 B3011C B3011,C0

Ceiling Insulation R-30 Blown Cellulose 6 B3012A B3012,A0

Ceiling Insulation R-30 Fiberglass Batt 6 B3012B B3012,B0

Ceiling Insulation R-30 Blown Mineral Wool 6 B3012C B3012,C0

Ceiling Insulation R-30 Blown Fiberglass 6 B3012D B3012,D0

Interior Wall Finishes Virgin Latex Paint 7 C3012A C3012,A0
132

Interior Wall Finishes Recycled Latex Paint 7 C3012B C3012,B0

Floor Coverings Ceramic Tile with Recycled Glass 6 C3020A C3020,A0

Floor Coverings Linoleum 10 C3020B C3020,B0

Floor Coverings Vinyl Composition Tile 10 C3020C C3020,C0

Floor Coverings Composite Marble Tile 6 C3020D C3020,D0

Floor Coverings Terrazzo 6 C3020E C3020,E0

Floor Coverings Nylon Carpet Tile w/Traditional Glue 6 C3020F C3020,F0

Floor Coverings Wool Carpet Tile w/Traditional Glue 6 C3020G C3020,G0

Floor Coverings Recycled Polyester Tile w/Traditional

Glue

6 C3020H C3020,H0

Floor Coverings Nylon Carpet Tile w/Low-VOC Glue 6 C3020I C3020,I0

Floor Coverings Wool Carpet Tile w/Low-VOC Glue 6 C3020J C3020,J0

Floor Coverings Recycled Polyester Tile w/Low-VOC

Glue

6 C3020K C3020,K0

Floor Coverings Nylon Broadloom Carpet w/Traditional

Glue

6 C3020L C3020,L0

Floor Coverings Wool Broadloom Carpet w/Traditional

Glue

6 C3020M C3020,M0

Floor Coverings Recycled Polyester Broadloom

w/Traditional Glue

6 C3020N C3020,N0

Floor Coverings Nylon Broadloom Carpet w/Low-VOC

Glue

6 C3020O C3020,O0

Floor Coverings Wool Broadloom Carpet w/Low-VOC

Glue

6 C3020P C3020,P0

Floor Coverings Recycled Polyester Broadloom Carpet

w/Low-VOC Glue

6 C3020Q C3020,Q0

Parking Lot Paving 100 % Cement Content Concrete 10 G2022A G2022,A0

Parking Lot Paving 15 % Fly Ash Content Concrete 10 G2022B G2022,B0

Parking Lot Paving 20 % Fly Ash Content Concrete 10 G2022C G2022,C0

Parking Lot Paving Asphalt w/GSB88 Emulsified SealerBinder Maintenance10 G2022D G2022,D0

Parking Lot Paving Asphalt w/Cement Maintenance 10 G2022E G2022,E0

Driveways 100 % Cement Content Concrete 10 G2022A G2031,A0

Driveways 15 % Fly Ash Content Concrete 10 G2022B G2031,B0

Driveways 20 % Fly Ash Content Concrete 10 G2022C G2031,C0

Driveways Asphalt w/Sealer Maintenance 10 G2031D G2031D

over 50 years of use (except concrete paving), and cost (in 2000 dollars) per 0.09 m2 (1 ft2) for all

other products, including concrete paving, over 50 years of use.

Warning: If you change any of the data in the environmental or economic performance data files,

you will need to reinstall BEES to restore the original BEES data.
133

5. Future Directions

Development of the BEES tool does not end with the release of version 2.0. Plans to expand and

refine BEES include releasing updates every 12 months to 18 months with model and software

enhancements as well as expanded product coverage. A BEES training program is also being

considered. Listed below are a number of directions for future research that have been proposed

in response to obvious needs and through feedback from the 1300 BEES 1.0 users:

Proposed Model Enhancements

• Combine building products to permit comparative analyses of entire building components,

assemblies, and ultimately entire buildings

• Based on input from homebuilders, residential designers, and product suppliers, tailor the

BEES tool to the residential sector (results of this effort may be disseminated as a separate

software tool)

• Conduct and apply research leading to the refinement of indoor air performance measurement

and to the inclusion of more environmental impacts for all BEES products, such as ecological

toxicity, human toxicity, ozone depletion, smog, and land use.

• Update the BEES LCA methodology in line with future advances in the evolving LCA field,

such as the anticipated development of national benchmarks for scoring environmental impacts

• Add a third performance measure to the overall performance score—product technical

performance

• Characterize uncertainty in the underlying environmental and cost data, and reflect this

uncertainty in BEES performance scores

Proposed Data Enhancements

• Solicit cooperation from industry to include, manufacturer-specific building products in BEES

version 3.0 (known as the "BEES Please" program)

• Add generic building products covering many more building elements, and add more products

to currently covered elements

• Refine all data to permit U.S. region-specific BEES analyses. This enhancement would yield

BEES results tailored to regional fuel mixes and labor and material markets, and would permit

inclusion of local environmental impacts such as locally scarce resources (e.g., water)

• Permit flexibility in study period length and in product specifications such as useful lives.

• Every five years, revisit products included in previous BEES releases for updates to their

environmental and cost data

• In support of the U.S. EPA Environmentally Preferable Purchasing Program, add key nonbuilding products to the BEES tool to assist the Federal procurement community in carrying

out the mandate of Executive Order 13101 (results of this effort may be disseminated as a

separate software tool)

Proposed Software Enhancements

• Add feature permitting users to easily enter their own environmental and cost data for BEES

analysis

• Add feature permitting integrated sensitivity analysis so that the effect on BEES results of

changes in parameter settings may be displayed on a single graph
134

Appendix A. BEES Computational Algorithms

A.1 Environmental Performance

BEES environmental performance scores are derived as follows.

∑=

=

p

k 1

EnvScorej IAScorejk, where

EnvScorej = environmental performance score for building product alternative j;

p = number of environmental impact categories;

IAScorejk = weighted, normalized impact assessment score for alternative j with

 respect to environmental impact k:

*100

Max{IA ,IA ...IA }

IA IVwt IAScore

1k 2k mk

jk

jk

∗ k

= , where

IVwtk = impact category importance weight for impact k;

m = number of product alternatives;

IAjk = raw impact assessment score for alternative j with respect to impact k:

∑=

= ∗

n

i 1

IAjk Iij IAfactori , where

i = inventory flow;

n = number of inventory flows in impact category k;

Iij = inventory flow quantity for alternative j with respect to

 flow i, from environmental performance data file (See section 4.4.);

IAfactori = impact assessment factor for inventory flow i

The BEES life-cycle stage scores, LCScoresj, which are displayed on the environmental

performance by life-cycle stage graph, are derived as follows:

∑=

= ∗ ∗

n

i 1

LCScoresj IAScorejk IPercentij LCPercentsij , where

LCScoresj = life cycle stage score for alternative j with respect to stage s;

∑=

∗

∗

= n

i 1

ij i

ij i

ij

I IAfactor

I IAfactor IPercent

∑=

= r

s 1

sij

sij

sij

I

I

LCPercent , where
135

Isij = inventory flow quantity for alternative j with respect to flow i for life

 cycle stage s;

r = number of life cycle stages

A.2 Economic Performance

BEES measures economic performance by computing the product life-cycle cost as follows:

∑= +

=

N

t 0

t

t

j

(1 d)

C

LCC , where

LCCj = total life-cycle cost in present value dollars for alternative j;

Ct = sum of all relevant costs, less any positive cash flows, occurring in year t;

N = number of years in the study period;

d = discount rate used to adjust cash flows to present value

A.3 Overall Performance

The overall performance scores are derived as follows:

[ ] 



























= + *100

( , ,..., )

Score * *

1 2

j

n

j

j Max LCC LCC LCC

LCC

EnvWt EnvScore EconWt , where

Scorej = overall performance score for alternative j;

EnvWt, EconWt = environmental and economic performance weights, respectively

 (EnvWt + EconWt = 1);

n = number of alternatives;

EnvScorej = (see section A.1);

LCCj = (see section A.2);
136

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