PNNL-14073 

Energy Savings and Economic Analysis of Updating 

New Mexico’s Commercial Building Energy Code 

D.W. Winiarski 

D.B. Belzer 

K.A. Cort 

E.E. Richman 

January 2003 

Prepared for the Building Energy Codes Program, U.S. Department of Energy 

Prepared by Pacific Northwest National Laboratory, Operated for the U.S. 

Department of Energy by Battelle 
Executive Summary

This paper presents an assessment of the energy savings and economic impact for New Mexico to adopt 

the 2000 International Energy Conservation Code (2000 IECC). Currently, the state of New Mexico 

bases its commercial building energy code on the 1986 Model Energy Code, which in turn references

American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE) Standard 90a1980 for the commercial building portion of the energy code. New Mexico also has a separate and statedeveloped energy standard for school construction, the 1995 Energy Efficiency Standards for 

Construction and Remodeling Procedure for Public School Buildings (hereafter referred to as the NM 

School Standard).

New Mexico’s Energy, Minerals and Natural Resources Department requested that the U.S. Department 

of Energy compare the energy usage and economic cost of New Mexico’s current commercial building 

energy code (ASHRAE 90a-1980) with the 2000 IECC for a small office and small retail building. In 

addition, the department requested a comparison of the energy and economic costs for a typical 

elementary school building constructed to meet both the NM School Standard and the 2000 IECC. 

For both the office and retail buildings examined, it was clear that substantial cost-effective energy

savings were available for the adoption the 2000 IECC over the current New Mexico code. An 

assessment of the change from adoption of the higher equipment efficiency requirements in the 2000 

IECC was not made since the 2000 IECC equipment efficiency standards are already captured as 

minimum federal manufacturing standards, and the heating, ventilation, and air-condition (HVAC) and 

service water heating (SWH) equipment typical for these buildings is no longer produced at the 90a-1980 

efficiency levels. 

A comparison of the energy and economic impact of adopting the 2000 IECC in place of the NM School 

Standard was not as clear. The NM School Standard is more of a guide to construction choices than a 

traditional prescriptive energy code. This is particularly evident in its requirement that evaporative 

cooling be considered in the building design if it is “cost effective.” For this reason, in the evaluation of 

the energy code for school buildings, two different HVAC cooling systems were examined: a building 

with standard, direct expansion (DX)-packaged equipment and a building with a 2-stage (i.e., indirect and 

direct) evaporative cooler and no DX cooling. These were compared to a similar building assuming use 

of DX-packaged equipment and assuming construction under the 2000 IECC requirements. In this 

comparison, implementation of the 2000 IECC standard resulted in a more efficient and cost-effective 

building than either the DX-cooled building or the building with a combined indirect/direct evaporative 

system constructed under the NM School Standard. In addition, simulations were conducted that looked 

at including only the envelope or only the lighting sections of 2000 IECC while keeping all the remaining 

requirements of the current New Mexico state building code. A detailed description of the building 

energy use and economic analysis are provided in the report. 
Contents 

1. INTRODUCTION ..............................................................................................................................................5

1.1 OBJECTIVE ....................................................................................................................................................5

1.2 SCOPE ...........................................................................................................................................................5

2. BACKGROUND .................................................................................................................................................6

3. MODELING ASSUMPTIONS..........................................................................................................................7

3.1 BASE BUILDINGS SIMULATED.......................................................................................................................7

3.2 BUILDING ENVELOPE....................................................................................................................................7

3.3 BUILDING ENVELOPE REQUIREMENTS ..........................................................................................................8

3.4 LIGHTING REQUIREMENTS ..........................................................................................................................10

3.5 EQUIPMENT.................................................................................................................................................12

3.6 SIMULATION TOOL AND MODELING ...........................................................................................................13

4. SIMULATION RESULTS ...............................................................................................................................15

5. ECONOMIC ANALYSIS ................................................................................................................................17

5.1 ENVELOPE...................................................................................................................................................18

5.2 LIGHTING....................................................................................................................................................19

5.3 MECHANICAL EQUIPMENT ..........................................................................................................................22

6. RESULTS ..........................................................................................................................................................24

6.1. OFFICE AND RETAIL....................................................................................................................................24

6.2. EDUCATION ................................................................................................................................................24

7. CONCLUSION .................................................................................................................................................30

8. REFERENCES..................................................................................................................................................31

APPENDIX -- ANALYSIS OF PROPOSED LIGHTING AMENDMENT .........................................................33

3
Acronyms

AF Area factor 

ASHRAE American Society of Heating, Refrigeration and Air-Conditioning Engineers 

BLAST Building Loads Analysis and System Thermodynamics 

BLCC Building Life-Cycle Cost Program 

CBECS Commercial Building Energy Consumption Survey 

CFL Compact fluorescent light 

DOE U.S. Department of Energy 

DX Direct expansion 

ECMD Energy Conservation and Management Division 

EPACT Energy Policy Act 1992 

EPCA Energy Policy and Conservation Act 

HID High-intensity discharge 

HVAC Heating, ventilation, and air-condition 

IECC International Energy Conservation Code 

IES Illuminating Engineering Society 

LCC Life-cycle cost 

LPD Lighting power density 

MEC Model Energy Code 

NAECA National Appliance Efficiency and Conservation Act 

NMEMNRD New Mexico Energy, Minerals and Natural Resources Department 

OMB Office of Management and Budget 

RCR Room cavity ratio 

RF Room factor 

SUF Space utilization factor 

SWH Service water heating 

UPD Unit power density 

VAV Variable air volume

WWR Window-wall-ratio 

4
1. Introduction 

1.1 Objective 

The state of New Mexico has ASHRAE Standard 90A-1980 as well the NM School Standard as the 

statewide building energy efficiency codes. This report was prepared in response to a request for 

technical assistance from the State of New Mexico’s Energy, Minerals and Natural Resources

Department, Energy and Economic Division. The request specified the need for an objective analysis 

that would assess the impacts of adopting 2000 IECC as the state commercial building energy code. The 

request specified that the analysis focus on three building types including a retail, office, and school 

building. 

1.2 Scope 

This report provides an analysis with the scope limited to office, retail, and schools, which represent 

approximately 60% of the commercial construction in New Mexico (Census 2000). Within these building 

types, the impacts of the building envelope and lighting requirements are assessed. Changes in 

mechanical equipment efficiency requirements were not addressed since the 2000 IECC equipment 

efficiency standards are already captured as minimum federal manufacturing standards, and the heating, 

ventilation, and air-condition (HVAC) and service water heating (SWH) equipment typical for these 

buildings is no longer produced at the 90a-1980 efficiency levels1

. 

The study period is forty years. This time horizon was chosen to capture the economic impact of changes 

in building energy consumption from required energy-related designs and materials that occur over the 

life of the building. Specific simulation and Life Cycle Cost (LCC) assumptions are discussed in the 

respective sections of this report. 

This report includes a summary of background information regarding various building code requirements, 

and a description of the assumptions required to complete the quantitative analysis. The report includes 

sections that describe the building simulation process as well as the economic model and the assumptions 

used to calculate LCC savings for each building type. Detailed quantitative results are included Section 6. 

In addition, an energy and LCC analysis of adopting 2000 IECC with a proposed amendment to allow up 

to 2.0 watts per square foot (W/ft2

) of lighting in any building is included in the appendix. 

 1

 In addition, a new federal manufacturing standard as referenced under the Energy Policy and Conservation Act 

(EPCA) will soon be adopted. Under this legislation, the energy efficiency of most of the heating cooling, air 

conditioning (HVAC) and service water heating (SWH) equipment regulated under IECC will be updated to levels 

at least as stringent as those in 2001 IECC. The potential quantitative impact of the equipment standards has been

evaluated in detail in the report, Screening Analysis for EPACT-Covered Commercial HVAC and Water heating 

Equipment.

5
2. Background 

In November 2001, the New Mexico Energy, Minerals and Natural Resources Department 

(NMEMNRD), Energy Conservation and Management Division (ECMD), serving as the State Energy 

Office, requested the U. S. Department of Energy (DOE) to provide an energy and economic analysis of 

the impact of adopting the 2000 version of the International Energy Conservation Code (herein referred to 

as the 2000 IECC). The request specified that the commercial analysis target three building types: 1) a 

10,000 sq ft retail building, 2) a 10,000 sq ft office building, and 3) a 100,000 sq ft elementary school 

building.2

 

The comparison would use as its basis the current commercial energy codes used by New Mexico. For 

privately funded construction, such as the office and retail buildings, New Mexico currently uses the 1986 

Model Energy Code (MEC), which references ANSI/ASHRAE/IES 90a-1980 (herein referred to as 

Standard 90a-1980 or 90a-1980) for commercial construction. For school buildings, NMEMNRD 

analyzes all public school designs to see that they meet the 1995 Energy Efficiency Standards for 

Construction and Remodeling Procedure for Public School Buildings (hereafter referred to as the NM 

School Standard). This procedural guide serves as the minimum energy code for school building 

construction by providing guidance on design choices as well as a process for reviewing school 

construction. 

 2 This building was later revised to a 50,000 sq ft building after discussions with the state energy office 

representative, Harold Trujillo. 

6
3. Modeling Assumptions 

The 2000 IECC has two distinct paths to compliance: Chapter 7, which requires the user to meet the 

requirements of ANSI/ASHRAE/IES 90.1-1989 for compliance, and Chapter 8, which provides an 

alternative and generally simplified path to compliance. Discussions with representatives from

NMEMNRD indicated that NMEMNRD’s primary interest for a state code was in the Chapter 8 path. 

For this exercise, we modeled the 2000 IECC’s Chapter 8 requirements. 

3.1 Base Buildings Simulated 

The aspect ratio and window-wall-ratio (WWR) for the simulation were based on a review of the 1992 

Commercial Building Energy Consumption Survey (CBECS) microdata (EIA 1992) and (EIA 1995). 

This data provides the results of detailed surveys of building characteristics for the United States. For 

office and retail buildings, the CBECS data was queried for buildings less than 25,000 ft2

 in floor area in 

the western census region to develop representative WWR and aspect ratios. For the elementary school 

construction, the average WWR and aspect ratio was obtained for buildings less than 50,000 ft2

 floor area. 

Buildings with non-square or non-rectangular shapes were not utilized in the aspect ratio calculation. 

These characteristics were then used for the modeled buildings. Table 1 lists the characteristics chosen 

for the prototype buildings. The buildings were modeled as lightweight frame wall construction. 

Table 1. Characteristics for Simulated Buildings 

Building Type Floor Area 

(ft2

)

Number of Floors Aspect Ratio WWR 

Office 10,000 2 2 19%

Retail 10,000 1 2.6 12%

Elementary School 50,000 1 2.6 17%

3.2 Building Envelope 

Envelope characteristics were obtained from three different sources. The current New Mexico state energy

code references the 1986 MEC, which in turn references ASHRAE Standard 90a-1980 for most commercial 

structures. The requirements found in ASHRAE Standard 90a-1980 were used to define the envelope and 

lighting energy requirements for office and retail buildings under the current standard. For schools, New 

Mexico has a separate standard for school construction, the NM School Standard, which was used to 

develop the baseline energy characteristics for the school building. The NM School Standard has minimum 

requirements for the building wall, roof, and perimeter (i.e., slab edge) insulation. It also requires doublepane windows for schools in Albuquerque. In addition, the NM School Standard has maximum limits for 

WWR in specific orientations. Finally, the standard requires vestibules or “non-thermostated” corridors at 

all public entrances. However, the standard allows any of these requirements to be omitted in construction 

if it can be shown that they are not able to pay for themselves in less than 10 years. 

 

Based on discussions with NMEMNRD3

, all buildings were presumed to be built with metal frames, 

built-up roofs, and a slab-on-grade construction. In addition, roof plenums were assumed for the analysis. 

 3 Conversation between Harold Trujillo and David Winiarski, 1/22/02.

7
3.3 Building Envelope Requirements 

Section 4.0 of Standard 90a-1980 has separate overall wall performance criteria for heating and cooling. 

In addition, there are total thermal performance criteria for roofs (including skylights). A spreadsheet was 

developed for the office and retail buildings to determine specific combinations of wall, roof, and 

fenestration construction elements that met the wall and roof performance requirements of Standard 90a1980 for the Albuquerque climate. Because of the need to meet both the heating and cooling performance 

requirements, as well as the discrete performance available in real building materials, it is not possible to 

exactly match the 90a-1980 performance requirements. Rather, we selected from a large set of window 

and wall assemblies that are typical construction choices, those that would provide minimum compliance 

with the Standard 90a-1980 heating and cooling envelope requirements. 

The 2000 IECC offers essentially two paths to envelope compliance for commercial buildings: Chapter 7, 

which references ANSI/ASHRAE/IESNA 90.1-1989, and Chapter 8, which provides an alternative set of 

envelope criteria. The 2000 IECC’s Chapter 8 relies on geographically based climate maps to determine 

criteria, with nine distinct climate zones for New Mexico. The Albuquerque metropolitan area, alone, is 

spread across three counties, each with a different climate zone. Because the bulk of the population is in 

the county of Bernalillo, the corresponding 2000 IECC climate zone (i.e., 9B) for this county was used for 

the analysis. 

Tables 2 - 4 show the envelope requirements for the current New Mexico codes and for the 2000 IECC, 

Zone 9B, for each of the buildings examined. In addition, the tables show the corresponding 

requirements from Standard 90.1-1999, Table B-13, which shows the appropriate

ANSI/ASHRAE/IESNA 90.1-1999 prescriptive envelope requirements for the Albuquerque climate4

. 

Table 2. Envelope Requirements for Office Building, 19% WWR

Building Type 90a-1980 IECC Chapter 8 90.1-1999 

Roof U-Value (Btu/ft2-F) 0.085 0.051 0.063

Roof Description R-11 Continuous R-19 Continuous R-15 Continuous 

Opaque Wall U-Value (Btu/ft2-F) 0.132 0.132 0.124

Opaque Wall Description Steel frame, 16” 

OC, R-11 

Steel frame, 16” 

OC, R-11 

Steel frame, 16” 

OC, R-13 

Window U-Value (Btu/ft2-F) 0.98 0.5 0.57

Window SC 0.85 0.5 0.45 

Window Description Vinyl frame, 

single-pane clear 

glass 

Not described Aluminum frame, 

thermally broken, 

double-pane, Low 

E 

Slab on Grade Edge Insulation R-3.8 for 48” N.R. N.R. 

 4

 ANSI/ASHRAE/IESNA 90.1-1999, is currently referenced in Chapter 7 of the most current, 2001 version, IECC,

so the information may be of interest to the state of New Mexico if they later choose to adopt the 2001 or subsequent

versions of the IECC.

8
Table 3. Envelope Requirements for Retail Building, 12% WWR 

Building Type 90a-1980 IECC Chapter 8 90.1-1999 

Roof U-Value (Btu/ft2-F) 0.085 0.051 0.063

Roof Description R-11 Continuous R-19 Continuous R-15 Continuous 

Opaque Wall U-Value (Btu/ft2-F) 0.132 0.132 0.124

Opaque Wall Description Steel frame, 16” 

OC, R-11 

Steel frame, 16” 

OC, R-11 

Steel frame, 16” 

OC, R-13 

Window U-Value (Btu/ft2-F) 1.22 0.5 0.57

Window SC 0.85 0.5 0.45 

Window Description Aluminum frame, 

single- pane clear 

glass 

Likely an 

aluminum frame 

thermally broken, 

double-pane, 

Pyrolytic Low E 

Aluminum frame, 

thermally broken, 

double-pane, Low 

E 

Table 4. Envelope Requirements for Elementary School Building, 17% WWR

Building Type Current New 

Mexico Codes 

IECC Chapter 8 90.1-1999 

Roof U-Value (Btu/ft2-F) 0.032 0.051 0.063

Roof Description R-30 Continuous R-19 Continuous R-15 Continuous 

Opaque Wall U-Value (Btu/ft2-F) 0.070 0.132 0.124

Opaque Wall Description Steel frame, 16” 

OC, 

R-6+R-13 

Steel frame, 16” 

OC, R-11 

Steel frame, 16” 

OC, R-13 

Window U-Value (Btu/ft2-F) 0.79 0.5 0.57

Window SC 0.68 0.5 0.45 

Window Description Aluminum frame 

w/o thermal break, 

double-pane 

Not described. 

Likely an 

aluminum frame 

thermally broken, 

double-pane, 

Pyrolytic Low E 

Aluminum frame, 

thermally broken, 

double-pane, Low 

E 

Slab on Grade Edge Insulation R-5 N.R. N.R. 

In comparing the envelope requirements for the office and retail buildings, it is clear that the 2000 IECC 

is more stringent than 90a-1980 for the roof and windows, with similar requirements for the wall 

insulation level. ASHRAE 90a-1980 is more stringent for slab insulation; however, it appears that the 

2000 IECC is the more stringent standard for the overall envelope. For the office and retail buildings 

modeled, the ASHRAE 90.1-1999 envelope requirements lie somewhere between the ASHRAE 90a-1980

and the 2000 IECC. 

In comparison to the requirements for school buildings, the NM School Standard has minimum

requirements for roof, walls, and slabs that are more stringent than those assumed for the 2000 IECC, but 

9
has less stringent requirements for window U-Values and solar heat gain coefficient (SHGC) than the 

2000 IECC baseline building, at least for the assumed 17% WWR. However, because of the variation in 

the 2000 IECC envelope requirements for buildings with a different WWR, a school building with less 

than 10% WWR would typically have less stringent U-Value and SHGC requirements under the 2000 

IECC. Because the assumed building design had 17% WWR on all orientations, the current NM School 

Standard’s limits on glazing by orientation did not come into play for this analysis. These limits on 

glazing would effectively prevent construction of some potentially inefficient building designs that would 

otherwise be permitted under the 2000 IECC. On the other hand, the 2000 IECC envelope requirements 

would become significantly more stringent for high WWR buildings, which would also effectively limit 

energy inefficient designs with high WWR. 

3.4 Lighting Requirements 

Uniform Power Density Requirements 

The ASHRAE 90a-1980 lighting procedure follows the full Illuminating Engineering Society (IES) 

Lumen method, but refers to the IES Unit Power Density procedure as the "recommended" method for

application. The IES Unit Power Density procedure,5

 referred to as “LEM-1,”was used to develop 90a1980 lighting requirements in the form of UPDs. LEM-1 includes a base Unit Power Density (UPD), an 

Area Factor (AF), or Room Factor (RF) adjustment and an additional Space Utilization Factor (SUF). 

To ensure consistent application of the lighting design among the different standards, each space type 

UPD as prescribed by the 90a-1980 standard (LEM-1) was applied to the models that were used to 

develop current ASHRAE/IESNA lighting requirements 6

 to come up with comparable whole building 

lighting power density (LPD) requirements for the building types addressed in this study (See Table 5). 

The ASHRAE/IESNA Standard 90.1 models are based on the lighting requirements and configuration of 

various space types (e.g., office, hallway, sales area, etc.) found within a given building type. In order to 

compare the two standards, the LEM-1 UPD values for each space type are matched with the space types 

used to develop the ASHRAE/IESNA lighting models wherever possible. Where space type matches 

were not possible between LEM-1 and the ASHRASE/IESNA models, lighting values from

ASHRAE/IESNA 90.1-1999 were used since these represent a best guess at current “good” lighting 

practices. 

The current ASHRAE lighting model forces the AF/RF factors for space types into three main Room

Cavity Ratios (RCR). The RCR is a factor that characterizes room configuration as a ratio between the 

walls and ceiling and is based upon room dimension. Again, in order to compare the two standards, the 

Area and Room Factors from the 90a-1980 were placed into the three RCR categories prescribed by

ASHRAE/IES, which is a necessary assumption to make when individual room dimensions are unknown 

 5

 Found in the IES LEM-1-19182 publication 6

 The methodology for the space type and LPD models is incorporated in a large spreadsheet that was developed by

the lighting subcommittee of the SSPC 90.1 ASHRAE Standards Committee in support of the ASHRAE/IESNA 

90.1-1999 energy standard. A working version of the spreadsheet tool with additional detailed descriptions of the 

various parts is available for review on the IESNA Web site, available URL: http://206.55.31.90/cgibin/lpd/lpdhome.pl. An offline version of the spreadsheet was modified in three ways: 1) Technologies for magnetic 

ballasts and T-12 lamps were added, 2) A series of worksheets to estimate lighting system costs was added, and 3) A

revised formula (consistent with the most recent ASHRAE/IES work) was used in the calculation of LPDs. 

10
and “typical” space assumptions have to be made. 

 

The SUF is a reduction factor for those cases where it can be determined that the total area of visual tasks 

in the room is less than 50% of the total room area. A similar factor does not exist in the IECC or in the 

ASHRAE/IESNA lighting models. However, the 1999 lighting models do apply task and general footcandle levels with associated areas. A review of all the space models determined that for all but a few 

(half dozen or so) of the cases where this 50% rule applied, there was no SUF applied by LEM-1. 

Because LEM-1 is SUF applied only to specific situations and given that there is no way to identify

specific task data, no SUF values were incorporated into this study. 

NM School Standard Lighting Requirements 

The NM School Standard for school construction requires the use of LEM-27

 for determining UPDs. 

Most of the differences between LEM-1 and LEM-2 are minor and do not impact the resulting allowable 

LPD requirements. For example, LEM-2 includes a reference to use high-intensity discharge (HID) 

lighting in warehouse, shops and outdoor fixtures, but this would have no impact on the allowable LPD. 

The NM School Standard also includes a requirement for photocells on all outdoor lighting and user 

controls for all rooms and indoor areas as well as general requirement to maximize day lighting. The 

2000 IECC does not regulate the effectiveness of lighting technology; however, it does require photocells 

on outdoor lighting and bi-level switching (a “part-level” capability) in most building areas unless there is 

only one luminaire for the area or if the lighting is controlled by an occupant sensor. Because of the 

similarity to the NM School Standard, it is believed that these bi-level switching requirements in the 2000 

IECC would provide for similar levels of energy savings in daylit areas and possibly greater levels of 

savings through the prescriptive requirements for bi-level switching in non-daylit areas. It is not possible 

to evaluate the NM School Standard’s clause regarding “maximum use of day lighting,” as it does not 

provide any guidance as to how this should be accomplished. 

Table 5 shows the results of the lighting analysis for the four building types in terms of whole building 

LPDs. The 2000 IECC has lower LPD allowances than 90a-1980. ASHRAE 90.1-1999 and the 2000 

IECC are equivalent across these three building types. 

Table 5. Allowed Whole Building Uniform Lighting Power Densities 

Lighting Power Density (w/ft2 Building type )

90a-1980 or Current 

NM Schools 

Standard 

90.1-1999 2000 IECC

Office 1.91 1.3 1.3

Retail 3.31 1.9 1.9

School 1.95 1.5 1.5

 7

 Found in the IES LEM-2-1984 publication 

11
3.5 Equipment 

Space Cooling, Heating and Service Hot Water Equipment 

For small buildings in the United States, direct expansion (DX) cooling systems predominate, with either 

an electric furnace, heat pump, or gas furnace backup. While the majority of these systems are forced air, 

both water loop heat pumps and ground source/ground water heat pumps are used. For this analysis, we 

assume that the majority of the equipment used for these small buildings is single-zone in nature, and 

using an average energy efficiency ratio (EER) rating for all classes of equipment can best reflect the 

relative energy use between standards. For this analysis, we used shipment weighted EER estimates for 

all unitary and applied heat pumps and air-conditioners, as well as room air-conditioners. We specifically

did not include packaged terminal air-conditioners and heat pumps since they are overwhelmingly used 

by a single building category (i.e., Lodging) that was not included in this analysis. 

Virtually all of the shipped capacity for this equipment is covered by federal minimum manufacturing 

standards, as referenced in the Energy Policy and Conservation Act (EPCA), as amended, either by

equipment covered under the National Appliance Efficiency and Conservation Act (NAECA) (NAECA 

1987) or, for commercial equipment, the Energy Policy Act 1992 (EPACT) (EPACT 1992). This means 

that for states citing ASHRAE 90a-1980 building standards, the equipment efficiencies shown in 

ASHRAE 90a-1980 can no longer legally be purchased or sold in the United States. The EPACT, whose 

source was essentially ASHRAE 90.1-1989 and whose requirements were incorporated into the 2000 

IECC, defines the current manufacturing standards for most commercial air-conditioning equipment. 

Thus, there is no real difference between what is required by the 2000 IECC, and what the minimum is 

that can actually be purchased in the United States today. The principle, single-zone HVAC products not 

currently covered under manufacturing standards are ground source heat pumps, which were not 

referenced at all in ASHRAE 90a-1980 and are still relatively uncommon in commercial buildings in the 

United States. Unit heaters as well as water chillers (which are generally too large to be used in the 

buildings being examined) are not commonly found in the building types being analyzed. Since the 

applicability of these products to this analysis is small, they have been ignored, and no effective change in 

equipment efficiency is assumed between the two code levels. 

School buildings under New Mexico’s NM School Standard are required to: 

1. Use gas-fired heating equipment with a minimum efficiency of 80% (assumed combustion) 

2. Use refrigerant cooling only when one-, two-, or three-stage evaporative cooling does not have a 

simple payback of less than 10 years 

3. Use economizers 

4. Use variable air volume designs with variable speed drives used to control air volume on fans and 

blowers with motors greater than 5 hp 

5. Use air-to-air heat recovery or heat pipe heat exchangers for buildings simultaneously heated and 

cooled 

6. Have night setback capability and time clock controls for HVAC systems 

7. Load shedding capability for high-demand applications 

8. Ensure specific equipment load calculations with a maximum 10% over sizing for safety factor. 

Requirements similar to several of the above exist in the 2000 IECC. The 2000 IECC has requirements 

for night setback and time clock control and equipment sizing. It also requires economizers for the 

Albuquerque climate; however, the requirements only apply to systems over 7.5 tons cooling capacity. 

12
Thus, economizers would typically be required when package systems serve multiple classrooms, but 

would not be required when individual cooling equipment is used for each classroom. The 2000 IECC 

does not regulate fuel source for heating, but when gas equipment is used, the 80% combustion efficiency

would be typical of current products under federal law. 

The 2000 IECC does not have any requirements similar to New Mexico’s current limitation on refrigerant 

cooling or for variable air volume system designs with variable speed drives on systems with fans motors 

greater than 5 hp. The load shedding capability in the current New Mexico code does not appear to be an 

energy savings issue, but rather a demand limiting requirement. 

To simulate the NM School Standard’s limitations on refrigerant cooling, simulations were performed 

using an indirect evaporative cooler model. Although Appendix A of the NM School Standard suggests 

that single-stage evaporative cooling is appropriate for Albuquerque’s climate, a 2-stage evaporative 

cooling model was determined to be the most typical design to make use of evaporative cooling while still 

maintaining comfort conditions roughly equivalent to a refrigerated cooling system. 

The requirement for variable air volume was not directly modeled, since VAV was only required on fan 

systems with fan motors greater than 5 hp and only when it is shown to have a 10-year payback or less. It 

is not clear on what type of systems this requirement would apply. VAV systems are not commonly

available on standard rooftop equipment under 20 tons; only schools that use large, central HVAC system

designs typically use VAV equipment. 

 

Service hot water requirements for school buildings are similar in both the New Mexico efficiency

standard and the 2000 IECC. No detailed modeling of SWH loads or efficiency was attempted in this 

analysis. 

3.6 Simulation Tool and Modeling 

Building simulations were completed using the Building Loads Analysis and System Thermodynamics

(BLAST) software tool (BLAST 1991) Version 3. To simplify modeling of the impacts of the lighting

and envelope options, a four-zone building model was used to assess the impact of the lighting and 

envelope changes under the standard for all buildings. For the two-story office building, each of the four 

zones covers both a portion of the lower and upper floors of the building. In all cases, the long axis of the 

buildings examined was oriented north to south. It is noted that this orientation enhances the impact of 

solar loads from the large east-facing and west-facing sides of the building. 

Each of the buildings was assumed to be both heated and cooled for the analysis, with a cooling setpoint 

of 75° F and a heating set point of 70° F. Setback controls are not required under ASHRAE 90a-1980 but

are required under ASHRAE 90.1-1999 and the IECC. Although these controls are not required in 90a1980, most cooling control systems currently on the market and used for this type of HVAC system have 

the capability for setback control. Since the capability for control likely exists under both standard 

scenarios, we have treated both scenarios equivalently, with a heating setback to 55° F and a cooling 

setpoint to 85° F. 

For simulation of the school facility built to the current New Mexico Standard, two different systems 

were analyzed. The first system assumed standard DX equipment, each serving one of the four different 

zones for the building. These systems assumed a constant volume system with overall efficiencies typical 

13
of DX equipment under the current EPCA requirements. A 9.27 EER was assumed for BLAST’s 

constant-volume, packaged DX system model. The second design replaced the DX cooling equipment 

with a two-stage indirect/direct evaporative cooler. Specifications for the indirect/direct evaporative 

cooler were based on discussions with Spec-Air.8

 These systems were modeled as constant-volume 

systems using BLAST’s Evaporative Cooler Model9

. 

Building schedules and peak building loads used in the analysis have been developed at the Pacific 

Northwest National Laboratory (PNNL) for other building simulation work and are referenced in Barwig, 

1996. All systems simulated assumed natural gas was used for both space and water heat for the 

buildings. Table 6 shows a list of the simulation runs attempted with a brief description of the building 

code assumptions used for each run. 

Table 6. Building Code Simulation Performed 

Simulation Building

Type 

Building Code Description Cooling System Heating 

System 

OFF-1 Office 90a-1980 Rooftop packaged Gas furnace 

OFF-2 Office 2000 IECC Rooftop packaged Gas furnace 

OFF-3 Office 90a-1980 with 2000 IECC Envelope Req. Rooftop packaged Gas furnace 

OFF-4 Office 90a-1980 with 2000 IECC Lighting Req. Rooftop packaged Gas furnace 

RET-1 Retail 90a-1980 Rooftop packaged Gas furnace 

RET-2 Retail 2000 IECC Rooftop packaged Gas furnace 

RET-3 Retail 90a-1980 with 2000 IECC Envelope Req. Rooftop packaged Gas furnace 

RET-4 Retail 90a-1980 with 2000 IECC Lighting Req. Rooftop packaged Gas furnace 

EDU-DX-1 Education 1995 N.M. School Std Rooftop packaged Gas furnace 

EDU-DX-2 Education 2000 IECC Rooftop packaged Gas furnace

EDU-DX-3 Education 1995 N.M. School Std with 2000 IECC 

Envelope Req.

Rooftop packaged Gas furnace 

EDU-DX-4 Education 1995 N.M. School Std with 2000 IECC 

Lighting Req. 

Rooftop packaged Gas furnace 

EDU-EV-1 Education 1995 N.M. School Std 2-stage evaporative cooler Gas furnace 

EDU-EV-2 Education 2000 IECC Rooftop packaged Gas furnace

EDU-EV-3 Education 1995 N.M. School Std with 2000 IECC 

Envelope Req.

2-stage evaporative cooler Gas furnace 

EDU-EV-4 Education 1995 N.M. School Std with 2000 IECC 

Lighting Req. 

2-stage evaporative cooler Gas furnace 

 8 Spec-Air provides commercial evaporative coolers either for stand-alone operation or use in conjunction with other 

HVAC equipment. Specifications are based on personal discussions with Mike Worth, vice president of Spec-Air. 9

 As a test, an additional simulation consisting of an indirect evaporative cooler used to pre-cool air for the DX 

system was examined. However, the additional pressure drop added to this system was such that it did not appear to

save energy over the baseline DX system. As such, this design would not be required under New Mexico’s NM

School Standard. This illustrates a difficulty with the requirements of the current New Mexico Standard. While 

there is a requirement for evaporative cooling, it effectively has to be shown to meet 10-year payback criteria. 

Because of the different variations in evaporative cooling design, it seems difficult to enforce without detailed 

review of all plan drawings. 

14
4. Simulation Results 

Table 7 shows the simulated energy use for each of the different simulation runs in terms of annual fuel 

use, annual site energy use, and estimated annual energy cost based on the energy costs discussed in 

Section 3.2. To determine annual energy cost, electricity costs of $0.0720/kWh were used based on 

average New Mexico commercial electricity costs for 2001 and natural gas costs of $4.90/MCF were used 

based on average New Mexico gas costs for 2000 as reported by the Energy Information Administration 

(EIA) 10. 

Table 7. Building Energy Simulation Results 

Simulation Lights

and Plugs 

HVAC Space Heat

and SWH 

Total Site 

Energy 

Energy 

Cost 

% Energy 

Cost 

Savings 

 kWh/yr kWh/yr Therms/yr Mbtu/yr ($/build

ing/yr) 

OFF-1 103967 48775 581 579 11278

OFF-2 82356 36370 598 465 8836 21.7%

OFF-3 103967 41629 489 546 10720 5.0%

OFF-4 82356 44357 703 503 9461 16.1%

RET-1 146499 52863 229 703 14468

RET-2 92036 32751 312 457 9136 36.9%

RET-3 146499 47190 222 683 14055 2.8%

RET-4 92036 39130 345 482 9611 33.6%

EDU-DX-1 332259 142778 6296 2251 37216

EDU-DX-2 268151 126487 7734 2120 32112 13.7%

EDU-DX-3 332259 139965 6949 2307 37326 -0.3%

EDU-DX-4 268151 129007 7049 2060 31967 14.1%

EDU-EV-1 332259 77765 6296 2029 32534

EDU-EV-2 268151 126487 7734 2120 32112 1.3%

EDU-EV-3 332259 76600 6949 2090 32762 -0.7%

EDU-EV-4 268151 69555 7049 1857 27685 14.9%

Annual energy cost savings above the appropriate current New Mexico baseline (e.g., OFF-1, RET-1, 

EDU-DX-1, or EDU-EV-1) are shown as a percentage of reduction in the annual energy cost. In the case 

of the education building, it is relevant to examine the energy savings and cost reduction assuming either 

evaporative or DX cooling. 

 10 Electric Power Monthly. May 2002. “EIA 2001 Fuel Prices: Table 55 - Estimated U.S. Electric Utility Average 

Revenue per Kilowatt hour to Ultimate Consumers by Sector, Census Division, and State, Year-to-Date (February)

2002 and 2001 (Cents), Natural Gas Monthly, June 2001,” Table 22 - Average Price of Natural Gas Sold to

Commercial Consumers, by State, 2000-2002 (Dollars per Thousand Cubic Feet). Assumed 1028 MMBtu/MCF 

conversion factor.” Gas costs for 2000 were used to eliminate a gas price bubble that occurred in 2001 that is not 

adjusted for in EIA’s fuel escalation rates. 

15
Based on these simulation results, it is clear that, for the office and retail buildings, significant energy cost 

savings are obtained from the use of the 2000 IECC requirements in place of the requirements specified 

by ASHRAE 90a-1980. Examining the OFF-3 (90a-1980 lighting, but using the 2000 IECC envelope 

requirements) and OFF-4 (90a-1980 envelope, but using the 2000 IECC lighting requirements) 

simulations, it is clear that the majority of energy cost savings comes from the reduction in allowed 

lighting power. Similarly, a majority of the energy cost savings for the retail buildings comes from the 

lighting requirements. In both cases, however, it is clear there are savings to be achieved simply from the 

improved envelope requirements in the 2000 IECC. 

Review of the education building case with direct expansion cooling equipment assumed (baseline EDUDX-1) clearly indicates that there is substantial energy cost savings to be gained in using the 2000 IECC 

envelope and lighting requirements instead of the envelope and lighting requirements modeled for the 

NM School Standard. However, these savings come purely from the lower lighting LPDs mandated by

the 2000 IECC. When only the envelope requirements of the 2000 IECC are applied, energy costs 

increase relative to the energy costs resulting from the NM School Standard for the specified building. 

The energy usage of the education building constructed to the NM School Standard, substituting 2000 

IECC envelope requirements, has an annual energy cost slightly higher (i.e., <1%) than that of the 

education building constructed solely to the NM School Standard. Slight reductions in installed lighting 

power below that specified by the NM School Standard would result in less energy usage in education 

buildings. 

16
5. Economic Analysis 

The economic benefit and costs of adopting an energy code over the current baselines are assessed by

evaluating the anticipated energy cost savings over a specified time horizon and then comparing these to 

the associated capital costs of complying with the code. This analysis for New Mexico uses the life-cycle 

cost (LCC) method for this comparison, which weighs the values of costs and benefits over time using the 

time value of money (expressed using an assumed discount rate). For this study, the LCC is a general 

measure of the cost of operating a building over its lifetime, including the initial incremental construction 

cost, replacement of key components, and annual energy expenditures. 

The primary costs associated with code adoption are incremental costs of required materials and 

installation that result in different (and hopefully reduced) annual energy consumption (e.g., higher levels 

of insulation, more efficient light fixtures) relative to the cost of building materials that would satisfy the 

current baseline requirements. These costs are often referred to as first costs, as they are incurred when 

the building is first built. The collection and treatment of first costs for lighting and building envelope 

materials is discussed in the following sections. In addition, the analysis tracks replacement costs for 

components that will need to be replaced during the study period (assumed to be 40 years). The sum of 

the first cost and the replacement cost will be referred to as the total investment cost. Ongoing 

maintenance costs (excluding replacement costs) have not been examined in this analysis (i.e., it can be 

interpreted that maintenance costs are assumed to be the same under various requirements). 

In addition to first costs, the ongoing incremental costs and benefits of adopting all or a portion of the 

90.1-1999 standard are compared to that of an assumed baseline. The primary, ongoing impact of a 

building energy code is the energy cost reduction over the life of a building. These savings are valued 

using the New Mexico state average commercial gas and electricity rates over a specified time horizon 

(EIA 2001a). The average fuel rates are escalated throughout the first 20 years of the study period based 

on the Annual Energy Outlook 2002 forecasts (EIA 2001b) and are assumed to stay flat the remaining 

years of the study period. These values are then discounted appropriately to a present value. This study

uses a constant 7% (real) discount rate. This value has been used in prior U.S. Department of Energy

(DOE) analyses of residential and commercial equipment efficiency standards11. 

The economic impacts are calculated using a spreadsheet-based LCC model that can perform LCC 

comparisons of alternative sets of building technologies corresponding to different building standards. 

The model borrows elements of the Building Life-Cycle Cost Program (BLCC), which is a product from

the National Institute of Standards and Technology and the DOE Federal Energy Management Program12. 

 11 This particular value is motivated by the recommendation of the Office of Management and Budget (OMB) in

Circular A-94, (OMB1992). Circular A-94 indicates that this value corresponds to the approximate marginal pretax

rate of return on the average investment in the private sector in recent years. All rates are reported as “real” rates, 

which refers to the discount rate above any nominal inflation rate. 12 Portions of a spreadsheet version of the BLCC, developed by M.S. Addison and Associates (Tempe, AZ) were

adapted for use in the more extensive LCC model used for this study. 

17
5.1 Envelope 

Construction costs reflect the volume of material and/or equipment purchased, as well as the actual 

components used. The volume of material reflects the size of the building. The component performance 

is described and the component costs are based on costs normalized to a per-unit basis (e.g., per square 

foot). 

The costs for various building envelope materials are derived on a per-unit basis. Costs for walls, roofs, 

and floors are dependent on the type of construction (e.g., masonry wall versus frame or flat built-up roof 

versus pitched roof with attic) and vary with thermal performance. The component costs used for this 

work reflect marginal construction costs over fixed baselines and not the entire construction cost for a 

component. For example, window costs shown reflect the marginal construction costs for purchase and 

installation of a specific window type over purchase and installation of single-pane glazing. Likewise, 

costs shown for opaque walls represent the marginal cost for a fully framed and insulated wall with the 

specified insulation level above that of a metal framed wall constructed without insulation. Thus the cost 

differential between components built to different codes is more relevant to the reader than the magnitude 

of the component costs shown. 

Discrete costs for various assembly types are based on cost estimates gathered during the development of 

the 90.1-1999 standard by the ASHRAE envelope subcommittee. These costs for windows and glazing 

materials were gathered and compiled by Charles Eley Associates. Although costs were collected from

1994 to1997, all costs are appropriately inflated to 2001 by using price indexes from the Producer Price 

Index for specific building materials

13. 

The building envelope costs are measured and reported as incremental costs to achieve a certain level of 

thermal integrity (e.g., U-factor for walls, roofs, and windows; R-values for slab insulation). For the roof

and opaque walls, the costs are estimated relative to a base wall and roof assembly containing no 

insulation. The window costs measure the incremental costs of glazing that has a specific U-factor and 

shading coefficient, as compared to a window with a single pane of clear glass. 

For all envelope components, the spreadsheet model estimates the incremental costs per square foot for 

alternative levels of standards. The incremental costs per square foot are multiplied by the appropriate 

component areas in the building (e.g., roof, walls, windows) to generate a total incremental building 

envelope cost. 

 13 US Bureau of Labor Statistics. 2002. Producer Price Index Industry Series. Public Use Data available on BLS 

Web site, available URL: http://data.bls.gov/labjava/outside/jsp?survey=pc

18
5.2 Lighting 

The lighting requirements in all codes examined are essentially expressed as a limitation on installed 

connected lighting power per square foot of building area. The inherent flexibility in meeting these type 

of requirements makes evaluating the first cost of changes to the lighting requirements challenging as 

there are alternative ways to comply with the standard. Although a variety of alternatives may result in 

similar energy use outcomes, each alternative has its own distinct cost implication. 

In order to assess the economic impacts of lighting code changes, the factors impacting lighting design 

choices must be considered. Primary lighting design choices affecting the lighting technology and the 

total connected power installed in a space are: 

• Luminance level - this varies based on the needs of the space, including task requirements, 

occupants, and overall desired atmosphere of the environment, and is generally driven by the 

recommendation made by the Illuminating Engineering Society

• Lighting technology type - e.g., incandescent, fluorescent, HID, etc. and ballast choices) 

• Light distribution technology type - e.g., lenses, louvers, reflective luminaries, reflective 

materials) 

• Maximum allowed connected power by code. 

It is anticipated that a lighting design change based on a stricter energy code involves primarily 

technology changes only. Other potential methods of complying with a new code include a simple 

lighting level reduction and/or total redesign of the space using advanced lighting techniques. Total 

redesign of the space, however, is considered to be uncommon in practice and will not be considered in 

this analysis. 

An assessment of typical lighting technologies for a range of buildings is found in the ASHRAE/IESNA 

Lighting Design Models, as discussed in Section 3.4 of this document, in establishing the light levels 

building code simulations. Each space (e.g., office, hallway, sales area) within each building type in the 

ASHRAE 90.-1999 Whole Building Space Data Allocations is associated with up to three different 

lighting types with each type representing a different lighting technology and associated fixture14. The 

amount of light specified for each space (determined by IES recommendations and the ASHRAE 

subcommittee input) is further allocated to each of these lighting types (up to three). Each of these types 

is also further defined by an efficacy of the technology (e.g., lumens per watt) and standard adjustment 

factors (e.g., lumen depreciation, room surface). 

The set of space type allocations listed in the ASHRAE 90.1-1999 Space Type Models provides one 

method for meeting the lighting power limit requirements of 90.1-1999/IECC 2000. These models, based 

on actual designer and experience input, are considered the most accurate and detailed of their kind 

available for providing efficient and effective lighting. The models also serve as the basis for comparison 

with other standards or current practice scenarios. 

 

 14 For example, the three lighting types for an office conference room include linear fluorescent, wall wash

fluorescent, and halogen down lights. 

19
The approach used to evaluate lighting benefits utilizes lighting costs for systems of lighting, which 

include the lamp, fixture, and ballast combination. First, the ASHRAE Space Type Models are applied to 

the spaces in each building type to determine the lighting system that meets the standard at the lowest 

cost. The power densities and costs are then developed for each space and lighting system, and 

aggregated to the whole building level for the analysis 

The assignment of differences in power densities between the 1999 standard and the 1989 standard can be 

evaluated as either differences in light level or the efficacy of lighting technologies—or both. Some 

assumptions are made to permit a reasonable assessment of the actual difference in design in order to 

meet the two standards and allow a comparison of energy consumption and costs. Because of the vast 

difference in lighting design, it is impractical to assign too much detail to a scenario; however, many

common space types within buildings exhibit some common lighting design attributes. Examples of this 

are listed in Table 8. 

Table 8. Comparison of Common Space Types to Attributes 

Common Space Type Common Lighting Design Attributes 

Typical open office areas fluorescent troffers, even spacing, little decoration 

Typical enclosed offices fluorescent troffers 

Hallways/lobbies fluorescent troffers, incandescent downlights 

Large Retail spaces Overhead fluorescent troffers, incandescent displaylights 

The 2000 IECC requirements are essentially identical to the Standard 90.1-1999 requirements for the 

buildings examined in this study and are expected to have the same lighting technologies, lighting types, 

and fixture counts. Since the lighting requirements for Standard 90.1-1999 are well defined through the 

use of the Space Type Models, they were used as a baseline for determining capital costs for lighting 

under other codes. 

To assess the first cost to meet the less-stringent Standard 90a-1980 for the office and retail buildings, the 

first step assumed a technology substitution involving two types of lighting systems: 

1. Magnetic ballast-T12 lamps for electronic ballast-T8 lamps 

2. Incandescent lamps for compact fluorescent lamps in downlight applications. 

These substitutions were made for all the space types used in the ASHRAE methodology underlying the 

development of the 1999 lighting standard.15 The 90.1-1999 whole-building LPD will increase by

different percentage amounts over 90.1-1989, depending upon the assumed fractions of floor space to be 

served by the technologies in each of the building types. 

 15 The methodology for the space type and LPD models is incorporated into a large spreadsheet that was developed 

by the lighting subcommittee of the SSPC 90.1 ASHRAE standards committee in support of the ASHRAE/IESNA 

90.1-1999 energy standard. A working version of the spreadsheet tool with additional detailed descriptions of the 

various parts is available for review on the IESNA Web site, available URL: http://206.55.31.90/cgibin/lpd/lpdhome.pl. An offline version of the spreadsheet was modified in three ways: 1) technologies for magnetic 

ballasts and T-12 lamps were added, 2) a series of worksheets to estimate lighting system costs was added, and 3) a 

revised formula (consistent with the most recent ASHRAE/IES work) was used in the calculation of LPDs. 

20
The first two columns of Table 9 show the building-level LPDs that were used in the economic 

analysis. Column 3 displays the efficiency improvement in the LPD between the 1999 and 1989 

standard. Column 4 shows the increase from the 1999 standard brought about solely by the 

technology substitution discussed above. For office and education buildings, the technology 

substitution (as described in numbers (1) and (2) above) results in an increase in the LPD that is 

very close to the requirements of the 1989 standard. 

Table 9. Change in Lighting Power Densities from Technology Substitution 

1999 LPD(a) 1989 LPD(a) Percent

Change 

Technology 

Substitution 

(Percent 

Change) 

 Office 1.30 w/ft2 1.63 w/ft2 25.4% 24.0%

 Retail 1.9 w/ft2 2.36 w/ft2 24.2% 16.0%

 Education 1.5 w/ft2 1.79 w/ft2 19.3 % 20.8%

(a) As used in the building energy simulations. 

As a first step, cost estimates were developed for the linear fluorescent and incandescent/compact 

fluorescent light (CFL) applications to the 90.1-1999 standard based upon the ASHRAE models. The 

less-efficient technologies (e.g. incandescent lights) were then applied to the same models (i.e., assuming 

the same illumination levels). A ratio was computed between the reduction in cost and the increase in the 

predicted LPD, going from the more-efficient to the less-efficient lighting technologies (the change in 

predicted LPD is equal to the percentage change in Column 4 in Table 9, multiplied by the 1999 LPD in 

Column 1). This ratio was then applied to the actual difference in the LPD between the two standards to 

make an estimate in the change in cost. 

For office and education buildings, this procedure yields essentially the same cost difference as that 

generated by the technology substitution without any adjustment. Since the predicted change in the LPD 

for retail buildings was lower than the actual difference (16% vs. 24% in Table 9), this procedure 

provides an upper bound to the cost difference (and, concomitantly, a conservative estimate of the LCC 

reduction) between the two standards for this building type. A further calibration was performed to 

account for a revision in the way in which the LPDs were calculated in the ASHRAE models for this 

study, as compared to how these models were employed when developing the published standard.16

The investment associated with higher lighting levels found in Standard 90a-1980 and the NM School 

Standard could not be explained by a further technology substitution from the 90.1-1989 lighting power 

densities, particularly since efficiencies for most common fluorescent lighting ballasts are now regulated 

under EPACT and lower efficiency fluorescent ballasts are unavailable. Rather, costs for the Standard 

90a-1980 office and retail buildings lighting power densities were modeled as scaling linearly with the 

costs for the lighting power densities in Standard 90.1-1989. This represents essentially an increase in the 

 16 The use of the revised formula in the LPD spreadsheet (see previous footnote) causes the calculated 90.1-1999 

LPDs to be higher than those published for the 1999 standard. The calculated LPDs were: 1) office, 1.40 watts/ft

2

, 

2) retail, 2.14 watts/ft2, and 3) education 1.54 watts/ft

2

. The revised formula ensures that the economic benefits 

from a technology substitution are consistent across building types. Unfortunately, it requires that the cost 

calibration must be performed on the basis of percentage changes rather than the absolute levels of the LPDs. 

21
number of fixtures and lamps allowed compared with Standard 90.1-1989 as well as an increase in 

illumination level. 

For the Education buildings, where high-efficiency lights and ballasts are already required in the NM 

School Standard, the lighting costs are based on scaling the 90.1-1999 lighting cost estimates with the 

ratio of this current New Mexico standard and the lighting power allowed in 90.1-1999. No technology 

substitutions were assumed. Note that this is essentially an increase in the number of fixtures and lamps 

allowed compared with Standard 90.1-1999. It is believed that this makes a more credible scenario than 

the assumption of significantly greater use of incandescent lighting in the current ASHRAE models. 

Lighting costs are measured in terms of total lighting cost in dollars per square foot for linear fluorescent 

and incandescent/CFL systems. These costs include the cost of a fixture, ballast, and lamp plus the labor 

to install the assembly. The linear fluorescent lighting cost estimates are based on data from the 

Technical Support Document for the DOE’s rulemaking related to fluorescent lamp ballasts (DOE 1999). 

For compact fluorescent and incandescent systems, data were developed from the input data used in the 

commercial module of the National Energy Modeling System (NEMS) and from a PNNL analysis of 

contractor prices from Grainger Industrial Supply. Although the lighting cost may vary for any particular 

building due to the type of lighting technology used, the above derivations are representative of the cost 

differentials. 

5.3 Mechanical Equipment 

As discussed in Section 3.6, mechanical equipment efficiencies were not changed between the minimum

purchased under federal law and what is required under the 2000 IECC. However, to model the impact of 

the evaporative cooling technology in the NM School Standard, it was necessary to price and size both the 

costs for the packaged DX equipment and the evaporative cooling equipment that would be used in the 

education building under the different building codes. The first cost analysis for the cooling equipment 

was carried out for the other retail and office buildings, although with these buildings it is only the impact 

of changes in required cooling equipment capacity that impact the economics. 

To account for this change in capacity, the total tonnage of required cooling capacity was extracted from

the simulation results and costed on a $/ton basis. The required cooling capacity was based on the peak 

cooling design day loads sizing from BLAST. BLAST’s design day calculations were based on 

ASHRAE’s 1% design day mean coincident wet bulb conditions (ASHRAE 2001)17. No oversizing 

beyond these peak design day loads was included in these equipment costs. Any oversizing of cooling 

equipment to account for pickup loads or the discrete size availability of packaged equipment would serve 

to increase the total differential first cost for the building’s cooling equipment under different codes. 

Differential first costs for heating equipment of different sizes were not examined in this study18. For the 

evaporative cooling systems analyzed in the education building, a simplifying assumption was made that 

 17 ASHRAE 2001 Handbook of Fundamentals (ASHRAE 2001). 18 The capacity and cost for gas furnace heating systems in rooftop cooling equipment is closely tied to the cooling 

capacity of the equipment in available products, and relatively small variations in required heating capacity do not

practically result in different first costs for packaged equipment. 

22
the heating requirements would be met by duct furnaces that cost no more than the furnace in the original 

package product19. 

Differential first costs for cooling equipment were examined in this study. Costs for the packaged DX 

equipment analyzed were based on estimated first costs developed by the ASHRAE 90.1-1999 

mechanical subcommittee for 7.5 ton packaged cooling equipment with an efficiency level of 9.27 EER. 

To this was added a 25% contractor markup for the final installed cost of $565/ton. 

Costs for the two-stage evaporative cooling system were based on a cost differential of $760/ton that was 

reported in the NM School Standard. A 25% markup was assumed to be applied to this. This cost 

compares well with estimated costs from manufacturers; consultation with Spec-Air representatives20

confirmed similar costs. Spec-Air provided estimated costs for stand-alone, two-stage evaporative coolers 

of approximately $1,400/ton for 5 ton products and $650/ton for 20 ton, two-stage evaporative cooling 

systems. It is noted that for small (i.e., 3-5 ton) packaged DX cooling systems, less expensive, preengineered two-stage evaporative cooling modules that attach to the rooftop DX system are available at 

about 50% of the costs shown here for the standalone 5-ton system. Given the range of possible designs, 

it was felt that the costs used in the NM School Standard were very reasonable for this study. 

It is also noted here that for the engineering analysis, it was assumed that outside air was used as the “wet 

side” of the evaporative cooling units. A more efficient option when stringent outside air requirements 

exist is to use building exhaust air as the air supply to the wet side of the evaporative cooler. This was not 

something that could be modeled in BLAST, however, this solution has twofold benefits. First, because 

the building supply air starts out as cooler than the outside air, the two-stage evaporative cooler, using 

exhaust air, can provide cooler supply air to the building using the same unit. The second benefit is more 

significant. Because the exhaust air is being routed through an exhaust air/outdoor air heat exchanger, 

exhaust air heat recovery can be achieved during the heating season by simply turning off the water 

supply to the heat exchanger. According to Spec-Air, nearly 50% of the systems they sell for school 

applications are configured in this manner. 

 19 This may under-represent the cost of the heating equipment used in the evaporatively cooled building studied. 20 Personal conversation with Todd Freund of Spec-Air on 8/29/2002.

23
6. Results 

Tables 10, 11, 12 and 13 show the results of the LCC analysis completed for each simulation. These 

tables show the relative cost assumptions for each component in the building examined, the energy

savings as calculated from the simulation, the energy cost savings, and three methods of economic 

valuation: 1) the building LCC savings, 2) the savings-to-investment ratio, and 3) the adjusted internal 

rate of return on the capital cost investments. Each of these economic criteria is calculated for the 

simulations differently than the baseline assumptions (using 90a-1980 for office or retail buildings and 

the NM School Standard for school buildings with and without evaporative cooling assumptions). 

It is particularly important to look at the LCC savings for the 2000 IECC, but also for the baseline 

building with 2000 IECC lighting levels. Progress in cost-effective, high-efficiency lighting technology 

has advanced much faster than cost-effective, efficiency improvements in the building envelope. For that 

reason, much of the current building construction in New Mexico likely has connected lighting power 

levels already significantly lower than the levels prescribed by the baseline codes. Hence, the reported 

first cost and energy usage for lighting at the current code levels may not represent a realistic baseline for 

assessing the actual energy savings New Mexico would gain in going to the 2000 IECC. 

6.1. Office and Retail 

Table 10 shows the results of the LCC analysis for a small office, while Table 11 represents the LCC 

analysis results for a retail building. The results of this study clearly indicate that there are significant 

LCC savings to be gained through adoption of the 2000 IECC over 90a-1980 for office and retail 

buildings, although the lighting energy savings drives these LCC savings almost completely. The energy 

savings from adoption of the 2000 IECC envelope is largely offset by the first cost of transitioning to the 

2000 IECC envelope. Although the office building results imply a modest LCC cost savings of $678 with 

adoption of the IECC envelope requirements, the LCC increases by $2407 (negative LCC savings are 

distinguished with brackets) with the adoption of the IECC envelope requirements for the retail building. 

Slight changes in fuel cost or first cost assumptions could swing these numbers into negative or positive 

realms, and it is, therefore, difficult to judge these as significant LCC impacts for the building envelope 

change. However, it is clear that adopting the 2000 IECC for these buildings would remove the potential 

for excessive lighting energy use that currently exists in the 90a-1980 baselines. 

 

6.2. Education 

In examining the school building with DX cooling, it is clear that the 2000 IECC offers significant LCC 

savings over the current NM School Standard, nearly $150,000 savings in LCC and over $5100 in 

estimated annual energy costs savings. This LCC savings is due to both the lighting power reduction 

discussed previously, as well as lower costs for construction of the 2000 IECC building envelope. Even 

assuming the current standard with the 2000 IECC lighting levels as the baseline, the LCC savings would 

be approximately $37,000 with the 2000 IECC ($149,923 minus $112,833), the difference in LCC 

between these two scenarios shown in Table 12. This scenario, however, would have a slight increase 

($145/yr) in energy costs with the 2000 IECC over this second baseline ($32,112 minus $31,967). 

In examining the school building with the two-stage evaporative cooling (Table 13), the 2000 IECC still 

shows significant LCC savings over the current standard ($91,920). However the highest LCC savings is 

produced when combining the current New School Mexico Standard with the 2000 IECC lighting 

24
requirements. This appears to be due to the cost effectiveness of the evaporative cooling system. The 

NM School Standard baseline, in this second example, would experience a savings of approximately

$5000/yr compared to the NM School Standard with DX cooling. 

25
Table 10. Engineering and Cost Summary for Small Office Building 

26

Small Office (WWR=0.19) 

 Bldg. Size 10,000 sq. ft. Standard Level

90A-1980 

Base IECC2000

90A-1980 

w/2000 Env.

90A-1980

w/2000 Light

Envelope Area (sq. ft.)

Windows 1,482 u-value(std) 0.980 0.500 0.500 0.980

 sh. coef.(std) 0.850 0.500 0.500 0.850

(Window-Wall Ratio = 0.19) u-value(cost) 0.730 0.497 0.497 0.730

sh. coef.(cost) 0.840 0.506 0.506 0.840

 cost ($/sqft) $4.55 $8.70 $8.70 $4.55

Opaque Walls 6,318 u-value 0.132 0.132 0.132 0.132

 cost ($/sqft) $0.33 $0.33 $0.33 $0.33

Roof 5,000 u-value 0.085 0.051 0.051 0.085

 cost ($/sqft) $0.91 $1.36 $1.36 $0.91

 (feet)

Slab perimeter 300 u-value 0.125 not req'd 0.125 not req'd

 cost ($/ft)* $4.12 $0.00 $0.00 $4.12

 *24-inch depth 

 Envelope Cost (incremental) $14,615 $21,774 $21,774 $14,615

Lighting

Lighting Power Density watts/sqft 1.91 1.30 1.91 1.30

Lighting Cost per Sq. Foot $/sqft $1.84 $1.75 $1.84 $1.75

 Total Lighting Cost $18,361 $17,504 $18,361 $17,504

HVAC Equipment1 Capacity Central, Air-Source AC >65 and < 135 kBtu/h

 (kBtu/h)

EER 9.27 9.27 9.27 9.27

Unit Cost/ton $565 $565 $565 $565

Number of Units (Tons) 15.57 11.37 13.06 14.13

Total Equipment Cost $8,795 $6,422 $7,379 $7,983

Construction Cost $41,772 $45,700 $47,515 $40,102

Annual Energy Consumption 

Electricity, lights and plugs MMBtu 355 281 355 281

Electricity, HVAC MMBtu 166 124 142 151

Natural Gas MMBtu 58 60 49 70

Total Annual Energy Cost2 $11,278 $8,836 $10,720 $9,461

Economic Measures

Life-Cycle Cost Savings $26,898 $678 $25,169

Savings-to-Investment Ratio (SIR) 9.0 1.1 Invest. < 0

Adjusted IRR 13.1% 7.3% Invest. < 0

Notes:

1 Economizer used

2 2001 electricity price = 7.2 cents/kWh 2001 gas price = $4.77 /MMBtu

3 Years for Analysis = 40 Discount Rate = 7.0%

 Life-cycle cost savings includes replacement costs and residual values
Table 11. Engineering and Cost Summary for Small Retail Building 

Small Retail (WWR=0.12) 

 Bldg. Size 10,000 sq. ft. Standard Level

90A-1980 

Base IECC2000

90A-1980 

w/2000 Env.

90A-1980

w/2000 Light

Envelope Area (sq. ft.)

Windows 697 u-value(std) 1.220 0.500 0.500 1.220

 sh. coef.(std) 0.850 0.500 0.500 0.850

(Window-Wall Ratio = 0.12) u-value(cost) 1.213 0.497 0.497 1.213

sh. coef.(cost) 0.693 0.506 0.506 0.693

 cost ($/sqft) $1.56 $8.70 $8.70 $1.56

Opaque Walls 5,108 u-value 0.132 0.132 0.132 0.132

 cost ($/sqft) $0.33 $0.33 $0.33 $0.33

Roof 10,000 u-value 0.085 0.051 0.051 0.085

 cost ($/sqft) $0.91 $1.36 $1.36 $0.91

 (feet)

Slab perimeter 447 u-value 0.125 not req'd 0.125 not req'd

 cost ($/ft)* $4.12 $0.00 $0.00 $4.12

 *24-inch depth

 Envelope Cost (incremental) $13,709 $21,334 $21,334 $13,709

Lighting

Lighting Power Density watts/sqft 3.31 1.90 3.31 1.90

Lighting Cost per Sq. Foot $/sqft $2.20 $1.80 $2.20 $1.80

 Total Lighting Cost $22,044 $17,983 $22,044 $17,983

HVAC Equipment1 Capacity Central, Air-Source AC >65 and < 135 kBtu/h

 (kBtu/h)

EER 9.27 9.27 9.27 9.27

Unit Cost/ton $565 $565 $565 $565

Number of Units (Tons) 14.31 9.20 12.68 11.04

Total Equipment Cost $8,088 $5,198 $7,167 $6,236

Construction Cost $43,841 $44,515 $50,545 $37,928

Annual Energy Consumption 

Electricity, lights and plugs MMBtu 500 314 500 314

Electricity, HVAC MMBtu 180 112 161 134

Natural Gas MMBtu 23 31 22 34

Total Annual Energy Cost2 $14,468 $9,136 $14,055 $9,611

Economic Measures

Life-Cycle Cost Savings $66,404 ($2,407) $67,843

Savings-to-Investment Ratio (SIR) Invest. < 0 0.7 Invest. < 0

Adjusted IRR Invest. < 0 6.0% Invest. < 0

Notes:

1 Economizer used

2 2001 electricity price = 7.2 cents/kWh 2001 gas price = $4.77 /MMBtu

3 Years for Analysis = 40 Discount Rate = 7.0%

 Life-cycle cost savings includes replacement costs and residual values

27
Table 12. Engineering and Cost Summary for Elementary School with DX Cooling 

28

Elementary School (WWR=0.17) 

 Bldg. Size 50,000 sq. ft. Standard Level

NM School

Standard IECC2000

NM School 

Standard

w/IECC2000 

Env.

NM School 

Standard

w/IECC2000 

Light

Envelope Area (sq. ft.)

Windows 2,207 u-value(std) 0.790 0.500 0.500 0.790

 sh. coef.(std) 0.680 0.500 0.500 0.680

(Window-Wall Ratio = 0.17) u-value(cost) 0.730 0.497 0.497 0.730

sh. coef.(cost) 0.590 0.506 0.506 0.590

 cost ($/sqft) $5.13 $8.70 $8.70 $5.13

Opaque Walls 10,773 u-value 0.07 0.132 0.132 0.07

 cost ($/sqft) $0.86 $0.33 $0.33 $0.86

Roof 50,000 u-value 0.032 0.051 0.051 0.032

 cost ($/sqft) $2.04 $1.36 $1.36 $2.04

 (feet)

Slab perimeter 998 u-value 0.125 not req'd 0.125 not req'd

 cost ($/ft)* $4.31 $0.00 $0.00 $4.31

 *24-inch depth 

 Envelope Cost (incremental) $126,966 $90,678 $90,678 $126,966

Lighting

Lighting Power Density watts/sqft 1.95 1.50 1.95 1.50

Lighting Cost per Sq. Foot $/sqft $2.54 $1.95 $2.54 $1.95

 Total Lighting Cost $126,918 $97,629 $126,918 $97,629

HVAC Equipment1 Capacity Central, Air-Source AC >65 and < 135 kBtu/h

 (kBtu/h)

EER 9.27 9.27 9.27 9.27

Unit Cost/ton $565 $565 $565 $565

Number of Units (Tons) 56.50 51.01 57.53 52.93

Total Equipment Cost $31,923 $28,819 $32,506 $29,905

Construction Cost $285,808 $217,126 $250,102 $254,500

Annual Energy Consumption 

Electricity, lights and plugs MMBtu 1,134 915 1,134 915

Electricity, HVAC MMBtu 487 432 478 440

Natural Gas MMBtu 630 773 695 705

Total Annual Energy Cost2 $37,216 $32,112 $37,326 $31,967

Economic Measures

Life-Cycle Cost Savings $149,923 $35,053 $112,883

Savings-to-Investment Ratio (SIR) Invest. < 0 Invest. < 0 Invest. < 0

Adjusted IRR Invest. < 0 Invest. < 0 Invest. < 0

Notes:

1 Economizer used

2 2001 electricity price = 7.2 cents/kWh 2001 gas price = $4.77 /MMBtu

3 Years for Analysis = 40 Discount Rate = 7.0%

 Life-cycle cost savings includes replacement costs and residual values
Table 13. Engineering and Cost Summary for Elementary School with Evaporative Cooling 

29

Elementary School (WWR=0.17) 

 Bldg. Size 50,000 sq. ft. Standard Level

NM School 

Standard IECC2000

NM School 

Standard 

w/IECC2000 

Env.

NM School 

Standard 

w/IECC2000 

Light

Envelope Area (sq. ft.)

Windows 2,207 u-value(std) 0.790 0.500 0.500 0.790

 sh. coef.(std) 0.680 0.500 0.500 0.680

(Window-Wall Ratio = 0.17) u-value(cost) 0.730 0.497 0.497 0.730

sh. coef.(cost) 0.590 0.506 0.506 0.590

 cost ($/sqft) $5.13 $8.70 $8.70 $5.13

Opaque Walls 10,773 u-value 0.07 0.132 0.132 0.07

 cost ($/sqft) $0.86 $0.33 $0.33 $0.86

Roof 50,000 u-value 0.032 0.051 0.051 0.032

 cost ($/sqft) $2.04 $1.36 $1.36 $2.04

 (feet)

Slab perimeter 998 u-value 0.125 not req'd 0.125 not req'd

 cost ($/ft)* $4.31 $0.00 $0.00 $4.31

 *24-inch depth

 Envelope Cost (incremental) $126,966 $90,678 $90,678 $126,966

Lighting

Lighting Power Density watts/sqft 1.95 1.50 1.95 1.50

Lighting Cost per Sq. Foot $/sqft $2.54 $1.95 $2.54 $1.95

 Total Lighting Cost $126,918 $97,629 $126,918 $97,629

HVAC Equipment1 Capacity Central, Air-Source AC >65 and < 135 kBtu/h

 (kBtu/h)

EER 9.27 9.27 9.27 9.27

Unit Cost/ton $1,325 $565 $1,325 $1,325

Number of Units (Tons) 56.50 51.01 57.53 52.93

Total Equipment Cost $74,864 $28,819 $76,230 $70,129

Construction Cost $328,749 $217,126 $293,826 $294,725

Annual Energy Consumption 

Electricity, lights and plugs MMBtu 1,134 915 1,134 915

Electricity, HVAC MMBtu 265 432 261 237

Natural Gas MMBtu 630 773 695 705

Total Annual Energy Cost2 $32,534 $32,112 $32,762 $27,685

Economic Measures

Life-Cycle Cost Savings $91,920 $33,582 $107,921

Savings-to-Investment Ratio (SIR) Invest. < 0 Invest. < 0 Invest. < 0

Adjusted IRR Invest. < 0 Invest. < 0 Invest. < 0

Notes:

1 No economizer used

2 2001 electricity price = 7.2 cents/kWh 2001 gas price = $4.77 /MMBtu

3 Years for Analysis = 40 Discount Rate = 7.0%

 Life-cycle cost savings includes replacement costs and residual values
7. Conclusion 

Figure 1 provides a comparison of the LCC savings per square foot by building type for adoption of 

the 2000 IECC envelope and lighting requirements, each individually and together. 

-1.00 0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00

Small Office (WWR=0.19)

Small Retail (WWR=0.12)

Elementary School - DX Cooling

Elementary School - Evaporative Cooling

($)

Source: Tables 10,11,12 & 13

Envelope & Lighting

Lighting Only

Envelope Only

Figure 1. A Comparison of Life Cycle Cost Saving Per Square Foot Between Different Types of Buildings

The 2000 IECC lighting requirements appear to be highly cost-effective for these building types in 

terms of LCC savings relative to the 90a-1980 baseline. The LCC savings from the adoption of 2000 

IECC envelope requirements are less substantial than those generated from the lighting requirements 

and are negative for small retail buildings with relatively low window-to-wall ratios. When lighting 

and envelope requirements are combined, all of the simulated buildings display savings in energy

use, annual fuel cost, and life-cycle costs. Based on these limited quantitative results, it appears that 

adopting the 2000 IECC standard in New Mexico would provide positive net economic benefits to 

the state relative to the building and design requirements prescribed in ASHRAE 90a-1980 and to the 

New Mexico School Standard. 

30
8. References 

American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). 2001. 2001 

ASHRAE Fundamentals Handbook. Atlanta, Georgia. 

American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) and Illuminating 

Engineering Society of North America (IESNA). 1980. Energy Conservation in New Building Design. 

American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) and Illuminating 

Engineering Society of North America (IESNA). 1989. Energy Standard for Buildings Except Low-Rise 

Residential Buildings. 

American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) and Illuminating 

Engineering Society of North America (IESNA). 1999. ASHRAE Standard Energy Standard for 

Buildings Except Low-Rise Residential Buildings. 

Barwig FE, et al. 1996. Preliminary Findings; Analysis of Commercial Space-Conditioning and Storage 

Water-Heating Equipment Efficiencies. PNNL-11191, Pacific Northwest National Laboratory, Richland, 

Washington. 

BLAST Support Office (BLAST). 1991. Volume 1: BLAST User Manual. University of Illinois at 

Urbana-Champaign, Illinois. 

Energy Information Administration (EIA). 2001a. “Annual Electric Utility Report,” and EIA-826, 

“Monthly Electric Utility Sales and Revenue Report with State Distributions.” EIA-861, U.S. Department 

of Energy. Summer, 2001. Washington D.C. 

Energy Information Administration (EIA). 2001b. Annual Energy Outlook 2002 with Projections to 

2020. U.S. Department of Energy. December 2001. Washington D.C. 

Energy Information Administration (EIA). 1992. Commercial Building Energy Consumption and 

Expenditures Survey 1992 (CBECS 92), Public Use Data, Micro-data files on EIA website. [Online]. 

Available: ftp://ftp.eia.doe.gov/pub/consumption/commercial/micro.data/ U.S. Department of Energy. 

Washington D.C. 

Energy Information Administration (EIA). 1995. Commercial Building Energy Consumption and 

Expenditures Survey 1995 (CBECS 95), Public Use Data, Micro-data files on EIA website. [Online]. 

Available: ftp://ftp.eia.doe.gov/pub/consumption/commercial/micro.data/ U.S. Department of Energy. 

Washington D.C. 

Energy Information Administration (EIA). 2000. National Energy Modeling System (NEMS) U.S. 

Department of Energy. 2000. Washington D.C. 

Energy Policy Act of 1992 (EPACT). Public Law 102-486, 1096 Stat 2776. 

Energy Policy and Conservation Act (EPCA). 42 USC 62901, et seq. 

31
Illumination Engineering Society. 1982. LEM-1-1982.

International Code Council. 2000. International Energy Conservation Code, Falls Church, VA. 

National Appliance Energy Conservation Act (NAECA) of 1987. Public Law 100-12. 

New Mexico Energy Minerals and Natural Resources Department. 1995. Energy Efficiency Standards 

Construction and Remodeling Procedure for Public School Buildings, Sante Fe, New Mexico.

Office of Management and Budget (OMB). 1992. Guidelines and Discount Rates for Benefit-Cost 

Analyses of Federal Programs. OMB Circular A-94, available URL: 

http://www.whitehouse.gov/OMB/circulars/a094/a094.html

Somasundaram, S. et. al. 2000. Screening Analysis for EPACT-Covered Commercial HVAC and WaterHeating Equipment. Pacific Northwest National Laboratory, PNNL-13232. April 2000. 

U.S. Census Bureau (Census). 2000. “1997 Economic Census Construction Geographic Area Series.” 

U.S. Department of Commerce, March 2000. Washington D.C.Energy

U.S. Department of Energy (DOE) 2000. January 2000. “Fluorescent Lamp Ballast Technical Support

Document.” Available online DOE website: [Online]. 

Available: http://www.eren.doe.gov/buildings/codes_standards/reports/ballasts/index.htm

W. W. Grainger Industrial Supply - Lighting Catalog 2000-01. 2000. W. W. Grainger, Incorporated. 

Lake Forest, IL. 

32
APPENDIX -- Analysis of Proposed Lighting Amendment 

A request was made by the state of New Mexico to provide an analysis of the energy and life-cycle cost 

impact of adoption of the 2000 IECC with an amendment to allow for up to 2.0 watts per square foot 

(w/ft2

) of lighting in any building type. The energy analysis was carried out by modifying the 2000 IECC 

simulations to use 2 0 w/ft2

 for all buildings. Lighting component costs were also adjusted by scaling the 

cost estimates for the 90.1-1989 standard (see the discussion in Section 8) by the ratio of LPD between 

that standard and 2.0 w/ft2

. 

Tables A.1-A.4 show the energy and life-cycle cost impacts of building to the IECC with the 2.0 w/ft2

allowance for the four building configurations simulated in this document. In addition, the tables show 

the energy and life-cycle cost impacts of the standards shown in Tables 12-15, the current New Mexico 

code baselines and the 2000 IECC with no modification. Since much of the energy savings in the IECC 

is from the lighting changes, the 2.0 w/ft2

-allowance dramatically reduces the energy savings for this 

“amended” 2000 IECC version when compared to the 2000 IECC for the office and education buildings 

studied. For the retail building, the 2000 IECC gives an allowance of up to 1.9 w/ft2

, so the 2.0 w/ft2

allowance for the retail building results in a relatively smaller increase in building energy use. 

It is noted that the 2.0 w/ft2

 value is actually more than the current New Mexico code (ASHRAE 90a1980) allows in the case of the office building and, for that building type, appears to be a step backwards 

in terms of building code efficiency, increasing building energy use for lighting as well as increasing the 

first cost of building construction. Using the amended IECC resulted in a minor reduction in annual 

energy cost of $282/year ($11,278 minus $10,996) for the office building simulated, but resulted in a 

negative overall LCC. 2.0 w/ft2

 is a reduction in the currently allowed LPD for the retail and education 

buildings, but the “amended” 2000 IECC still appears to reduce building life-cycle costs when compared 

to the current New Mexico codes for these buildings. The “amended” 2000 IECC, however, reduces 

energy use in only the retail building when compared to the current baseline. The “amended” 2000 IECC 

increases energy use for both the education buildings simulated when compared to the existing New 

Mexico School Standard. 

33
Table A-1a. Engineering and Cost Summary

Small Office (WWR=0.19) 

 Bldg. Size 10,000 sq. ft. Standard Level

90A-1980

Base IECC2000

IECC2000_2

wsf

90A-1980 

w/2000 Env.

90A-1980 

w/2000 Light

Envelope Area (sq. ft.)

Windows 1,482 u-value(std) 0.980 0.500 0.500 0.500 0.980

 sh. coef.(std) 0.850 0.500 0.500 0.500 0.850

(Window-Wall Ratio = 0.19) u-value(cost) 0.730 0.497 0.497 0.497 0.730

sh. coef.(cost) 0.840 0.506 0.506 0.506 0.840

 cost ($/sqft) $4.55 $8.70 $8.70 $8.70 $4.55

Opaque Walls 6,318 u-value 0.132 0.132 0.132 0.132 0.132

 cost ($/sqft) $0.33 $0.33 $0.33 $0.33 $0.33

Roof 5,000 u-value 0.085 0.051 0.051 0.051 0.085

 cost ($/sqft) $0.91 $1.36 $1.36 $1.36 $0.91

 (feet)

Slab perimeter 300 u-value 0.125 not req'd not req'd 0.125 not req'd

 cost ($/ft)* $4.12 $0.00 $0.00 $0.00 $4.12

 *24-inch depth 

 Envelope Cost (incremental) $14,615 $21,774 $21,774 $21,774 $14,615

Lighting

Lighting Power Density watts/sqft 1.91 1.30 2.00 1.91 1.30

Lighting Cost per Sq. Foot $/sqft $1.84 $1.75 $1.92 $1.84 $1.75

 Total Lighting Cost $18,361 $17,504 $19,227 $18,361 $17,504

HVAC Equipment1 Capacity Central, Air-Source AC >65 and < 135 kBtu/h

 (kBtu/h)

EER 9.27 9.27 9.27 9.27 9.27

Unit Cost/ton $565 $565 $565 $565 $565

Number of Units (Tons) 15.57 11.37 11.37 13.06 14.13

Total Equipment Cost $8,795 $6,422 $6,422 $7,379 $7,983

Construction Cost $41,772 $45,700 $47,423 $47,515 $40,102

Annual Energy Consumption 

Electricity, lights and plugs MMBtu 355 281 366 355 281

Electricity, HVAC MMBtu 166 124 145 142 151

Natural Gas MMBtu 58 60 48 49 70

Total Annual Energy Cost2 $11,278 $8,836 $10,996 $10,720 $9,461

Economic Measures

Life-Cycle Cost Savings $26,898 ($2,677) $678 $25,169

Savings-to-Investment Ratio (SIR) 9.0 0.6 1.1 Invest. < 0

Adjusted IRR 13.1% 5.5% 7.3% Invest. < 0

Notes:

1 Economizer used

2 2001 electricity price = 7.2 cents/kWh 2001 gas price = $4.77 /MMBtu

3 Years for Analysis = 40 Discount Rate = 7.0%

 Life-cycle cost savings includes replacement costs and residual values

34
Table A-1b. Engineering and Cost Summary

Small Retail (WWR=0.12) 

 Bldg. Size 10,000 sq. ft. Standard Level

90A-1980

Base IECC2000

IECC2000_2

wsf

90A-1980 

w/2000 Env.

90A-1980 

w/2000 Light

Envelope Area (sq. ft.)

Windows 697 u-value(std) 1.220 0.500 0.500 0.500 1.220

 sh. coef.(std) 0.850 0.500 0.500 0.500 0.850

(Window-Wall Ratio = 0.12) u-value(cost) 1.213 0.497 0.497 0.497 1.213

sh. coef.(cost) 0.693 0.506 0.506 0.506 0.693

 cost ($/sqft) $1.56 $8.70 $8.70 $8.70 $1.56

Opaque Walls 5,108 u-value 0.132 0.132 0.132 0.132 0.132

 cost ($/sqft) $0.33 $0.33 $0.33 $0.33 $0.33

Roof 10,000 u-value 0.085 0.051 0.051 0.051 0.085

 cost ($/sqft) $0.91 $1.36 $1.36 $1.36 $0.91

 (feet)

Slab perimeter 447 u-value 0.125 not req'd not req'd 0.125 not req'd

 cost ($/ft)* $4.12 $0.00 $0.00 $0.00 $4.12

 *24-inch depth 

 Envelope Cost (incremental) $13,709 $21,334 $21,334 $21,334 $13,709

Lighting

Lighting Power Density watts/sqft 3.31 1.90 2.00 3.31 1.90

Lighting Cost per Sq. Foot $/sqft $2.20 $1.80 $1.75 $2.20 $1.80

 Total Lighting Cost $22,044 $17,983 $17,490 $22,044 $17,983

HVAC Equipment1 Capacity Central, Air-Source AC >65 and < 135 kBtu/h

 (kBtu/h)

EER 9.27 9.27 9.27 9.27 9.27

Unit Cost/ton $565 $565 $565 $565 $565

Number of Units (Tons) 14.31 9.20 9.20 12.68 11.04

Total Equipment Cost $8,088 $5,198 $5,198 $7,167 $6,236

Construction Cost $43,841 $44,515 $44,022 $50,545 $37,928

Annual Energy Consumption 

Electricity, lights and plugs MMBtu 500 314 327 500 314

Electricity, HVAC MMBtu 180 112 115 161 134

Natural Gas MMBtu 23 31 30 22 34

Total Annual Energy Cost2 $14,468 $9,136 $9,482 $14,055 $9,611

Economic Measures

Life-Cycle Cost Savings $66,404 $63,055 ($2,407) $67,843

Savings-to-Investment Ratio (SIR) Invest. < 0 Invest. < 0 0.7 Invest. < 0

Adjusted IRR Invest. < 0 Invest. < 0 6.0% Invest. < 0

Notes:

1 Economizer used

2 2001 electricity price = 7.2 cents/kWh 2001 gas price = $4.77 /MMBtu

3 Years for Analysis = 40 Discount Rate = 7.0%

 Life-cycle cost savings includes replacement costs and residual values

35
Table A-1c. Engineering and Cost Summary

Elementary School (WWR=0.17) 

 Bldg. Size 50,000 sq. ft. Standard Level

90A-1980

Base IECC2000

IECC2000_2

wsf

90A-1980 

w/2000 Env.

90A-1980 

w/2000 Light

Envelope Area (sq. ft.)

Windows 2,207 u-value(std) 0.790 0.500 0.500 0.500 0.790

 sh. coef.(std) 0.680 0.500 0.500 0.500 0.680

(Window-Wall Ratio = 0.17) u-value(cost) 0.730 0.497 0.497 0.497 0.730

sh. coef.(cost) 0.590 0.506 0.506 0.506 0.590

 cost ($/sqft) $5.13 $8.70 $8.70 $8.70 $5.13

Opaque Walls 10,773 u-value 0.07 0.132 0.132 0.132 0.07

 cost ($/sqft) $0.86 $0.33 $0.33 $0.33 $0.86

Roof 50,000 u-value 0.032 0.051 0.051 0.051 0.032

 cost ($/sqft) $2.04 $1.36 $1.36 $1.36 $2.04

 (feet)

Slab perimeter 998 u-value 0.125 not req'd not req'd 0.125 not req'd

 cost ($/ft)* $4.31 $0.00 $0.00 $0.00 $4.31

 *24-inch depth 

 Envelope Cost (incremental) $126,966 $90,678 $90,678 $90,678 $126,966

Lighting

Lighting Power Density watts/sqft 1.95 1.50 2.00 1.95 1.50

Lighting Cost per Sq. Foot $/sqft $2.54 $1.95 $2.00 $2.54 $1.95

 Total Lighting Cost $126,918 $97,629 $100,110 $126,918 $97,629

HVAC Equipment1 Capacity Central, Air-Source AC >65 and < 135 kBtu/h

 (kBtu/h)

EER 9.27 9.27 9.27 9.27 9.27

Unit Cost/ton $565 $565 $565 $565 $565

Number of Units (Tons) 56.50 51.01 51.01 57.53 52.93

Total Equipment Cost $31,923 $28,819 $28,819 $32,506 $29,905

Construction Cost $285,808 $217,126 $219,607 $250,102 $254,500

Annual Energy Consumption 

Electricity, lights and plugs MMBtu 1,134 915 1,158 1,134 915

Electricity, HVAC MMBtu 487 432 483 478 440

Natural Gas MMBtu 630 773 686 695 705

Total Annual Energy Cost2 $37,216 $32,112 $37,910 $37,326 $31,967

Economic Measures

Life-Cycle Cost Savings $149,923 $74,192 $35,053 $112,883

Savings-to-Investment Ratio (SIR) Invest. < 0 Invest. < 0 Invest. < 0 Invest. < 0

Adjusted IRR Invest. < 0 Invest. < 0 Invest. < 0 Invest. < 0

Notes:

1 Economizer used

2 2001 electricity price = 7.2 cents/kWh 2001 gas price = $4.77 /MMBtu

3 Years for Analysis = 40 Discount Rate = 7.0%

 Life-cycle cost savings includes replacement costs and residual values

36
Table A-1d. Engineering and Cost Summary

Elementary School (WWR=0.17) 

 Bldg. Size 50,000 sq. ft. Standard Level

90A-1980

Base IECC2000

IECC2000_2

wsf

90A-1980 

w/2000 Env.

90A-1980 

w/2000 Light

Envelope Area (sq. ft.)

Windows 2,207 u-value(std) 0.790 0.500 0.500 0.500 0.790

 sh. coef.(std) 0.680 0.500 0.500 0.500 0.680

(Window-Wall Ratio = 0.17) u-value(cost) 0.730 0.497 0.497 0.497 0.730

sh. coef.(cost) 0.590 0.506 0.506 0.506 0.590

 cost ($/sqft) $5.13 $8.70 $8.70 $8.70 $5.13

Opaque Walls 10,773 u-value 0.07 0.132 0.132 0.132 0.07

 cost ($/sqft) $0.86 $0.33 $0.33 $0.33 $0.86

Roof 50,000 u-value 0.032 0.051 0.051 0.051 0.032

 cost ($/sqft) $2.04 $1.36 $1.36 $1.36 $2.04

 (feet)

Slab perimeter 998 u-value 0.125 not req'd not req'd 0.125 not req'd

 cost ($/ft)* $4.31 $0.00 $0.00 $0.00 $4.31

 *24-inch depth 

 Envelope Cost (incremental) $126,966 $90,678 $90,678 $90,678 $126,966

Lighting

Lighting Power Density watts/sqft 1.95 1.50 2.00 1.95 1.50

Lighting Cost per Sq. Foot $/sqft $2.54 $1.95 $2.00 $2.54 $1.95

 Total Lighting Cost $126,918 $97,629 $100,110 $126,918 $97,629

HVAC Equipment1 Capacity Central, Air-Source AC >65 and < 135 kBtu/h

 (kBtu/h)

EER 9.27 9.27 9.27 9.27 9.27

Unit Cost/ton $1,325 $565 $565 $1,325 $1,325

Number of Units (Tons) 56.50 51.01 51.01 57.53 52.93

Total Equipment Cost $74,864 $28,819 $28,819 $76,230 $70,129

Construction Cost $328,749 $217,126 $219,607 $293,826 $294,725

Annual Energy Consumption 

Electricity, lights and plugs MMBtu 1,134 915 1,158 1,134 915

Electricity, HVAC MMBtu 265 432 483 261 237

Natural Gas MMBtu 630 773 686 695 705

Total Annual Energy Cost2 $32,534 $32,112 $37,910 $32,762 $27,685

Economic Measures

Life-Cycle Cost Savings $91,920 $16,189 $33,582 $107,921

Savings-to-Investment Ratio (SIR) Invest. < 0 Invest. < 0 Invest. < 0 Invest. < 0

Adjusted IRR Invest. < 0 Invest. < 0 Invest. < 0 Invest. < 0

Notes:

1 No economizer used

2 2001 electricity price = 7.2 cents/kWh 2001 gas price = $4.77 /MMBtu

3 Years for Analysis = 40 Discount Rate = 7.0%

 Life-cycle cost savings includes replacement costs and residual values

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