The Environmental and Societal Value of Extruded Polystyrene Foam Insulation

Barbara A. Fabian, Owens Corning

Tallmadge, OH 44278; USA 

Susan Herrenbruck, Extruded Polystyrene Foam Association

Woodbridge, VA 22193

Alisa Hoffee, Pactiv Corporation

Atlanta, GA 30328; USA

Keywords: extruded polystyrene foam, thermoplastic, green building, recycled-content; 

reusability, recyclability, sustainable.

In recent years, the building community has taken a more active role in the sustainable design of 

buildings. The concept of environmentally-conscious building design (“green building”) has 

already been incorporated into tools that measure environmental performance of buildings and 

building materials. Tools such as LEED (Leadership in Energy and Environmental Design) 

strive to utilize design and construction practices that significantly reduce or eliminate the impact 

of materials and buildings on the environment and its inhabitants. Optimizing material selection 

is a key component in building “green”. Extruded polystyrene foam insulation (XPS) is an 

excellent choice as one potential environmentally-responsible alternative to other types of 

building insulation. XPS ranks well in most of the key attributes of a “green” building material, 

i.e., recycled and/or recovered content; reusability/recyclability; durability, embodied energy, 

and air quality. 

Abstract

Due to the thermoplastic nature of XPS, virtually 100% of all in-plant scrap is recycled and 

reused in the primary extrusion process, thus resulting in very high material utilization. 

Additionally, the thermoplastic nature of XPS makes it an excellent candidate for using postconsumer and post-industrial recycled and/or recovered polystyrene foam. The increasing costs 

of material disposal and landfilling make the reusability of XPS a very attractive option. XPS 

building insulation reduces energy consumption,1 while increasing the comfort level of

occupants compared to under-insulated buildings.2 The many outstanding attributes of XPS, 

stable R-value, moisture resistance, and high compressive strength, make it an excellent material 

choice for insulation. In a variety of harsh and unique applications, XPS is often the only 

product accepted by building code agencies. 

This paper discusses both the environmental and societal aspects of extruded polystyrene foam 

insulation from its manufacture to beyond end-use. 

 

1 Energy and Environmental Benefits of Extruded Polystyrene Foam and Fiberglass Insulation Products in U.S. Residential and 

Commercial Buildings, Merle F. McBride, Owens Corning, Granville, OH, USA 43023; regarding insulated vs. uninsulated 

buildings.

2 Department of Energy Insulation Fact Sheet; DOE/CE-0180 2002 states: “To maintain comfort, the heat lost in winter must be 

replaced by your heating system and the heat gained in summer must be removed by your air conditioner. Insulating ceilings, 

walls, and floors decreases this heat flow by providing an effective resistance to the flow of heat.” Found at 

http://www.ornl.gov/sci/roofs+walls/insulation/ins_02.html. Publication issued by Assistant Secretary, Energy Efficiency and 

Renewable Energy.
The Environmental and Societal Value of Extruded Polystyrene Foam Insulation

Authors: Barbara Fabian, Susan Herrenbruck, and Alisa Hoffee

Prepared for: Earth Tech Forum 200; April 15, 2004 Page 2 of 16

Decisions about insulation usage are among the most important an architect or designer will 

make relative to the environmental impact of a building. In recent years, the building 

community has taken a more active role in the utilization of green or sustainable building design. 

Sustainable building design can be as narrow as choosing to use materials with recycled content 

or by achieving energy efficiency. It can also be complex by encompassing a systems approach 

using recyclability, reusability, durability, embodied energy and air quality. The building 

community has adopted tools such as LEED (Leadership in Energy and Environmental Design) 

to measure the environmental performance of a building. The use of extruded polystyrene foam 

insulation can play an effective and important role in responsible environmental stewardship in 

building design and construction.

Introduction

XPS foam, which is technically referred to as extruded polystyrene, is an ideal thermal insulation 

because it offers a high strength to weight ratio and an excellent balance between cost and 

performance. XPS foam is manufactured by expanding a mixture of molten polystyrene and 

low-conductivity blowing agents into a low density, closed cell foam. The strength of the 

resulting product can be engineered to achieve a variety of compressive strengths.

XPS Manufacturing Process

In the XPS foam process, a feed system introduces polystyrene resin and other minor 

components (such as a nucleating agent, colorant, flame retardant, etc.) into an extruder where it 

is melted and mixed. A pressurized blowing agent in a liquid state is then introduced and the 

resulting mixture is extruded at an elevated temperature and pressure through a slot-shaped 

orifice at ambient temperature and atmospheric pressure (or in some cases at a partial vacuum). 

As the molten mixture passes through the orifice, the blowing agent vaporizes because of the 

reduced pressure and the molten mixture expands to form a cellular foam. The material is 

extruded as a continuous board with high-density skin surfaces that are formed as a result of 

friction when the board moves through mechanical plates used to shape the flat sheets.

As the foam board moves down a conveyor system, it is printed on the top surface with the 

manufacturer’s logo, R-value and other important information. Further downstream, the boards

are trimmed to the finished dimensions and profile (e.g. square, tongue and groove, or shiplap) 

prior to final packaging. Trim material is captured at the cutting stage and conveyed to a grinder 

that chops it into small pieces of foam (commonly referred to as fluff). The polystyrene fluff is 

then either stored for future reprocessing or is immediately conveyed to a reclaim system, where 

it is melted and re-extruded into pellets. The pellets are then conveyed to a storage silo or reused in the original extrusion process. This reprocessed polystyrene (commonly referred to as 

industrial scrap resin or post-industrial resin) is combined with virgin polystyrene resin pellets at 

typical loadings of 0 – 30 wt%, depending on the product type being made. 

Key XPS Foam Attributes

Durability of an insulation material is a very important environmental consideration. An 

essential attribute for any environmentally-preferred product, especially insulation, is the ability 

Durability
The Environmental and Societal Value of Extruded Polystyrene Foam Insulation

Authors: Barbara Fabian, Susan Herrenbruck, and Alisa Hoffee

Prepared for: Earth Tech Forum 200; April 15, 2004 Page 3 of 16

of the product to perform its intended function for its useful life. Good insulation performance is 

essential for the proper design of a building’s heating and air conditioning systems as well as its 

management of water and water vapor. 

The many outstanding attributes of XPS, stable R-value, moisture resistance, and strength make 

it the best, if not only, product acceptable in a variety of harsh and unique applications.

Extruded polystyrene foam insulation products (XPS) in North America have a closed-cell 

structure filled with a blowing agent, HCFC 142b, specifically selected for its low thermal 

conductivity and low diffusivity to enhance the thermal performance of the foam.

Stable (Long-Term) R-Value

Over a long period of time (i.e., 30 to 50 years), the blowing agent diffuses through the thickness 

of the foam, and air diffuses into these same closed cellular volumes. Because of this gas 

movement, the overall thermal resistance (i.e., R-value) of the insulation product changes over 

time. This phenomenon is typically called “aging”. Foam aging is not new and has been 

discussed in numerous papers over the years. Recent long-term data published by Paquet and Vo 

3

confirm the slow diffusion rate of CFC 12, HCFC 142b and HFC 134a through XPS foam

which results in a very slow aging process. This data demonstrates the excellent long term 

thermal performance of XPS foams in the laboratory as well as under field conditions. 

The impact of material changes in foam formulations must be analyzed in terms of their resulting 

thermal performance for a total environmental assessment. To this end, the following 

information should be considered when evaluating the “energy efficiency” of a product.

Energy Efficiency

According to the website of the United States Environmental Protection Agency (EPA), and also 

the Energy Star Program4 “... Carbon dioxide (CO2) is the key greenhouse gas responsible for 

global warming concerns. The overwhelming share of U.S. and world CO2 emissions5 comes 

from burning fossil fuels, such as oil, coal and gas – our main sources of energy. Burning fossil 

fuel causes emissions of other greenhouse gases as well, such as methane (CH4) and nitrous 

oxide (NO2).”

The energy efficiency “payback” from the high levels of long-term R per inch that is used to 

insulate buildings and residences far exceeds the marginal contribution of ozone depletion 

potential (ODP) coming from HCFCs and HFCs deployed in XPS use until their Montreal 

Protocol required phase-out dates.

6

 3 Vo, Chau V., Dow Deutschland GmbH; Rheinmuenster, Germany, D-77836; Paquet, Andrew N., The Dow Chemical 

Company, Midland, MI, USA 48674; An Evaluation Of The Thermal Conductivity For Extruded Polystyrene Foam Blown 

With HFC-134a or HCFC-142b; Journal of Cellular Plastics, 2004

4 All members of XPSA, The Dow Chemical Company, Owens Corning, Inc., and Pactiv Corporation are allies of the Energy 

Star Homes Program.

5 EPA Website at: http://www.epa.gov/globalwarming/emissions/national/co2.html.

6 Energy and Environmental Benefits of Extruded Polystyrene Foam and Fiberglass Insulation Products in U.S. Residential and 

Commercial Buildings, Merle F. McBride, Owens Corning, Granville, OH, USA 43023; regarding insulated vs. uninsulated 

buildings.
The Environmental and Societal Value of Extruded Polystyrene Foam Insulation

Authors: Barbara Fabian, Susan Herrenbruck, and Alisa Hoffee

Prepared for: Earth Tech Forum 200; April 15, 2004 Page 4 of 16

 

There is a further environmental aspect that must be considered in assessing the total

environmental impact of the materials used in the production of foam insulating materials—that 

of energy efficiency and conservation relative to Global Climate Change. In May of 1999 the 

technical experts working on both the Montreal and Kyoto Protocols collaborated in Petten, 

Netherlands at the Joint IPCC/TEAP Expert Meeting on “Options for the Limitation of Emissions 

of HFC’s and PFC’s”. One of its conclusions was that the use of foams enable higher levels of 

energy efficiency. Specifically, they stated, “Insulating foams account for at least 30% of the 

overall global insulating market despite their higher cost per unit.” They noted that “an average 

increase in global energy efficiency of 1% in buildings would equate to an annualized reduction 

of CO2 emissions of some 50-80,000 tons.

A.D. Little conducted a study, “Global Comparative Analysis of HFC and Alternative 

Technologies for Refrigeration, Air Conditioning, Foam, Solvent, Aerosol Propellant and Fire 

Protection Applications” which included a Life Cycle Climate Performance (LCCP) and 

provided an analysis of Insulating Sheathing for Residential Wood Frame Walls. It concluded, 

“These results show that far more energy is saved than consumed by manufacturing the foam and 

that far more greenhouse gas emissions due to space condition energy consumption are avoided 

than are emitted in the manufacture of the foam.” Thus, the impact of material changes in foam 

formulation must be analyzed in terms of their resulting thermal performance for a total 

environmental assessment. 

A critical factor affecting long-term thermal performance is the ability of an insulating material 

to resist the intrusion of moisture. Moisture can come in contact with insulation not only during 

construction, but throughout the life of the building. If absorbed, its effect is to drastically reduce 

thermal efficiency (R-value). The closed-cell structure and lack of voids in XPS helps it to resist 

moisture penetration better than other types of insulating materials without the need for a facer or 

laminate to achieve this property.

Moisture Resistance 

7

 The excellent moisture resistance of XPS foam insulation has 

been confirmed repeatedly and consistently in laboratory tests and under field use conditions.8

Without the need for a facer or laminate, XPS products only absorb 0.3% by weight 9

.

With its closed-cell structure, XPS foam products form a natural "skin" surface which is not 

conducive to moisture absorbency. Thus, when installed in walls, XPS shifts damaging dew 

points minimizing the potential for condensation to occur within a wall. This helps to ensure the 

insulating power remains in the wall and does not degrade due to moisture intrusion. 

 7 ASTM Standard, C 578-03a for molded expanded (EPS) and extruded (XPS) rigid cellular polystyrene thermal insulation, 

ASTM 1289-02 for faced rigid cellular polyisocyanurate thermal insulation board; and ASTM C 1029 for spray applied rigid 

cellular polyurethane thermal insulation. 

8 Development of Experimental Data on Extruded Polystyrene Roofing Insulation under Simulated Winter Exposure Conditions, 

Report #SPI-6443, by Energy Materials Testing Laboratory, Biddeford, ME 04005. U.S. Army Cold Regions Research and 

Engineering Laboratories Report: Moisture in the Roofs of Cold Storage Buildings, Wayne Tobiasson and Alan Greatorex 

November 1998. Report found at: http://www.crrel.usace.army.mil/techpub/CRREL_Reports/reports/SR98_13.pdf ; Various 

ASTM material standards

9 ASTM Standard, C 578-03a
The Environmental and Societal Value of Extruded Polystyrene Foam Insulation

Authors: Barbara Fabian, Susan Herrenbruck, and Alisa Hoffee

Prepared for: Earth Tech Forum 200; April 15, 2004 Page 5 of 16

Mold, Mildew, Corrosion Resistance

Because XPS foam is a plastic material, it will not corrode or rot or support the growth of mold 

or mildew. It is resistant to microorganisms found in soil and provides no nutrient value to 

vermin. These properties make it an outstanding insulating material for below grade applications. 

Compressive Strength

The closed-cell structure of XPS imparts excellent long-term compressive strength and 

durability. It is dimensionally stable and products are available in a wide range of compressive 

strengths (from 15 psi to 100 psi) to suit a variety of application requirements.

Applications Where XPS Insulation Excels

With a long-term R-value from 3 [for 1⁄2 -in. thick (13 mm) sheathing boards] to 5 [for 1-in.-thick 

(25 mm) boards], XPS sheathing boards increase the R-value of the entire wall. XPS sheathing 

boards provide a continuous layer of protection against water moisture infiltration while 

guarding against thermal bridging. Thermal bridging occurs 

due to wood studs and other un-insulated parts of the wall, 

such as framing, ducts, wiring, and plumbing – which 

typically account for over 25% of the exterior walls in an 

average home. When properly installed, it also forms a 

continuous air barrier that minimizes convection currents and 

air infiltration, the leading cause of energy loss. When 

moisture gets into a wall assembly it compromises wood 

components and as a result can reduce the overall R-value of 

the building envelope. 

Exterior Wall Sheathing 

Unlike many other types of sheathing, XPS does not have to 

rely on facers or laminates to obtain compressive strength or 

achieve its ability to resist water moisture intrusion. Therefore, it is an excellent choice for 

ensuring a building’s envelope will be properly sheathed and assure that its subsequent 

performance will not be compromised during installation of the sheathing due to nails, glue and 

other materials.

XPS is the product of choice for cold storage buildings. In 1997, Owens Corning completed a 

survey of the moisture content in the roofing systems of existing cold storage buildings. Owens 

Corning engaged the U.S. Army Corps of Engineers Cold Regions Research and Engineering 

Laboratories 

Cold Storage

(CRREL) to conduct the building evaluations. In a report issued by CRREL10

 10Tobiasson, Wayne and Greatorex, Alan; U.S. Army Cold Regions Research and Engineering Laboratories Report: Moisture in 

the Roofs of Cold Storage Buildings, November 1998. 

, they 

discussed insulation including: fibrous glass, fiberboard, perlite, wood fiber, expanded 

polystyrene, extruded polystyrene, polyisocyanurate, and phenolic. Areas of wet insulation were 

found in 8 of the 10 roofs evaluated. Representatives from CRREL performed daytime indoor 

and nighttime, on the roof, infrared roof moisture surveys (Tobiasson and Korhonen 1985 and 

Special Report 98-13) to identify wet sections of the roofs.
The Environmental and Societal Value of Extruded Polystyrene Foam Insulation

Authors: Barbara Fabian, Susan Herrenbruck, and Alisa Hoffee

Prepared for: Earth Tech Forum 200; April 15, 2004 Page 6 of 16

Core sampling of the membranes and insulation were 

collected for laboratory evaluation. The specimens 

were evaluated for:

• Dry Density

• Moisture Content

• Thermal Resistance – as sampled

• Thermal Resistance-after drying

The conclusions reached by CRREL from the roof 

study state that due to the intense vapor drive and air 

infiltration and the propensity of the cold storage roofs to exhibit water infiltration, the only roof 

insulation available that can offer much improved moisture resistance in the roofs of freezers and 

coolers is XPS.11

XPS is the only code approved product for use in horizontal applications in code-compliant 

FPSF. The concept of FPSF involves the placement of rigid foam insulation in a way that raises 

the frost penetration depth around a building to permit foundation footing depths as shallow as 

16 inches, even in cold climates. According to the FPSF Design Guide issued by the Department 

of Housing and Urban Development, “The frost-protected shallow foundation technology offers 

builders an opportunity to excavate less earth, use less material, and build homes more cost 

effectively.

Frost Protected Shallow Foundations (FPSF)

12 Although relatively new in the United States, FPSF has been extensively used in 

Scandinavian countries for over 40 years. 

During this time, in excess of one (1) million 

homes have been successfully built using this 

construction method. FPSF is commonly used 

in monolithic slab on grade; independent slab 

and stem wall; and permanent wood foundation 

applications. Moisture resistance is extremely

important in FPSF because of the insulation’s 

placement in potentially wet soil and because of 

the freeze/thaw cycles that may occur. 

The exceptional moisture resistance along with 

a stable R-value in the presence of moisture, 

make XPS the product of choice and the only 

insulation material approved by U.S. building codes for horizontal applications of below-grade 

insulation in the FPSF application.

 11 Ibid 9.

Geofoam

12 Design Guide for Frost-Protected Shallow Foundations, U.S. Department of Housing and Urban Development; Office of 

Policy Development and Research. HUD-1497-PDR (1); April 1995
The Environmental and Societal Value of Extruded Polystyrene Foam Insulation

Authors: Barbara Fabian, Susan Herrenbruck, and Alisa Hoffee

Prepared for: Earth Tech Forum 200; April 15, 2004 Page 7 of 16

Design and construction on soft ground has been a challenge to geotechnical engineers for years. 

The growing population around the world has demanded innovative and economical solution for 

site development. XPS has been used as a light weight fill material for slope stabilization, 

retaining walls, and abutment backfill. Also due to the stable R-value, high resistance to water 

moisture absorption, and high compressive 

strength, XPS has been used to minimize frost 

heave on roadways and airport runways as a 

subgrade insulation.13 

Drawings from “Properties & Applications of 

GEOFOAM”©, D.Negussey, PhD, P.Eng for 

Society of the Plastics Industry, Inc. 1997

The depth requirements for pipeline burials below frost penetration could be reduced if geofoam 

is used.

14 

A Protected Roof Membrane Assembly (PMRA) differs 

from a conventional roof design in that the membrane is 

placed under the insulation layer, maximizing 

membrane life by protecting it from temperature 

extremes, freeze/thaw cycles, UV degradation, and 

traffic wear. A PMRA begins with the application of 

the EPDM membrane, followed by the XPS boards, the 

protective scrim, and finally the ballast. Extruded 

polystyrene foam is the only type of insulation 

recommended for use in a PRMA system because it 

resists moisture and crushing so thoroughly — critical properties in the selection of PRMA 

insulation.

Roof Recover and PRMA Applications

 13Negussey, D. PhD, P. Eng.,1997. Properties & Applications of Geofoam, Society of the Plastics Industry, Inc.

14 Ibid.
The Environmental and Societal Value of Extruded Polystyrene Foam Insulation

Authors: Barbara Fabian, Susan Herrenbruck, and Alisa Hoffee

Prepared for: Earth Tech Forum 200; April 15, 2004 Page 8 of 16

Reduce

Reuse

Recycle

Incineration

Land 

filling

Due to its compressive strength, stable long-term thermal performance and moisture resistance,

XPS offers exceptional performance in plaza, protected membrane roof assemblies (PMRA) and 

garden roof applications.

PMR roof (blue line) – the membrane temperature remains 

relatively constant.

Conventional roof (yellow line) – membrane temperature 

fluctuates widely 

The important properties are:

• Extends plaza deck or roof life, providing 

protection from ultraviolet deterioration;15

• Protects roof membranes against 

weathering, physical abuse and damage; 

• Maintains the membrane at a relatively 

constant temperature, minimizing effects of 

freeze-thaw cycling and excessive heat (see 

diagram Membrane Temperatures above); 

• Reduces installation, material and repair 

expenditures;

• Provides for easy removal and re-installation 

of ballast and insulation if re-roofing 

becomes necessary, and

• Provides high moisture resistance and 

strength to allow vegetation growth

The hierarchy of waste management for green building design is as follows:

Green Building Principles

 15ASTM D6630 standard, Method P is used to evaluate and is intended to establish minimum performance levels for 

insulated roof membrane assemblies and lists pertinent design guidelines. 
The Environmental and Societal Value of Extruded Polystyrene Foam Insulation

Authors: Barbara Fabian, Susan Herrenbruck, and Alisa Hoffee

Prepared for: Earth Tech Forum 200; April 15, 2004 Page 9 of 16

Ideally, during the design stage, one would like to minimize waste generated from a project. 

Once the end-of-life of the original application is reached, there are several options to consider. 

If a material or system can be reused, the life of the materials can be extended which in turn,

minimizes energy spent and the impact on the environment. Recycling has traditionally been 

seen as the most effective way to protect and preserve the environment. Recycling has been 

viewed by much of the public as primarily a social issue. In reality, recycling is a very complex 

issue which we will discuss below. Incineration is seen as less desirable but even it can have 

some benefits when XPS is involved. Landfilling is usually viewed as the last viable option to be 

considered for waste management.

The ability to reuse rather than discard a building’s insulation can provide important cost and 

environmental benefits. Some materials reach the end of their life because they simply wear out 

and are not capable of performing their intended function. This is not true of extruded 

polystyrene insulation. Consider the example of commercial roofing . In commercial roofing 

applications, roofing replacements can occur every 10 to 15 years due to the failure of the roof 

membrane. XPS typically will outlast the roofing membrane under which it was installed. Due 

to its outstanding water resistance, XPS maintains excellent thermal and compressive strength 

properties over the life cycle of the building. In 1995, Single Ply Roofing Institute (SPRI) 

conducted an insulation reuse survey of members from SPRI, National Roofing Contractors 

Association (NRCA), and Roof Consultants Institute (RCI). The survey was designed to look at 

the factors important for insulation reuse.

Reuse

16 The critical factor cited by 80% of the respondents 

was the issue of moisture. The U.S. Army Corps of Engineers Cold Regions Research and 

Engineering Laboratory (CRREL) 

uses the criteria of the ratio of an 

insulations wet thermal resistivity 

to its dry thermal resistivity, 

expressed as a percentage to 

determine the materials thermal 

resistance ratio (TRR).

17 

CRREL considers an insulation 

wet and unacceptable if the TRR is 

less than 80 %. The TRR curves

(to the left) exhibit that XPS is 

extremely resistant to moisture and 

maintains a TRR above 80% out to 

at least 1000 days in the CRREL 

wetting tests.

 16 Sheahan, J.P. and Desjarlais, Andre O.,1997, Insulation Reuse in Low Slope Roofing in the USA: An Industry Survey, 

Proceedings of the Fourth International Symposium on Roofing Technology, National Roofing Contractors Association, 

Rosemont, IL

17 Tobiasson, Wayne; Greatorex, Alan, and Van Pelt, Doris, 1991, New wetting curves for common roof insulations, Third 

International Symposium on Roofing Technology, Montreal, Quebec, Canada

0

20

40

60

80

100

0 100 200 300 400 500 600 700

Time in Wetting Test (days)

% TRR (Therma

Resistance Ratio

Foamular Isocyanurate Perlite Fiberboard

Lowest acceptable value for roof insulation

Figure 1. Data from “New wetting curves for common roof 

insulations” Wayne Tobiasson, Alan Greatorex and Doris Van Pelt, 

U.S. Army Corps of Engineers Cold Regions Research and 

Engineering Laboratory Hanover, New Hampshire
The Environmental and Societal Value of Extruded Polystyrene Foam Insulation

Authors: Barbara Fabian, Susan Herrenbruck, and Alisa Hoffee

Prepared for: Earth Tech Forum 200; April 15, 2004 Page 10 of 16

A tremendous example of the reusability of XPS 

was evident during the 2003 re-roofing of the 

Dallas Fort Worth International Airport. Because 

the airport roof manager chose a PMRA design, 

almost 90% of the existing XPS material on the 

roof was able to be reused. The XPS material on 

the roof was over 17 years old. Samples of the 

17-year material were submitted to the Owens 

Corning R&D Laboratory for thermal and 

physical property testing. The testing showed that 

the in-situ material had lost little of its original Rvalue, maintained its original compressive 

strength, and absorbed virtually no moisture. 

In this particular application, the benefits of recycling the insulation included:

 Minimal business interruption. New insulation did not have to be loaded on to the airport roof,

curtailing airport operations

 Economically attractive (saved $100,000 in labor costs and $180,000 in new material purchases)

 Much lower environmental impact. Fewer trips to the landfill ($15,000 saved in hauling and 

landfill fees) and less waste disposal (avoided landfilling of 3,036 squares of material)

 Less fossil fuel use in raw materials, manufacturing, and transportation of the new and waste 

insulation 

 Greenhouse gas emissions avoided by minimizing resource processing

 Continual energy savings provided by the insulation

Figure 4. Dallas/Fort Worth reroofing project with Owens Corning Foamular XPS 

insulation.
The Environmental and Societal Value of Extruded Polystyrene Foam Insulation

Authors: Barbara Fabian, Susan Herrenbruck, and Alisa Hoffee

Prepared for: Earth Tech Forum 200; April 15, 2004 Page 11 of 16

Because XPS foam insulation is a thermoplastic, it can be easily “reworked” (see below) and can 

also include many types of recycled polystyrene streams.

Recyclability

In September 1990, the American Society for Testing and Materials (ASTM) published a 

standard that contains definitions for various types of plastics (ASTM D 5033-90, “Standard 

Guide for The Development of Standards Relating to the Proper Use of Recycled Plastics”). The 

XPS manufacturing process offers a unique opportunity to use several of these types:

Types of Polystyrene Resins

Reworked plastic – a plastic from a processor’s own production that has been reground, 

palletized, or solvated after having been previously processed by molding, extrusion, and so 

forth.

Post-industrial scrap – The XPS manufacturing process is capable of consuming its own scrap. 

This is usually in the form of trimmings as the boards are cut to finished dimensions, but also 

includes boards that are damaged in storage or shipment or otherwise do not meet specifications. 

The amount of trim scrap varies depending on product thickness and width, surface treatment

(skinned versus planed), and edge and end treatments (square versus shiplap versus tongue and 

groove). In general, geographic regions such as the European Union (EU) or the Pacific that 

produce mainly 24-inch (600 mm) wide products have a higher fraction of planed material which 

will have trimmings on the order of 20 – 30%. In North America, where most products are made 

48-inch (1200 mm) wide, are somewhat thinner, and where integral skins are kept intact, the 

range is more typically 10 – 25%. 

Post-industrial scrap can also be obtained from other extrusion processes within the same 

manufacturing plant (e.g., from food service XPS foam sheet trimmings) or from outside 

sources. For example, some manufacturers of polystyrene products are not able to consume all 

of the internally-generated scrap and, as a result, will sell the material that they are unable to use 

through a polystyrene resin broker.

Post-consumer plastic material – a plastic material or finished product that has served its 

intended use and has been diverted or recovered from waste destined for disposal, having 

completed its life as a consumer item. 

Recovered material – a plastic material and by-products that have been diverted from or 

recovered from solid waste, but not including those materials and by-products generated from, 

and commonly reused within, an original manufacturing process.

Since 1985, when the plastics industry founded the Plastics Recycling Foundation, millions of 

dollars have been spent on developing better technology for recycling plastics products and new 

uses for post-consumer plastics. In 1988, the plastics industry formed and funded the Council 

for Solid Waste Solutions, an industry group offering programs to educate consumers and 

communities that wish to participate in recycling programs. In June 1989, The National 

The History of Polystyrene Recycling
The Environmental and Societal Value of Extruded Polystyrene Foam Insulation

Authors: Barbara Fabian, Susan Herrenbruck, and Alisa Hoffee

Prepared for: Earth Tech Forum 200; April 15, 2004 Page 12 of 16

Polystyrene Recycling Company (NPRC), a multi-million dollar joint venture of eight 

polystyrene manufacturers, launched the first U.S. network of polystyrene recycling centers with 

the ability to collect, and recycle post-consumer polystyrene and market the recycled resin. In 

1991, the Canadian Polystyrene Recycling Association (CPRA) opened their polystyrene 

recycling plant outside Toronto; they recycle up to 3,500 tons of polystyrene per year18. 

Recycled polystyrene can be used to make a variety of products such as office and school 

supplies, audio and video cassettes, thermal insulation, playground equipment, reusable cafeteria 

trays, traffic signs, and toys.

Introduced in the mid-1950’s, XPS foam is a relatively new insulation in the building industry. 

Demolition of entire buildings built after the mid-1950’s and containing XPS foam has been 

minimal in the U.S. Other than roofing, there has not been much opportunity to reuse or recycle 

XPS from other building sections such as walls and foundations. 

To reuse or recycle is not always an option depending upon the installation techniques used to 

secure the material for its intended application. Many conventional roofing systems fully adhere 

the insulation making it virtually impossible to remove as a separate material. In such cases, 

landfilling or incineration are the only options. The loose attachment methodology of PRMA 

roofing provides an excellent opportunity for material reuse. Perhaps by working with and 

educating the construction industry, new construction techniques could be developed which 

would allow the reuse or recyclability of a greater percentage of XPS as it becomes available.

In many circumstances, the economic realities of recycling are often overlooked in favor of the 

perceived societal value of recycling. Collection and transportation costs for XPS insulation are 

not favorable. Due to the light weight of the material, XPS must be densified or baled to get a 

sufficiently high density to make transportation over long distances cost effective. Recycling 

does not end with collection. Recycling is only complete when the recycled XPS has been 

manufactured into new products and there is a consumer demand for the product. Even though 

the building community is becoming more and more environmentally aware, building materials 

are still very cost sensitive. At present, the marketplace is not willing to pay more for “green 

materials” Unfortunately, a pound of recycled polystyrene can cost as much if not more than a 

pound of virgin polystyrene resulting in a higher finished good price.

The recycling of polystyrene is an involved process which can encompass washing, drying, 

grinding and re-processing the polystyrene into pellet form. The finished recycle polystyrene 

pellets are typically of lower quality than virgin, un-used polystyrene pellets. The recycle pellets

are blended with virgin and reworked pellets and converted into items such as fence posts, park 

benches, boat docks, insulation, etc.

XPS Insulation with Recycle Content

In 1989, Amoco Foam Products Company, a wholly-owned subsidiary of Amoco Corporation 

(now Pactiv Building Products, a Pactiv Corporation company), opened the first polystyrene 

post-consumer recycling facility in Brooklyn, New York. The facility was used to process post-

 18 Canadian Polystyrene Recycling Association (CPRA) website, www.cpra-canada.com
The Environmental and Societal Value of Extruded Polystyrene Foam Insulation

Authors: Barbara Fabian, Susan Herrenbruck, and Alisa Hoffee

Prepared for: Earth Tech Forum 200; April 15, 2004 Page 13 of 16

consumer polystyrene foam products such as foam packaging products and lunch trays collected 

from restaurants and schools where collection programs were implemented.

In 1990, Amoco Foam Products Company introduced the first extruded polystyrene insulation 

board made with recycled polystyrene resin. AMOFOAM-RCY, was made with a minimum of 

50% recycled polystyrene, consisting of a blend of post-consumer and recovered polystyrene 

resins. The AMOFOAM-RCY met the foam plastic requirements of the National, Standard and 

Uniform Building Codes. In addition, the product was certified for recycled content by 

Scientific Certification Systems.

Amoco Foam Products Company eventually discontinued AMOFOAM-RCY due to difficulties 

encountered with respect to inclusion in federal government procurement programs and the 

resulting lack of acceptance and inclusion in job specifications. Although President Bush 

released an executive order on October 31, 1991 that instructed all federal agencies to implement 

procurement programs that required the purchase of materials with recycled content, the order 

conflicted with the long-standing competitive bidding policies that require bids from three 

potential suppliers. During the period when AMOFOAM-RCY was available, there were no 

other commercially-available extruded polystyrene insulation products containing post-consumer 

recycled-content. Furthermore, attempts to work with the U.S. Environmental Protection Agency 

to include AMOFOAM-RCY in the EPA Procurement Guidelines were futile. 

When XPS can not be reused or recycled, landfilling or incineration are possible alternatives. 

When properly incinerated, polystyrene is no more toxic than burning wood. Polystyrene 

consists solely of carbon and hydrogen. When it is completely combusted, it gives off water, 

carbon dioxide and ash, the same by-products as paper or wood. In some cases, polystyrene can 

actually help the incineration process. Polystyrene can produce energy which compares 

favorably with coal and oil. The energy value of polystyrene is18,400 Btu’s per pound while the 

energy value of coal is approximately 13,000 Btu’s per pound and oil at 19,000 Btu per pound.

Incineration

19 

Because of its high fuel value, polystyrene in properly designed incinerators, can help to burn 

wet garbage efficiently and maintain the high burning temperatures necessary for safe 

combustion. The incineration of plastics can generate energy. This energy source is already 

being harnessed by some overseas countries in Western Europe and Japan as well as in the 

U.S.

20.

Mark and Vehlow, et al, conducted a study in which the co-combustion of pretreated plastic 

waste from the packaging, automobile, electronic, and building construction industry 

incinerators was investigated21

 19 West Virginia National AFV Day Odyssey website hosted by West Virginia University National Research Center for Coal 

and Energy, 

. The XPS foams evaluated in the study contained 

www.wvodyseey.nrcce.wvu/edu.

20 Polystyrene Australia Pty Ltd. (PSA) website, www.psa.com.au.

21 Mark, F. E.. and Vehlow, J. 2000 Co-combustion of Plastic Waste in Waste Combustion Systems, VGB Technische 

Vereinigung der Frosskraftwerksbetreiber and Vehlow, Jurgen; Bergfeldt, Britta; Hunsinger, Hans; Jay, Klaus; Seifert, 

Helmut; Mark, Frank E., 2003; Effects of Various Plastic Wastes on Municipal Waste Incineration, Friedrich Vieweg & Sohn 

Verlagsgesellschaft mbH.
The Environmental and Societal Value of Extruded Polystyrene Foam Insulation

Authors: Barbara Fabian, Susan Herrenbruck, and Alisa Hoffee

Prepared for: Earth Tech Forum 200; April 15, 2004 Page 14 of 16

fluorochlorohydrocarbons as the foaming agent and bromine containing flame retardants. The 

study showed that more than 99 % of the organic matter in the incinerators decomposed and 

there was a decrease in the total organic carbon content (TOC) by approximately 50 %. The 

increase of the thermal value by the plastics improved the completeness of combustion. 

Additionally, incineration provides an escape from the foam “end of life” issues due to the total 

consumption of the polystyrene as well as the blowing agent. 

The least desirable waste management option for XPS foam is landfilling. Polystyrene degrades 

very slowly in typical landfills compared to other organic waste materials and therefore 

continues to represent an increasing percentage of the landfill volume over time. Plastics

account for 7% by weight and 20% by volume of our municipal landfills. Of the total plastic 

content, 15.9% are polystyrenes, yielding 1.1% by weight and 3.2% by volume of polystyrene in 

the landfills

Landfilling

22. The good news is that polystyrene is inert and remains unaffected in the landfill. 

If applied properly, the addition of XPS foam to a landfill can help stabilize an otherwise 

unstable site. See the discussion on “Geofoam” above.

In the U.S., the most viable green building tool is U.S. Green Building Council’s LEED

(Leadership in Energy & Environmental Design) program. Some have recognized shortfalls in 

the LEED approach, however LEED has gained prominence within the building and architectural 

community. 

Green and Sustainable Building Programs

Currently, the LEED rating tool is the foremost system being specified and used in the building 

industry. LEED is a voluntary, consensus-based, market driven building rating system that is 

based on accepted energy and environmental principles and strikes a balance between established 

practices and emerging concepts. It evaluates environmental performance from a whole-building 

perspective, providing a definitive standard for what constitutes a “green building”. As 

mentioned above, some believe a shortfall with the LEED approach is that it is too allencompassing and does not consider performance of whole building systems like walls or roofs. 

Within LEED, there are five (5) major categories where various points can be attained for 

“green” aspects of the building project. Points are earned for satisfying performance criteria 

established in the rating system. XPS fits well into many of the LEED performance categories 

such as:

 Category 1: Sustainable Sites - XPS is one of the few insulation materials that work well 

in garden roof designs as well as under highly-reflective roofing membranes such as 

thermoplastic polyolefin (TPOs). XPS used as highway insulation and light-weight fill 

help the site lower the highway or bridge abutment maintenance costs.

 Category 3: Energy & Atmosphere – As a prerequisite, each project must comply with 

ASHRAE 90.1 or the local energy code. XPS insulation plays a vital role in this energy 

compliance. Additionally, credit is given for reducing the design energy cost of a 

building established in ASHRAE 90.1

 22 Hewlett-Packard Development Company, L.P., Guidelines for Environmentally Responsible Packaging, www.packaging.hp.com
The Environmental and Societal Value of Extruded Polystyrene Foam Insulation

Authors: Barbara Fabian, Susan Herrenbruck, and Alisa Hoffee

Prepared for: Earth Tech Forum 200; April 15, 2004 Page 15 of 16

Category 4: Materials & Resources – XPS can get credit for being reused, helps gain the recycle 

content credit and local/regionally manufactured product credit.

There are several misconceptions concerning the LEED system:

 LEED does not certify individual products

 LEED does not require product certification information as product or material 

submittal verification

 It is not necessary to accumulate points in every item under each category in order to 

amass sufficient total points to meet one of the ranking levels of LEED certification

 Individual products have little influence on a category’s points (i.e., Materials & 

Resources) because total points are weighted by the cost of all products used.

Both the Occupational Safety and Health Administration (OSHA) and the U.S. Environmental 

Protection Agency (EPA) recently cited indoor air quality as a critical environmental problem in 

the U.S. Only low-emitting products that do not compromise indoor air quality should be used 

in a green-design building. The GREENGUARD Environmental InstituteTM is a third party 

testing facility that certifies the indoor air quality of products which have been subjected to a set 

of rigorous tests and found to produce low emissions of formaldehyde, volatile organic 

compounds (VOCs), respirable particles and other pollutants. XPS has been tested and received 

GREENGUARD Certification demonstrating that the product contributes minimal emissions to 

the indoor environment. 

XPS and Indoor Air Quality

XPS thermal insulation has value in a variety of building and insulating applications especially in 

harsh and unique environments. In many of these applications such as cold storage, frost 

protected shallow foundation or protected roof membrane assemblies, XPS is the only 

recommended or approved material as a result of its durable qualities. 

Conclusions:

The ability to reuse over 90 % of the roofing insulation from the Dallas/Fort Worth International 

Airport shows that it is feasible to reuse or recycle XPS. There is both an environmental as well 

as an economic benefit to be gained from its reuse. XPS manufacturers are working with the 

construction industry towards a mutual goal of minimizing the landfilling of XPS. However, 

there are still tremendous challenges with the reuse or recyclability of XPS:

 Current building practices do not facilitate the easy removal or collection of XPS

 The conservative nature of the construction industry inhibits new construction practices 

which would allow more reuse or recycling

 Other than from roofing, there is not a great deal of XPS being removed from existing 

buildings at the present time due to the life span of buildings built after the mid-1950’s.

The XPS industry has demonstrated the ability to recycle and reuse post-industrial as well as 

post-consumer polystyrene in its products. One manufacturer provided an XPS foam which 

contained 50% recycled polystyrene yet could not get the support from the building community, 

government, or the consumer. The material was subsequently removed from the market. 

The U.S. consumer is not willing to pay more for a material based on its environmental 
The Environmental and Societal Value of Extruded Polystyrene Foam Insulation

Authors: Barbara Fabian, Susan Herrenbruck, and Alisa Hoffee

Prepared for: Earth Tech Forum 200; April 15, 2004 Page 16 of 16

performance. Programs like LEED are bringing environmental awareness to the building 

community and are constantly evolving.

Despite the current initiative towards “green building”, the U.S. has not embraced the

environmental challenges as have the European Union countries. Many of the benefits of XPS 

will not be practical until the U.S. is forced to be more environmentally conscious in terms of

energy efficiency, recyclability and reuse.

Acknowledgements

The authors would like to thank Dave Beatty, Bill Harris, Bill Ramsey, and Patrick Rynd of 

Owens Corning for their support and guidance during the writing of this paper. We would also 

like to thank Owens Corning, Pactiv Building Products and the Board of Directors of XPSA for 

its permission to publish this work.