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PCA R&D SN3042

Comparison of the Life Cycle Assessments of a Concrete Masonry House and a Wood Frame House by Medgar L. Marceau and Martha G. VanGeem

KEYWORDS Air pollution, concretes, concrete masonry, construction, embodied energy, emission, fly ash, gaseous emissions, life cycle assessment (LCA), life cycle impact assessment, life cycle inventory analysis, portland cement concrete, residential buildings, single-family house, sustainable construction, wood frame construction

ABSTRACT This report is an update of Life Cycle Assessment of an Concrete Masonry House Compared to a Wood Frame House (Marceau and VanGeem 2002). It presents the results of an assessment of the environmental attributes of concrete construction compared to wood-framed construction. A life cycle assessment (LCA) was conducted on a house modeled with two types of exterior walls: a wood-framed wall and a CMU wall. The LCA was carried out according to the guidelines in International Standard ISO 14044, Environmental Management – Life Cycle Assessment – Requirements and Guidelines. The house was modeled in five cities, representing a range of U.S. climates: Lake Charles, Tucson, St. Louis, Denver, and Minneapolis The 228-square meter (2450-square foot), two-story, single family house has four bedrooms and a two-car garage. The system boundary includes the inputs and outputs of energy, materials, and emissions to air, soil, and water from extraction of raw materials though construction, maintenance, and occupancy. The house energy use was modeled using DOE-2.1E and the life cycle impact assessment was modeled using SimaPro. The results show that for a given climate, the life cycle environmental impacts are similar for the wood and CMU houses. The most significant environmental impacts are not from construction materials but from the production of electricity and natural gas and the use of electricity and natural gas in the houses by the occupants.

REFERENCE Marceau, Medgar L., and VanGeem, Martha G., Comparison of the Life Cycle Assessments of a Concrete Masonry House and a Wood Frame House, SN3042, Portland Cement Association, Skokie, Illinois, USA, 2008, 59 pages.

TABLE OF CONTENTS Keywords ........................................................................................................................................ ii Abstract ........................................................................................................................................... ii Reference ........................................................................................................................................ ii List of Tables ...................................................................................................................................v List of Figures ................................................................................................................................ vi Acronyms and Abbreviations ....................................................................................................... vii Introduction ......................................................................................................................................1 Life Cycle Assessment .............................................................................................................1 Definition of Goal and Scope ..........................................................................................................2 Goal...........................................................................................................................................2 Scope.........................................................................................................................................2 Product Function. ..............................................................................................................2 Functional Unit. .................................................................................................................2 System Boundary...............................................................................................................2 Critical Review. .................................................................................................................3 Data Quality.......................................................................................................................3 House Description ............................................................................................................................3 Climate ......................................................................................................................................4 Building Envelope Requirements .............................................................................................4 Building Envelopes As-Modeled ..............................................................................................6 Windows. ...........................................................................................................................7 Roofs and Ceilings. ...........................................................................................................7 Exterior Walls. ...................................................................................................................7 Interior Walls and Floors. ..................................................................................................8 Slab Foundation. ................................................................................................................8 Occupant Behavior and Other Performance Characteristics ....................................................8 Heating, Ventilating, and Air-Conditioning. .....................................................................8 Domestic Hot Water. .........................................................................................................8 Other Energy Use. .............................................................................................................8 Air Infiltration. ..................................................................................................................9 Designed Life. ...................................................................................................................9

iii

Whole-Building Energy Use.....................................................................................................9 SimaPro Life CycLE Assessment Software ..................................................................................11 Life Cycle Inventory Analysis .......................................................................................................11 House Materials Inputs ...........................................................................................................11 Concrete and Other Cement-Based Materials. ................................................................12 All Other Building Materials. ..........................................................................................12 House Energy Inputs...............................................................................................................17 Construction. ...................................................................................................................17 Occupancy. ......................................................................................................................17 Demolition and disposal. .................................................................................................17 Transportation..................................................................................................................17 Life Cycle Impact Assessment.......................................................................................................17 Life Cycle Interpretation ................................................................................................................25 Sensitivity ...............................................................................................................................29 Conclusions ....................................................................................................................................29 Acknowledgements ........................................................................................................................30 References ......................................................................................................................................31 Appendix A – House Plans and Wall Cross-Sections ................................................................ A-1 Appendix B – Impact Assessment Methods ................................................................................B-1 Appendix C – Normalized and Weighted LCA Results ..............................................................C-1

LIST OF TABLES Table 1a. International Energy Conservation Code Insulation and Fenestration Requirements (SI Units) ..........................................................................................5 Table 1b. International Energy Conservation Code Insulation and Fenestration Requirements (U.S. Customary Units) ....................................................................5 Table 2a. International Energy Conservation Code Equivalent U-Factor Requirements (SI Units) ..........................................................................................5 Table 2b. International Energy Conservation Code Equivalent U-Factor Requirements (U.S. Customary Units) ....................................................................6 Table 3a. Fenestration and Insulation As-Modeled (SI Units) ........................................................6 Table 3b. Fenestration and Insulation As-Modeled (U.S. Customary Units) ..................................6 Table 4a. Building Envelope U-Factors As-Modeled (SI Units) .....................................................7 Table 4b. Building Envelope U-Factors As-Modeled (U.S. Customary Units) ..............................7 Table 5. Amount by Which As-Modeled Building Envelope Components Exceed International Energy Conservation Code Requirements..........................................7 Table 6. House Component Replacement Schedules ......................................................................9 Table 7. Annual Whole-Building Energy Use ...............................................................................10 Table 8. Maximum HVAC System Loads .....................................................................................11 Table 9a. House Materials List (SI Units) .....................................................................................13 Table 9b. House Materials List (U.S. Customary Units) ...............................................................14 Table 10a. Mix Designs for Concrete and Other Cement-Based Materials (SI Units) ................................................................................................................15 Table 10b. Mix Designs for Concrete and Other Cement-Based Materials (U.S. Customary Units)..........................................................................................15 Table 11. Sources of Upstream LCI Data ......................................................................................16 Table 12. Materials Excluded from the LCA because of Insufficient Data...................................16 Table 13. Impact Categories for Three Life Cycle Impact Assessment Methods .........................18 Table 14. Characterization of Life Cycle Inventory Data Assuming an Egalitarian Perspective Using the Eco-Indicator 99 Method of Characterization ...................19 Table 15. Characterization of Life Cycle Inventory Data Using a Hierarchic Perspective in the Eco-Indicator 99 Method of Characterization ..........................20 Table 16. Characterization of Life Cycle Inventory Data Using an Individualist Perspective in the Eco-Indicator 99 Method of Characterization ..........................21 Table 17. Characterization of Life Cycle Inventory Data using the EDIP/UMIP 97 Method of Characterization ...................................................................................22

Table 18. Characterization of Life Cycle Inventory Data using the EPS 2000 Method of Characterization ...................................................................................24 Table 19. Normalized and Weighted Single Score Summary .......................................................25 Table C-1. Normalized and Weighted LCA Results (Points) Using an Egalitarian Perspective in the Eco-Indicator 99 Method of Impact Assessment ...................C-1 Table C-2. Normalized and Weighted LCA Results (Points) Using a Hierarchic Perspective in the Eco-Indicator 99 Method of Impact Assessment ...................C-2 Table C-3. Normalized and Weighted LCA Results (Points) Using an Individualist Perspective in the Eco-Indicator 99 Method of Impact Assessment ...................C-3 Table C-4. Normalized and Weighted LCA Results (Points) Using the EDIP/UMIP 97 Method of Impact Assessment .............................................................................C-4 Table C-5. Normalized and Weighted LCA Results (Points) Using the EPS 2000 Method of Impact Assessment .............................................................................C-6

LIST OF FIGURES Figure 1. The system boundary (dashed line) defines the limits of the life cycle assessment.........3 Figure 2. Single-score life cycle inventory assessment of houses showing contribution of each major product and process stage. The data have been normalized and weighted according to the Eco-Indicator 99 method using the Hierarchic perspective. .......27 Figure 3. Single-score life cycle inventory assessment of construction materials in the houses showing contribution of each major product and process stage. The data have been normalized and weighted according to the Eco-Indicator 99 method using the Hierarchic perspective......................................................................................28

ACRONYMS AND ABBREVIATIONS ASHRAE American Society of Heating, Refrigerating and Air-Conditioning Engineers CMU

concrete masonry unit

EDIP

Environmental Design of Industrial Products (UMIP in Danish)

EPS

Environmental Priority Strategies

ETH

German abbreviation for Swiss Federal Technical University (Eidgenössische Technische Hochschule)

gram

IECC

International Energy Conservation Code

ISO

International Organization for Standardization

kBtu

thousand British thermal units (1×103 Btu)

kWh

kilowatt-hour

gigajoule (1×109 Joules) (1 GJ = 947817.1 Btu)

LCA

life cycle assessment

LCI

life cycle inventory analysis

LCIA

life cycle impact assessment

MBtu

million British thermal units (1×106 Btu)

megajoule (1×106 Joules)

International system of units

SHGC

solar heat gain coefficient

UMIP

Danish abbreviation for Environmental Design of Industrial Products

vii

Comparison of the Life Cycle Assessments of a Concrete Masonry House and a Wood Frame House by Medgar L. Marceau and Martha G. VanGeem1 INTRODUCTION This report is an update of Life Cycle Assessment of a Concrete Masonry House Compared to a Wood Frame House (Marceau and VanGeem 2002). It presents the results of an assessment of the environmental attributes of concrete masonry construction compared to wood-framed construction. Each house has the same layout but is modeled with different exterior wall systems. The purpose of this update is to incorporate the most recent life cycle inventory (LCI) data on portland cement and portland cement concrete and the latest requirements in building energy conservation codes. This is a significant update because it reflects the increased stringency of newer energy codes. As the previous report shows, occupant use of energy, particularly electricity and natural gas for cooling and heating, represents the largest source of negative environmental impacts.

Life Cycle Assessment Life cycle assessment (LCA) is a methodology for assessing the environmental aspects associated with a product over its life cycle—from raw material acquisition through production, use, and disposal (Goedkoop and others 2007). Performing an LCA is one of the possible methods of assessing a product’s environmental aspects and the potential impacts it has on the natural environment. The International Organization for Standardization (ISO) has developed international standards that describe how to conduct an LCA. The ISO standards describe three phases of an LCA. The first phase is a life cycle inventory analysis, which consists of a compilation of the energy and material inputs and the emissions to air, land, and water associated with the manufacture of a product, operation of a process, or provision of a service. The second phase is an assessment of the potential social, economic, and environmental impacts associated with those inputs and emissions. The third phase is the interpretation of the results of the inventory analysis and impact assessment phases in relation to the objectives of the study. These three phases are commonly referred to as (1) life cycle inventory analysis, (2) life cycle impact assessment, and (3) life cycle interpretation. The results of an LCA can be used to help choose among competing alternatives the alternative that has the most favorable attributes.

Building Science Engineer, CTLGroup, 5400 Old Orchard Road, Skokie, Illinois 60077 USA, (847) 972-3154, [emailprotected], www.CTLGroup.com; Principal Engineer, CTLGroup, (847) 972-3156, [emailprotected].

DEFINITION OF GOAL AND SCOPE The LCA described in this report follows the guidelines in International Standard ISO 14044, Environmental Management – Life Cycle Assessment – Requirements and Guidelines (ISO 2006a). The previous version of this report referenced the 1997 edition of International Standard ISO 14040, Environmental Management – Life Cycle Assessment – Principles and Framework, and the 1999 edition of International Standard ISO 14042, Environmental Management – Life Cycle Assessment – Life Cycle Impact Assessment. However, updated editions of these standards are now referenced in ISO 14044.

Goal The goal of this project is to compare the environmental impacts of a concrete masonry house to those of a wood frame house. To achieve this goal we use life cycle inventory data to conduct a life cycle assessment on two kinds of houses: one with concrete masonry unit (CMU) walls, the other with wood-frame walls. Since the largest source of negative environmental impacts in a house is from household use of energy, which is primarily a function of climate, the houses are modeled in five cities representing the range of climates in the US. The reason for doing this work is to disseminate information on the LCAs of houses, which are based on the most complete and up-to-date life cycle inventory data from concrete and concrete products. The intended audience is building professionals who are interested in green buildings.

Scope The scope of the LCA is defined by the function of a single-family house, the functional unit, and the system boundary. Product Function. The function of a single-family house is to shelter the inhabitants from the environment and provide space for habitation. Functional Unit. The functional unit, which is the basis for comparison, is defined in International Standard ISO 14040, Environmental Management - Life Cycle Assessment Principles and Framework (ISO 2006b), as the quantified performance of a product system. In this work, the functional unit is a single-family house. The life of the house is assumed to be 100 years, and it includes maintenance and replacement of components as they wear out. System Boundary. The system boundary is the interface between the functional unit and the environment. The system boundary in this work, shown in Figure 1, includes the inputs and outputs of energy and material from construction, occupancy, maintenance, demolition, and disposal. Transporting materials to and from the house is also included. This is called a second order system boundary because in addition to material and energy flows, it includes operations. Occupancy consists of household use of electricity and natural gas. Electricity is used for fans, lights, cooling (air conditioner), appliances, and plug loads. Natural gas is used for heating (furnace) and domestic hot water. Maintenance consists of the materials used to repair and replace items that normally wear out. The system boundary excludes capital goods (such as

existing infrastructure), human labor, impacts caused by people, and waste treatment after disposal. An LCA of buildings typically does not include measures of disaster resistance, occupant comfort, or occupant productivity. The ISO standards indicate that inputs to a product or process do not need to be included in an LCI if (1) they do not represent a significant fraction of the total mass of processed materials or product, (2) they do not contribute significantly to a toxic emission, and (3) they do not represent a significant amount of energy. Construction

Energy for heating, cooling, lighting, cooking, heating water, and plug loads

Maintenance

Transporting materials

Demolition and disposal

Occupancy

Upstream LCI profiles: concrete and other cement-based materials, wood, steel, and other materials

House system boundary

Recycling and landfill

Figure 1. The system boundary (dashed line) defines the limits of the life cycle assessment.

Critical Review. The previous version of this report was reviewed by the Technical Research Centre of Finland (VTT, Valtion Teknillinen Tutkimuskeskus). The reviewers found that it was a careful study on the environmental aspects of CMU and wood frame houses. They concluded that the report “properly uses the life cycle assessment approach in accordance with the framework described in the ISO 14040 and ISO 14042 standards” (Häkkinen and Holt, 2002). Both ISO 14040 and ISO 14042 are now referenced in ISO 14044. It is our opinion that an updated critical review is not required because the present version includes the same methodology as the previous version with the addition of more recent data, more specific data, and more complete data. Data Quality. From all the available data that could be used, preference is given to the most recent product-specific data for North America representing an average level of technology. When North American data are not available, European data are used.

HOUSE DESCRIPTION The houses were designed by CTLGroup. The designs are based on typical houses currently built in the US. Each house is a two-story single-family building with four bedrooms, 2.7-m (9-ft) ceilings, a two-story foyer and family room, and an attached two-car garage. Both the wood frame and CMU houses have the same layout. Each house has 228 square meters (2450 square feet) of living space, which is similar to the 2005 U.S. average of 226 square meters (2434 square feet) (NAHB 2007). Drawings of the house are shown in Appendix A. The floor plans are

shown in Figures A-1 and A-2 and the elevations are shown in Figures A-3 to A-6. Typical wall sections are shown in Figures A-7 and A-8.

Climate Since the energy use of a building depends on local climate, the houses are modeled in several different climates. Five cities that represent the range of climates in the US were chosen: Lake Charles, Louisiana; Tucson, Arizona; St. Louis, Missouri; Denver, Colorado; and Minneapolis, Minnesota. The locations selected are those often used by other energy analysts when estimating national energy use in buildings. The cities and the climate zone numbers are: • • • • •

Lake Charles, Louisiana —a hot – humid climate (Zone 2A). Tucson, Arizona—a hot – dry climate with large daily temperature swings (Zone 2B). St. Louis, Missouri —a mixed – humid climate (Zone 4A). Denver, Colorado—a cold – dry climate (Zone 5B). Minneapolis, Minnesota—a cold – humid climate (Zone 6).

The houses are designed to meet the requirements of the 2006 International Energy Conservation Code (IECC 2006) in all locations. The IECC is the most widely used residential energy code in the US. Household energy use is modeled using whole-building energy simulation software. The energy modeling is described in the section, “Whole-Building Energy Use”.

Building Envelope Requirements The 2006 IECC requirements for fenestration and insulation are presented in Table 1 for the five cities where the houses are modeled. U-factor and solar heat gain coefficients (SHGC) requirements are maximums, whereas RSI-values (R-values) are minimums. U-factor is a measure of thermal conductance and generally represents the overall rate of heat loss of a given assembly, whereas R-value is a measure of thermal resistance and generally represents the thermal resistance of a given thickness of material. For ease of compliance and enforcement, the 2006 IECC provides requirements for the added R-value of insulation between framing members. The 2006 IECC also presents equivalent U-factors which include the thermal resistance of the entire assembly. These are presented in Table 2. Compliance may be demonstrated using either the values from Table 1 or the U-factors from Table 2. U-factor is expressed in SI units as W/(m2·K) and U.S. customary units as Btu/(h·ft2·°F). R-value is expressed in SI units of (m2·K)/W and U.S. customary units of (h·ft2·°F)/Btu.

Table 1a. International Energy Conservation Code Insulation and Fenestration Requirements* (SI Units) Fenestration

Climate zone

City

Slab RSIvalue & depth

U-factor

SHGC

Lake Charles, Tucson

4.3

0.40

5.3

2.3

0.7

St. Louis

2.4

NR**

6.7

2.3

0.9

1.8, 0.6 m††

Denver

2.0

NR**

6.7

2.3

1.8, 0.6 m††

Minneapolis

2.0

NR**

8.6

2.6

1.8, 1.2 m††

4 except Marine 5 and Marine 4 6

Wood Mass wall frame wall RSI-value RSI-value

Ceiling RSI-value

3.3 or 2.3+0.9† 3.3 or 2.3+0.9†

*Adapted from IECC (2006) Table 401.1.1. U-factor in W/(m2·K) and RSI-value in (m2·K)/W. ** “NR” means no requirement. † “2.3+0.9” means RSI-2.3 cavity insulation plus R-0.9 insulated sheathing. †† “1.8, 0.6 m” means RSI-1.8 insulation 0.6 m deep.

Table 1b. International Energy Conservation Code Insulation and Fenestration Requirements* (U.S. Customary Units)

City

2 4 except Marine 5 and Marine 4 6

Wood Mass wall Ceiling Rframe wall R-value value R-value

Fenestration

Climate zone

Slab Rvalue & depth

U-factor

SHGC

Lake Charles, Tucson

0.75

0.40

St. Louis

0.40

NR**

10, 2 ft††

Denver

0.35

NR**

19 or 13+5†

10, 2 ft††

Minneapolis

0.35

NR**

19 or 13+5†

10, 4 ft††

*Adapted from IECC (2006) Table 401.1.1. U-factor in Btu/(h·ft ·°F) and R-value in (h·ft ·°F)/Btu. ** “NR” means no requirement. † “13+5” means R-13 cavity insulation plus R-5 insulated sheathing. †† “10, 2 ft” means R-10 insulation 2 ft deep.

Table 2a. International Energy Conservation Code Equivalent U-Factor Requirements* (SI Units) Wood Mass wall frame wall

Climate zone

City

Fenestration

Ceiling

Lake Charles, Tucson

4.3

0.20

0.47

0.937

St. Louis

2.3

0.17

0.47

0.801

Denver Minneapolis

2.0 2.0

0.17 0.15

0.34 0.34

0.466 0.341

4 except Marine 5 and Marine 4 6

*Adapted from IECC (2006) Table 402.1.3. U-factor in W/(m2·K). There is no U-factor equivalent for slab perimeter insulation.

Table 2b. International Energy Conservation Code Equivalent U-Factor Requirements* (U.S. Customary Units) Wood Mass wall frame wall

Climate zone

City

Fenestration

Ceiling

Lake Charles, Tucson

0.75

0.035

0.082

0.165

St. Louis

0.40

0.030

0.082

0.141

Denver Minneapolis

0.35 0.35

0.030 0.026

0.060 0.060

0.082 0.060

4 except Marine 5 and Marine 4 6

*Adapted from IECC (2006) Table 402.1.3. U-factor in Btu/(h·ft2·°F). There is no U-factor equivalent for slab perimeter insulation.

Building Envelopes As-Modeled The building envelope (roofs, exterior walls, windows, and slab-on-ground floors) in each location meets the requirements of the 2006 IECC using typical building materials and typical building practices. The fenestration and insulation used in the modeling are presented in Table 3. The as-modeled building envelope U-factors are shown in Table 4. The amount by which the asmodeled values differ from the 2006 IECC criteria is shown in Table 5. Table 3a. Fenestration and Insulation As-Modeled* (SI Units) Fenestration U-factor

SHGC

Lake Charles, Tucson

3.3

0.30

5.3

2.3

1.4

St. Louis

2.1

0.64

6.7

2.3

1.8, 0.6 m†

Denver

2.0

0.56

6.7

2.3+0.9**

2.3

1.8, 0.6 m†

Minneapolis

2.0

0.56

8.6

2.3+0.9**

2.6

1.8, 1.2 m†

City

2 4 except Marine 5 and Marine 4 6

Wood Mass wall Slab RSIframe wall (CMU) RSI- value & RSI-value value depth

Ceiling RSI-value

Climate zone

*U-factor in W/(m2·K) and RSI-value in (m2·K)/W. ** “2.3+0.9” means RSI-2.3 cavity insulation plus R-0.9 insulated sheathing. † “1.8, 0.6 m” means RSI-1.8 insulation 0.6 m deep.

Table 3b. Fenestration and Insulation As-Modeled* (U.S. Customary Units)

City

2 4 except Marine 5 and Marine 4 6

Wood Mass Wall Ceiling Rframe wall (CMU) Rvalue R-value value

Fenestration

Climate zone

Slab Rvalue & depth

U-factor

SHGC

Lake Charles, Tucson

0.57

0.30

St. Louis

0.37

0.64

10, 2 ft†

Denver

0.35

0.56

13+5**

10, 2 ft†

Minneapolis

0.35

0.56

13+5**

10, 4 ft†

*U-factor in Btu/(h·ft2·°F) and R-value in (h·ft2·°F)/Btu. ** “13+5” means R-13 cavity insulation plus R-5 insulated sheathing. † “10, 2 ft” means R-10 insulation 2 ft deep.

Table 4a. Building Envelope U-Factors As-Modeled* (SI Units) Wood Mass wall frame wall (CMU)

Climate zone

City

Fenestration

Ceiling

Lake Charles, Tucson

3.3

0.18

0.49

0.68

St. Louis

2.1

0.15

0.49

0.46

Denver

2.0

0.15

0.33

0.46

Minneapolis

2.0

0.12

0.33

0.43

4 except Marine 5 and Marine 4 6

*U-factor in W/(m2·K). U-factors include an interior air film of 0.39 m2·K/W. There is no U-factor equivalent for slab perimeter insulation.

Table 4b. Building Envelope U-Factors As-Modeled* (U.S. Customary Units) Wood Mass wall frame wall (CMU)

Climate zone

City

Fenestration

Ceiling

Lake Charles, Tucson

0.57

0.032

0.086

0.12

St. Louis

0.37

0.026

0.086

0.081

Denver

0.35

0.026

0.058

0.081

Minneapolis

0.35

0.021

0.058

0.075

4 except Marine 5 and Marine 4 6

*U-factor in Btu/(h·ft2·°F). U-factors include an interior air film of 0.68 h·ft2·°F/Btu. There is no U-factor equivalent for slab perimeter insulation.

Table 5. Amount by Which As-Modeled Building Envelope Components Exceed International Energy Conservation Code Requirements Climate zone

City

Fenestration

Ceiling

Lake Charles, Tucson

24%

100%

St. Louis

160%

Denver

Minneapolis

4 except Marine 5 and Marine 4 6

Wood Mass wall frame wall (CMU)

Windows. Windows are aluminum framed with thermal breaks and double panes. They are primarily located on the front and back façades, and the overall window-to-exterior wall ratio is 16%. Roofs and Ceilings. Roofs and ceilings are wood-frame construction. The ceilings have RSI-5.3 (R-30), RSI-6.7 (R-38), or RSI 8.6 (R-49) fiberglass batt insulation as required in the 2006 IECC, depending on climate. The U-factor includes RSI-1.0 (R-0.56) for 16-mm (0.625in.) gypsum board and RSI-0.11 (R-0.61) for interior air film heat flow up. Roofs are covered with medium-colored asphalt shingles. Exterior Walls. The exterior walls of the wood-frame houses with RSI-2.3 (R-13) insulation consist of medium-colored aluminum siding, 12-mm (½-in.) wood sheathing, RSI-2.3 (R-13) fiberglass batt insulation between 2×4 wood studs 400 mm (16 in.) on center, and 12-mm (½-in.) 7

painted gypsum board. This is typical of wood-framed construction in the US. The exterior walls of the wood-frame houses with RSI-2.3+0.9 (R-13+5) insulation is the same as above but with RSI-0.9 (R-5) continuous insulation utilized in-place of wood sheathing. The calculated U-factor of the as-modeled assembly shown in the tables includes an interior air film of 0.12 m2·K/W (0.68 h·ft2·°F/Btu). The concrete masonry unit (CMU) walls consist of partially grouted normal-weight CMUs, interior wood furring spaced 400 mm (16 in.) on center, gypsum wallboard on the inside surface, and stucco on the outside surface. Further, in Lake Charles and Tucson there is RSI-1.4 (R-8) insulation between the wood furring, in Washington (DC), St. Louis, and Denver there is RSI-2.3 (R-13) insulation, and in Minneapolis there is RSI-2.6 (R-15) insulation. Interior Walls and Floors. Interior walls and floors are wood-framed and uninsulated. Second story floors are covered with a combination of carpet and tile (bathrooms). Slab Foundation. In all cities, the houses are slab-on-ground construction. The slab-on-ground floor consists of 150-mm (6 in.) thick normal-weight concrete cast on soil and covered with a combination of carpet, linoleum (kitchen and laundry room), and tile (bathrooms). The slabs are insulated according to the requirements in the 2006 IECC.

Occupant Behavior and Other Performance Characteristics Occupant behavior is one of the most important factors affecting energy use in a house. Therefore, to create realistic models of the house, occupant behavior and other performance characteristics are assumed to be the same for all houses. This ensures that comparisons between houses within a given climate are fair and valid. Thus, the houses have identical air-infiltration rates and the house systems have identical controls, schedules, and performance characteristics for lighting, heating, air conditioning, and water heating. Heating, Ventilating, and Air-Conditioning. The heating, ventilating, and air-conditioning (HVAC) system consists of a natural gas high-efficiency forced-air furnace and an electric highefficiency central air conditioner. The efficiencies of the HVAC components are assumed to be identical in all cities. The heating thermal efficiency is 0.8 (that is, 80% efficient), and the cooling energy efficiency ratio is 0.9 including fan efficiency (that is, 90% efficient). HVAC equipment is sized for each location and for the peak heating and cooling loads of a particular house. Generally wood houses require larger HVAC equipment. The HVAC system is controlled by a residential thermostat located in the family room. The heating set-point temperature is 21°C (70°F), and the cooling set-point temperature is 24°C (75°F). Domestic Hot Water. Hot water is supplied by a natural gas water heater, which has a peak utilization of 9.5 liters/minute (2.5 gallons/minute). The hot water load-profile was taken from ASHRAE Standard 90.2-1993 (ASHRAE 1993). Other Energy Use. Occupant use of energy, other than for heating and cooling, is based on the daily internal heat gain profile in ASHRAE Standard 90.2-2004, Energy Efficient Design of LowRise Residential Buildings (ASHRAE 2004, Table 8.8.1). It is approximately 7300 kWh per year.

Air Infiltration. The fresh air ventilation rate is based on the minimum requirement to maintain acceptable indoor air quality in ASHRAE Standard 62.2-2003, Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings (ASHRAE 2003). Assuming a family of four, it is equivalent to an air infiltration rate of 7 liters/minute per m2 of conditioned floor area (0.02 cu ft/minute per sq ft). Designed Life. The life of the house is assumed to be 100 years. The replacement schedules for various building components are shown in Table 6. Table 6. House Component Replacement Schedules House component Siding, air barrier, and exterior fixtures Latex and silicone caulking Paint, exterior Doors and windows Roofing* Gable and ridge vents Bathroom fixtures Bathroom tiles and backer board Paint, interior Carpet and pad Resilient flooring, linoleum Bathroom furniture (toilet, sink, etc.) Garbage disposal Furnace Air conditioner Interior and exterior luminaries Water heater Large appliances Manufactured fireplace Kitchen and bathroom casework Kitchen counter tops

Replacement schedule (years) 33.3 10 5 33.3 20 and 40 33.3 25 25 10 10 10 25 20 20 20 33.3 20 15 50 25 25

*A new layer of shingles is added every 20 years, and every 40 years the existing layers of felt and shingles are replaced with a new layer of felt and shingles.

Whole-Building Energy Use Whole-building energy simulation software is used to model household energy use. The software is HVAC Sizing for Concrete Homes, Version 3.0 (PCA 2005). This software uses the U.S. Department of Energy DOE-2.1E hourly simulation tool as the calculation engine (Winkelmann and others 1993). It is used to simulate hourly energy use and peak demand over a one-year period. Programs that model hourly energy use are more accurate than other methods, especially for buildings with thermally massive exterior walls, such as concrete wall systems. Heating and cooling load vary with solar orientation, so the houses are modeled four times: once for each orientation of the front façade facing the four cardinal directions (north,

south, east, and west). Then the energy for heating, cooling, hot water, and occupant use is averaged to obtain energy use that is independent of building orientation. The annual energy use is presented in Table 7. Actual energy use will vary depending on climate, building type, use and occupancy, orientation, actual building materials, and fenestration amount and type. Although energy simulation is not an accurate predictor of energy use, it is a suitable tool for comparing and evaluating different design alternatives when the factors that affect energy use have been isolated. In each of the five climates, the CMU houses have similar household energy use as the wood frame houses (the difference is within 1 to 6%, depending on climate), even though the added R-values for the CMU house are generally less than those for the wood frame house (Table 3). Table 7. Annual Whole-Building Energy Use

Location

Material, lb Ready-mixed concrete** CMUs, normal weight Cement-based material, other fiber-cement backer board mortar grout stucco Metal aluminum copper galvanized steel sheet metal steel Wood framing treated plywood sheathing miscellaneous Gypsum wallboard Insulation, polystyrene Insulation, fiberglass Polymers and linoleum carpet and pad linoleum paint polyolefin (polyethylene) polyvinyl chloride (PVC) sealant general Roofing materials Windows Ceramic tile Lighting products Electrical wire Appliances and HVAC Total (rounded)

Wood frame house Normal weight CMU house Lake St. MinneLake St. MinneTucson Denver Tucson Denver Charles Louis apolis Charles Louis apolis 155,780 167,918 204,329 240,741 301,426 155,780 167,918 204,329 240,741 301,426 0 0 0 0 0 140,001 140,001 140,001 140,001 140,001 3,406 3,406 3,406 3,406 3,406 143,578 143,578 143,578 143,578 143,578 3,406 3,406 3,406 3,406 3,406 3,406 3,406 3,406 3,406 3,406 0 0 0 0 0 79,121 79,121 79,121 79,121 79,121 0 0 0 0 0 8,663 8,663 8,663 8,663 8,663 0 0 0 0 0 52,388 52,388 52,388 52,388 52,388 7,611 7,768 8,237 8,706 9,488 9,360 9,517 9,986 10,455 11,236 1,873 1,873 1,873 1,873 1,873 694 694 694 694 694 147 147 147 147 147 147 147 147 147 147 684 684 684 684 684 684 684 684 684 684 821 821 821 821 821 821 821 821 821 821 4,086 4,243 4,712 5,181 5,963 7,013 7,170 7,639 8,108 8,890 44,975 44,975 44,975 44,975 44,975 42,881 42,881 42,881 42,881 42,881 23,707 23,707 23,707 23,707 23,707 22,265 22,265 22,265 22,265 22,265 1,489 1,489 1,489 1,489 1,489 4,412 4,412 4,412 4,412 4,412 11,111 11,111 11,111 11,111 11,111 9,802 9,802 9,802 9,802 9,802 2,265 2,265 2,265 2,265 2,265 0 0 0 0 0 6,402 6,402 6,402 6,402 6,402 6,402 6,402 6,402 6,402 6,402 19,612 19,612 19,612 19,612 19,612 17,715 17,715 17,715 17,715 17,715 0 0 264 797 1,060 0 0 264 264 527 1,198 1,198 1,382 1,382 1,634 866 866 1,123 1,382 1,708 22,583 22,583 22,583 22,583 22,583 22,204 22,204 22,204 22,204 22,204 14,156 14,156 14,156 14,156 14,156 14,156 14,156 14,156 14,156 14,156 803 803 803 803 803 803 803 803 803 803 5,931 5,931 5,931 5,931 5,931 5,931 5,931 5,931 5,931 5,931 49 49 49 49 49 0 0 0 0 0 949 949 949 949 949 949 949 949 949 949 659 659 659 659 659 330 330 330 330 330 35 35 35 35 35 35 35 35 35 35 12,847 12,847 12,847 12,847 12,847 12,847 12,847 12,847 12,847 12,847 6,896 6,896 6,896 6,896 6,896 6,896 6,896 6,896 6,896 6,896 8,026 8,026 8,026 8,026 8,026 8,026 8,026 8,026 8,026 8,026 1,272 1,272 1,272 1,272 1,272 1,272 1,272 1,272 1,272 1,272 245 245 245 245 245 245 245 245 245 245 12,058 12,058 12,058 12,058 12,058 12,058 12,058 12,058 12,058 12,058 296,500 308,800 346,100 383,500 445,500 573,700 586,000 623,400 660,600 722,600

*Includes items replaced during the 100-year life. **More material is used in colder climates because foundations are deeper.

Table 10a. Mix Designs* for Concrete and Other Cement-Based Materials (SI Units) Mix constituent, kg/m3 Portland cement Fly ash Limestone Water Coarse aggregate Fine aggregate Total

20-MPa ready mixed concrete, 25% fly ash 167 56 0 141 1127 831 2322

Concrete masonry**, 25% fly ash 155 52 0 142 619 1414 2382

Mortar

Grout, 15% fly ash

Stucco

261 0 172 208 0 1365 2006

380 65 0 243 0 1305 1993

593 0 0 77 0 1721 2391

*Mix designs vary; these ones have been chosen because they are representative of residential applications. **Yield is 131 CMU/m3.

Table 10b. Mix Designs* for Concrete and Other Cement-Based Materials (U.S. Customary Units) Mix constituent, lb/yd3 Portland cement Fly ash Limestone Water Coarse aggregate Fine aggregate Total

3000-psi ready mixed concrete, 25% fly ash 282 94 0 237 1900 1400 3913

Concrete masonry**, 25% fly ash 262 88 0 240 1043 2384 4017

Mortar

Grout, 15% fly ash

Stucco

440 0 290 350 0 2300 3380

640 110 0 410 0 2200 3360

1000 0 0 130 0 2900 4030

*Mix designs vary; these ones have been chosen because they are representative of residential applications. **Yield is 100 CMU/yd3.

Table 11. Sources of Upstream LCI Data Material and energy Aluminum Cement-based materials

Database(s) Franklin US LCI PCA Ecoinvent Ceramic tile IDEMAT 2001 Ecoinvent Copper ETH-ESU 96 Franklin US LCI Eco-Invent Electrical wire IDEMAT 2001 ETH-ESU 96 Expanded polystyrene insulation Franklin US LCI Fiberglass insulation Ecoinvent Gypsum wall board Ecoinvent Lights ETH-ESU 96 Linoleum IDEMAT 2001 Paint ETH-ESU 96 Particle board Ecoinvent Polyester fabric IDEMAT 2001 Polyvinyl chloride (PVC) INDUSTRY DATA Franklin US LCI Roofing IDEMAT Steel: sheets and galvanized Franklin US LCI Franklin US LCI Ecoinvent Windows IDEMAT 2001 ETH-ESU 96 Wood: framing, treated, plywood, sheathing ETH-ESU 96 Diesel hydraulic excavator Ecoinvent Diesel tractor-trailer transportation Franklin US LCI Electricity, U.S. average Franklin US LCI Natural gas combustion in residential furnace Ecoinvent Franklin US LCI Concrete and cement plant fuels Ecoinvent

Reference(s) Norris 2003 Marceau and others 2006 and 2007 Frischknecht and others 2004 Remmerswaal 2001 Frischknecht and others 2004 Frischknecht and Jungbluth 2004 Norris 2003 Frischknecht and others 2004 Remmerswaal 2001 Frischknecht and Jungbluth 2004 Norris 2003 Frischknecht and others 2004 Frischknecht and others 2004 Frischknecht and Jungbluth 2004 Remmerswaal 2001 Frischknecht and Jungbluth 2004 Frischknecht and others 2004 Remmerswaal 2001 APME 2000 Norris 2003 Remmerswaal 2001 Norris 2003 Norris 2003 Frischknecht and others 2004 Remmerswaal 2001 Frischknecht and Jungbluth 2004 Frischknecht and Jungbluth 2004 Frischknecht and others 2004 Norris 2003 Norris 2003 Frischknecht and others 2004 Norris 2003 Frischknecht and others 2004

Table 12. Materials Excluded from the LCA because of Insufficient Data

Material Floor carpet and under-pad Appliances and HVAC Sealant Miscellaneous polymers Subtotal Total mass of house (average) Total mass excluded from LCA

Wood CMU Amount Amount kg lb kg lb 6,400 14,200 6,400 14,200 5,500 12,000 5,500 12,000 300 660 300 660 20 40 20 40 12,000 27,000 12,000 27,000 161,000 356,000 287,000 633,000 7% 4%

House Energy Inputs Construction. Apart from human labor, most of the energy used for on-site construction is in excavating the foundation. Depending on the foundation depth, between 110 to 340 m3 (4000 to 12000 ft3) of soil is excavated. Assuming a typical hydraulic excavator, the embodied energy of this process is 900 to 2700 MJ (850 to 2600 kBtu) (Frischknecht and others 2004). This represents approximately 1% of the annual household energy use and approximately 0.01% of the life cycle household energy use. Occupancy. Life cycle household energy use is the annual energy use (see Table 7) multiplied by 100. Demolition and disposal. The energy for demolition and disposal is assumed to be less than that used in excavation because it takes less energy to demolish a house than to build it. As such, demolition and disposal would be less than 0.01% of the life cycle household energy use. Therefore, no significant error is introduced by omitting this energy. Transportation. Transportation includes transporting the mass of all materials to the house throughout the life of the house, and transporting the mass of all material to a landfill at the end of life. All material is assumed to be transported by tractor-trailers using diesel fuel and traveling on paved roads. The average haul distance is assumed to be 80 kilometers (50 miles) for all material. The energy used in return trips (when an empty truck returns to its home base) is not included because this type of vehicle usually makes deliveries at more than one job site per trip. Therefore, the transportation energy is overestimated. However, depending on house style, the embodied energy of this process ranges from 22 to 54 GJ (21 to 51 MBtu) (Norris 2003), which is approximately 25% of the annual household energy use and approximately 0.25% of the life cycle household energy use.

LIFE CYCLE IMPACT ASSESSMENT Life cycle impact assessment (LCIA) is the “phase of life cycle assessment aimed at understanding and evaluating the magnitude and significance of the potential environmental impacts for a product system throughout the life of the product” (ISO 2006b). LCIA consists of category definition, classification, and characterization. Category definition consists of identifying which impact categories are relevant for the product being studied. Classification consists of grouping related substances into impact categories. For example, the greenhouse gases carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) contribute to global warming; as a result, they can be grouped together in an impact category called climate change. According to ISO 14044, the mandatory step in life cycle impact assessment is characterization. In characterization, weighting factors are assigned according to a substance’s relative contribution to the impact category. For example, in terms of global warming potential, one pound of methane is 20 times more potent than one pound of CO2, and one pound of N2O is 320 times more potent than one pound of CO2. Therefore, in assessing the potential for global warming, CO2 is assigned a weighting factor of 1, CH4 a factor of 20, and N2O a factor of 320. It is important to remember that there is no scientific basis for comparing across impact categories.

According to ISO 14042, life cycle impact assessment is not intended to identify, measure, or predict actual impacts or estimate threshold limits, or measure margins of safety. The methodology is still being developed, and there is no general and widespread practice of life cycle impact assessment at this time or an agreement on specific methodologies. Therefore, several of the available methods were used to measure the life cycle impact assessment. The methods chosen are Eco-Indicator 99 (Dutch/Swiss), EDIP/UMIP 97 (Danish), and EPS 2000 (Swedish). Furthermore, three different weighting sets in Eco-Indicator 99 were used. The Eco-Indicator 99 method is a damage-oriented approach, which is based on how a panel of experts weighted the different types of damage caused by the impact categories. The three versions of Eco-Indicator 99 reflect the subjective uncertainty inherent in LCA. Each one takes a different perspective on how to consider the potential damage from a particular substance. The egalitarian perspective takes an extremely long-term look at substances if there is any indication that they have some effect. The hierarchic perspective takes a long-term look at all substances if there is consensus regarding their effect. The individualist perspective takes a shortterm look (100 years or less) at substances if there is complete proof regarding their effect. The EDIP/UMIP 97 method is based on normalizing values to person-equivalents in 1990 and weighting factors are equivalent to politically-set target-emissions per person in 2000. The EPS 2000 method was designed as a tool for a company's internal product development process, and the weighting factors are based on a willingness to pay to avoid change. A listing of the impact categories in each method is shown in Table 13. A complete description of the category definitions, category endpoint, classification methods, and characterization factors for each of the three methods is too voluminous to be reproduced in this report. Please refer to Appendices B for a summary of each method and further references. Table 13. Impact Categories for Three Life Cycle Impact Assessment Methods Eco-Indicator 99 Carcinogens Respiratory organics Respiratory inorganics Climate change Radiation Ozone layer Ecotoxicity Acidification/eutrophication Land use Minerals Fossil fuels

EDIP/UMIP 97 Global warming potential (GWP 100) Ozone depletion Acidification Eutrophication Photochemical smog Ecotoxicity water, chronic Ecotoxicity water, acute Ecotoxicity soil, chronic Human toxicity, air Human toxicity, water Human toxicity, soil Bulk waste Hazardous waste Radioactive waste Slags/ashes Resources (all)

EPS 2000 Life expectancy Severe morbidity Morbidity Severe nuisance Nuisance Crop growth capacity Wood growth capacity Fish and meat production Soil acidification Production capacity of irrigation water Production capacity of drinking water Depletion of reserves Species extinction

Results of the characterization phase for each method are shown in Tables 14 through 18. The impact indicators in each category are approximately the same on average for the wood and

CMU houses. The CMU house performs better than the wood frame house in Tucson and St. Louis. The wood frame house performs better than the CMU house in Lake Charles and Minneapolis. Table 14. Characterization of Life Cycle Inventory Data Assuming an Egalitarian Perspective Using the Eco-Indicator 99 Method of Characterization Wood frame house Impact category

Unit*

Carcinogens Respiratory organics Respiratory inorganics Climate change Radiation Ozone layer Ecotoxicity Acidification/eutrophication Land use Minerals Fossil fuels

DALY DALY DALY DALY DALY DALY PAF·m2·yr PDF·m2·yr PDF·m2·yr MJ surplus MJ surplus

Impact category

Unit

Carcinogens Respiratory organics Respiratory inorganics Climate change Radiation Ozone layer Ecotoxicity Acidification/eutrophication Land use Minerals Fossil fuels

DALY DALY DALY DALY DALY DALY PAF·m2·yr PDF·m2·yr PDF·m2·yr MJ surplus MJ surplus

Impact category

Unit

Carcinogens Respiratory organics Respiratory inorganics Climate change Radiation Ozone layer Ecotoxicity Acidification/eutrophication Land use Minerals Fossil fuels

DALY DALY DALY DALY DALY DALY PAF·m2·yr PDF·m2·yr PDF·m2·yr MJ surplus MJ surplus

Lake Charles 2.4E-02 1.4E-03 1.1E+00 3.6E-01 8.1E-04 1.4E-04 5.8E+04 3.4E+04 3.2E+03 1.0E+04 2.0E+06

Tucson

St. Louis

Denver

2.5E-02 1.5E-03 1.2E+00 3.8E-01 7.7E-04 1.3E-04 5.9E+04 3.7E+04 3.0E+03 9.9E+03 2.0E+06

2.7E-02 1.7E-03 1.2E+00 4.4E-01 1.1E-03 1.9E-04 6.8E+04 3.7E+04 4.3E+03 1.2E+04 2.5E+06 CMU house

2.5E-02 1.5E-03 1.0E+00 4.0E-01 1.1E-03 1.8E-04 6.4E+04 3.2E+04 4.2E+03 1.2E+04 2.2E+06

Minneapolis 2.7E-02 1.6E-03 1.0E+00 4.5E-01 1.3E-03 2.1E-04 7.1E+04 3.2E+04 5.1E+03 1.4E+04 2.6E+06

Lake MinneTucson St. Louis Denver Charles apolis 2.4E-02 2.4E-02 2.7E-02 2.5E-02 2.8E-02 1.4E-03 1.5E-03 1.6E-03 1.5E-03 1.6E-03 1.1E+00 1.2E+00 1.2E+00 1.0E+00 1.0E+00 3.7E-01 3.7E-01 4.3E-01 4.0E-01 4.7E-01 8.0E-04 7.1E-04 1.1E-03 1.1E-03 1.4E-03 1.4E-04 1.3E-04 1.8E-04 1.8E-04 2.2E-04 5.8E+04 5.7E+04 6.6E+04 6.4E+04 7.3E+04 3.5E+04 3.7E+04 3.6E+04 3.1E+04 3.2E+04 3.2E+03 2.8E+03 4.1E+03 4.3E+03 5.4E+03 1.0E+04 9.5E+03 1.2E+04 1.2E+04 1.4E+04 2.0E+06 1.9E+06 2.4E+06 2.2E+06 2.7E+06 CMU house compared to wood frame house** Lake MinneTucson St. Louis Denver Charles apolis -3% 2% 3% 0% -3% -2% 2% 3% 2% -2% -4% -1% 1% 1% -2% -2% 3% 4% 0% -4% 1% 7% 6% -2% -5% 0% 6% 5% -2% -5% -1% 3% 3% 0% -2% -3% 0% 2% 2% -1% 0% 6% 5% -2% -5% 0% 3% 3% -2% -4% -1% 4% 4% 0% -4%

*The notation in the table is a modified scientific notation, for example 1.2E+04 means 1.2 × 104 which is equal to 12,000. DALY is disabilityadjusted life-years; it expresses the number of year-lives lost and the number of year-lives lived with a disability. PAF is potentially affected area. PDF is potentially disappeared fraction. MJ surplus is the additional energy needed for future extractions of scarcer minerals and fossil fuels. **Positive values indicate less impact for CMU house compared to wood frame house.

Table 15. Characterization of Life Cycle Inventory Data Using a Hierarchic Perspective in the Eco-Indicator 99 Method of Characterization Wood frame house Impact category

Unit*

Carcinogens Respiratory organics Respiratory inorganics Climate change Radiation Ozone layer Ecotoxicity Acidification/eutrophication Land use Minerals Fossil fuels

DALY DALY DALY DALY DALY DALY PAF·m2·yr PDF·m2·yr PDF·m2·yr MJ surplus MJ surplus

Impact category

Unit

Carcinogens Respiratory organics Respiratory inorganics Climate change Radiation Ozone layer Ecotoxicity Acidification/eutrophication Land use Minerals Fossil fuels

DALY DALY DALY DALY DALY DALY PAF·m2·yr PDF·m2·yr PDF·m2·yr MJ surplus MJ surplus

Impact category

Unit

Carcinogens Respiratory organics Respiratory inorganics Climate change Radiation Ozone layer Ecotoxicity Acidification/eutrophication Land use Minerals Fossil fuels

DALY DALY DALY DALY DALY DALY PAF·m2·yr PDF·m2·yr PDF·m2·yr MJ surplus MJ surplus

Lake Charles 2.4E-02 1.4E-03 1.1E+00 3.6E-01 8.1E-04 1.4E-04 5.8E+04 3.4E+04 3.2E+03 1.0E+04 2.2E+06

Tucson

St. Louis

Denver

2.5E-02 1.5E-03 1.2E+00 3.8E-01 7.7E-04 1.3E-04 5.9E+04 3.7E+04 3.0E+03 9.9E+03 2.1E+06

2.7E-02 1.7E-03 1.2E+00 4.4E-01 1.1E-03 1.9E-04 6.8E+04 3.7E+04 4.3E+03 1.2E+04 3.0E+06 CMU house

2.5E-02 1.5E-03 1.0E+00 4.0E-01 1.1E-03 1.8E-04 6.4E+04 3.2E+04 4.2E+03 1.2E+04 2.8E+06

Minneapolis 2.7E-02 1.6E-03 1.0E+00 4.5E-01 1.3E-03 2.1E-04 7.1E+04 3.2E+04 5.1E+03 1.4E+04 3.4E+06

MinneLake Tucson St. Louis Denver apolis Charles 2.4E-02 2.4E-02 2.7E-02 2.5E-02 2.8E-02 1.4E-03 1.5E-03 1.6E-03 1.5E-03 1.6E-03 1.1E+00 1.2E+00 1.2E+00 1.0E+00 1.0E+00 3.7E-01 3.7E-01 4.3E-01 4.0E-01 4.7E-01 8.0E-04 7.1E-04 1.1E-03 1.1E-03 1.4E-03 1.4E-04 1.3E-04 1.8E-04 1.8E-04 2.2E-04 5.8E+04 5.7E+04 6.6E+04 6.4E+04 7.3E+04 3.5E+04 3.7E+04 3.6E+04 3.1E+04 3.2E+04 3.2E+03 2.8E+03 4.1E+03 4.3E+03 5.4E+03 1.0E+04 9.5E+03 1.2E+04 1.2E+04 1.4E+04 2.2E+06 2.0E+06 2.8E+06 2.8E+06 3.5E+06 CMU house compared to wood frame house** Lake MinneTucson St. Louis Denver Charles apolis -3% 2% 3% 0% -3% -2% 2% 3% 2% -2% -4% -1% 1% 1% -2% -2% 3% 4% 0% -4% 1% 7% 6% -2% -5% 0% 6% 5% -2% -5% -1% 3% 3% 0% -2% -3% 0% 2% 2% -1% 0% 6% 5% -2% -5% 0% 3% 3% -2% -4% -1% 6% 5% -2% -5%

Table 16. Characterization of Life Cycle Inventory Data Using an Individualist Perspective in the Eco-Indicator 99 Method of Characterization Wood frame house Impact category

Unit*

Carcinogens Respiratory organics Respiratory inorganics Climate change Radiation Ozone layer Ecotoxicity Acidification/eutrophication Land use Minerals

DALY DALY DALY DALY DALY DALY PAF·m2·yr PDF·m2·yr PDF·m2·yr MJ surplus

Impact category

Unit

Carcinogens Respiratory organics Respiratory inorganics Climate change Radiation Ozone layer Ecotoxicity Acidification/eutrophication Land use Minerals

DALY DALY DALY DALY DALY DALY PAF·m2·yr PDF·m2·yr PDF·m2·yr MJ surplus

Impact category

Unit

Carcinogens Respiratory organics Respiratory inorganics Climate change Radiation Ozone layer Ecotoxicity Acidification/eutrophication Land use Minerals

DALY DALY DALY DALY DALY DALY PAF·m2·yr PDF·m2·yr PDF·m2·yr MJ surplus

Lake Charles 9.1E-03 1.3E-03 5.2E-01 3.4E-01 3.8E-05 1.1E-04 7.3E+03 3.4E+04 3.2E+03 1.0E+04

Tucson

St. Louis

Denver

9.7E-03 1.4E-03 5.7E-01 3.6E-01 3.6E-05 1.1E-04 7.4E+03 3.7E+04 3.0E+03 9.9E+03

1.1E-02 1.5E-03 5.5E-01 4.3E-01 5.0E-05 1.5E-04 8.7E+03 3.7E+04 4.3E+03 1.2E+04 CMU house

9.5E-03 1.4E-03 4.8E-01 3.8E-01 4.8E-05 1.4E-04 8.1E+03 3.2E+04 4.2E+03 1.2E+04

Minneapolis 1.0E-02 1.5E-03 4.8E-01 4.3E-01 5.9E-05 1.7E-04 9.0E+03 3.2E+04 5.1E+03 1.4E+04

Lake MinneTucson St. Louis Denver Charles apolis 9.3E-03 9.4E-03 1.0E-02 9.4E-03 1.0E-02 1.3E-03 1.4E-03 1.5E-03 1.3E-03 1.5E-03 5.4E-01 5.7E-01 5.5E-01 4.8E-01 4.9E-01 3.5E-01 3.5E-01 4.1E-01 3.8E-01 4.4E-01 3.7E-05 3.4E-05 4.7E-05 4.9E-05 6.1E-05 1.1E-04 1.0E-04 1.4E-04 1.5E-04 1.8E-04 7.3E+03 7.2E+03 8.4E+03 8.1E+03 9.3E+03 3.5E+04 3.7E+04 3.6E+04 3.1E+04 3.2E+04 3.2E+03 2.8E+03 4.1E+03 4.3E+03 5.4E+03 1.0E+04 9.5E+03 1.2E+04 1.2E+04 1.4E+04 CMU house compared to wood frame house** MinneLake Tucson St. Louis Denver apolis Charles -1% 3% 4% 2% -2% -2% 2% 3% 2% -2% -4% -1% 0% 1% -2% -2% 3% 4% 0% -4% 1% 7% 5% -2% -4% 0% 6% 5% -2% -5% -1% 3% 4% 0% -3% -3% 0% 2% 2% -1% 0% 6% 5% -2% -5% 0% 3% 3% -2% -4%

Table 17. Characterization of Life Cycle Inventory Data using the EDIP/UMIP 97 Method of Characterization Wood frame house Impact category

Unit*

Global warming (GWP 100) Ozone depletion Acidification Eutrophication Photochemical smog Ecotoxicity water chronic Ecotoxicity water acute Ecotoxicity soil chronic Human toxicity air Human toxicity water Human toxicity soil Bulk waste Hazardous waste Radioactive waste Slags/ashes Resources (all)

g CO2 g CFC11 g SO2 g NO3 g ethene m3 m3 m3 m3 m3 m3 kg kg kg kg kg

Impact category

Unit

g CO2 g CFC11 g SO2 g NO3 g ethene m3 m3 m3 m3 m3 m3 kg kg kg kg kg

Lake Charles 1.7E+09 1.3E+02 1.2E+07 6.0E+06 5.1E+05 9.2E+07 9.7E+06 2.5E+06 1.7E+11 4.8E+06 7.7E+04 1.9E+05 5.7E+01 4.3E+00 3.6E+01 5.3E+01 Lake Charles 1.8E+09 1.3E+02 1.2E+07 6.2E+06 5.2E+05 9.6E+07 9.9E+06 2.5E+06 1.7E+11 5.4E+06 7.7E+04 2.0E+05 5.7E+01 4.3E+00 3.4E+01 5.3E+01

Tucson

St. Louis

Denver

1.8E+09 1.3E+02 1.3E+07 6.5E+06 5.4E+05 9.5E+07 9.9E+06 2.3E+06 1.6E+11 5.1E+06 7.4E+04 2.1E+05 5.6E+01 4.0E+00 3.5E+01 5.2E+01

2.1E+09 1.8E+02 1.3E+07 6.6E+06 6.1E+05 1.1E+08 1.2E+07 3.7E+06 2.0E+11 5.5E+06 1.1E+05 2.0E+05 6.4E+01 6.5E+00 4.0E+01 6.6E+01 CMU house

1.9E+09 1.7E+02 1.1E+07 5.7E+06 5.4E+05 1.0E+08 1.1E+07 3.5E+06 1.9E+11 5.0E+06 1.0E+05 1.7E+05 6.4E+01 6.2E+00 4.0E+01 6.3E+01

Tucson

St. Louis

Denver

1.8E+09 1.2E+02 1.3E+07 6.5E+06 5.2E+05 9.4E+07 9.7E+06 2.2E+06 1.6E+11 5.6E+06 6.8E+04 2.1E+05 5.5E+01 3.6E+00 3.3E+01 5.0E+01

2.1E+09 1.7E+02 1.2E+07 6.5E+06 5.8E+05 1.1E+08 1.1E+07 3.4E+06 2.0E+11 6.0E+06 1.0E+05 2.0E+05 6.3E+01 6.1E+00 3.8E+01 6.4E+01

1.9E+09 1.7E+02 1.0E+07 5.6E+06 5.4E+05 1.0E+08 1.1E+07 3.6E+06 2.0E+11 5.5E+06 1.1E+05 1.7E+05 6.4E+01 6.4E+00 3.9E+01 6.4E+01

*The notation in the table is a modified scientific notation, for example 1.2E+04 means 1.2 × 104 which is equal to 12,000. **Positive values indicate less impact for CMU house compared to wood frame house.

Minneapolis 2.2E+09 2.0E+02 1.1E+07 5.8E+06 6.0E+05 1.1E+08 1.2E+07 4.5E+06 2.2E+11 5.4E+06 1.3E+05 1.7E+05 6.9E+01 8.0E+00 4.4E+01 7.4E+01 Minneapolis 2.2E+09 2.1E+02 1.1E+07 5.9E+06 6.1E+05 1.2E+08 1.3E+07 4.7E+06 2.3E+11 6.0E+06 1.4E+05 1.7E+05 7.1E+01 8.5E+00 4.3E+01 7.7E+01

Table 17. Characterization of Life Cycle Inventory Data using the EDIP/UMIP 97 Method of Characterization (Continued)

Impact category

Unit

g CO2 g CFC11 g SO2 g NO3 g ethene m3 m3 m3 m3 m3 m3 kg kg kg kg kg

CMU house compared to wood frame house** MinneLake Tucson St. Louis Denver apolis Charles -2% 3% 4% 0% -4% 0% 6% 5% -2% -5% -2% 0% 2% 3% 0% -3% 0% 2% 2% -2% -1% 3% 4% 1% -2% -3% 0% 1% -2% -5% -2% 2% 3% -1% -4% -1% 7% 6% -3% -6% -1% 4% 4% -1% -4% -14% -10% -8% -10% -13% 0% 7% 6% -3% -5% -3% 0% 1% 3% 0% 0% 2% 2% -1% -2% 0% 9% 7% -3% -6% 4% 6% 6% 3% 1% -1% 4% 4% -2% -4%

Table 18. Characterization of Life Cycle Inventory Data using the EPS 2000 Method of Characterization Wood frame house Impact category Life expectancy Severe morbidity Morbidity Severe nuisance Nuisance Crop growth capacity Wood growth capacity Fish and meat production Soil acidification Prod. cap. irrigation water Prod. cap. drinking water Depletion of reserves Species extinction Impact category Life expectancy Severe morbidity Morbidity Severe nuisance Nuisance Crop growth capacity Wood growth capacity Fish and meat production Soil acidification Prod. cap. irrigation water Prod. cap. drinking water Depletion of reserves Species extinction Impact category Life expectancy Severe morbidity Morbidity Severe nuisance Nuisance Crop growth capacity Wood growth capacity Fish and meat production Soil acidification Prod. cap. irrigation water Prod. cap. drinking water Depletion of reserves Species extinction

Unit* PersonYr PersonYr PersonYr PersonYr PersonYr kg kg kg H+ eq. kg kg ELU NEX Unit PersonYr PersonYr PersonYr PersonYr PersonYr kg kg kg H+ eq. kg kg ELU NEX Unit PersonYr PersonYr PersonYr PersonYr PersonYr kg kg kg H+ eq. kg kg ELU NEX

Lake Charles 2.1E+00 5.6E-01 1.2E+00 1.7E-01 6.8E+01 4.7E+03 -7.8E+04 -1.4E+02 1.8E+04 8.1E+01 8.1E+01 4.5E+05 2.0E-08

Tucson

St. Louis

Denver

2.3E+00 5.8E-01 1.3E+00 1.7E-01 7.4E+01 4.9E+03 -8.2E+04 -1.5E+02 2.0E+04 8.1E+01 8.1E+01 4.4E+05 2.1E-08

2.6E+00 7.1E-01 1.5E+00 1.8E-01 7.3E+01 5.5E+03 -9.4E+04 -1.5E+02 2.0E+04 8.1E+01 8.1E+01 6.0E+05 2.5E-08 CMU house

2.3E+00 6.4E-01 1.4E+00 1.8E-01 6.2E+01 4.8E+03 -8.3E+04 -1.3E+02 1.7E+04 8.1E+01 8.1E+01 5.6E+05 2.2E-08

Minneapolis 2.5E+00 7.3E-01 1.5E+00 1.8E-01 6.1E+01 5.2E+03 -9.3E+04 -1.3E+02 1.7E+04 8.1E+01 8.1E+01 6.8E+05 2.6E-08

MinneLake Tucson St. Louis Denver apolis Charles 2.2E+00 2.2E+00 2.5E+00 2.3E+00 2.6E+00 5.7E-01 5.6E-01 6.8E-01 6.4E-01 7.6E-01 1.3E+00 1.3E+00 1.5E+00 1.4E+00 1.6E+00 1.7E-01 1.7E-01 1.8E-01 1.8E-01 1.9E-01 6.9E+01 7.4E+01 7.1E+01 6.0E+01 6.1E+01 4.8E+03 4.9E+03 5.3E+03 4.8E+03 5.4E+03 -7.9E+04 -8.0E+04 -9.1E+04 -8.3E+04 -9.6E+04 -1.4E+02 -1.5E+02 -1.5E+02 -1.3E+02 -1.4E+02 1.9E+04 2.0E+04 1.9E+04 1.6E+04 1.7E+04 8.1E+01 8.1E+01 8.1E+01 8.1E+01 8.1E+01 8.1E+01 8.1E+01 8.1E+01 8.1E+01 8.1E+01 4.5E+05 4.2E+05 5.7E+05 5.7E+05 7.1E+05 2.0E-08 2.0E-08 2.4E-08 2.3E-08 2.7E-08 CMU house compared to wood frame house** Lake MinneTucson St. Louis Denver Charles apolis -3% 1% 3% 0% -3% -2% 3% 4% -1% -4% -2% 2% 3% 0% -3% 0% 1% 1% 0% -1% -2% 0% 2% 3% 0% -2% 1% 3% 1% -3% -2% 2% 3% 0% -3% -3% 0% 1% 1% -2% -2% 0% 2% 3% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% -1% 5% 5% -2% -4% -2% 3% 4% -1% -4%

*The notation in the table is a modified scientific notation, for example 1.2E+04 means 1.2 × 104 which is equal to 12,000. ELU is environmental load unit. NEX is no extinction. **Positive values indicate less impact for CMU house compared to wood frame house.

Other methods of impact assessment, such as damage assessment, normalization, and weighting, are optional. In damage assessment, impact categories that have equivalent units are added. In normalization, the impact assessment values are compared to some reference, such as the average yearly environmental load in a country divided by the number of people in the country. In weighting, the impact assessment values in several or all categories are multiplied by weighting factors and added together to get a single score. However, the weighting factors used are always subjective and reflect societal or personal values. Furthermore, according to ISO 14042, weighting cannot be used to make comparative assertions disclosed to the public. The tables in Appendix C show the normalized and weighted results for each category of each method. In each of the five methods, the CMU house has a lower score than the wood frame house in almost all impact categories in Tucson and St. Louis. The CMU house has a higher score than the wood frame house in almost all impact categories in Lake Charles and Minneapolis. In Denver the scores are approximately equal. A summary of the normalized and weighted single-score results is shown in Table 19. Table 19. Normalized and Weighted Single Score Summary Method Eco-Indicator 99 Egalitarian Hierarchic Individualist Lake Charles 99,000 110,000 74,000 Tucson 103,000 111,000 78,000 Wood frame St. Louis 121,000 142,000 85,000 house Denver 108,000 130,000 76,000 Minneapolis 121,000 154,000 82,000 Lake Charles 101,000 111,000 76,000 Tucson 101,000 107,000 77,000 CMU house St. Louis 116,000 136,000 83,000 Denver 108,000 132,000 76,000 Minneapolis 125,000 160,000 84,000

House style

Location

EDIP/ UMIP 97 2,730 2,760 3,480 3,220 3,760 2,800 2,690 3,370 3,290 3,940

EPS 2000 707,000 712,000 910,000 840,000 986,000 716,000 685,000 872,000 850,000 1,027,000

LIFE CYCLE INTERPRETATION Life cycle interpretation is the “phase of life cycle assessment in which the findings of either the inventory analysis or the impact assessment, or both, are evaluated in relation to the defined goal and scope in order to reach conclusions and recommendations” (ISO 2006b). A breakdown of the LCA by major process and product stage shows that most of the environmental load is from the household use of natural gas and electricity during the life of the houses. Figure 2 shows the breakdown for each house using the hierarchic perspective of EcoIndicator 99. The household-use of electricity and natural gas represents 97% of the environmental impacts of the CMU houses and 97% of the environmental impacts of the wood frame houses. Because energy use is the dominant factor in LCA results, the results comparing energy use of CMU to wood frame in Table 7 are similar to the resulting comparisons in Tables 14 to 18. The household use of electricity (mostly for cooling) contributes the most to the total environmental impacts in cooling-dominant climates like Tucson. The household use of natural gas (mostly for heating) contributes the most to the total environmental impacts in heating-

dominant climates like Minneapolis. In all locations, cement-based materials represent a small fraction of the total environmental impacts. Furthermore, the data in Figure 2 show that the most significant impact categories are fossil fuel depletion and respiratory inorganics. The other methods of life cycle impact assessment produce similar results. Figure 3 shows a breakdown of the environmental impacts of buildings materials for each of the houses using the hierarchic perspective of the Eco-Indicator 99 Method. Most of the environmental impacts from construction materials are due to aluminum siding, ceramic tiles, paint, roof shingles, cement-based materials, steel, and cast iron. Furthermore, the impact categories that contribute the most to the total environmental impacts are fossil fuel depletion and respiratory inorganics.

120 Eco-indicator 99, points × 1000

Eco-indicator 99, points × 1000

120

Fossil fuels

100 80

Respiratory inorganics

Climate change

Acidification/ eutrophication

20 0

100 80 60 40 20 0

Cement-based materials

Non-cement materials

Transportation Construction (materials to/ from house)

Household electricity

Household natural gas

Cement-based materials

Non-cement materials

Wood house, Lake Charles

Eco-indicator 99, points × 1000

100 80 60 40 20

Household natural gas

100 80 60 40 20 0

Cement-based materials

Non-cement materials

Transportation Construction (materials to/ from house)

Household electricity

Household natural gas

Cement-based materials

Non-cement materials

Wood house, Tucson

Transportation (materials to/ from house)

Construction

Household electricity

Household natural gas

Household electricity

Household natural gas

Household electricity

Household natural gas

Household electricity

Household natural gas

Concrete masonry house, Tucson 120 Eco-indicator 99, points × 1000

120 Eco-indicator 99, points × 1000

Household electricity

120

100 80 60 40 20 0

Cement-based materials

Non-cement materials

Transportation Construction (materials to/ from house)

Household electricity

Household natural gas

Cement-based materials

Non-cement materials

Wood house, St. Louis

Transportation (materials to/ from house)

Construction

Concrete masonry house, St. Louis 120 Eco-indicator 99, points × 1000

120 Eco-indicator 99, points × 1000

Construction

Concrete masonry house, Lake Charles

120

100 80 60 40 20 0

Cement-based materials

Non-cement materials

Transportation Construction (materials to/ from house)

Household electricity

Household natural gas

Cement-based materials

Non-cement materials

Wood house, Denver

Transportation (materials to/ from house)

Construction

Concrete masonry house, Denver 120 Eco-indicator 99, points × 1000

120 Eco-indicator 99, points × 1000

Transportation (materials to/ from house)

100 80 60 40 20 0

Cement-based materials

Non-cement materials

Transportation Construction (materials to/ from house)

Household electricity

Household natural gas

Cement-based materials

Non-cement materials

Wood house, Minneapolis

Transportation (materials to/ from house)

Construction

Concrete masonry house, Minneapolis

Fossil fuels

Respiratory inorganics

Climate change

Acidification/eutrophication

Ecotoxicity

Carcinogens

Minerals

Land use

Respiratory organics

Radiation

Ozone layer

Figure 2. Single-score life cycle inventory assessment of houses showing contribution of each major product and process stage. The data have been normalized and weighted according to the Eco-Indicator 99 method using the Hierarchic perspective.

Aluminum

Wood house components, Denver CMU house components, Denver

1400 1400

1000

800

600

400

28 1200

1000

800

600

200 400

200

0 0

Wood house components, Minneapolis Wood

1600

Wood

1600 Steel & cast iron

0 Cementitious mat'ls

200

Steel & cast iron

200

Cementitious mat'ls

400

Windows

600

Windows

800

Roofing mat'ls

1000

Roofing mat'ls

1400

Pipe, pvc

1400

Pipe, copper

1600

Pipe, pvc

Wood house components, St. Louis

Pipe, copper

1600

Fossil fuels

Respiratory inorganics

Climate change

Acidification/eutrophication

Ecotoxicity

Carcinogens

Minerals

Land use

Respiratory organics

Radiation

Ozone layer

CMU house components, Minneapolis

Figure 3. Single-score life cycle inventory assessment of construction materials in the houses showing contribution of each major product and process stage. The data have been normalized and weighted according to the Eco-Indicator 99 method using the Hierarchic perspective. Wood

Steel & cast iron

Cementitious mat'ls

Windows

Roofing mat'ls

Pipe, pvc

Pipe, copper

Particle board

200

Particle board

200

Paint

400

Paint

600

Paint

800

Linoleum

1000

Linoleum

1400

Linoleum

1400

Light bulbs

1600

Light bulbs

Wood house components, Tucson

Light bulbs

1600 Wood

Steel & cast iron

Cementitious mat'ls

Windows

Roofing mat'ls

Pipe, pvc

Pipe, copper

Particle board

Paint

Linoleum

Light bulbs

Insul., polystyrene

200

Insul., polystyrene

Wood house components, Lake Charles

Insul., polystyrene

200

Insul., fiberglass

400

Insul., fiberglass

600

Insul., fiberglass

800

Insul., fiberglass

1000

Gypsum wallboard

1400

Electrical wire

1400

Gypsum wallboard

1600

Electrical wire

1600 Aluminum

Wood

Steel & cast iron

Cementitious mat'ls

Windows

Roofing mat'ls

Pipe, pvc

Pipe, copper

Particle board

Paint

Linoleum

Light bulbs

Insul., polystyrene

Insul., fiberglass

Gypsum wallboard

Electrical wire

Ceramic tiles

Gypsum wallboard

Aluminum

200

Ceramic tiles

200

Electrical wire

Aluminum

400 Eco-indicator 99, points

Climate change

Ceramic tiles

1200

Eco-indicator 99, points

Wood

Steel & cast iron

Cementitious mat'ls

Windows

Roofing mat'ls

Pipe, pvc

800

Gypsum wallboard

Aluminum

1200

Eco-indicator 99, points

Wood

Steel & cast iron

Cementitious mat'ls

Windows

Roofing mat'ls

Pipe, copper

Particle board

Paint

Linoleum

Light bulbs

Acidification/ eutrophication

Ceramic tiles

1200

Eco-indicator 99, points

Wood

Steel & cast iron

Cementitious mat'ls

Windows

Roofing mat'ls

Pipe, pvc

Pipe, copper

Particle board

Paint

Linoleum

Light bulbs

Insul., polystyrene

Insul., fiberglass

1200

Electrical wire

1200

Eco-indicator 99, points

Wood

Steel & cast iron

Cementitious mat'ls

Windows

Roofing mat'ls

Pipe, pvc

Pipe, copper

Particle board

Paint

Linoleum

Light bulbs

Insul., polystyrene

Gypsum wallboard

Electrical wire

Fossil fuels

Ceramic tiles

Aluminum

Wood

Steel & cast iron

Cementitious mat'ls

Windows

Roofing mat'ls

Pipe, pvc

Pipe, copper

Particle board

Paint

Linoleum

Light bulbs

Insul., polystyrene

Insul., fiberglass

Gypsum wallboard

Electrical wire

Aluminum Ceramic tiles

Eco-indicator 99, points

Respiratory inorganics

Pipe, pvc

Pipe, copper

Particle board

Paint

Linoleum

Light bulbs

Insul., polystyrene

Insul., fiberglass

Gypsum wallboard

Electrical wire

Aluminum Ceramic tiles

Eco-indicator 99, points 600

Insul., fiberglass

Gypsum wallboard

Electrical wire

Aluminum Ceramic tiles

Eco-indicator 99, points 1000

Insul., polystyrene

Aluminum Ceramic tiles

Eco-indicator 99, points 1400

Insul., fiberglass

Gypsum wallboard

Electrical wire

Ceramic tiles

Eco-indicator 99, points

1600 1600

1400

1200

1000 800

600

400

CMU house components, Lake Charles

1200

1000 800

600

400

CMU house components, Tucson

1200

1000

800

600

400

CMU house components, St. Louis

1200

1000

800

600

400

Sensitivity Approximately 95% of the negative environmental impacts are associated with household use of electricity and natural gas (including the environmental impacts embodied in the electricity and natural gas). Similarly, approximately 95% of the life cycle energy use is from household use of electricity and natural gas. Less than 0.5% of the life cycle energy use is embodied in the concrete portion of the house. Therefore, the house life cycle energy use is not sensitive to variations in cement manufacturing or concrete production. Furthermore, after climate, occupant behavior is the single most important factor contributing to energy consumption in houses. As a result, the house life cycle energy use is a function of climate and occupant behavior, not concrete content.

CONCLUSIONS This report presents the results of an assessment of the environmental attributes of concrete construction compared to wood-framed construction. A life cycle assessment (LCA) was conducted on a house modeled with two types of exterior walls: a wood-framed wall and a CMU wall. The LCA was carried out according to the guidelines in International Standard ISO 14044, Environmental Management – Life Cycle Assessment – Requirements and Guidelines. The house was modeled in five cities, representing a range of U.S. climates: Lake Charles, Tucson, St. Louis, Denver, and Minneapolis. Each house is a two-story single-family building with a contemporary design. The house system boundary includes the inputs and outputs of energy and material from construction, occupancy, maintenance, demolition, and disposal. The system boundary excludes capital goods, human labor, impacts caused by people, and waste treatment after disposal. An LCA of buildings typically does not include measures of disaster resistance, occupant comfort, or occupant productivity. The life of the houses is 100 years. The LCA was conducted by first assembling the relevant LCI data from published reports and commercially available databases. The LCA software tool, SimaPro, was used to perform a life cycle impact assessment. Impact assessment is not completely scientific, so three different models were used. The methods chosen are Eco-Indicator 99 (Dutch/Swiss), EDIP/UMIP 97 (Danish), and EPS 2000 (Swedish). Furthermore, three different weighting sets in EcoIndicator 99 were used. The data show that in all cases for all five methods, on average, the impact indicators in each category are similar for the wood and CMU houses. The most significant environmental impacts are not from construction materials but from the production of electricity and natural gas and the use of electricity and natural gas in the houses by the occupants. Furthermore, the largest impacts from these uses are in the form of depletion of fossil fuel reserves (categorized as damage to natural resources) and release to the air of respiratory inorganics (categorized as damage to human health). The household use of electricity and natural gas represents 97% of the negative impacts in the CMU house, and 97% of the negative impacts in the wood frame house. For this reason, energy use is a predictor of LCA results. The CMU house has similar energy performance as the wood frame house even though the CMU house has significantly less added insulation. This is due to the thermal mass of the concrete.

When considering only the construction materials, most of the environmental impacts are from aluminum siding, ceramic tiles, paint, roof shingles, cement-based materials, steel, and cast iron.

ACKNOWLEDGEMENTS The research reported in this paper (PCA R&D Serial No. 3042) was conducted by CTLGroup with the sponsorship of the Portland Cement Association (PCA Project Index No. 06-01). The contents of this report reflect the views of the authors, who are responsible for the facts and accuracy of the data presented. The contents do not necessarily reflect the views of the Portland Cement Association.

REFERENCES APME, INDUSTRY DATA Database, Association of Plastics Manufacturers in Europe, Brussels, Belgium, (included in all version of SimaPro). ASHRAE, 2005 ASHRAE Handbook Fundamentals SI Edition, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., Atlanta, Georgia, USA, 2005, page 18.3. ASHRAE, ANSI/ASHRAE Standard 90.2-2004, Energy Efficient Design of Low-Rise Residential Buildings, American Society of Heating Refrigerating, and Air Conditioning Engineers, Inc., Atlanta, Georgia, USA, 2004, 46 pages. ASHRAE, ANSI/ASHRAE Standard 62.2-2003, Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings, American Society of Heating Refrigerating, and Air Conditioning Engineers, Inc., Atlanta, Georgia, USA, 2003, 18 pages. ASHRAE, ASHRAE Standard 90.2-1993, Energy-Efficient Design of New Low-Rise Residential Buildings, American Society of Heating Refrigerating, and Air Conditioning Engineers, Inc., Atlanta, Georgia, USA, 1995. Frischknecht, R. and Jungbluth, N., SimaPro Database Manual: The ETH-ESU 96 Libraries, PRé Consultants Amersfoort, The Netherlands, 2004, 62 pages. Frischknecht, R., Jungbluth, N., Althaus, H.-J., Doka, G., Heck, T., Hellweg, S., Hischier, R., Nemecek, T., Rebitzer, G., Spielmann, M., Overview and Methodology: Ecoinvent Report No. 1, Swiss Centre for Life Cycle Inventories, Dübendorf, Switzerland, 2004, 75 pages. Goedkoop, Mark, De Schryver, An, and Oele, Michiel, Introduction to LCA with SimaPro 7, http://www.pre.nl/download/manuals/SimaPro7IntroductionToLCA.pdf, PRé Consultants, Amersfoort, The Netherlands, 2007. Häkkinen, Tarja and Holt, Erika, Review of the Life Cycle Inventory of Portland Cement Manufacture and Three Life Cycle Assessment Studies Prepared by Construction Technology Laboratories for Portland Cement Association, VTT Technical Research Centre of Finland, http://www.vtt.fi/index.jsp, Finland, 2002, 5 pages. IECC, 2006 International Energy Conservation Code, International Code Council, Inc., Country Club Hill, Illinois, USA, 2006, 72 pages. ISO, International Standard ISO 14044, Environmental Management - Life Cycle Assessment – Requirements and Guidelines, International Organization for Standardization, Geneva, Switzerland, 2006a 54 pages. ISO, International Standard ISO 14040, Environmental Management - Life Cycle Assessment Principles and Framework, International Organization for Standardization, Geneva, Switzerland, 2006b, 28 pages.

ISO, International Standard ISO 14042, Environmental Management - Life Cycle Assessment – Life Cycle Impact Assessment, International Organization for Standardization, Geneva, Switzerland, 2000. 24 pages. Marceau, Medgar L., Nisbet, Michael A., and VanGeem, Martha G., Life Cycle Inventory of Portland Cement Concrete, SN3011, Portland Cement Association, Skokie, Illinois, USA, 2007, 120 pages. Marceau, Medgar L., Nisbet, Michael A., and VanGeem, Martha G., Life Cycle Inventory of Portland Cement Manufacture, SN2095b, Portland Cement Association, Skokie, Illinois, USA, 2006, 49 pages. Marceau, Medgar L., and VanGeem, Martha G., Life Cycle Assessment of a Concrete Masonry Unit House Compared to a Wood Frame House, SN2572, Portland Cement Association, Skokie, Illinois, USA, 2002b, 165 pages. NAHB, Housing Facts, Figures and Trends May 2007, National Association of Home Builders, http://www.nahb.org/fileUpload_details.aspx?contentTypeID=7&contentID=2028, Washington, DC, 2007, 18 pages. Norris, Gregg A., SimaPro Database Manual: The Franklin US LCI Library, PRé Consultants Amersfoort, The Netherlands, 2003, 30 pages. PCA, HVAC Sizing for Concrete Homes, Version 3.0, CD044, Portland Cement Association, Skokie, Illinois, USA, 2005. Remmerswaal, Han, IDEMAT 2001 Database, Faculty of Industrial Design Engineering, Delft Technical University, The Netherlands, 2001, included in all version of SimaPro. Winkelmann, F.C., Birdsall, B.E., Buhl, W.F., Ellington, K.L., Erdem, A.E., Hirsch, J.J., and Gates, S., DOE-2 Supplement, Version 2.1E, LBL-34947, Lawrence Berkley National Laboratory. Berkley, California, USA, 1993, 810 pages.

APPENDIX A – HOUSE PLANS AND WALL CROSS-SECTIONS

Figure A-1. Floor plan of the lower level (ground floor).

A-1

Figure A-2. Floor plan of the upper level (second floor).

A-2

Figure A-3. Front elevation.

Figure A-4. Rear elevation.

A-3

Figure A-5. Right elevation.

Figure A-6. Left elevation.

A-4

Gypsum Wallboard 2x4 Wood Framing w/ Fiberglass Insulation Plywood Aluminum Siding

130 mm (51 8 in.)

Figure A-7. Wood frame wall cross-section.

Gypsum Wallboard 2x4 Wood Framing w/ Fiberglass Insulation (As Required) Normal Weight CMU Stucco

330 mm (13 in.)

Figure A-8. CMU wall cross-section.

A-5

APPENDIX B – IMPACT ASSESSMENT METHODS This appendix contains a description of the impact assessment methods, copied with permission, from Goedkoop, Mark, Oele, Michiel, and Effting, Suzanne, SimaPro Database Manual: Methods library, PRé Consultants, Amersfoort, The Netherlands, 2004, 34 pages.

B-1

SimaPro Database Manual

Methods library

2.4 Eco-indicator 99 v2.1 2.4.1 Introduction Eco-indicator 99 is the successor of Eco-indicator 95. Both methods use the damage-oriented approach. The development of the Eco-indicator 99 methodology started with the design of the weighting procedure. Traditionally in LCA the emissions and resource extractions are expressed as 10 or more different impact categories, like acidification, ozone layer depletion, ecotoxicity and resource extraction. For a panel of experts or non-experts it is very difficult to give meaningful weighting factors for such a large number and rather abstract impact categories. It was concluded that the panel should not be asked to weight the impact categories but the different types of damage that are caused by these impact categories. The other improvement was to limit the number of items that are to be assessed. As a result the panel, consisting of 365 persons from a Swiss LCA interest group, was asked to assess the seriousness of three damage categories: 1. Damage to Human Health, expressed as the number of year life lost and the number of years lived disabled. These are combined as Disability Adjusted Life Years (DALYs), an index that is also used by the Worldbank and WHO. 2. Damage to Ecosystem Quality, express as the loss of species over an certain area, during a certain time 3. Damage to Resources, expressed as the surplus energy needed for future extractions of minerals and fossil fuels. In order to be able to use the weights for the three damage categories a series of complex damage models had to be developed. In figure 2 these models are represented in a schematic way.

Mining Converter

Extraction of minerals and fossil fuels

Concentration of ores

Surplus energy at future extraction

Availability of fossil fuels

Surplus energy at future extraction

Land-use and land conversion

Decrease of natural area's

Regional effect on species numbers

Pressing Transport

NOx SOx NH3 Pesticides Heavy metals CO2 HCFC Nuclides (Bq) SPM VOC’s PAH’s

Invetory analysis

Step 1

Altered pH.+nutrient

Effect on Target species

Concentration in soil

Ecotoxicity: toxic stress (PAF)

Concentration of greenhouse gas

Climate change (disease + displacement)

Concentration ozone depl.

Ozonlayer depletion (cancer + cataract)

Concentration radionuclides

Radiation effects (cancer)

Concentration fine dust, VOC .

Respiratory effects

Concentr. air, water and food

Cancer

Resource analysis Land-use analysis Fate analysis

Exposure and effect analysis

Step 2

Indicator

Damage to ecosystems [% plant species *m2 *yr]

Local effect on species numbers

Milling

Disposal

Damage to resources [MJ surplus energy]

Damage to Human health [disability adjusted life years (DALY)]

Damage analysis

Normalisation and Weighting

Step 3

Figure 1: Detailed representation of the damage model

In general, the factors used in SimaPro do not deviate from the ones in the (updated) report. In case the report contained synonyms of substance names already available in the substance list of the SimaPro database, the existing names in the database are used. A distinction is made for emissions to agricultural soil and industrial soil, indicated with respectively (agr.) or (ind.) behind substance names emitted to soil.

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2.4.2 Characterisation Emissions Characterisation is factors are calculated at end-point level (damage). The damage model for emissions includes fate analysis, exposure, effects analysis and damage analysis. This model is applied for the following impact categories: •

Carcinogens Carcinogenic affects due to emissions of carcinogenic substances to air, water and soil. Damage is expressed in Disability adjusted Life Years (DALY) / kg emission.

•

Respiratory organics Respiratory effects resulting from summer smog, due to emissions of organic substances to air, causing respiratory effects. Damage is expressed in Disability adjusted Life Years (DALY) / kg emission.

•

Respiratory inorganics Respiratory effects resulting from winter smog caused by emissions of dust, sulphur and nitrogen oxides to air. Damage is expressed in Disability adjusted Life Years (DALY) / kg emission.

•

Climate change Damage, expressed in DALY/kg emission, resulting from an increase of diseases and death caused by climate change.

•

Radiation Damage, expressed in DALY/kg emission, resulting from radioactive radiation

•

Ozone layer Damage, expressed in DALY/kg emission, due to increased UV radiation as a result of emission of ozone depleting substances to air.

•

Ecotoxicity Damage to ecosystem quality, as a result of emission of ecotoxic substances to air, water and soil. Damage is expressed in Potentially Affected Fraction (PAF)*m2*year/kg emission.

•

Acidification/ Eutrophication Damage to ecosystem quality, as a result of emission of acidifying substances to air. Damage is expressed in Potentially Disappeared Fraction (PDF)*m2*year/kg emission.

Land use Land use (in man made systems) has impact on species diversity. Based on field observations, a scale is developed expressing species diversity per type of land use. Species diversity depends on the type of land use and the size of the area. Both regional effects and local effects are taken into account in the impact category: •

Land use Damage as a result of either conversion of land or occupation of land. Damage is expressed in Potentially Disappeared Fraction (PDF)*m2*year/m2 or m2a.

Resource depletion Mankind will always extracts the best resources first, leaving the lower quality resources for future extraction. The damage of resources will be experienced by future generations, as they will have to use more effort to extract remaining resources. This extra effort is expressed as “surplus energy”. •

Minerals Surplus energy per kg mineral or ore, as a result of decreasing ore grades.

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Fossil fuels Surplus energy per extracted MJ, kg or m3 fossil fuel, as a result of lower quality resources.

2.4.3 Uncertainties Of course it is very important to pay attention to the uncertainties in the methodology that is used to calculate the indicators. Two types are distinguished: 1. Uncertainties about the correctness of the models used 2. Data uncertainties Data uncertainties are specified for most damage factors as squared geometric standard deviation in the original reports, but not in the method in SimaPro. It is not useful to express the uncertainties of the model as a distribution. Uncertainties about the model are related to subjective choices in the model. In order to deal with them we developed three different versions of the methodology, using the archetypes specified in Cultural Theory. The three versions of Eco-indicator 99 are: 1. the egalitarian perspective 2. the hierarchist perspective 3. the individualist perspective

Hierchist perspective In the hierarchist perspective the chosen time perspective is long-term, substances are included if there is consensus regarding their effect. For instance all carcinogenic substances in IARC class 1, 2a and 2b are included, while class 3 has deliberately been excluded. In the hierarchist perspective damages are assumed to be avoidable by good management. For instance the danger people have to flee from rising water levels is not included. In the case of fossil fuels the assumption is made that fossil fuels cannot easily be substituted. Oil and gas are to be replaced by shale, while coal is replaced by brown coal. In the DALY calculations age weighting is not included.

Egalitarian perspective In the egalitarian perspective the chosen time perspective is extremely long-term, Substances are included if there is just an indication regarding their effect. For instance all carcinogenic substances in IARC class 1, 2a, 2b and 3 are included, as far as information was available. In the egalitarian perspective, damages cannot be avoided and may lead to catastrophic events. In the case of fossil fuels the assumption is made that fossil fuels cannot be substituted. Oil, coal and gas are to be replaced by a future mix of brown coal and shale. In the DALY calculations age weighting is not included.

Individualist perspective In the individualist perspective the chosen time perspective is short-term (100 years or less). Substances are included if there is complete proof regarding their effect. For instance only carcinogenic substances in IARC class 1 included, while class 2a, 2b and 3 have deliberately been excluded. In the individualist perspective damages are assumed to be recoverable by technological and economic development. In the case of fossil fuels the assumption is made that fossil fuels cannot really be depleted. Therefore they are left out. In the DALY calculations age weighting is included.

Damage assessment Damages of the impact categories result in three types of damages: 1. Damage to Human Health, expressed as the number of year life lost and the number of years lived disabled. These are combined as Disability Adjusted Life Years (DALYs), an index that is also used by the World bank and the WHO. 2. Damage to Ecosystem Quality, express as the loss of species over an certain area, during a certain time 3. Damage to Resources, expressed as the surplus energy needed for future extractions of minerals and fossil fuels.

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2.4.4 Normalisation Normalisation is performed on damage category level. Normalisation data is calculated on European level, mostly based on 1993 as base years, with some updates for the most important emissions.

2.4.5 Weighting In this method weighting is performed at damage category level (endpoint level in ISO). A panel performed weighting of the three damage categories. For each perspective, a specific weighting set is available. The average result of the panel assessment is available as weighting set.

2.4.6 Default The hierchist version of Eco-indicator 99 with average weighting is chosen default. In general value choices made in the hierachist version are scientifically and politically accepted.

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2.6 EPS 2000 v2.1 2.6.1 Introduction The EPS 2000 default methodology (Environmental Priority Strategies in product design) is a damage oriented method. In the EPS system willingness to pay to restore changes in the safe guard subjects is chosen as the monetary measure. The indicator unit is ELU (Environmental Load Unit). This method includes characterisation and weighting. Normalisation is not applied. The top-down development of the EPS system has led to an outspoken hierarchy among its principles and rules. The general principles of its development are: • • • • •

The top-down principle (highest priority is given to the usefulness of the system); The index principle (ready made indices represent weighted and aggregated impacts) The default principle (an operative method as default is required) The uncertainty principle (uncertainty of input data has to be estimated) Choice of default data and models to determine them

The EPS system is mainly aimed to be a tool for a company's internal product development process. The system is developed to assist designers and product developers in finding which one of two product concepts has the least impact on the environment. The models and data in EPS are intended to improve environmental performance of products. The choice and design of the models and data are made from an anticipated utility perspective of a product developer. They are, for instance not intended to be used as a basis for environmental protection strategies for single substances, or as a sole basis for environmental product declarations. In most of those cases additional site-specific information and modelling is necessary. The EPS 2000 default method is an update of the 1996 version. The impact categories are identified from five safe guard subjects: human health, ecosystem production capacity, abiotic stock resource, biodiversity and cultural and recreational values.

2.6.2 Classification Emissions and resources are assigned to impact categories when actual effects are likely to occur in the environment, based on likely exposure.

2.6.3 Characterisation Empirical, equivalency and mechanistic models are used to calculate default characterisation values.

Human Health In EPS weighting factors for damage to human health are included for the following indictors: • Life expectancy, expressed in Years of life lost (person year) • Severe morbidity and suffering, in person year, including starvation • Morbidity, in person year, like cold or flu • Severe nuisance, in person year, which would normally cause a reaction to avoid the nuisance • Nuisance, in person year, irritating, but not causing any direct action

Ecosystem production capacity The default impact categories of production capacity of ecosystems are: • Crop production capacity, in kg weight at harvest • Wood production capacity, in kg dry weight • Fish and meat production capacity, in kg full weight of animals • Base cat-ion capacity, in H+ mole equivalents (used only when models including the other indicators are not available) • Production capacity of (irrigation) water, in kg which is acceptable for irrigation, with respect to persistant toxic substances • Production capacity of (drinking) water, in kg of water fulfilling WHO criteria on drinking water.

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Abiotic stock resources Abiotic stock resource indicators are depletion of elemental or mineral reserves and depletion of fossil reserves. Some classification factors are defined 0 (zero). In SimaPro characterisation values for abiotic depletion result from both the impact of depletion and impacts due to extraction of the element/mineral or resource.

Biodiversity Default impact category for biodiversity is extinction of species, expressed in Normalised Extinction of species (NEX).

Cultural and recreational values Changes in cultural and recreational values are difficult to describe by general indicators as they are highly specific and qualitative in nature. Indicators should be defined when needed, and thus are not included in the default methodology in SimaPro.

2.6.4 Weighting In the EPS default method, weighting is made through valuation. Weighting factors represent the willingness to pay to avoid changes. The environmental reference is the present state of the environment. The indicator unit is ELU (Environmental Load Unit).

2.6.5 References: Bengt Steen (1999) A systematic approach to environmental strategies in product development (EPS). Version 2000 - General system characteristics. Centre for Environmental Assessment of Products and Material Systems. Chalmers University of Technology, Technical Environmental Planning. CPM report 1999:4. Download as PDF file (246 kb) from http://www.cpm.chalmers.se/cpm/publications/EPS2000.PDF Bengt Steen (1999) A systematic approach to environmental strategies in product development (EPS). Version 2000 - Models and data of the default methods. Centre for Environmental Assessment of Products and Material Systems. Chalmers University of Technology, Technical Environmental Planning. CPM report 1999:5. Download as zipped PDF file (1140 kb) from http://www.cpm.chalmers.se/cpm/publications/EPS1999_5.zip

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2.7 EDIP v2.1 2.7.1 Introduction The EDIP method (Environmental Design of Industrial Products, in Danish UMIP) was developed in 1996. Excluded in this version of the method in SimaPro are working environment and emissions to waste water treatment plants (WWTP). An update of the method is expected by the beginning of 2002.

2.7.2 Characterisation Global warming is based on the IPCC 1994 Status report. Is SimaPro GWP 100 is used. Stratospheric ozone depletion potentials are based on the status reports (1992/1995) of the Global Ozone Research Project (infinite time period used in SimaPro). Photochemical ozone creation potentials (POCP) were taken from UNECE reports (1990/1992). POCP values depend on the background concentration of NOx, in SimaPro we have chosen to use the POCPs for high background concentrations. Acidification is based on the number of hydrogen ions (H+) that can be released. Eutrophication potential is based on N and P content in organisms. Waste streams are divided in 4 categories, bulk waste (not hazardous), hazardous waste, radioactive waste and slags and ashes. All wastes are reported on a mass basis. Ecotoxicity is based on a chemical hazard screening method, which looks at toxicity, persistency and bioconcentration. Fate or the distribution of substances into various environmental compartments is also taken account. Ecotoxicity potentials are calculated for acute and chronic ecotoxicity to water and chronic ecotoxicity for soil. As fate is included, an emission to water may lead not only to chronic and acute ecotoxicity for water, but also to soil. Similarly an emission to air gives ecotoxicity for water and soil. This is the reason you will find emissions to various compartments in each ecotoxicity category. Human toxicity is based on a chemical hazard screening method, which looks at toxicity, persistency and bioconcentration. Fate or the distribution of substances into various environmental compartments is also taken account. Human toxicity potentials are calculated for exposure via air, soil, and surface water. As fate is included, an emission to water may lead not only to toxicity via water, but also via soil. Similarly an emission to air gives human toxicity via water and soil. This is the reason you will find emissions to various compartments in each human toxicity category.

Resources As resources use a different method of weighting, it cannot be compared with the other impact categories, for which reason the weighting factor is set at zero. Resources should be handled with great care when analysing results, the characterisation and normalisation results cannot be compared with the other impact categories. To give the user some information in a useful way all resources have been added into one impact category. As equivalency factor the result of the individual normalisation and weighting scores have been used, i.e. the resulting score per kg if they would have been calculated individually. For detailed information on resources, including normalisation and weighting, choose the "EDIP/UMIP resources only" method. EDIP v2.0 resources only In the "EDIP/UMIP resources only" method only resources are reported. Opposite to the default EDIP/UMIP method, resources are given in individual impact categories, on a mass basis of the pure resource (i.e. 100% metal in ore, rather than ore). Normalisation is based on global production per world citizen, derived from World Resources 1992. Weighting of non-renewables is based on the supplyhorizon (World Reserves Life Index), which specifies the period for which known reserves will last at current rates of consumption. If no normalisation data are known for an individual impact category, the normalisation value is set at one and the calculation of the weighting factor is adjusted so that the final result is still consistent. However this may give strange looking graphs in the normalisation step.

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2.7.3 Normalisation The normalisation value is based on person equivalents for 1990. For resources, normalisation and weighing are already included in the characterisation factor and therefore set at zero.

2.7.4 Weighting The weighting factors are set to the politically set target emissions per person in the year 2000, the weighted result are expressed except for resources which is based on the proven reserves per person in 1990. For resources, normalisation and weighing are already included in the characterisation factor and therefore set at zero. A note on weighting: Presenting the EDIP method as a single score (addition) is allowed, however it is not recommended by the authors. Note that due to a different weighting method for resources (based on reserves rather than political targets), resources may never be included in a single score. This is the reason that the weighting factor for resources is set at zero.

2.7.5 References: For background information, and information on how to calculate additional factors, please read: Environmental Assessment of Products. Volume 1 (methodology, tools and case studies in product development) Henrik Wenzel, Michael Hauschild and Leo Alting Chapman and Hall, 1997, ISBN 0 412 80800 5 See http://www.wkap.nl/book.htm/0-7923-7859-8 Environmental Assessment of Products. Volume 2 (scientific background) Michael Hauschild and Henrik Wenzel Chapman and Hall, 1998, ISBN 0 412 80810 2 See http://www.wkap.nl/book.htm/0-412-80810-2

APPENDIX C – NORMALIZED AND WEIGHTED LCA RESULTS Table C-1. Normalized and Weighted LCA Results (Points) Using an Egalitarian Perspective in the Eco-Indicator 99 Method of Impact Assessment Wood frame house Impact category Total Carcinogens Respiratory organics Respiratory inorganics Climate change Radiation Ozone layer Ecotoxicity Acidification/eutrophication Land use Minerals Fossil fuels Impact category Total Carcinogens Respiratory organics Respiratory inorganics Climate change Radiation Ozone layer Ecotoxicity Acidification/eutrophication Land use Minerals Fossil fuels Impact category Total Carcinogens Respiratory organics Respiratory inorganics Climate change Radiation Ozone layer Ecotoxicity Acidification/eutrophication Land use Minerals Fossil fuels

Lake Charles 9.9E+04 4.6E+02 2.8E+01 2.1E+04 7.0E+03 1.6E+01 2.7E+00 5.7E+02 3.3E+03 3.1E+02 3.4E+02 6.6E+04

Tucson

St. Louis

Denver

1.0E+05 4.8E+02 2.9E+01 2.3E+04 7.3E+03 1.5E+01 2.6E+00 5.7E+02 3.6E+03 2.9E+02 3.3E+02 6.8E+04

1.2E+05 5.3E+02 3.2E+01 2.3E+04 8.6E+03 2.2E+01 3.6E+00 6.7E+02 3.6E+03 4.2E+02 4.2E+02 8.3E+04 CMU house

1.1E+05 4.8E+02 2.9E+01 2.0E+04 7.7E+03 2.1E+01 3.4E+00 6.2E+02 3.1E+03 4.1E+02 4.1E+02 7.5E+04

Minneapolis 1.2E+05 5.2E+02 3.1E+01 2.0E+04 8.7E+03 2.6E+01 4.2E+00 6.9E+02 3.1E+03 5.0E+02 4.7E+02 8.7E+04

MinneLake Tucson St. Louis Denver apolis Charles 1.0E+05 1.0E+05 1.2E+05 1.1E+05 1.3E+05 4.7E+02 4.7E+02 5.2E+02 4.8E+02 5.4E+02 2.8E+01 2.8E+01 3.1E+01 2.8E+01 3.1E+01 2.2E+04 2.3E+04 2.3E+04 2.0E+04 2.0E+04 7.2E+03 7.1E+03 8.3E+03 7.7E+03 9.0E+03 1.6E+01 1.4E+01 2.1E+01 2.1E+01 2.7E+01 2.7E+00 2.5E+00 3.4E+00 3.5E+00 4.4E+00 5.7E+02 5.6E+02 6.4E+02 6.3E+02 7.1E+02 3.4E+03 3.6E+03 3.5E+03 3.0E+03 3.1E+03 3.1E+02 2.8E+02 4.0E+02 4.2E+02 5.2E+02 3.4E+02 3.2E+02 4.0E+02 4.2E+02 4.9E+02 6.7E+04 6.5E+04 8.0E+04 7.6E+04 9.0E+04 CMU house compared to wood frame house** MinneLake Tucson St. Louis Denver apolis Charles -2% 2% 3% 0% -3% -3% 2% 3% 0% -3% -2% 2% 3% 2% -2% -4% -1% 1% 1% -2% -2% 3% 4% 0% -4% 1% 7% 6% -2% -5% 0% 6% 5% -2% -5% -1% 3% 3% 0% -2% -3% 0% 2% 2% -1% 0% 6% 5% -2% -5% 0% 3% 3% -2% -4% -1% 4% 4% 0% -4%

*The notation in the table is a modified scientific notation, for example 1.2E+04 means 1.2 × 104 which is equal to 12,000. ELU is environmental load unit. **Positive values indicate less impact for CMU house compared to wood frame house.

C-1

Table C-2. Normalized and Weighted LCA Results (Points) Using a Hierarchic Perspective in the Eco-Indicator 99 Method of Impact Assessment Wood frame house Impact category* Total Carcinogens Respiratory organics Respiratory inorganics Climate change Radiation Ozone layer Ecotoxicity Acidification/ Eutrophication Land use Minerals Fossil fuels Impact category Total Carcinogens Respiratory organics Respiratory inorganics Climate change Radiation Ozone layer Ecotoxicity Acidification/eutrophication Land use Minerals Fossil fuels Impact category Total Carcinogens Respiratory organics Respiratory inorganics Climate change Radiation Ozone layer Ecotoxicity Acidification/eutrophication Land use Minerals Fossil fuels

Lake Charles 1.1E+05 4.6E+02 2.8E+01 2.1E+04 7.0E+03 1.6E+01 2.7E+00 4.5E+02 2.6E+03 2.5E+02 3.6E+02 7.7E+04

Tucson

St. Louis

Denver

1.1E+05 4.8E+02 2.9E+01 2.3E+04 7.4E+03 1.5E+01 2.6E+00 4.6E+02 2.9E+03 2.3E+02 3.5E+02 7.6E+04

1.4E+05 5.4E+02 3.2E+01 2.3E+04 8.7E+03 2.2E+01 3.7E+00 5.3E+02 2.9E+03 3.4E+02 4.4E+02 1.1E+05 CMU house

1.3E+05 4.8E+02 2.9E+01 2.0E+04 7.8E+03 2.1E+01 3.4E+00 5.0E+02 2.5E+03 3.2E+02 4.3E+02 9.8E+04

Minneapolis 1.5E+05 5.4E+02 3.1E+01 2.0E+04 8.8E+03 2.6E+01 4.2E+00 5.5E+02 2.5E+03 4.0E+02 5.0E+02 1.2E+05

Lake MinneTucson St. Louis Denver Charles apolis 1.1E+05 1.1E+05 1.4E+05 1.3E+05 1.6E+05 4.7E+02 4.8E+02 5.2E+02 4.9E+02 5.5E+02 2.8E+01 2.9E+01 3.1E+01 2.8E+01 3.2E+01 2.2E+04 2.4E+04 2.3E+04 2.0E+04 2.0E+04 7.2E+03 7.2E+03 8.4E+03 7.8E+03 9.2E+03 1.6E+01 1.4E+01 2.1E+01 2.2E+01 2.8E+01 2.7E+00 2.5E+00 3.5E+00 3.5E+00 4.4E+00 4.6E+02 4.5E+02 5.2E+02 5.0E+02 5.7E+02 2.7E+03 2.9E+03 2.8E+03 2.4E+03 2.5E+03 2.5E+02 2.2E+02 3.2E+02 3.3E+02 4.2E+02 3.6E+02 3.4E+02 4.3E+02 4.4E+02 5.2E+02 7.8E+04 7.2E+04 1.0E+05 1.0E+05 1.3E+05 CMU house compared to wood frame house** Lake MinneTucson St. Louis Denver Charles apolis -2% 4% 4% -1% -4% -3% 2% 3% 0% -3% -2% 2% 3% 2% -2% -4% -1% 1% 1% -2% -2% 3% 4% 0% -4% 1% 7% 6% -2% -5% 0% 6% 5% -2% -5% -1% 3% 3% 0% -2% -3% 0% 2% 2% -1% 0% 6% 5% -2% -5% 0% 3% 3% -2% -4% -1% 6% 5% -2% -5%

C-2

Table C-3. Normalized and Weighted LCA Results (Points) Using an Individualist Perspective in the Eco-Indicator 99 Method of Impact Assessment Wood frame house Impact category* Total Carcinogens Respiratory organics Respiratory inorganics Climate change Radiation Ozone layer Ecotoxicity Acidification/eutrophication Land use Minerals Impact category Total Carcinogens Respiratory organics Respiratory inorganics Climate change Radiation Ozone layer Ecotoxicity Acidification/eutrophication Land use Minerals Impact category Total Carcinogens Respiratory organics Respiratory inorganics Climate change Radiation Ozone layer Ecotoxicity Acidification/eutrophication Land use Minerals

Lake Charles 7.4E+04 6.1E+02 8.8E+01 3.4E+04 2.3E+04 2.5E+00 7.4E+00 4.1E+01 1.9E+03 1.8E+02 1.4E+04

Tucson

St. Louis

Denver

7.8E+04 6.4E+02 9.3E+01 3.8E+04 2.4E+04 2.4E+00 7.2E+00 4.1E+01 2.0E+03 1.7E+02 1.3E+04

8.5E+04 7.1E+02 1.0E+02 3.7E+04 2.8E+04 3.3E+00 1.0E+01 4.8E+01 2.0E+03 2.4E+02 1.7E+04 CMU house

7.6E+04 6.3E+02 9.1E+01 3.2E+04 2.5E+04 3.2E+00 9.5E+00 4.5E+01 1.8E+03 2.3E+02 1.6E+04

Minneapolis 8.2E+04 6.9E+02 9.9E+01 3.2E+04 2.9E+04 3.9E+00 1.2E+01 5.0E+01 1.8E+03 2.8E+02 1.9E+04

MinneLake Tucson St. Louis Denver apolis Charles 7.6E+04 7.7E+04 8.3E+04 7.6E+04 8.4E+04 6.2E+02 6.3E+02 6.8E+02 6.2E+02 7.0E+02 8.9E+01 9.1E+01 9.9E+01 9.0E+01 1.0E+02 3.6E+04 3.8E+04 3.7E+04 3.2E+04 3.2E+04 2.3E+04 2.3E+04 2.7E+04 2.5E+04 3.0E+04 2.5E+00 2.2E+00 3.1E+00 3.3E+00 4.1E+00 7.4E+00 6.8E+00 9.5E+00 9.7E+00 1.2E+01 4.1E+01 4.0E+01 4.7E+01 4.5E+01 5.2E+01 1.9E+03 2.0E+03 2.0E+03 1.7E+03 1.8E+03 1.8E+02 1.6E+02 2.3E+02 2.4E+02 3.0E+02 1.4E+04 1.3E+04 1.6E+04 1.7E+04 1.9E+04 CMU house compared to wood frame house** Lake MinneTucson St. Louis Denver Charles apolis -3% 1% 2% 0% -3% -1% 3% 4% 2% -2% -2% 2% 3% 2% -2% -4% -1% 0% 1% -2% -2% 3% 4% 0% -4% 1% 7% 5% -2% -4% 0% 6% 5% -2% -5% -1% 4% 4% 0% -3% -3% 0% 2% 2% -1% 0% 6% 5% -2% -5% 0% 3% 3% -2% -4%

C-3

Table C-4. Normalized and Weighted LCA Results (Points) Using the EDIP/UMIP 97 Method of Impact Assessment Wood frame house Impact category* Total Global warming (GWP 100) Ozone depletion Acidification Eutrophication Photochemical smog Ecotoxicity water chronic Ecotoxicity water acute Ecotoxicity soil chronic Human toxicity air Human toxicity water Human toxicity soil Bulk waste Hazardous waste Radioactive waste Slags/ashes Impact category Total Global warming (GWP 100) Ozone depletion Acidification Eutrophication Photochemical smog Ecotoxicity water chronic Ecotoxicity water acute Ecotoxicity soil chronic Human toxicity air Human toxicity water Human toxicity soil Bulk waste Hazardous waste Radioactive waste Slags/ashes

Lake Charles 2.7E+03 2.6E+02 1.5E+01 1.2E+02 2.4E+01 3.1E+01 4.5E+02 4.6E+02 1.9E+02 5.0E+01 2.0E+02 6.2E+02 1.6E+02 3.0E+00 1.3E+02 1.1E-01 Lake Charles 2.8E+03 2.7E+02 1.5E+01 1.3E+02 2.5E+01 3.1E+01 4.7E+02 4.7E+02 1.9E+02 5.1E+01 2.3E+02 6.3E+02 1.6E+02 3.0E+00 1.3E+02 1.1E-01

Tucson

St. Louis

Denver

2.8E+03 2.7E+02 1.5E+01 1.3E+02 2.6E+01 3.2E+01 4.6E+02 4.7E+02 1.8E+02 5.0E+01 2.2E+02 6.0E+02 1.7E+02 3.0E+00 1.3E+02 1.1E-01

3.5E+03 3.2E+02 2.0E+01 1.3E+02 2.7E+01 3.6E+01 5.4E+02 5.6E+02 2.8E+02 6.2E+01 2.3E+02 8.9E+02 1.6E+02 3.4E+00 2.0E+02 1.3E-01 CMU house

3.2E+03 2.9E+02 1.9E+01 1.1E+02 2.3E+01 3.3E+01 5.0E+02 5.2E+02 2.7E+02 5.9E+01 2.1E+02 8.5E+02 1.4E+02 3.4E+00 1.9E+02 1.3E-01

Tucson

St. Louis

Denver

2.7E+03 2.6E+02 1.4E+01 1.3E+02 2.6E+01 3.1E+01 4.6E+02 4.6E+02 1.7E+02 4.8E+01 2.4E+02 5.5E+02 1.7E+02 2.9E+00 1.1E+02 1.0E-01

3.4E+03 3.1E+02 1.9E+01 1.3E+02 2.6E+01 3.5E+01 5.3E+02 5.5E+02 2.6E+02 6.0E+01 2.5E+02 8.4E+02 1.6E+02 3.4E+00 1.9E+02 1.2E-01

3.3E+03 2.9E+02 1.9E+01 1.1E+02 2.3E+01 3.2E+01 5.1E+02 5.3E+02 2.8E+02 6.0E+01 2.3E+02 8.7E+02 1.4E+02 3.4E+00 2.0E+02 1.2E-01

Minneapolis 3.8E+03 3.2E+02 2.3E+01 1.1E+02 2.3E+01 3.6E+01 5.6E+02 5.9E+02 3.4E+02 6.8E+01 2.3E+02 1.1E+03 1.4E+02 3.7E+00 2.5E+02 1.4E-01 Minneapolis 3.9E+03 3.4E+02 2.4E+01 1.1E+02 2.4E+01 3.7E+01 5.8E+02 6.2E+02 3.6E+02 7.0E+01 2.5E+02 1.1E+03 1.4E+02 3.8E+00 2.7E+02 1.4E-01

C-4

Table C-4. Normalized and Weighted LCA Results (Points) Using the EDIP/UMIP 97 Method of Impact Assessment (Continued)

Impact category Total Global warming (GWP 100) Ozone depletion Acidification Eutrophication Photochemical smog Ecotoxicity water chronic Ecotoxicity water acute Ecotoxicity soil chronic Human toxicity air Human toxicity water Human toxicity soil Bulk waste Hazardous waste Radioactive waste Slags/ashes

CMU house compared to wood frame house** MinneLake Tucson St. Louis Denver apolis Charles -3% 3% 3% -2% -5% -2% 3% 4% 0% -4% 0% 6% 5% -2% -5% -2% 0% 2% 3% 0% -3% 0% 2% 2% -2% -1% 3% 4% 1% -2% -3% 0% 1% -2% -5% -2% 2% 3% -1% -4% -1% 7% 6% -3% -6% -1% 4% 4% -1% -4% -14% -10% -8% -10% -13% 0% 7% 6% -3% -5% -3% 0% 1% 3% -0% 0% 2% 2% -1% -2% 0% 9% 7% -3% -6% 4% 6% 6% 3% 1%

C-5

Table C-5. Normalized and Weighted LCA Results (Points) Using the EPS 2000 Method of Impact Assessment Impact category* Total Life expectancy Severe morbidity Morbidity Severe nuisance Nuisance Crop growth capacity Wood growth capacity Fish and meat production Soil acidification Prod. cap. irrigation water Prod. cap. drinking water Depletion of reserves Species extinction Impact category Total Life expectancy Severe morbidity Morbidity Severe nuisance Nuisance Crop growth capacity Wood growth capacity Fish and meat production Soil acidification Prod. cap. irrigation water Prod. cap. drinking water Depletion of reserves Species extinction Impact category Total Life expectancy Severe morbidity Morbidity Severe nuisance Nuisance Crop growth capacity Wood growth capacity Fish and meat production Soil acidification Prod. cap. irrigation water Prod. cap. drinking water Depletion of reserves Species extinction

Wood frame house Tucson St. Louis Denver Minne-apolis 7.1E+05 9.1E+05 8.4E+05 9.9E+05 1.9E+05 2.2E+05 1.9E+05 2.1E+05 5.8E+04 7.1E+04 6.4E+04 7.3E+04 1.3E+04 1.5E+04 1.4E+04 1.5E+04 1.7E+03 1.8E+03 1.8E+03 1.8E+03 7.4E+03 7.3E+03 6.2E+03 6.1E+03 7.4E+02 8.2E+02 7.2E+02 7.8E+02 -3.3E+03 -3.7E+03 -3.3E+03 -3.7E+03 -1.5E+02 -1.5E+02 -1.3E+02 -1.3E+02 2.0E+02 2.0E+02 1.7E+02 1.7E+02 2.4E-01 2.4E-01 2.4E-01 2.4E-01 2.4E+00 2.4E+00 2.4E+00 2.4E+00 4.4E+05 6.0E+05 5.6E+05 6.8E+05 2.3E+03 2.8E+03 2.5E+03 2.8E+03 CMU house Lake Charles Tucson St. Louis Denver Minne-apolis 7.2E+05 6.8E+05 8.7E+05 8.5E+05 1.0E+06 1.9E+05 1.9E+05 2.1E+05 1.9E+05 2.2E+05 5.7E+04 5.6E+04 6.8E+04 6.4E+04 7.6E+04 1.3E+04 1.3E+04 1.5E+04 1.4E+04 1.6E+04 1.7E+03 1.7E+03 1.8E+03 1.8E+03 1.9E+03 6.9E+03 7.4E+03 7.1E+03 6.0E+03 6.1E+03 7.2E+02 7.3E+02 8.0E+02 7.2E+02 8.0E+02 -3.2E+03 -3.2E+03 -3.6E+03 -3.3E+03 -3.8E+03 -1.4E+02 -1.5E+02 -1.5E+02 -1.3E+02 -1.4E+02 1.9E+02 2.0E+02 1.9E+02 1.6E+02 1.7E+02 2.4E-01 2.4E-01 2.4E-01 2.4E-01 2.4E-01 2.4E+00 2.4E+00 2.4E+00 2.4E+00 2.4E+00 4.5E+05 4.2E+05 5.7E+05 5.7E+05 7.1E+05 2.2E+03 2.2E+03 2.6E+03 2.5E+03 2.9E+03 CMU house compared to wood frame house** Lake Charles Tucson St. Louis Denver Minne-apolis -1% 4% 4% -1% -4% -3% 1% 3% 0% -3% -2% 3% 4% -1% -4% -2% 2% 3% 0% -3% 0% 1% 1% 0% -1% -2% 0% 2% 3% 0% -2% 1% 3% 1% -3% -2% 2% 3% 0% -3% -3% 0% 1% 1% -2% -2% 0% 2% 3% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% -1% 5% 5% -2% -4% -2% 3% 4% -1% -4% Lake Charles 7.1E+05 1.8E+05 5.6E+04 1.2E+04 1.7E+03 6.8E+03 7.0E+02 -3.1E+03 -1.4E+02 1.8E+02 2.4E-01 2.4E+00 4.5E+05 2.2E+03

C-6

[PDF] Comparison of the Life Cycle Assessments of a Concrete Masonry House and a Wood Frame House - Free Download PDF (2024)

References