Life-Cycle Benefits of Energy Code- Compliant Roof ...

Life-Cycle Benefits of Energy Code-Compliant Roof Replacements

October 01, 2021

Submitted to: Justin Koscher PIMA

Submitted by: ICF


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Table of Contents Acronyms and Abbreviations .......................................................................................................... 4

Introduction ....................................................................................................................................... 5

Energy Code-Compliant Roof Replacements ................................................................................. 6 Development of Whole-Building Energy Savings ........................................................................... 7

Development of Baseline Scenario ..................................................................................................... 7 Development of Code-Compliant Roofing Replacement Scenario ...................................................... 8 Energy Savings Results from Simulation of Building Energy Models .................................................. 9

Calculation of Economic Benefits ................................................................................................. 11 Energy Cost Savings ......................................................................................................................... 11 Incremental Material and Labor Capital Costs .................................................................................. 11 Economic Analysis ............................................................................................................................ 12 Sensitivity Analysis ............................................................................................................................ 14

Calculation of Emissions Benefits ................................................................................................. 15

Conclusion ....................................................................................................................................... 16 Code-Compliant Roof Replacement Analysis Results .................................................................. 16 Life-Cycle Benefits of Code-Compliant Roof Replacements ......................................................... 16

Appendix A – Energy Savings ....................................................................................................... 17

Appendix B – Range of Economics ............................................................................................... 18

Appendix C – Modeling Data Sources ........................................................................................... 19

Appendix D - Attachments ............................................................................................................. 21

Appendix E – Resources ................................................................................................................ 22

Appendix F – Building Summaries ................................................................................................ 23


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List of Figures Figure 1 – Methodology for Development of Energy, Economics, and Emissions Benefits .......... 6 Figure 2 – Average Energy Savings by Building Type and Climate Zone City ............................. 9 Figure 3 – Average Energy Savings by Fuel Type, Building Type, and Climate Zone City ........ 10 Figure 4 – Benefit-to-Cost Ratio by Building Type and Climate Zone City ................................. 13 Figure 5 – BCR for Primary School, Climate Zone 6 .................................................................. 14 Figure 6 – Benefit-to-Cost Ratio (BCR) by Building Type and Climate Zone.............................. 18

List of Tables Table 1 – Building Energy Modeling Characteristics .................................................................... 7 Table 2 – Baseline Scenario Models by Building Type and Climate Zone ................................... 8 Table 3 – Insulation Entirely Above Deck R-value and Incremental Thickness Increase ............. 8 Table 4 – Average Energy Savings by Building Type and Climate Zone ................................... 10 Table 5 – Average Energy Cost Savings by Building Type and Climate Zone ........................... 11 Table 6 – Average Incremental Capital Cost by Building Type and Climate Zone ..................... 11 Table 7 – Life-Cycle Cost Economic Modeling Assumptions ...................................................... 12 Table 8 – Average Economics by Building Type and Climate Zone ........................................... 13 Table 9 – Average Avoided Emissions by Building Type and Climate Zone .............................. 15 Table 10 – Building Energy, Economics, and Emissions Summary – Primary School ............... 23 Table 11 – Building Energy, Economics, and Emissions Summary – Small Office .................... 24 Table 12 – Building Energy, Economics, and Emissions Summary – Stand Alone Retail .......... 25 Table 13 – Building Energy, Economics, and Emissions Summary – Strip Mall ......................... 26


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Acronyms and Abbreviations ANSI American National Standards Institute

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

BCL Building Component Library

BCR Benefit to Cost Ratio

BEM Building Energy Models

CASE Codes and Standards Enhancement

CBECS EIA’s Commercial Building Energy Consumption Survey

CFA Conditioned Floor Area

CZ Climate Zone

DOE U.S. Department of Energy

eGRID Emissions and Generation Resource Integrated Database

EIA U.S. Energy Information Administration

EPA U.S. Environmental Protection Agency

EPD Environmental Product Declaration

EUI Energy Use Index (kBtu/sf/yr)

EUL Effective Useful Life

FEMP U.S. DOE’s Federal Energy Management Program

GHG Greenhouse Gas Emissions

HVAC Heating, Ventilation, and Air Conditioning

IEAD Insulation Entirely Above Deck

IECC-C International Energy Code Council – Commercial Provisions

IES Illuminating Engineering Society

IN Inch

LB Pound

PAT Parametric Analysis Tool

PIMA Polyisocyanurate Insulation Manufacturers Association

SF Square Foot

NIST National Institute of Standards

NPV Net Present Value

NREL National Renewable Energy Laboratory

YR Year


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Introduction A roof replacement project consists of a full replacement of a roof's membrane, insulation, and other components down to the roof deck and is typically performed between 20 to 40 years after a building’s construction. In contrast to roofing recover projects, roofing replacement projects must meet the building envelope requirements of the commercial building energy codes: ANSI/ASHRAE/IES Standard 90.1 Energy Standard for Buildings Except Low-Rise Residential Buildings and Commercial Provisions of the International Energy Code Council and the 2021 International Energy Conservation Code. For low-sloped roofs with insulation entirely above deck, the standard requires roof insulation be installed in two continuous layers that are overlapped and meet the minimum R-value requirement for the prescriptive path of compliance, based on climate zone, space conditioning category, and roof construction type.

In 2020, PIMA conducted a survey of roof system manufacturers regarding installed levels of roof insulation for commercial new construction and roof replacement projects across nine states located in climate zones 2 through 6. While the results for new construction showed mixed results in terms of energy code-compliance, roof insulation thickness and insulation R-value obtained from more than 3,000 buildings covering more than 50 million square feet of commercial roof replacements found a significant lack of compliance, with some notable geographic exceptions, with the prescriptive minimum R-value requirements in the majority of surveyed jurisdictions.

To encourage better code-compliance for roof replacements, PIMA commissioned this study to assess and quantify the life-cycle energy, economics, and carbon emission benefits of code-compliant roof replacements for a select number of commercial building types constructed with low-sloped roofs and representative city/climate zone combinations. In support of communication with building owners, policy makers, and other industry and marketplace stakeholders, a compendium of supporting fact sheets summarizes the energy, economic, and environmental benefits of installing code-compliant insulation at the time of roof replacement. In contrast to the fact sheets, this report documents details of the analytical approach, including its methods, data sources, and assumptions. Detailed intermediate and final calculations can be found in the accompanying M.S. Excel datafiles referenced in Appendix D – Attachments.


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Energy Code-Compliant Roof Replacements This analysis was conducted to assess the energy, economic, and emissions benefits for installation of code-compliant roof insulation at time of a roof replacement compared to replacement with like-in-kind similar levels of insulation. A primary assumption is that roofs being replaced today were originally constructed on buildings that precede widespread adoption of building energy codes and are therefore under insulated. A roof replacement project consists of a full replacement of a roof's membrane, insulation and other components down to the roof deck and is required to comply with the building thermal envelope requirements of the ASHRAE Standard 90.1 and the 2021 IECC commercial building energy codes.

Figure 1 – Methodology for Development of Energy, Economics, and Emissions Benefits

The approach illustrated in Figure 1 was used to estimate the energy, economic, and environmental benefits of code-compliant roof replacements for four commercial building types with low-sloped roofs in seven representative cities of mid-to-large construction markets, across five climate zones.

First, building energy models were developed to represent the baseline and code-compliant scenarios. Both sets of models were simulated to produce estimates of whole-building energy use and their energy use was subtracted to produce incremental energy savings.

Second, energy cost savings were calculated as the product of energy savings by fuel type and the corresponding price of fuel and then combined with secondary research on incremental material and labor capital costs to produce life-cycle economic metrics.

Finally, emissions benefits were developed directly from energy savings as the product of energy savings by fuel type and the corresponding emissions factor.


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Development of Whole-Building Energy Savings

Incremental energy savings were calculated as the difference between the baseline and code-compliant building energy models simulated whole-building energy performance. Baseline building models were derived from DOE’s commercial prototypical building models and their roof insulation R-values modified to represent installed levels of existing building roof insulation as documented in literature. Similarly, code-compliant models were developed from the same DOE commercial prototypical building models but with their roof insulation R-values modified to represent the prescriptive roof insulation values required by the most current version of the commercial building energy codes: ASHRAE 90.1-2019 and 2021 IECC.

Development of Baseline Scenario

Baseline building energy models were developed from DOE’s commercial prototypical building models. The prototypical building models were created within DOE’s OpenStudio building energy modeling environment using the “Create DOE Prototype Building” measure from the National Renewable Energy Laboratory’s (NREL’s) Building Component Library (BCL). Models were created for the small office, stand-alone retail, primary school, and strip mall building types, in five U.S. climate zones, and the 2004 building energy model vintage, as shown in Table 1.

The 2004 DOE vintage building model was selected as the baseline because it was the most defensible and will be the easiest to communicate to stakeholders. Secondary research conducted on building characteristics such as lighting from EIA’s 2015 Commercial Building Energy Consumption Survey (CBECS) did not yield defensible data that could be used to update building model inputs, nor did sample modeling of alternative vintage models such as pre-1980 show significant variations in energy performance that would lead to the recommended use of an alternate baseline model.

Table 1 – Building Energy Modeling Characteristics

DOE Commercial Building Types

DOE Model Vintage Climate Zone City Locations

Small Office New Construction (2004) 2A Hot Humid Tampa, FL (2A)

Stand-alone Retail

3A Warm Humid Atlanta, GA (3A)

Primary School 4A Mixed Humid New York City, NY (4A)

Strip Mall 5A Cool Humid

Chicago, IL (5A)

Buffalo, NY (5A)

6A Cold Humid Montreal, Canada (6A)

Rochester, MN (6A)

The prototypical building models were then modified to represent the baseline scenarios. First, the small office building model roof construction was modified from Typical Wood Joist Attic Floor Insulation Only to be a low-sloped roof with Insulation Entirely Above Deck. Second, roof insulation R-values for each of the four building model types, in each climate zone, were modified from the DOE prototypical baseline insulation values to be R12.5, for all building types and all climate zones, using the “Increase R-value of Insulation for Roofs by a Specified Percentage” BCL measure developed by NREL, as depicted in Table 2.


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Table 2 – Baseline Scenario Models by Building Type and Climate Zone

Climate Zone

Small Office Strip Mall Stand Alone

Retail Primary School

2004 2004 2004 2004 Typical IEAD

Roof Typical IEAD

Roof Typical IEAD

Roof Typical IEAD

Roof

2A 12.5 12.5 12.5 12.5

3A 12.5 12.5 12.5 12.5

4A 12.5 12.5 12.5 12.5

5A 12.5 12.5 12.5 12.5

6A 12.5 12.5 12.5 12.5

The baseline R-value of R-12.5 was selected in consultation with PIMA to represent typical roof insulation values found in commercial buildings 20-years and older with low-sloped roofs. It is based on secondary research conducted by PIMA that found baseline levels of insulation to be between R-10 and R-15 for existing low-slope roofs. A primary assumption is that roofs being replaced today were originally constructed on buildings that date back prior to the widespread adoption of building energy codes and remain under insulated, where common practice was to install a single layer of 2” to 2.5” insulation.

Development of Code-Compliant Roofing Replacement Scenario

Code-compliant building energy models were developed from the same DOE commercial prototypical building models as the baseline models. After the baseline energy models were developed, their roof insulation R-values were modified again using the same OpenStudio BLC “Increase R-value of Insulation for Roofs by a Specified Percentage” measure to automatically change the roof insulation value to be compliant with the prescriptive roof insulation R-value requirements of ASHRAE 90.1-2019 (and 2021 IECC-C) specific to each climate zone, as depicted in Table 3.

Table 3 – Insulation Entirely Above Deck R-value and Incremental Thickness Increase

Climate Zone Baseline Roof

Insulation R-Value

Code-Compliant Roof Insulation

R-Value

Incremental Roof Insulation Thickness

Increase (in)

2A 12.5 25.0 2.2

3A 12.5 25.0 2.2

4A 12.5 30.0 3.1

5A 12.5 30.0 3.1

6A 12.5 30.0 3.1

Table 3 also includes the baseline roof insulation R-values from Table 2 and the incremental roof insulation thickness increase assuming an average Polyiso insulation board value of R-5.7 per inch.


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Energy Savings Results from Simulation of Building Energy Models

Incremental energy savings were calculated as the difference between the simulated whole-building energy performance of the baseline scenario and the code-compliant roofing replacement building energy models. Energy savings are the result of increased roof insulation that reduces heat transfer through the roof assembly, reduces space heating and space cooling requirements (a function of load and efficiency), and decreases energy use.

DOE’s Parametric Analysis Tool (PAT) was used to simulate the baseline and code-compliant building energy models in EnergyPlus. Raw energy performance data from the EnergyPlus simulations, by building type, climate zone, and representative city location were post-processed to produce absolute (total) and relative (percent) values of whole-building energy savings and energy savings by electric and natural gas fuel types, the latter presented in Figure 2 and Figure 3, respectively.

Figure 2 – Average Energy Savings by Building Type and Climate Zone City

Absolute energy savings (not pictured) varied significantly according to building type and climate zone, with the greatest energy savings occurring for buildings with larger floor areas (e.g., primary school) and buildings located in the heating dominated climate zones (e.g., climate zone 6). City locations within specific climate zones also produced nuanced differences in absolute energy savings, based on local weather conditions. Relative energy savings exhibited a similar pattern across climate zones but not by building types.


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Figure 3 – Average Energy Savings by Fuel Type, Building Type, and Climate Zone City

In total, and on average, the greatest absolute and relative energy savings were from the reduction in natural gas use to meet space heating loads, compared to a smaller reduction of electric use from a reduction in space cooling requirements. However, when viewed at the climate zone level, the absolute energy savings tend to follow the predominate mode of either space heating or space cooling, according to building type and climate zone, with electric energy savings generally greater for the cooling dominated climate zones and natural gas for the heating dominated climate zones as depicted in Table 4.

Table 4 – Average Energy Savings by Building Type and Climate Zone

Energy Savings

Building Type Climate Zone

Primary School

Small Office

Stand-alone Retail

Strip Mall

2A 3A 4A 5A 6A

First Year (Physical Units)

Electric (kWh) 28560 3590 6083 10410 16785 12932 12546 11319 10112

Natural Gas (Therms) 5937 44 1083 927 193 869 2082 2232 3189

Total (MMBtu) 691 17 129 128 77 131 251 262 353

First Year (MMBtu)

Electric (MMBtu) 97 12 21 36 57 44 43 39 35

Natural Gas (MMBtu) 594 4 108 93 19 87 208 223 319

Total (MMBtu) 691 17 129 128 77 131 251 262 353

Annual EUI (kBtu/SF/year) 9.35 3.03 5.17 5.70 2.02 3.12 5.69 6.45 8.48

Energy Savings (%) 8.8% 5.6% 5.6% 5.2% 2.7% 4.2% 6.6% 7.1% 8.1%


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Calculation of Economic Benefits

Installation of code-compliant levels of roof insulation at the time of roof replacement results in the downstream benefits of energy savings such as operational savings (e.g., energy cost savings) that can be monetized over the life of the roof replacement project to quantify the economic benefits of roof replacements, compared to the baseline scenario.

Energy Cost Savings

Energy cost savings occur from the incremental reduction in space heating and space cooling requirements and corresponding reduction in electric and natural gas usage. Energy cost savings were calculated as the product of energy savings and energy price, by fuel type, inclusive of energy price escalation over the effective useful life of the roofing replacement project. Table 5 depicts the average first year and cumulative energy cost savings and the cumulative energy cost savings per square foot of conditioned building floor area by building type and climate zone. Similar to energy savings, the greatest energy cost savings occur for buildings with larger floor areas (e.g., primary school) and buildings located in the heating dominated climate zones (e.g., climate zone 6) and is predominately driven by reduction in natural gas use in heating dominated climate zones and reduction in electricity use in cooling dominated climate zones.

Table 5 – Average Energy Cost Savings by Building Type and Climate Zone

Energy Cost Savings


Primary School

Small Office

Stand-alone Retail

Strip Mall

2A 3A 4A 5A 6A

First Year $7,715 $427 $1,503 $1,856 $1,986 $2,087 $2,982 $2,964 $3,572

Cumulative $337,771 $17,037 $65,388 $78,352 $79,200 $87,079 $129,321 $129,481 $158,948

Cumulative ($/sf) $4.57 $3.10 $2.62 $3.48 $2.24 $2.41 $3.43 $3.68 $4.33

Incremental Material and Labor Capital Costs

Incremental capital costs were developed using the 2019 RS Means national average material and labor costs per square foot for Polyiso insulation. Incremental costs were used to isolate the incremental benefit of code-compliant insulation compared to the baseline scenario. 2019 RS Means was selected as the most recent year for which to base the representative analysis. It provides cost details for insulation thicknesses ranging from 0.75 to 4.4 inches but is exclusive of cost data for the baseline (R-12.5: 2.2 inches at R-5.7/inch) and code-compliant (R-25: 4.4 inches at R-5.7/inch; and R-30: 3.1 inches at R-5.7/inch) scenarios evaluated in this analysis.

Table 6 – Average Incremental Capital Cost by Building Type and Climate Zone

Capital Costs


Primary School

Small Office

Stand-alone Retail

Strip Mall

2A 3A 4A 5A 6A

Insulation Costs ($/sf) $1.50 $1.50 $1.50 $1.50 $1.17 $1.17 $1.63 $1.63 $1.63


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For the baseline and code-compliant scenarios, capital costs were developed as the sum of the material and labor costs, inclusive of overhead and profit. Material costs are generally linear with respect to installed insulation thickness and were therefore estimated as the product of the average material unit cost, with overhead and profit, and the installed insulation thickness. In contrast, labor costs, are generally not linear with installed insulation thickness and were therefore developed from a logarithmic expression of insulation R-value and costs per square foot. Average incremental capital investment costs by building type and climate zone are presented in Table 6.

Economic Analysis

Economic benefits associated with code-compliant roof replacements were quantified using two life-cycle cost analysis methods: the net present value (NPV) and the benefit-to-cost ratio (BCR).

NPV and BCR both use a life-cycle cost approach to account for the time value of money. This enables a comparison of the project’s benefits and costs over its effective useful life and is the economic method referenced by DOE in their Methodology for Evaluating Cost-Effectiveness of Commercial Energy Code Changes document and is also a method used by utility program administrators and implementers in development of cost-effective demand-side management incentive programs.

Benefit-to-Cost Ratio is calculated as the ratio of the present value of benefits to the present value of costs. A roofing replacement is cost-effective when the BCR is greater than 1.0, indicating its life-cycle benefits exceed its cost.

Net Present Value is calculated by subtracting the present value of the code-compliant roofing replacement scenario from the present value of the baseline scenario. A positive NPV indicates the project is cost-effective with the net present value equal to the net benefits provided by the roofing project over its 30-year effective useful life.

For each modeled scenario, the NPV and BCR of code-compliant roofing replacements were calculated using inputs of energy cost savings, incremental material and labor capital costs, and the modeling assumptions listed in Table 7. Details and data sources for the assumptions in Table 7 can be found in Appendix C – Modeling Data Sources.

Table 7 – Life-Cycle Cost Economic Modeling Assumptions

Variable Value Source

Discount Rate 1.41% DOE, FEMP

Effective Useful Life (EUL) 30 years PIMA/CASE Study

Electricity Commodity Cost ($/kWh) $0.1094 DOE/EIA

Electricity Annual Escalation Rate 1.80% DOE/EIA

Natural Gas Commodity Cost ($/therm) $0.7732 DOE/EIA

Natural Gas Annual Escalation Rate 2.90% DOE/EIA

Average economic benefits associated with code-compliant roof replacements compared to the baseline scenario, by building type and climate zone are summarized in Table 8. Similar to energy savings and energy cost savings, economics were more attractive for buildings with


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larger floor areas (e.g., primary school) and buildings located in the heating dominated climate zones (e.g., climate zone 6) compared to smaller buildings or buildings located in cooling dominated climate zones.

Table 8 – Average Economics by Building Type and Climate Zone

Economics


Primary School

Small Office

Stand-alone Retail

Strip Mall

2A 3A 4A 5A 6A

NPV $159,846 $5,493 $15,014 $29,216 $26,731 $32,872 $51,976 $52,056 $75,528

BCR 2.41 1.63 1.39 1.87 1.54 1.66 1.69 1.81 2.13

Nevertheless, all combinations of building types, climate zones, and representative cities produced results that were economically attractive, when viewed through the lens of BCR and NPV, with BCR illustrated in Figure 4. Box and Whisker figures illustrating the range of BCR results by building type and climate zone can be found in Appendix B – Range of Economics.

Figure 4 – Benefit-to-Cost Ratio by Building Type and Climate Zone City


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Sensitivity Analysis

Select input variables to the economic analysis were subjected to a range of values to ascertain how economic performance varies according to changes in discount rate and capital costs, two economic factors that include uncertainty because in practice they are likely to be project specific. The discount rate was varied between 1% and 10% and capital cost between +0% and +20% to provide confidence roof replacements can be cost-effective not only as conservatively modeled, but also under a range of input conditions that produce diminishing economics.

Figure 5 provides an example output of the BCR from the sensitivity analysis for the primary school type in climate zone 6, conditions which produce the most favorable energy savings and economics. In Figure 5, it is only when the roofing replacement project is subjected to a discount rate of 9% and 10% and an increase in capital cost of 15% and 10%, respectively, does the roof replacement project no longer remain economically attractive.

Figure 5 – BCR for Primary School, Climate Zone 6


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Calculation of Carbon Emissions Savings Benefits

Reductions in building emissions are the direct result of energy savings that occur from a reduction in space heating and cooling requirements and the corresponding reduction in onsite combustion of natural gas and purchased electricity. Scope 1 direct and Scope 2 indirect emissions were calculated as the product of the site energy savings (derived as the difference in energy use between the baseline and code-compliant scenarios), by fuel type, and the corresponding EPA national-level emissions factor for that fuel type and constituent emission source. Average emissions savings data are presented in Table 9 by building type and climate zone.

Table 9 – Average Avoided Emissions by Building Type and Climate Zone

Emissions


Primary School

Small Office

Stand-alone Retail

Strip Mall

2A 3A 4A 5A 6A

Cumulative, CO2e/SF (lb) 74.80 35.35 42.03 50.42 24.73 31.03 50.02 55.25 69.1

Cumulative, CO2 (lb) 3373547 177602 654990 795654 825947 888996 1297197 1294495 1576004

Cumulative, CH4 (lb) 39373 304 7188 6172 1339 5793 13814 14803 21131

Cumulative, N2O (lb) 3942 31 719 618 136 581 1383 1482 2114

Cumulative, CO2e (lb) 5532448 194434 1049169 1134338 900068 1207051 2054757 2106206 2734447


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Conclusion The energy, economic, and emissions analysis produced first year and cumulative estimates of whole-building energy savings, energy savings by electric and natural gas fuel types, and the downstream benefits of energy savings including energy costs savings and reduction in carbon emissions. Incremental energy savings from code-compliant roof replacements in comparison to the baseline condition of a roof replacement with like-in-kind insulation R-values is derived from a reduction in conduction through the building’s opaque roofing assembly, the coincidental reduction in space heating and space cooling loads required to offset that heat transfer, and the respective reduction in natural gas and electricity energy use. Results and benefits of the analysis include the following:

Code-Compliant Roof Replacement Analysis Results

Absolute energy savings are primarily driven by a reduction in natural gas use. For all building types, natural gas used for space heating is the primary mode of energy savings for all climate zones except 2A.

Energy fuel type saved is generally a function of climate zone. The predominate type of energy saved is driven by the primary mode of either space heating or space cooling, which is generally, but not always, a function of climate zone.

Relative energy savings tend to be greater for larger buildings. Larger buildings have a greater roof to wall area ratio and therefore exhibit greater energy savings on a relative and per square foot basis.

Life-Cycle Benefits of Code-Compliant Roof Replacements

Roof replacements are economical under various conditions. Economic results showed the incremental benefit of roof replacements to be cost-effective from both a life-cycle cost analysis, even when subjected to higher incremental insulation costs and discount rates.

Roof replacements support transition to building electrification. Energy savings from roof replacements, on average, reduces natural gas fossil fuel use by 15% and can support a cost-effective transition to electric heating solutions desired for decarbonization.

Roof replacements support building performance standards and carbon reduction goals. Roof replacements can be a cost-effective tool to help building owners reduce their carbon footprint to meet corporate carbon reduction goals and local building performance standards by locking in energy saving at time of replacement.


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Appendix A – Energy Savings

Building Type Climate

Zone City Location

Absolute Energy Savings

Relative Energy Savings

Annual Electricity Savings (kWh)

Annual Natural

Gas Savings (therms)

Annual Electricity Energy Savings

(%)

Annual Natural

Gas Energy Savings

(%)

Annual Total

Energy Savings

(%)

Primary School 2A Tampa 41,381 660 2.5% 8.0% 3.3%

Primary School 3A Atlanta 29,408 2,769 2.2% 16.2% 6.1%

Primary School 4A New York City 29,528 6,506 2.5% 19.4% 10.2%

Primary School 5A Buffalo 23,922 6,939 2.2% 17.6% 10.2%

Primary School 5A Chicago 28,975 5,926 2.5% 15.9% 9.0%

Primary School 6A Rochester 25,367 9,012 2.3% 17.1% 11.0%

Primary School 6A Montreal 21,336 9,748 2.0% 18.9% 12.0%

Strip Mall 2A Tampa 13,819 52 2.6% 19.6% 2.8%

Strip Mall 3A Atlanta 11,978 318 2.5% 11.5% 3.9%

Strip Mall 4A New York City 10,594 807 2.5% 10.3% 5.2%

Strip Mall 5A Buffalo 8,511 1,149 2.1% 10.2% 5.8%

Strip Mall 5A Chicago 10,761 1,121 2.5% 10.7% 6.0%

Strip Mall 6A Rochester 9,014 1,547 2.2% 9.9% 6.3%

Strip Mall 6A Montreal 8,192 1,498 2.1% 9.6% 6.1%

Stand-alone Retail 2A Tampa 9,744 60 2.0% 5.4% 2.2%

Stand-alone Retail 3A Atlanta 8,028 385 1.8% 12.3% 3.6%

Stand-alone Retail 4A New York City 6,419 998 1.6% 14.2% 5.8%

Stand-alone Retail 5A Buffalo 3,575 1,340 0.9% 13.9% 6.4%

Stand-alone Retail 5A Chicago 6,394 1,289 1.6% 14.1% 6.6%

Stand-alone Retail 6A Rochester 4,489 1,773 1.1% 13.8% 7.3%

Stand-alone Retail 6A Montreal 3,933 1,740 1.0% 13.6% 7.3%

Small Office 2A Tampa 2,197 0 2.7% 33.3% 2.7%

Small Office 3A Atlanta 2,314 3 3.1% 20.5% 3.2%

Small Office 4A New York City 3,642 15 4.8% 13.7% 5.2%

Small Office 5A Buffalo 4,114 36 5.3% 14.3% 6.0%

Small Office 5A Chicago 4,297 56 5.4% 18.8% 6.8%

Small Office 6A Rochester 4,283 58 5.4% 18.2% 6.8%

Small Office 6A Montreal 4,283 141 5.5% 17.0% 8.2%


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Appendix B – Range of Economics

Figure 6 – Benefit-to-Cost Ratio (BCR) by Building Type and Climate Zone


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Appendix C – Modeling Data Sources

Model Input Data Source Description of Data Source and Use

Data Location

Baseline: Building Energy Model

DOE New Construction (2004 vintage) Commercial Reference Buildings

2004 DOE Commercial Prototype Building Models created using OpenStudio Building Component Library (BCL) measure, modified, and simulated in OpenStudio/EnergyPlus. Small Office building type roof insulation type modified from Wood Joist Attic Floor Insulation to IEAD Roof. Baseline roof insulation R-value modified to be R12.5 for all modeled building types, in all climate zones.

https://www.energy.gov/eere/buildings/commercial‐reference‐buildings https://www.energy.gov/eere/buildings/new‐construction‐commercial‐reference‐buildings

Code Compliant: Roof Insulation R-Value

DOE Building Codes Program, ANSI/ASHRAE/IES Standard 90.1-2019: Envelope

Baseline building energy models modified to meet ANSI/ASHRAE/IES Standard 90.1-2019: Envelope minimum prescriptive R-value requirements, by climate zone and construction type.

https://www.energycodes.gov/technical‐assistance/training/courses/ansiashraeies‐standard‐901‐2019

Economics: Energy Rates

EIA's Annual Energy Outlook 2021

Obtained from DOE’s EIA Annual Energy Outlook 2021 – national average.

https://www.eia.gov/outlooks/aeo/data/browser/#/?id=3‐AEO2021&region=1‐0&cases=ref2021&start=2019&end=2050&f=A&linechart=~ref2021‐d113020a.79‐3‐AEO2021.1‐0~ref2021‐d113020a.80‐3‐AEO2021.1‐0&map=ref2021‐d113020a.4‐3‐AEO2021.1‐0&ctype=linechart&chartindexed=0&maptype=0&sid=~~~~&sourcekey=0

Economics: Energy Escalation Rates

EIA's Annual Energy Outlook 2021

Obtained from DOE’s EIA Annual Energy Outlook 2021 – national average, escalated annually.

https://www.eia.gov/outlooks/aeo/data/browser/#/?id=3‐AEO2021&region=1‐0&cases=ref2021&start=2019&end=2050&f=A&linechart=~ref2021‐d113020a.79‐3‐AEO2021.1‐0~ref2021‐d113020a.80‐3‐AEO2021.1‐0&map=ref2021‐d113020a.4‐3‐AEO2021.1‐0&ctype=linechart&chartindexed=0&maptype=0&sid=~~~~&sourcekey=0

Economics: Capital Costs

RS Means, 2019 Derived from 2019 RS Means ($/ft2) for materials and labor – national average, varies by baseline-to-code compliant difference.

Not publicly available

Economics: Discount Rate

DOE, Energy Efficiency & Renewable Energy, Federal

2021 nominal discount rate. https://www.energy.gov/eere/femp/articles/2021‐discount‐rates


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Model Input Data Source Description of Data Source and Use

Data Location

Energy Management Program

Economics: Effective Useful Life

Insulation Effective Useful Life (EUL)

Determined through consultation with PIMA based on PIMA's Environmental Product Declaration and validated with the California Energy Codes and Standards Non-Residential High Performance Envelope CASE Report.

https://cdn.ymaws.com/www.polyiso.org/resource/resmgr/health&environment/EPD_Roof_2020.pdf https://title24stakeholders.com/measures/cycle‐2022/nonresidential‐high‐performance‐envelope/ https://title24stakeholders.com/wp‐content/uploads/2020/10/2020‐T24‐NR‐HP‐Envelope‐Final‐CASE‐Report.pdf

Emission Factors: Electric

EPA eGRID National-level emission factors obtained from Table 1: Subregion Output Emission Rates (eGRID2018).

https://www.epa.gov/sites/default/files/2020‐01/documents/egrid2018_summary_tables.pdf

Emission Factors: Natural Gas

EPA Emission Factors for Greenhouse Gas Inventories

National-level emission factors obtained from Table 1: Stationary Combustion for natural gas.

https://www.epa.gov/sites/default/files/2021‐04/documents/emission‐factors_mar2020.pdf


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Appendix D - Attachments

File Name File Description

Building Energy Modeling Results_10_01_2021

Summarizes energy savings results from simulation of building energy models. Contains raw energy performance data obtained from simulation of the baseline and code-compliant building energy models. Raw energy performance data was used to calculate whole-building absolute and relative energy savings, and energy savings by energy type. Data are presented in a series of two-way tables for inclusion in the final report, and pivot tables for assessing data trends, for quality control.

Energy Economic Emissions Analysis_10_01_2021

Quantifies energy, economic, and emissions benefits from the installation of ASHRAE 90.1-2019 (2021 IECC-C) code-compliant roof insulation compared to the baseline roof insulation scenario. Uses building energy modeling results to calculate climate zone representative building first-year and lifetime (cumulative) benefits. Benefits are presented in a series of two-way tables and charts for inclusion in the final report. Underlying economic and emissions assumptions are included in the datafile along with links to corresponding data sources.


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Appendix E – Resources

Polyisocyanurate Insulation Manufacturers Association (PIMA); Environmental Product Declaration; Polyiso Roof Insulation Boards; November 4, 2020; Found at: https://www.polyiso.org/page/EPDs

U.S. Department of Energy, Energy Efficiency & Renewable Energy, Prepared by Pacific Northwest National Laboratory; Methodology for Evaluating Cost-Effectiveness of Commercial Energy Code Changes; August 2005. Found at: Methodology for Evaluating Cost-effectiveness of Commercial Energy Code Changes (energycodes.gov)

National Renewable Energy Laboratory; U.S. Department of Energy Commercial Reference Building Models of the National Building Stock; Technical Report, NREL/TP-5500-46861; February 2011. Found at: U.S. Department of Energy Commercial Reference Building Models of the National Building Stock (nrel.gov)

National Institute of Standards and Technology, U.S. Department of Commerce; NIST Handbook 135, Life Cycle Costing Manual for the Federal Energy Management Program; NIST.HB.135-2020. Found at: Life Cycle Cost Manual for the Federal Energy Management Program (nist.gov)

Codes and Standards Enhancement (CASE) Initiative 2022 California Energy Code; Nonresidential High-Performance Envelope, Final CASE Report; Prepared by Energy Solutions and Determinant; 2022-NR-ENV1-F, Envelope, October 2020. Found at: 2020-T24-NR-HP-Envelope-Final-CASE-Report.pdf (title24stakeholders.com)

U.S. Department of Energy, Energy Efficiency & Renewable Energy, Building Energy Codes Program; ANSI/ASHRAE/IES Standard 90.1-2019: Envelope; Prepared by Pacific Northwest National Laboratory for the U.S. Department of Energy; PNNL-SA-153209; May 2020. Found at: ANSI/ASHRAE/IES Standard 90.1-2019 | Building Energy Codes Program

Lawrence Berkeley National Laboratory, Building Technologies Department, Environmental Energy Technologies Division, University of California; Commercial Heating and Cooling Loads Component Analysis; LBNL-37208; November 1999. Found at: Commercial Heating and Cooling Loads Component Analysis (lbl.gov)

GAF, EnergyGuard™ ISO Sell Sheet (COMGT318); Updated May 2015; Found at: 898708.pdf (construction.com)

Appendix F – Building Summaries

Table 10 – Building Energy, Economics, and Emissions Summary – Primary School

Category Metric 2A 3A 4A 5A 6A

Energy Savings

First Year, Electric Savings (kWh) 41,381 29,408 29,528 26,449 23,351

First Year, Natural Gas Savings (Therms) 660 2,769 6,506 6,432 9,380

First Year, Total Savings (MMBtu) 207 377 751 733 1,018

Annual, EUI Reduction (kBtu/SF/year) 2.80 5.10 10.16 9.92 13.76

Annual Total Energy Savings (%) 3% 6% 10% 10% 11%

Energy Cost Savings

First Year, Total Energy Cost Savings ($) $5,038 $5,358 $8,261 $7,867 $9,808

Cumulative, Total Energy Cost Savings ($) $201,921 $226,740 $362,535 $346,616 $439,985

Cumulative, Total Energy Cost Savings per SF ($) $2.73 $3.07 $4.90 $4.69 $5.95

Capital Cost Incremental Insulation Cost per SF ($/in-SF) $1.17 $1.17 $1.63 $1.63 $1.63

Economics NPV of Investment ($) $76,215 $95,563 $169,927 $157,104 $231,505

BCR (Savings to Investment Ratio) 1.88 2.10 2.41 2.30 2.92

Emissions Savings

Cumulative, Total CO2e per SF (lb) 31.78 44.77 80.89 78.28 104.81

Cumulative, CO2 (lb) 2,100,875 2,300,044 3,616,981 3,451,988 4,346,479

Cumulative, CH4 (lb) 4,521 18,422 43,140 42,641 62,124

Cumulative, N2O (lb) 459 1,847 4,319 4,268 6,216

Cumulative, CO2e (lb) 2,350,422 3,310,850 5,982,367 5,789,856 7,751,894


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Table 11 – Building Energy, Economics, and Emissions Summary – Small Office


Energy Savings


First Year, Natural Gas Savings (Therms) 0 3 15 46 99

First Year, Total Savings (MMBtu) 8 8 14 19 25



Energy Cost Savings

First Year, Total Energy Cost Savings ($) $240 $255 $410 $496 $545






Emissions Savings


Cumulative, CO2 (lb) 99,279 105,580 169,678 206,025 228,314

Cumulative, CH4 (lb) 9 29 111 318 672

Cumulative, N2O (lb) 1 3 12 33 68

Cumulative, CO2e (lb) 99,854 107,248 175,933 223,652 265,352


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Table 12 – Building Energy, Economics, and Emissions Summary – Stand Alone Retail


Energy Savings


First Year, Natural Gas Savings (Therms) 60 385 998 1,314 1,756




Energy Cost Savings







Emissions Savings


Cumulative, CO2 (lb) 461,166 497,614 640,237 686,443 806,516

Cumulative, CH4 (lb) 432 2,574 6,625 8,712 11,631

Cumulative, N2O (lb) 45 259 664 872 1,164

Cumulative, CO2e (lb) 485,273 639,025 1,003,582 1,164,086 1,444,068


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Table 13 – Building Energy, Economics, and Emissions Summary – Strip Mall


Energy Savings


First Year, Natural Gas Savings (Therms) 52 318 807 1,135 1,522




Energy Cost Savings







Emissions Savings


Cumulative, CO2 (lb) 642,468 652,747 761,894 833,526 922,709

Cumulative, CH4 (lb) 395 2,150 5,379 7,542 10,098

Cumulative, N2O (lb) 42 217 540 756 1,011

Cumulative, CO2e (lb) 664,727 771,083 1,057,148 1,247,233 1,476,474

END OF REPORT

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