PNNL-16284 

Energy Efficiency of the 2003 

International Energy Conservation 

Code in West Virginia

R.G. Lucas 

December 2006 

Prepared for 

U.S. Department of Energy 

under Contract DE-AC05-76RL01830
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(8/00)
Energy Efficiency of the 2003 International 

Energy Conservation Code in West Virginia 

R.G. Lucas 

December 2006 

Prepared for 

the U.S. Department of Energy 

under Contract DE-AC05-76RL01830 

Pacific Northwest National Laboratory 

Richland, Washington 99352 
iii 

Summary 

 DOE has requested Pacific Northwest National Laboratory (PNNL) to estimate the 

energy savings, economic impacts, and pollution reduction from adopting the 2003 

International Code Council’s (ICC) 2003 International Energy Conservation Code

(IECC) (ICC 2003a) as the mandatory residential energy efficiency code in the state of 

West Virginia. The state currently allows a less stringent replacement option. This 

report addresses the impacts for low-rise residential buildings only. 

The analysis indicates that homes built to meet the IECC requirements will save West 

Virginia homeowners money by reducing long-term energy costs by far more than the 

construction-related cost increases. Energy costs will be reduced 16% to 17%. 

Homeowners with a typical mortgage should realize a net positive cash flow within less 

than a year. Benefit/cost ratios range from 4.3 to 5.2. The analysis also indicates that a 

significant improvement in pollution reduction can be achieved over time as more and 

more buildings are built to the code. Construction cost increases and energy savings will 

vary depending on many factors, including location, fuel prices, house size and 

characteristics, material and labor costs, and the specific energy efficiency measures used 

to comply with the 2003 IECC 
iv 

Contents 

Summary............................................................................................................................iii

Introduction......................................................................................................................... 1 

Methodology....................................................................................................................... 2 

West Virginia Replacement of Chapter 11 of the IRC ....................................................... 3 

The 2003 IECC ................................................................................................................... 4 

Comparative Analysis......................................................................................................... 6 

Construction Costs.............................................................................................................. 9 

Fuel Costs and HVAC Equipment.................................................................................... 10 

Energy Analysis................................................................................................................ 11 

Economic Impacts Accounting for Mortgages................................................................. 12 

Conclusion ........................................................................................................................ 14 

References......................................................................................................................... 15 
v 

Figures 

Figure 1. West Virginia Replacement Envelope Requirements by Climate...................... 3 

Figure 2. IECC Envelope Requirements by Climate (15% Window Area) ...................... 5 

Tables 

Table 1. Comparison of WV Replacement to the 2003 IECC1.......................................... 6 

Table 2. 2003 IECC Compliance Measures Using REScheck........................................... 8 

Table 3. Incremental Construction Costs for IECC Energy Efficiency Measures Relative 

to the West Virginia Replacement Code............................................................................. 9 

Table 4. Annual Heating and Cooling Energy Costs in Charleston ................................ 11 

Table 5. Annual Heating and Cooling Energy Costs in Elkins........................................ 11 

Table 6. Impacts to Consumers’ Cash Flow from Compliance with IECC Accounting for 

Mortgage........................................................................................................................... 13 
1 

Introduction 

The West Virginia State Building Code1

 contains two options for energy efficiency 

requirements in one- and two-family dwellings. One is the IECC (ICC 2003a) (87-4-

4.1.6). The second is a West Virginia developed replacement for Chapter 11 of the ICC 

International Residential Code (IRC) (ICC 2003b) (87-4-4.1.7). The West Virginia 

Energy Efficiency Program, West Virginia Development Office, has asked the U.S. 

Department of Energy (DOE) to compare the energy use and economic impacts resulting 

from the application of the 2003 IECC code and the IRC code, as amended by West 

Virginia. The Department’s Pacific Northwest National Laboratory (PNNL) compared 

the energy use from compliance with the 2003 IECC to the West Virginia replacement 

for Chapter 11 of the IRC, which is referred to as the West Virginia replacement. The 

West Virginia replacement is less stringent than the 2003 IECC2

. The results of this 

analysis are presented below. 

 

1

 http://www.wvsos.com/adlaw/rules/verify.asp?TitleSeries=87-04 Title 87, Series 4 of the Code of State 

Rules. 

2

 People will often use the least stringent option available to them in the code to minimize their 

construction costs. Therefore, although the West Virginia building codes include the 2003 IECC, the 

requirements in the West Virginia replacement of Chapter 11 of the IRC are assumed to be the minimum 

code baseline here. 
2 

Methodology 

The analysis examined the typical cost and energy savings from the incremental 

improvements from the West Virginia replacement to the 2003 IECC using computer 

simulations. Two locations in West Virginia were examined: Charleston and Elkins. 

These cities represent a climate in the warmer and colder parts of West Virginia, 

respectively. The house design considered was a 2000 ft2 two-story house, 25x40 ft, 

15% window–to-wall area ratio, and a full unconditioned basement. Heating with a 

natural gas furnace and central electric air conditioning were assumed. 
3 

West Virginia Replacement of Chapter 11 of the IRC 

The prescriptive envelope requirements for the West Virginia replacement, that are 

constant throughout the state, are shown below. 

• R-13 above-grade wall insulation 

• R-4 slab-on-grade insulation, 2-ft deep 

• R-8 crawl space wall insulation (if the crawl space does not have floor insulation) 

• R-4 basement wall insulation with depth to approximately 3 ft below grade 

• U-0.39 doors with one door exempt 

• 6 sq. ft of window area exempt from the U-factor requirements 

• Standard air infiltration requirements to seal the building envelope 

• R-5 duct insulation 

• Ducts outside the building envelope must be sealed by gaskets, mastics, or tapes. 

Three building envelope component requirements vary by heating degree-days (HDD), 

ceilings, windows, and floors. These envelope component requirements, along with the 

above-grade and basement wall requirements, are shown in Figure 1 below (this map uses 

average heating degree-days by county). 

 

Figure 1. West Virginia Replacement Envelope Requirements by Climate 
4 

The 2003 IECC 

The 2003 IECC has three alternative compliance paths: systems analysis, component 

performance, and simplified prescriptive requirements. The systems analysis compliance 

path compares an annual energy analysis of the proposed design to that of a standard 

design based on criteria in the component performance approach. The proposed design 

must use the same or less energy than the standard design. The component performance 

compliance path has a set of figures and tables that set U-factor or R-value requirements 

for each envelope component as a function of HDD. The simplified prescriptive 

compliance path has tables of requirements for insulation R-values and window Ufactors. 

The envelope requirements in the prescriptive compliance path vary with changes to the 

window-to-wall area ratio. For example, the prescriptive requirements for a house in 

Charleston with a window area of 12% of the wall area have a window U-factor 

requirement of 0.50, while a house with a window area of 18% of the wall area has a 

window U-factor requirement of 0.37 (see Tables 502.2.4(2) and 502.2.4(4), 2003 IECC). 

The prescriptive requirements shown for the IECC in Figure 2 are for a window-to-wall 

area ratio of 15%. The 15% area is likely to be a little higher than the average window 

area in new West Virginia houses (estimated to be between 12 and 14% on average, 

although there will a distribution with some houses up to 20% or more and others down 

to 10% or less). Therefore, Figure 2 presents a slightly conservative, more stringent 

representation of the IECC code envelope requirements. 
Figure 2. IECC Envelope Requirements by Climate (15% Window Area) 
6 

Comparative Analysis 

A direct comparison of primary requirements of the West Virginia replacement and the 

component performance compliance path, at 15% window-to-wall area ratio, are 

presented in Table 1. 

Table 1. Comparison of WV Replacement to the 2003 IECC1

Code HDD Ceiling 

Window/ 

Skylight Doors2

Exterior 

Wall Floor 

Basement 

Wall 

Slab 

Perimeter3 

Crawl 

Space 

Wall 

Ducts 

Outside 

Envelope 

4,500-

4,999 R-26 U-0.654 R-13 WV Replacement 5,000-

6,499 R-30 U-0.554 

U-0.39 R-13 

R-19 

R-4, 3 ft.5 R-4, 2 ft. R-8 R-5 

4,500-

4,999 R-16 R-6, 2 ft. 

5,000-

5,499 

U-0.456 R-19 R-97 

R-6, 2 ft. 

R-17 

5,500-

5,999 U-0.406 R-9, 2 ft. R-19 

2003 

IECC 

6,000-

6,499 

R-38 

U-0.356 

U-0.35 

R-18 

R-21 R-107 

R-9, 4 ft. R-20 

R-8 

supply 

1. Criteria at 15% glazing area, Table 502.2.4(3) of the IECC 

2. One door is exempt in both code criteria. 

3. R-value and depth of insulation. 

4. Six square feet of window is exempt. Skylights are required to be double-glazed and wood, vinyl, or fiberglass. 

5. To a depth of 3 feet below grade. 

6. 1% of the window area is exempt. 

7. To a depth of 10 feet below grade or to the level of the basement floor, whichever is less. 

 

The IECC has more stringent envelope requirements than the West Virginia replacement. 

In comparison to the IECC, the replacement code has lower insulation requirements, less 

stringent window U-factor requirements, and reduced supply duct insulation. These 

factors are accounted for in the energy analysis below. 

The replacement code also differs from the IECC in ways that may further reduce energy 

efficiency, which are not examined in the energy analysis. Section N1101.4.5 in the 

West Virginia replacement of the IRC does not prohibit vents in crawl spaces with crawl 

space wall insulation. Open vents in winter will allow cold air to flow into the crawl 

space and therefore undercut the benefit of the wall insulation. Occupants may close the 

vents in the winter, but codes traditionally decline to depend on occupant intervention. 

The energy efficiency requirements in the IECC do not allow vents if the method of 

insulating the crawl space is with insulation on the crawl space walls. 

Table N1101, note 5 and Section N1101.4.6 of the West Virginia replacement require 

that basement wall insulation extend down to the frost depth, which will be about 3 ft 

below grade in West Virginia. The IECC requires basement wall insulation to extend 
down to the basement floor. There will be greater heat loss from the lower area of the 

basement wall without full basement insulation. 

The West Virginia replacement allows heated basements to completely forgo wall 

insulation if, 1) not more than 12 inches of the top of the wall is above ground, and 2) the 

gas furnace efficiency is 88% or higher or the heat pump efficiency (HSPF) is 7.8 or 

higher. Uninsulated basement walls are permitted even if the basement is a conditioned 

living space. The Federal manufacturing standard for heat pumps was updated in January 

2006. It requires a minimum HSPF of 7.7 for all heat pumps manufactured or imported 

into the U.S. Therefore, the West Virginia replacement allows basement wall insulation 

to be eliminated for a tiny improvement in heat pump efficiency. The IECC requires R-9 

or R-10 basement wall insulation, depending on location. 

No wall insulation for basements that are conditioned living spaces is a major flaw 

regardless of how efficient the furnace or heat pump is because this allows the top of the 

wall to be exposed to outdoor air with nothing but highly conductive concrete or 

masonry. Note that even the West Virginia replacement requires above-grade (excluding 

basements) walls to have insulation in climates as warm as Miami. 

Unlike the IECC, there is no U-factor requirement for skylights in the replacement code. 

However, skylights must be double-glazed, and cannot be metal frame, so the skylight 

requirement in the replacement code could be met with a wood (or vinyl) framed unit 

with a typical U-factor of about 0.50, compared with an IECC U-factor requirement of U0.35 to U-0.45. Such a unit is reasonably energy efficient. 

 

While the IECC does not have these prescriptive trade-offs, the system performance 

compliance path allows trade-offs that do not increase the annual energy consumption of 

the proposed house above that of the standard design. The REScheck software, 

developed by the U.S. Department of Energy,3

 allows users to easily examine different 

energy efficiency measures, under the component performance approach, to determine if 

they comply with a particular code. The energy efficiency requirements were set in 

REScheck to comply with the 2003 IECC for the 2000 ft2

 house examined here. In the 

case of Charleston, a lower ceiling R-value and wall R-value insulation were used in a 

trade-off for a better window U-factor and furnace efficiency. In the case of Elkins, 

lower wall and floor R-values were traded-off for a higher furnace efficiency. The 

REScheck-compliant packages, shown in Table 2, were then used in the energy analysis. 

 

3

 http://www.energycodes.gov/REScheck. 
Table 2. 2003 IECC Compliance Measures Using REScheck

Ceiling 

R-value 

Window 

U-factor

Wall 

R-value 

Floor (Over 

Unconditioned 

Basement) 

R-value 

Furnace 

AFUE(a)

Charleston 30 0.40 13 19 80% 

Elkins 38 0.35 13 19 80% 

(a) annual fuel utilization efficiency 
9 

Construction Costs 

This section identifies the construction cost increases for improving from the West 

Virginia replacement to the 2003 IECC. Floor insulation cost increases from R-13 to R19 were obtained from R.S. Means (2004) and are $0.16/ft2

 for R-19 floor insulation 

compared to R-13. For ceiling insulation, R.S. Means reports $0.18/ft2 for the 

improvement from R-30 to R-38. These costs were used in the analysis. 

Improvements to windows needed to achieve U-factors low enough to comply with the 

IECC are expected to be primarily from the addition of low-E coatings on double-pane 

windows. A Building America team member estimates typical cost increases of $300 for 

a typical house for windows meeting Energy Star (U-0.35 in cold climates) ratings 

(Edminster et al. 2000). The Northwest Energy Star Window Project reports an 

incremental retail cost of $0.89/ft2

 from seven manufacturers to improve windows from 

U-0.44 to U-0.34 (Quantec 2002). A recent report from California suggests a $0.15/ft2

incremental cost for manufacturing low-E windows (PGE 2006). A conservatively high 

cost of $1/ft2 was assumed for the addition of low-E coatings to a vinyl or wood doublepane window. This improvement is assumed achieve both the U-0.40 requirement in 

Charleston and the U-0.35 requirement in Elkins, as numerous low-E window are below 

U-0.35. Approximately 60% of new residential windows nationwide are low-E, 

indicating the cost of this feature is apparently low enough that it is close to becoming 

standard practice (Door and Window Maker Magazine, April 2005). 

A supply duct surface area of 216 ft2 and a return duct surface area of 100 ft2 in the 

basement was assumed. The total cost for insulating the ducts to R-5 is $692. The 2003 

IECC requires R-8 on supply ducts in unconditioned spaces. R.S. Means (2004) reports 

only an extra 2 cents/ft2 in material cost for 1-1/2 in. insulation compared to 1 in. 

insulation for duct wrap. However, the California Database for Energy Efficient 

Resources (DEER) (Itron 2005) estimates a higher cost of $0.68/ft2, or $147 for the 

supply ducts in the basements to increase from R-4.2 to R-8 (R-5 was not included in the 

California database). This cost is assumed here. Table 3 shows the incremental 

construction costs assumed in this analysis. 

Table 3. Incremental Construction Costs for IECC Energy Efficiency Measures Relative to the West 

Virginia Replacement Code 

Ceiling 

Insulation 

Window 

U-factor

Floor (Over 

Unconditioned 

Basement) 

Insulation 

Duct 

Insulation 

Total 

Charleston 0 $332 $160 $147 $639 

Elkins $180 $332 0 $147 $659 
10 

Fuel Costs and HVAC Equipment 

A natural gas furnace and a central air conditioner are assumed in the analysis. The latest 

available costs for natural gas and electricity were obtained from the DOE Energy 

Information Administration. Natural gas prices have increased dramatically in the past 5 

years, and peaked above $15 per thousand cubic feet (approximately equal to a million 

Btus) in West Virginia for the residential market last winter (DOE/EIA 

http://tonto.eia.doe.gov/dnav/ng/ng_pri_sum_dcu_SWV_m.htm). Recent (September 

2006) DOE fuel price Short Term Energy Outlook projections (DOE/EIA 2006 

http://www.eia.doe.gov/emeu/steo/pub/8ctab.html) estimate residential natural gas prices 

in the South Atlantic region (which West Virginia is in) to stay at or above $15 per 

thousand cubic feet for the next few years during the winter. A natural gas cost of 

$15/MBtu was assumed in this analysis. The electricity price for air conditioning was 

assumed to be 6.41 cents/kWh based on June 2006 prices in West Virginia (DOE/EIA 

http://www.eia.doe.gov/cneaf/electricity/epm/table5_6_a.html). 
11 

Energy Analysis 

The EnergyGauge simulation tool (Florida Solar Energy Center) was used to estimate the 

savings from improving energy efficiency of a home designed to the replacement code to 

instead comply with the 2003 IECC (using the measures in Table 2). EnergyGauge 

utilizes the DOE-2 simulation model that estimates the building energy use for all 8760 

hours in a year. Tables 4 and 5 show the comparative energy costs and saving 

differential for the home in Charleston and Elkins. These tables include space heating and 

air conditioning only. Note that this energy analysis is based on the exact prescriptive 

requirements discussed above. Actual measures installed in homes may exceed these 

requirements in some cases (notably window U-factors in the replacement code). 

Table 4. Annual Heating and Cooling Energy Costs in Charleston 

 

2003 IECC 

Replacement 

Code 

Heating $704 $867 

Cooling $92 $87 

Total $796 $954 

Energy cost savings of 

IECC 

$158 or 17% 

Table 5. Annual Heating and Cooling Energy Costs in Elkins 

 

2000 IECC 

Replacement 

Code 

Heating $963 $1160 

Cooling $36 $33 

Total $999 $1193 

Energy cost savings of 

IECC 

$194 or 16% 
12 

Economic Impacts Accounting for Mortgages 

Because most houses are financed, consumers will be very interested in the financial 

impacts of buying a home that complies with the 2003 IECC requirements. Mortgages 

spread the payment for the cost of a house over a long period of time. In this analysis, a 

fixed-rate mortgage was assumed. It was also assumed that homebuyers will deduct the 

interest portion of the payments from their income taxes. 

The financial and economic parameters required for input to this analysis are summarized 

below. These parameters are used to calculate the costs and benefits of increased energy 

efficiency from the homeowner's perspective. A relatively low down payment and a 

moderate Federal income tax rate were selected. 

• New-home mortgage parameters: 

- 7.0% mortgage interest rate (fixed rate) 

- points and loan fees equal to 1.6% of the mortgage amount 

- 30-year loan term 

- 10% down payment. 

• Other rates and economic parameters: 

- 7% nominal discount rate 

- 28% marginal Federal income tax 

- 1.2% property tax 

- 3% nominal inflation for fuel prices 

- 30-year analysis period, no residual/salvage value. 

Table 6 shows the impacts to consumers’ cash flow resulting from IECC compliance. 

The up-front costs include the down payment, points, and loan fees. The savings from 

income tax deductions for the mortgage interest will slowly decrease over time. The 

annual values shown in the table are for the first year. Table 6 also includes increases in 

annual property taxes because of the higher assessed house values. The net annual cash 

flow includes energy costs, mortgage payments, mortgage tax deductions, and property 

taxes but not the up-front costs. 

 
Table 6. Impacts to Consumers’ Cash Flow from Compliance with IECC Accounting for Mortgage 

Charleston Elkins 

Up-Front Costs $72 $74 

Annual Energy 

Savings 

$158 $194 

Annual 

Mortgage 

Increase 

$48 $49 

Annual Income 

Tax Deduction 

Increase 

$12 $12 

Annual Property 

Tax Increase

$6 $6 

Net Annual Cash 

Flow Savings 

(excluding upfront costs) 

$121 $157 

Benefit/Cost 

Ratio 

4.3 5.2 

Net Present 

Value Savings 

$2771 $3406 

Time to Net 

Positive Cash 

Flow 

Under 1 

year 

 Under 1 

year 
14 

Conclusion 

In almost all respects, the West Virginia replacement is less stringent than the 2003 

IECC. This includes less stringent envelope and duct insulation levels; window, door and 

skylight U-factors; crawl space wall insulation; and the trade-off that allows a heated 

basement to be uninsulated. Building a home to the requirements of the 2003 IECC is 

estimated to reduce energy use from space heating and air conditioning by between 16% 

and 17% in typical new homes in West Virginia, compared to the minimum requirements 

of the replacement code. Accounting for the impacts of a typical mortgage, the home 

buyer will begin to realize a net savings in less than 1 year. 

A homeowner will pay between $150 and $200 more per year in energy costs for a home 

built to the West Virginia replacement code compared to the a home built to the IECC. 
15 

References 

Door and Window Maker Magazine, April 2005: 

http://www.usglassmag.com/Door_and_Window_Maker/Backissues/April%202005/ 

Wealth%20of%20Knowledge.htm 

Edminster, A. V., B. Pettit, K. Ueno, S. Menegus, and S. Baczek. 2000. “Case Studies in 

Resource Efficient Residential Building: The Building America Program.” In 

Proceedings for the 2000 ACEEE Summer Study, vol. 2, p. 79. American Council for an 

Energy-Efficient Economy, Washington, D.C. 

International Code Council (ICC). 2003a. 2003 International Energy Conservation 

Code. Falls Church, Virginia. 

International Code Council (ICC). 2003b. 2003 International Residential Code. Falls 

Church, Virginia. 

Itron. 2005. 2004/2005 Database for Energy Efficient Resources Update Report. 

http://eega.cpuc.ca.gov/deer/ 

Pacific Gas and Electric. 2006. Case Study for Residential Windows. 

http://www.energy.ca.gov/title24/2008standards/documents/2006-05-

18_workshop/2006-05-16_RES_WINDOWS.PDF

Quantec. 2002. Market Progress Evaluation Report for the Energy Star Windows 

Project. Northwest Energy Efficiency Alliance, Portland, Oregon. 

R. S. Means Company, Inc. (Means). 2004. Means Residential Cost Data--2005, 24th 

Annual Edition. Kingston, Massachusetts. 

Sherman, M. H., I. S. Walker, and D. J. Dickerhoff. 2000. “Stopping Duct Quacks: 

Longevity of Residential Duct Sealants.” In Proceedings for the 2000 ACEEE Summer 

Study, vol. 2, p. 79. American Council for an Energy-Efficient Economy, Washington, 

D.C. 

U.S. Department of Energy, Energy Information Administration. 2006. 

http://www.eia.doe.gov/cneaf/electricity/epm/table5_6_a.html 

http://tonto.eia.doe.gov/dnav/ng/ng_pri_sum_dcu_SWV_m.htm 

http://www.eia.doe.gov/emeu/steo/pub/8ctab.html