Methodology for Estimated Energy Savings from Cost-Effective Air Sealing and Insulating
Research insights
Methodology for Estimated Energy Savings from Cost-Effective Air Sealing and Insulating
Table of Contents
Energy efficiency improvements can significantly reduce household energy costs. The Environmental Protection Agency (EPA) estimates that homeowners can save an average of 15% on heating and cooling costs (or 11% on total energy costs) by implementing air sealing and insulating their homes. These estimates are based on energy modeling of cost-effective improvements made to a representative sample of typical U.S. homes.
This methodology considers construction characteristics, regional climate factors, and fuel types to estimate realistic energy savings.
Defining the "Typical" U.S. Home for Energy Modeling
The Residential Energy Consumption Survey (RECS) from the U.S. Energy Information Administration (EIA) shows that a large portion of U.S. housing stock was built after the 1973 oil embargo. Energy efficiency became a growing concern, influencing home construction standards.
EPA’s modeling is based on homes constructed between 1970 and 1989, representing a typical U.S. home. The key characteristics of these homes include:
1,700 square feet of conditioned floor area
15% window-to-floor-area ratio
23% total system duct leakage
Four bedrooms
Wood-frame construction ("stick-built")
Batt insulation in walls and blown insulation in attics
Geographic Factors and Climate Considerations
EPA incorporated climate factors, regional construction styles (basement, crawl space, or slab-on-grade), and fuel type variations (natural gas, electricity, or oil heating) to refine energy estimates. The Residential Energy and Costs Analysis Methodology from the U.S. Department of Energy (DOE) accounted for these regional differences.
Energy use was then calculated using Beacon Residential™, an energy modeling tool that relies on the DOE-2 hourly simulation software.
Estimating Energy Savings from Sealing and Insulating
For estimating potential energy savings, EPA assumes that a knowledgeable homeowner or contractor can implement the following upgrades cost-effectively:
Sealing air leaks in key areas such as attics, foundations, windows, and doors, achieving a 25% reduction in total air infiltration.
Insulation should be added to attics, floors above unconditioned spaces, and basement walls to meet the 2012 International Energy Conservation Code (IECC) insulation standards.
Key Findings from the Energy Savings Analysis
Higher energy savings occur in colder climates due to greater heating demands.
Air sealing and insulation upgrades can significantly reduce energy bills for homeowners across all climate zones.
Climate Zone Classification and Energy Savings Estimates
Energy savings estimates were calculated for various climate zones across the continental United States. The following table presents estimated utility bill reductions based on climate zone classification.
U.S. Climate Zone Breakdown
The map divides the U.S. into eight climate zones, with Zone 1 being the warmest and Zone 8 being the coldest. These zones are used in energy efficiency and insulation standards to determine the most effective ways to reduce building energy loss.
Zone 1 (Warmest) – Covers Hawaii, Guam, Puerto Rico, and the Virgin Islands.
Zone 2 – Includes parts of southern Texas, southern Florida, and southern California.
Zone 3 – Covers much of the Southeastern U.S., including parts of Georgia, Alabama, Mississippi, Louisiana, Texas, and southern Arizona.
Zone 4 – Covers a large portion of the central U.S., from North Carolina to parts of the West Coast.
Zone 5 – Includes much of the Midwest, the Pacific Northwest, and parts of New England.
Zone 6 – Covers the Northern U.S., including most of Minnesota, Wisconsin, and parts of the Northeast.
Zone 7 – Includes the coldest parts of the continental U.S., such as northern Montana and North Dakota, and the northernmost parts of the Midwest and Northeast.
Zone 8 (Coldest) – Applies primarily to specific boroughs in Alaska, such as Fairbanks, Nome, and North Slope.
These climate zones are key in determining appropriate insulation levels for homes and buildings. Areas in warmer zones (1-3) require less insulation, while colder zones (6-8) need heavier insulation to minimize heat loss. The map is commonly referenced by building codes, the Department of Energy (DOE), and the Environmental Protection Agency (EPA) for energy efficiency programs.
Table 1: Estimated Annual Energy Savings from Home Sealing and Insulating
Mary Watson
