Energy Savings from Cost-Effective Air Sealing and Insulating

For the purpose of energy estimating savings, EPA assumed that a knowledgeable homeowner or contractor could cost-effectively:

Establishing a 'Typical' U.S. Existing House

The Residential Energy Consumption Survey (RECS) indicates that a large block of existing U.S. housing stock was constructed between 1975 and 1985, just after the 1973 oil embargo, when there was a new increased awareness of energy use in homes. As a result, EPA based its modeling around the common construction characteristics of homes built in this era as a proxy for a 'typical' existing U.S. home.

Construction characteristics for the 1975–85 era were determined based on a review of RECS data from the U.S. Department of Energy, 1997 EDS (Energy Data Sourcebook for the U.S. Residential Sector and earlier versions) data from Lawrence Berkeley National Laboratory, and other supporting data, including anecdotal experience of ENERGY STAR staff and stakeholders. Based on these sources, EPA assumed the following characteristics for a house from the 1975–85 era:

• 1,500 square feet of conditioned floor area;
• 14% window-to-floor-area ratio;
• 20% duct leakage to the outside;
• three bedrooms;
• "stick" construction (wooden studs, joists and rafters), with batt insulation in walls and blown insulation in attics

Geographic climate factors, regional construction styles (e.g., basement, crawl space or slab-on-grade), and fuel type characteristics (e.g., natural gas or electricity) were then proportionally weighted; and estimated energy use calculated for "typical" composite houses in two climates that represented a weighted average for a Northern and a Southern home.

Estimating Energy Savings from Improvements Made to the 'Typical' Home

Construction characteristics for the 1975–85 era were determined based on a review of RECS data from the U.S. Department of Energy, 1997 EDS (Energy Data Sourcebook for the U.S. Residential Sector and earlier versions) data from Lawrence Berkeley National Laboratory, and other supporting data, including anecdotal experience of ENERGY STAR staff and stakeholders. Based on these sources, EPA assumed the following characteristics for a house from the 1975–85 era:

• Seal air leaks throughout the house, focusing on leaks to the attic space, through the foundation, and around windows and doors. An average documented baseline value of 0.91 ACHNAT (natural air changes per hour) was used for Northern homes and 0.94 ACHNAT was used for Southern homes. Both Northern and Southern homes were estimated to be improved to a leakage level of 0.50 ACHNAT.
• Add insulation to improve R-values from the average documented attic insulation values of R-15 in the North and R-13 in the South to R-38; improve basement rim joists from R-0 to R-11; and improve floors over crawl spaces from R-0 to R-11.

Note: In estimating savings opportunities, EPA considered that the 1975–85 construction era coincided with the period after the 1973 oil-embargo when early residential energy conservation measures were first becoming widespread (e.g., storm windows over single-pane/clear glass windows, some caulking & sealing to reduce air leaks, increased attic insulation, etc.). EPA also assumed that original, as-built HVAC and water heating equipment was replaced in the 1990s by 1993–2000 MEC/NAECA-era equipment.

Based on these projected cost-effective improvements, EPA estimates the following potential energy and utility bill savings:

2 From US Dept. of Energy, Energy Information Administration 2007 Short Term Outlook projected US natural gas and electricity prices.

Conservatively rounding these projected energy and cost savings, and corroborating modeled results with the field experience of professional home energy contractors, EPA estimates that homeowners can typically save up to 20% of heating and cooling costs (or up to 10% of total energy costs) by air sealing their homes and adding insulation in attics, floors over crawl spaces, and accessible basement rim joists.

The Lowest hanging Fruit

This built up dust is definitely insulation in the wrong place! These coils are heat sinks that rely on the surrounding air to disperse heat. A good cleaning will save energy and increase the life span of this refrigerator.

Thank-you for your assistance on my home energy efficiency project, which cut my electric bill in half, made my house incredibly quiet by blocking exterior noise and made my home interior temperature much more uniform.

Here is the project summary for my 1800 sq ft house:

• Commonwealth Building Sciences energy audit:  $325.
• caulk and weatherstripping for doors, windows, electric outlets, wall switchplates : $120
• window solar film:  $400
• single-component 16 oz spray cans for sealing pipe and wire penetrations of walls, ceilings, crawl space, floors: $80
• two-component closed cell foam for sealing attic, crawl space, storage room:  $ 3354.67
• energy auditor recheck after insulating and air sealing:  $75
• Virginia Energy Efficiency Rebate: -$595
• income tax: IRS Residential Energy Credit estimated:  -$400

TOTAL:  $3359.67

Time to recover investment: about 1 1/2 years.

• Practice wearing the protective gear before working with the foams.  I had a lot of experience with protective gear in my medical work, home chemical use and winter sports, but you will find this gear hot and awkward unless you practice.
• Before you suit up, be sure to use the toilet and then drink 24 ounces of water to prevent lost momentum due to potty breaks and dehydration.
• Before you suit up, rub your entire body and your hair with bath oil to reduce the amount of spray foam that sticks to you.
• Wear head sock, Tyvek suit, safety glasses, organic vapor-rated respirator mask, head lamp, gloves, socks, shoes you will discard after the project.
• Put on a pair of shorts with pockets over the Tyvek suit so you can carry paper towels, spare spray nozzles, spare gloves, spare safety glasses.
• After 2 hours of work, to avoid dehydration and heat exhaustion, you should strip off, shower, drink 24 ounces of water and cool down before suiting up again.
• Wear a triple layer of latex disposable gloves so that when one glove gets a build-up of foam, tears or gets glued to something, you can quickly tear off the glove and have protection underneath it.
• Buy spares of all protective gear.  The foams do not come off!  Buy several safety glasses so you can throw one away when it gets clouded by foam specks, then quickly put on a new pair.
• Tyvek suits can be re-used many times and are machine washable.  Do not put them in the dryer. The suits shrink in the dryer.

After the project, immediatly take a shower, then sit down with a tall, cold drink and enjoy the quietness and uniformly comfortable temperature of your newly-sealed home.

Cold outside air has gotten into the wall where the thermostat is located. The thermostat is mounted to that cold wall so warm air from the room will be convected toward it. The thermostat cannot accurately detect the actual air temperature of the room due to warm air directed toward the thermostat and the cold wall housing the thermostat.