Tight Construction Reduced Air Infiltration

Many ENERGY STAR qualified new homes feature tighter construction than that of homes built to the Model Energy Code.
Tighter house construction can improve the energy efficiency, air quality, and comfort of your home by eliminating unwanted drafts.
image map of house with links to ducts, envelope, windows, insulation, and equipment

Tighter home construction can offer you:

* Improved comfort — reduces drafts, noise, and moisture.
* Improved indoor air quality — keeps dust, pollen, car exhaust, and insects out of the home.
* Lower costs — reduces escape of conditioned air.

Unfortunately, there are hundreds of penetrations through a typical home’s exterior. These gaps and holes are often incurred during framing, and from penetrations for wiring, plumbing, and ducts. Air sealing the house’s envelope combined with proper ventilation, can reduce your energy bills and eliminate unwanted drafts and pollutants.

Reduced air infiltration combined with proper ventilation can not only reduces your energy bills but it can also improve the quality of your indoor air. Outdoor air that leaks indoor makes it difficult to maintain comfort and energy efficiency. In addition, air leakage accounts for 25–40% of the energy used for heating and cooling in a typical home.

Today, off-the-shelf technologies such as house wraps, sealants, foams, and tapes reduce air infiltration. In energy-efficient homes, builders use these tools to seal the myriad of cracks and gaps in framing along with hundreds of holes for plumbing, mechanical equipment, and electrical wiring.

View the fact sheets below to learn more detailed information regarding proper air sealing and ventilation.
Air Sealing United States
Air and Radiation Environmental Protection (6202J) December 2000 Agency
EPA 430-F-97-028
The U.S. Environmental Protection Agency’s ENERGY STAR® Program promotes the use of high-efficiency technologies and equipment. ENERGY STAR labeled homes use at least 30% less energy than homes built to meet the national Model Energy Code while maintaining or improving indoor air quality. These fact sheets are designed to help consumers learn more about the energy-efficient improvements to their ENERGY STAR labeled homes.
A IR S EALING
BUILDING ENVELOPE IMPROVEMENT
Air will leak through a building envelope that is not well prevent air leakage, it is important to seal the building sealed. This leakage of air decreases the comfort of a envelope during construction prior to installation of the residence by allowing moisture, cold drafts, and drywall. Once covered, many air leakage paths cannot unwanted noise to enter and may lower indoor air be accessed and properly sealed. There are many quality by allowing in dust and airborne pollutants. In products available for air sealing including caulks, addition, air leakage accounts for between 25 percent foams, weatherstripping, gaskets, and door sweeps. and 40 percent of the energy used for heating and
cooling in a typical residence. Air sealing the building envelope is one of the most
critical features of an energy efficient home. Look The amount of air leakage in a house depends on two for the results of a “blower door” test (typically factors. The first is the number and size of air leakage included with a Home Energy Rating) to ensure that paths through the building envelope. As shown in your ENERGY STAR labeled home had all air leakage Figure 1, these paths include joints between building paths identified and sealed using appropriate materials, gaps around doors and windows, and materials. penetrations for piping, wiring, and ducts. The second
factor is the difference in air pressure between the Once a house is tightly sealed, you will want to make inside and outside. Pressure differences are caused sure there is adequate fresh air for ventilation. It is by wind, indoor and outdoor temperature differences better to use controlled or active ventilation than to (stack effect), chimney and flue exhaust fans, rely on air leakage. In many ENERGY STAR labeled equipment with exhaust fans (dryers, central homes, an active ventilation system is installed along vacuums) and ventilation fans (bath, kitchen). To with air sealing to ensure that fresh air is provided.
Consumer Guide to Home Energy Savings(Wilson and Morrill), 5th edition, 1996, available from the American Council for an Energy Efficient Economy at 510-549-9914
Homemade Money(Heede and the staff of RMI), 1995, available from the Rocky Mountain Institute at 970-927-3851
Caulking and Weatherstripping
fact sheet available from the

Air sealing the building envelope can provide many benefits including:
Improved comfort. A tighter building envelope reduces the amount of unconditioned air, drafts, noise, and moisture that enter your home. Proper air sealing will also minimize temperature differences between rooms. As a result, tight envelopes can maintain a more consistent level of comfort throughout a house.
Improved indoor air quality. A tighter building envelope reduces the infiltration of outdoor air pollutants, dust and radon as well as eliminating paths for insect infestation. Properly sealing the building envelope will also reduce moisture infiltration from outdoor air in humid climates.
Increased quality. Building codes establish the legal minimum construction standards. ENERGY STAR labeled homes, constructed to exceed these codes with air sealing, can offer a better quality product.
Lower utility bills. Air leakage accounts for 25 percent to 40 percent of the energy used for heating and cooling and also reduces the effectiveness of other energy-efficiency measures such as increased insulation and high-performance windows. Thus, air sealing results in lower utility bills.
Fewer condensation problems. Condensation can lead to mold and mildew problems. In hot, humid climates, moisture can enter into wall cavities through exterior cracks and result in costly damage to framing and insulation. In cold climates, gaps in the interior walls allow moisture from warm indoor air to enter wall cavities and attics. This moisture can condense on cold surfaces and lead to structural damage. By significantly reducing air leakage, ENERGY STAR labeled homes can reduce or eliminate these problems.
Reduced obsolescence. Based on recent trends for improved efficiency and higher indoor air quality, tighter building envelopes are expected to become standard practice for the building industry. Since it is both difficult and costly to make the building envelope tighter after a house is constructed, it is best to seal all joints, holes and seams during construction. ENERGY STAR labeled homes constructed to exceed current building codes are therefore, expected to be less vulnerable to obsolescence.
Improved resale position. Air sealing a home can provide the many impressive benefits discussed above and lead to a more comfortable, quieter and better quality home with lower utility bills, fewer condensation problems, and reduced obsolescence. These benefits can translate into higher resale value//www.energystar.gov

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