Air infiltration (AI or air leakage) is the passage of air in or out of a building. You’ll find the AI or air leakage rating on all windows and doors NFRC label. Leakage happens through cracks and gaps in the outside shell. Windows leaking air is a significant culprit for air infiltration, and thus energy loss. Poor insulation around windows, doors, and vents contribute to air infiltration as well. Any home energy audit will test first for air infiltration — consequently, the lower the air infiltration number, the more airtight your home or building.

What does it mean for my home?

According to an ENERGY STAR website estimate, air leakage accounts for 25–40% of the energy used for heating and cooling in a typical home. For example, in today’s homes, builders use products such as house wraps, sealants, foams, and tapes to tighten the home’s envelope to reduce air infiltration. However, this was not always common practice. Homes built before the 21st century could have air infiltration problems. Windows leaking air is one of the biggest culprits for air infiltration, especially in older homes.

House Showing Causes of Air Infiltration

Defending against air leakage

Modern windows have advanced weather stripping and engineered sash locking technology that helps reduce energy. Also, Harvey windows have some of the industry’s lowest air leakage ratings.

The industry-standard air leakage rating is 0.3cfm (cubic feet per minute) or the equivalent of 2.25 gallons of air per minute. Harvey windows average 0.05cfm or .375 gallons of air per minute. But how does that compare?

air infiltration air leakage harvey ai vs aama minimum

Harvey vs. Competitors

Lower quality vinyl and composite windows aren’t engineered to the same standards as Harvey windows, which have advanced integrated weatherseals and sash-locking technology. When these features are lacking, it leads to excessive air passing through the gaps where the sash meets the frame or around the perimeter of a closed window, otherwise known as a high rate of air infiltration (AI), a value that is determined through independent, 3rd party testing.

As mentioned, the American Architectural Manufacturers Association (AAMA) mandates a minimum air exchange rate of 0.30 cfm/sf at 1.57 psf (25 mph). Harvey vinyl windows have air infiltration ratings ranging from .01-.07 cfm/sf. That’s quite a difference—up to 96% better than the industry standard.

Why? Because Harvey windows were born in the Northeast where keeping out the cold is a priority. And, in the summer homeowners benefit by keeping cooler air in. If you choose a window with a higher AI, the more drafty a room will be, and the more energy will be used from frequent heating and cooling cycles, while a low AI rate can help homeowners save money and prevents additional wear and tear on
their HVAC systems.

Additional Resource

For more on what makes a window energy-efficient or view our post on Understanding a Windows Thermal Performance Rating.

Other options to help reduce air infiltration

We understand that replacing windows is not an option for everyone. For example, for those with historical requirements, Harvey offers storm windows. They are easy-to-operate, self-contained units that provide extra insulating value. We custom fit the exact dimensions of your existing windows. Storm windows are a lower cost option to help with windows leaking air and can provide energy savings.

Find what is causing draftiness

As previously stated, old windows and doors and poor insulation can cause significant drafts. But, here are some exterior problem areas to inspect for gaps:

    • Outdoor water faucets
    • Where siding and chimneys meet
    • Areas where the foundation and the bottom of exterior brick or siding come together
    • All outside corners

Inside your home, inspect around the following areas for any cracks and gaps that could cause air leaks:

    • Electrical outlets
    • Switchplates
    • Door and window frames
    • Electrical and gas service entrances
    • Baseboards
    • Weatherstripping around doors
    • Fireplace dampers
    • Attic hatches
    • Wall- or window-mounted air conditioners
    • Cable TV and phone lines
    • Where dryer vents pass through walls
    • Vents and fans
    • Mail slots

In all cases, you want to check to see if the caulking and weatherstripping are suitably applied, leaving no gaps or cracks, and are in good condition. For more tips on making your home energy efficient, visit the Energy Saver section of


Remember a tighter house construction can improve the energy efficiency, but also air quality, and comfort of your home by eliminating unwanted drafts. 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 the escape of conditioned air.

A more-tightly sealed home will also increase condensation, provided your home’s humidity is too high. Learn more about condensation causes and cures. Different window styles will affect air leakage, as well. Learn about the difference between double hung and single hung and all the different window styles windows and where to put them.

Ready to improve your home by reducing air infiltration? Find, compare, and get quotes from contractors through the Harvey ProZone.

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