Follow Us On:
Call Us: 713.864.2747

Window Energy Efficiency: Air Leakage

When storm winds blow, can you feel air drafting through the corners or meeting points of your windows?  Do you notice that you are having to clean the dust from your window sills more often? These are signs that your windows have air leakage that is costing you in energy efficiency and allowing more dust and pollutants into your home. Older single-pane aluminum windows are especially prone to air leakage as the caulk around the glass and the older felt seals age and deteriorate.

Even the most energy-efficient windows on the market allow a tiny bit of air to leak in or out. The key is knowing which window restricts this airflow the most. Read more here. #CustomWindowsTX Click To Tweet

What Window AL Means

Window air leakage, commonly abbreviated as window AL, refers to the amount of air that makes its way through your window. The lower the number, the less air can escape through the window and the more insulated your home will be. While you’ll never see an AL value of zero, a well-made window should have a very low number.

Recognizing a Good Window Air Leakage Rating

NFRC-certified windows are required to have an AL value of 0.3 or lower, meaning that less than a third of a cubic foot of air can make it through the window every minute. This AL value is also required for any window to receive the Energy Star seal of approval. But while 0.3 is the maximum allowable AL level, plenty of especially energy-efficient windows have even lower levels and allow far less air to leak in or out. The exact results depend on the type of window, the frame materials, and the seal design.

Pro Tip: Even a window with a less-than-ideal air leakage level will provide a significant boost in energy efficiency over older, single-pane windows.

Finding Reliable Replacement Windows

A truly energy-efficient window relies on several different design choices to keep your home at a comfortable temperature and reduce your energy bill. As you shop for replacement windows, don’t forget to check the AL rating. The better the rating, the better the window will be for your home.

Contact us to learn more about our window models and their air leakage levels.