When it comes to buying windows, many people want to see the energy efficiency ratings and rightfully so. The whole reason you're getting new windows is probably because the ones you currently have are experiencing problems such as air leakage or seal failure.
However, people often only take into consideration features like u-factor or solar heat gain coefficient. These ratings measure a window's ability to insulate and regulate heat loss - the science behind a window's energy efficiency.
A common assumption people make is that their new windows won't be letting in any air at all and forget about the air leakage window rating. In reality, air leakage is one of the most important factors to consider.
In this article, we'll go over everything you need to know about air leakage and what to look for when buying new windows or replacing your old ones.
What Is Air Leakage (Air Infiltration)?
You might be thinking, "Wait, aren't new windows supposed to get rid of my draft problem?" Yes, they are and they will if you choose the right replacement company.
However, as the old adage goes, nothing is perfect - including your windows. This doesn't mean that new windows will be letting in copious amounts of air into your home. Air can sneak through anything, and windows have many parts so it's easy to understand why they don't create a vacuum in your home.
Air leakage, also known as air infiltration, is the measurement of air that passes through the window assembly itself. So what does infiltration mean in this context? It simply refers to the infiltration of air through gaps or imperfections in the window unit — air leakage and air infiltration are two terms for the same thing.
Air leakage is measured on a scale of 0.1-0.3 with 0.1 being the least amount of air that passes through the window. The National Fenestration Ratings Council (NFRC) is also responsible for this rating as it is with others like u-factor and visible transmittance.
How Is the Air Leakage Rating Calculated?
Air infiltration is calculated by how many cubic feet of air can pass through a window in a matter of a minute's time. That number is then divided by the total area of the window.
This is where the number can get a little tricky. Since the air leakage is calculated in terms of the overall size of the window, sometimes that number can be misinterpreted.
For example, some company might compare their window to another one of a different size that has a higher air leakage rating. However, the window they're comparing to might be of a different size and therefore have a different rating.
When you're in the market for replacement windows, keep an eye out for things like this so you know exactly what you're getting.
Another thing to keep in mind is that the air leakage rating is based on a constant wind speed of 25mph. Regardless of where you live, it's safe to say that your windows won't be constantly hit with that much wind.
This measurement is part of a standardized air infiltration test. During air infiltration testing, the window is placed in a controlled environment where pressure differences simulate wind conditions, and the volume of air passing through is recorded. The result is the window air leakage rating you see on the NFRC label.
Why Is Air Infiltration an Important Rating?
Obviously, the amount of air that passes through a window is an important rating. However, you shouldn't put all your eggs in one basket. In fact, air leakage ratings below 0.1 aren't even recognized by the NFRC.
The reason for this is because when the numbers are that low, there's basically no difference between one window and another. The NFRC feels that the difference is so insignificant that you won't be able to tell them apart.
Also, air leakage isn't a required window rating. Some companies completely leave it out of the discussion. That's a sign to look out for if the company won't even display their window's air infiltration rating.
It's safe measure to know as much as possible about the windows before making such an important investment on your home.
As long as the number is below 0.3, then that is deemed an energy efficient window by the NFRC and Energy Star. A truly energy efficient air leakage rating for windows will be in the 0.1 range. When comparing your options, always check the air infiltration rating — windows with lower numbers will do a better job keeping drafts out.
Air leakage is a tricky window rating that has many ways of being misinterpreted. You shouldn't overlook it though because every aspect of your windows counts especially when you're trying to save money - which is probably a big reason why you're replacing your windows in the first place.
Which Windows Have the Best Air Leakage Ratings?
Now that you know what to look for and how air infiltration in windows is measured, what types of windows usually have the best ratings?
One thing is for certain, you can rule out wood, fiberglass and composite windows. These windows almost always have a higher air leakage rating than vinyl windows.
Vinyl windows with double or triple panes are excellent at keeping air out of your home. Their insulation properties are far better than wood, fiberglass and composite.
When you're shopping around for replacement windows, make sure you pay attention to all window energy ratings. If a company is really trying to sell you on a single rating such as air leakage or u-factor, then they're probably lacking in other categories.
When you choose Feldco, you know that you're getting the best replacement windows in the Midwest. In fact, we were named America's #1 window company for a reason. Our windows are made with energy efficient vinyl with insulated glass and frames.
Plus, your windows from Feldco will be installed by factory trained professionals with many years of experience to ensure a secure and proper fit to minimize air leakage.
Start your window replacement project with a free quote online and join the over 500,000 satisfied homeowners who trust Feldco.
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