Last Updated on March 9, 2022 by Kravelv
With energy prices high, it’s not unusual that more and more homeowners are looking for ways to make their homes more energy-efficient. There’s no getting around using energy, after all, so the next best thing that many can do is to take measures to improve energy efficiency in their properties. Choose your power plan wisely. Fortunately, there are many ways home energy-efficiency can be improved, one of which is replacing old, faulty windows. How does a window replacement help rake in energy savings?
Let’s back up first and define what energy efficiency is: energy efficiency is simply the use of less energy for the same service. It sounds a lot like energy conservation but the two are different. For example, energy efficiency is when you end up using less energy to cool your property because your home’s indoor temperature is stable. Energy conservation, on the other hand, is using less energy because you are using your air conditioning unit less.
How Windows Achieve Energy Efficiency
How do windows factor in then in your effort to improve energy efficiency in the home? It has a lot to do with how windows achieve energy efficiency in the first place.
Windows mainly promote energy efficiency by keeping passive heating and cooling at bay. It is important to keep passive heating and cooling at bay because they affect indoor temperature in the home. When it’s unnecessarily hot, for instance, such as when too much solar heat enters the home, your cooling system needs to work doubly hard to cool your home. And when it works doubly hard, your cooling system guzzles energy, leading to a spike in your energy bill.
To improve energy efficiency in the home, make sure you’re getting energy-efficient window replacements. And how do you do that? By checking a window replacement option’s NFRC label.
There are four ratings you will find in the NFRC label: Solar Heat Gain Coefficient (SHGC), U-Factor, Visible Transmittance (VT), and Air Leakage (AL). SHGC and U-factor are typically included in all NFRC labels while VT and AL are optional ratings. NFRC ratings will also vary depending on climate zones as different zones have different heating and cooling requirements.
A window’s overall energy efficiency is determined by the sum of its parts, with composite frames and low-emissivity window glass being the best combination.
Understanding the NFRC Label
A window’s SHGC is the measure of how much solar heat — that is, the heat from the sun’s light — the window lets in. The lower the SHGC, the less heat a window lets in. For those in warmer areas, like the Southern and South Central United States, a lower SHGC rating is recommended, preferably 0.25 or less. This will help keep the room cool and help to offset the need for air conditioning.
The window’s U-factor, on the other hand, is the measure of a window’s thermal resistance. Simply put, it’s how good the window is at preventing heat from getting out. The rating takes into consideration the entirety of the window (glass and frame) to assess performance in terms of thermal resistance, with a lower rating meaning lower potential for wasted heating. For the South Central U.S., a U-factor of 0.30 is acceptable, while in the warmer Southern states a U-factor of 0.40 is recommended.
VT is the measure of how much visible light a window lets through. The higher the VT, the higher the amount of natural light let in by a window. A VT of 1 normally indicates clear, single-pane glass; for today’s multi-pane windows, a VT of from 0.30 to 0.70 is typical. With the different window tint technologies available, it is possible to raise or lower a window’s ability to admit sunlight without affecting its ability to block or contain heat.
Lastly, AL is the measure of how much air in general a window lets through. All windows let in and out some level of air but the more airtight they are, the better. After all, less air let in or out means less heating and cooling energy wasted, which means more energy savings for you.
Energy-efficient Window Styles
When it comes to overall energy efficiency, two particular styles of window stand out: the picture window and the casement window.
Picture windows are at the top of the pack because they are fixed windows, meaning they are the most airtight of window styles. If you’re looking instead for an operable, energy-efficient window, casements are great alternatives to picture windows. They are operable so they have gaps that can let air in and out but casement window sashes press firmly against their frames when closed, creating an airtight seal as well.
Getting energy-efficient window replacements is nothing to scoff at so you’re going to want to make sure that you make the most of them. To make the most of your investment, make sure you only work with a reputable window expert in your area.
Nick Peterson is the marketing manager for Renewal by Andersen of Houston, passionate about helping clients improve their homes with the company’s superior range of replacement windows and doors. Outside of home improvement, he is also passionate about his three sons, animal welfare, the environment, and music. To catch updates from Nick, check out the company blog!