Everything to Know About Window Energy Efficiency Ratings

The energy efficiency of windows plays a vital role in keeping your homes cool or warm accordingly. If you install energy-efficient windows, you can save significantly on energy bills. But how do you figure out the energy efficiency of windows?

To help you make a firm decision, we’ve compiled some factors that may guide you to choose the ideal energy-efficient windows for your home.

1. The U-Factor

The capacity of a window to prevent heat loss from your home is called its U-factor. In other words, it’s resistant to heat loss. The better the resistance, the higher the insulation levels of the windows.

The U-factor is measured between 0.5 and 1.2 with lower values indicating that windows are more efficient in preventing the heat from escaping your home. This energy efficiency metric is the most significant in cold climatic regions. When we measure U-factor, we take into consideration the window glass, its frame, and glazing.

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2. Solar Heat Gain Coefficient (SHGC)

The energy efficiency factor that is responsible for preventing solar radiation is called the solar heat gain coefficient. Its values can lie between 0 and 1. The scale values are indirectly proportional to the resistance of windows to solar radiation and heat.

Choose windows with the lowest SHGC values in warmer areas to reduce the reliance on air conditioning. At the same time, you can choose windows with slightly higher SHGC ratings to allow heat to come inside your homes in cold states. Remember, higher U-values generally come with higher SHGC ratings, so choose them if you live in cooler areas.

3. Visible Transmittance (VT)

Visible transmittance measures the amount of light the window allows to pass through it. Its values range from 0 to 1, with the highest value meaning that the window allows the maximum light into your homes. On the other hand, if the VT value is low, your home won’t be as bright.

In the older days, solar heat gain and visible transmittance were not different. As the technology advanced, new windows came into the market that allowed natural illumination without affecting the heat intensity. It means that a home can both be lit and cool if windows are energy-efficient.

4. Air Leaks

Another critical factor in determining the energy efficiency ratings of a window is how much air probes inside and outside your home. Air leakage varies around 0.1 and 0.3, with 0.3 being the standard requirement for buildings.

If the value is less than 0.3, the windows are more effective in air protection. But air leakage capacity of a window can change with time due to expansion and warping. That’s why Energy Star standards don’t include air leakage as a typical factor to rate a window’s energy efficiency.

5. The Resistance to Condensation

Finally, the measurement of moisture/water collection on the window’s surface is called condensation resistance. It can be measured on a scale of 1 to 100. The lower the values, the more moisture a window allows accumulating, which increases the risk of mold and mildew build-up.

Thus, when you install or replace windows, make sure the high-quality window professionals install them.

At B&W, we provide window replacement and door replacement Orange County. Our vinyl windows and vinyl replacement doors Orange County offer high durability, maximum energy efficiency, and improved curb appeal.

For a consultation, schedule an appointment today!

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