Learn What The Energy Efficiency Ratings Mean On Replacement Windows

Posted on: 18 May 2017

When you have new windows installed, you want the most energy efficient products you can afford so your energy bills will be low. One way to tell if the windows are energy efficient is to look for the Energy Star label. Another way is to look for the more comprehensive rating label from the National Fenestration Rating Council. This is what the label from the NFRC lets you know about the windows you're going to buy.

The U-Factor Rates Heat Transfer

The U-factor rating on the windows lets you know how well the windows will block heat transfer. Blocking heat transfer is an important quality because it keeps warm air inside your house. Windows with a low U-factor are better at keeping warm air inside a room in the winter when it is cold on the other side of the glass. If you live in an area that has long, cold winters, you'll want to buy windows with a low U-factor so you can guard against heat loss in your home.

The Solar Heat Gain Coefficient Measures Warming From The Sun

The solar heat gain coefficient, or SHGC, is similar to the U-factor in that it is a way of measuring how well heat passes through the windows. In the case of SHGC, the measurement rates how much heat from the sun is allowed to pass through the windows and enter your home. You want to look for a low number because the lower the number, the less you'll pay for air conditioning in the summer. If your area has long, hot summers, then choosing windows with the lowest SHGC you can afford will help keep your power bills low.

Visible Transmittance Rates How Much Natural Light Shines Through

The visible transmittance rating is going to be important to you if you love your home to be flooded with natural light. If you want as much light to enter as possible, look for a high number on the label. One way windows are able to control how much solar heating and heat loss occur is to use film and coatings. Some of these also leave a colored tint behind that can be slightly gray to dark. Even clear coating can affect how light and heat move through the glass, so the visible transmittance rating is a way to tell in advance how much light will shine through and brighten your home. If a lot of light enters, you can cut down on the amount of artificial lighting you need to use and further reduce your power bill.

When it comes to new window installation, you'll have to consider your climate and whether it is more important to hold heat inside during the winter or block heat in the summer. As windows become more energy efficient, they also become more expensive. It isn't always necessary to buy the most efficient windows to see lower power bills. Contractors like Energy Star Construction can help you decide on the level of efficiency you need based on the usual weather conditions in your area and how well your home is insulated.