The Best Energy Efficient Windows

What are the best energy efficient windows? When we started looking for replacement windows for our home, I thought it would be like picking out a new washer. We'd look for the Energy Star logo, read a few online reviews and head to the store to compare prices.

When research led me to terms like Solar Heat Gain Coefficient and Visual Transmittance, I wondered if the closets were really that tiny in our former, maintenance-free apartment. Welcome to home ownership.

We all know that energy efficient windows benefit the environment. With the increasing costs of energy, it's nice to know that installing new windows can save money too. In roughly five years, new energy efficient windows pay for themselves.

The Simplest Way to Shop for Windows

Find out What Qualifies as Energy Efficient
The best energy efficient windows will vary depending on where you live and how your home is designed. So, the type of windows your brother has in upstate New York may not be the best for your home in Texas. To find out standards of efficiency in your region, check the Energy Star Climate Zone.

Verify Rebate & Tax Credit Qualifications
Although most retailers know which windows qualify for rebates and tax credits, it's best to double check. Guidelines change often and vary by region. For more information on qualified windows, see the Energy Star website.

Learn How to Read the Labels
The National Fenestration Rating Council independently tests all Energy Star windows and rates the performance in five ways.

1. U-Factor (.25 - 1.25)

The U-factor determines how well the window insulates. A low U-factor means lower overall heat is transferred from the window. Lower values mean better insulation.
2. Solar Heat Gain Coefficient (0 - 1)

Solar Heat Gain Coefficient (SHGC) calculates how much available heat a window transmits. It uses a scale of 0 (none) to 1 (100% of available sunlight), but most values range from .25 -.80. The direction your home faces, available shade, and other factors will determine the best number for your home.
3. Visual Transmittance (0 - 1)

Visible Transmittance (VT) determines the amount of light coming through a window. A scale from 0-1 is used, but most values fall within .25-.80. More natural light passes through windows with a higher VT.
4. Air Leakage

Measured in cubic feet, air leakage calculates the rate at which air passes through closed windows. The best energy efficient windows should allow for very little air leakage. The lower the number the better.
5. Condensation Resistance (0 - 100)

Condensation resistance determines how well windows resist to moisture. Scoring on a scale of 0-100, the higher number means better resistance.

Proper Installation
Even the best energy efficient windows can be a poor investment if they aren't installed correctly. Make sure they are installed according to the manufacturer instructions. If the retailer doesn't provide installation services, ask for a list of recommended professionals in your area.