How To Purchase Energy Efficient Windows

Choosing new replacement windows can be complicated enough with all of the designs, styles and colors available to you. Throw in the energy efficiency ratings and you’ll be left feeling quite overwhelmed. Knowing what those ratings mean however, is extremely important since windows are the easiest way to increase the insulation level of your home. You want to choose windows that keep out unwanted drafts, moisture and solar heat and the energy ratings show you which windows do just that.

The first thing you want to look for when browsing over new windows is the Energy Star logo. Energy star is a government program designed to help businesses and homeowners save money while protecting the environment. Energy Star tests and certifies products that are energy-efficient by reducing energy consumption and pollution.

From there, Energy Star will list several factors and ratings which may seem confusing or completely incomprehensible at first. These are the U-factor, SHGC, air leakage, visible transmission, light-to-solar gain, and condensation resistance.

• U-factor: The U-factor is a rating that measures the rate of heat transfer and gives an indication to the window’s insulation value. It ranges from .25-1.25 Btu/h·ft²·°F, with .25 being the best insulation quality with 1.25 being the worst. This means that a window with a low U-factor will reduce the amount of heat transmitted through the window, which ultimately saves you money.
• SHGC: The solar heat gain coefficient, or SHGC, measures the amount of solar energy that is transmitted or absorbed through the window and released into the interior of the home. A window with a high SHGC will be better at collecting solar heat during the winter so that your home requires less electric heat, and a window with a low SHGC is more effective at blocking heat gain from the sun. It is important to take your climate into consideration when looking at SHGC ratings. In Connecticut and surrounding areas, a high SHGC is recommended because of the cold winters!
• Air leakage (AL): AL is the rate at which air passes through the window pane or frame. The lower the AL value, the less air the window lets through into your home, so it is important to get the lowest value possible.
• Visible transmission (VT): VT is the amount of visible light that passes through the window, which has an average rating of .2-.8. The higher the VT rating, the more light that will enter the building through the window. Be aware, that this is visible light and not unwanted solar heat. The rating you choose is based on personal preference and the climate.
• Light-to-solar gain (LSG): This ratio compares the SHGC and VT for an indication of how much light the glass allows to pass through without accompanying solar heat. A higher score means more light and less heat, which is beneficial because you’ll receive lost of natural light without needing to increase your AC bill to compensate for the extra heat.
• Condensation resistance: On a scale of 0-100, a higher rating indicates more resistance to the build-up of condensation. This prevents moisture from gathering and settling on your window frame, which can cause a wooden material to crack, split or warp.

Advanced Window Systems would be proud to assist you in any of your replacement window needs! Contact us today for a free home estimate at 860-829-8044!