Quincy: Window Performance Ratings Label and How to Understand Them

By: Terry Quinn, CS

There is very value information on each of your new windows. These labels can help you determine how well a product will perform the functions of helping to cool your home in the summer, warm your building in the winter, keep out wind, and resist condensation.*

Starting from the top left and going left to right and top to bottom there are 5 ratings and we will explain each and whether or not to look for a HIGH or a LOW rating.performance ratings

1. U-Factor: measures the rate of heat transfer and tell you how well the window insulates. The LOWER the U-factor, the better the window insulates. This is the entire window, including the frame and spacer material.

2. Solar Heat Gain Coefficient measures the fraction of solar energy transmitted and tells you how well the product blocks heat caused by sunlight.
The LOWER the SHGC the less solar hear the window transmits, and is more effective at reducing cooling cost during the summer. Your homes orientation and external shading will determine the optimal SHGC for a particular window, door, or skylight.

3. Visible Transmittance (VT) measures the amount of light the window lets through. The HIGHER the VT, the more light you see. The VT you need for a window, door, or skylight should be determined by your home’s day lighting requirements and/or whether you need to reduce interior glare in a space.

4. Air Leakage (AL) measures the rate at which air passes through joints in the window. The LOWER the Al value the less air leakage, or the tighter the window.

5. Condensation Resistance measures how well the window resists water build-up. The HIGHER the condensation resistance factor, the less water build-up the window allows. One thing to remember, Windows DO NOT make water. High humidity in a home does that.

ENERGY STAR labels were established to make it easy for consumers to identify and purchase energy-efficient products that offer savings on energy bills without sacrificing performance, features, and comfort.

Your estimated savings in the Boston area when installing energy star qualified windows, doors and skylights, for a typical home for a year would be.

1. When replacing single-pane windows $501.00 or 156 gallons of gas (per year)
2. When replacing double-pane, clear glass windows $208.00 or 65 gallons of gas (per year)

The Remodeling Professionals at CAT Exteriors (a division of Almar Building & Remodeling Co, Hanover Ma) have been installing new and replacement windows, doors and skylights for over 50 years on the south shore, and would be happy to provide you with an estimate to start you saving money on your heating and cooling bills now. Financing is avilable.

Contact us at 781-924-5018 for a no obligation appointment and start saving now.

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*http://www.nfrc.org/label.aspx