Catalog

Performance Rating

Performance Rating

“ Get Smart” Key Elements to look for when selecting windows & exterior doors “ Get Smart” Key Elements to Look for When Selecting Windows & Exterior Doors U-Factor Measures the rate of heat transfer and tells you how well the window insulates. The lower the U-Factor, the better the window insulates. U-Factor values generally range from 0.25 to 1.25. In New Hampshire, the U-Factor is the number to which you should pay most attention. Look for a U-Factor value below 0.30. Solar Heat Gain Co-efficient (SHGC) Measures the fraction of solar energy admitted. The lower the SHGC, the less solar heat the window admits. SHGC is measured on a scale of 0 to 1; values typically range from 0.25 to 0.80. In areas where you mostly spend cooling dollars, the SHGC is the important number. Look for values below 0.30. Design Pressure (DP) Is a rating of the windows’ ability to resist wind. The higher the DP, the more resistant the window is to wind and wind-driven rain. DP is also a good indication of the overall quality of the window, whether or not you expect a hurricane. I.E. DP35 Air Leakage (AL) Measures the rate at which air passes through cracks in the window. AL is measured in cubic feet of air passing through one square foot of the window area per minute. The lower the U-value, the less air leakage. Most industry standard and building codes require an AL of 0.3cfrm/ft. or less . U-Factor Measures the rate of heat transfer and tells you how well the window insulates. The lower the U-Factor, the better the window insulates. U-Factor values generally range from 0.25 to 1.25. In New Hampshire, the U-Factor is the number to which you should pay most attention. Look for a U-Factor value below 0.30. Solar Heat Gain Co-efficient (SHGC) Measures the fraction of solar energy admitted. The lower the SHGC, the less solar heat the window admits. SHGH is measured on a scale of 0 to 1; val - ues typically range from 0.25 to 0.80. In areas where you mostly spend cooling dollars, the SHGC is the important number. Look for values below 0.30. Design Pressure (DP) Is a rating of the windows’ ability to resist wind. The higher the DP, the more resistant the window is to wind and wind-driven rain. DP is also a good indication of the overall quality of the window, whether or not you expect a hurricane. I.E. DP35 Air Leakage (AL) Measures the rate at which air passes through cracks in the window. AL is mea sured in cubic feet of air passing through one square foot of the window area per minute. The lower the U-value, the less air leakage. Most industry standard and building codes require an AL of 0.3 cfrm/ft. or less . Visible Transmission (VT) Measures amount of light the window lets through. The higher the VT, the more light you see. VT is measured on a scale of 0 to 1; values generally range from 0.20 to 0.80. Look for a VT above 0.45. Condensation Resistance Measures how well the window resists water buildup. The higher the condensation resistance factor, the less buildup the window allows. Condensation resistance is scored on a scale from 0 to 100. The higher the number, the less buildup the window allows. The rating is use ful when you’re comparing different products. Note, but Energy Star qualification is based only on U-Factor and SHGC. Impact Resistant Glass Just like the glass in your car windshield, impact-resistant glass is made by placing plastic film between layers of glass. That same film can also block UV light. Typical Window & Exterior Door Styles Visible Transmission (VT) Measures amount of light the window lets through. The higher the VT, the more light you see. VT is measured on a scale of 0 to 1; values generally range from 0.20 to 0.80. Look for a VT above 0.45. Measures how well the window resists water buildup. The higher the condensation resistance factor, the less buildup the window allows. Condensation resistance is scored on a scale from 0 to 100. The higher the number, the less buildup the window allows. The rating is useful when you’re comparing different products. Note, Energy Star qualification is based only on U-Factor and SHGC. Impact Resistant Glass Just like the glass in your car windshield, impact-resistant glass is made by placing plastic film between layers of glass. That same film can also block UV light.

Double Hung Casement

Awning

Picture

Specialty

Patio Hinged Patio Gliding Sidelight

Entrance

& Transom

April 2011

23

46

January 2023