Jackson Lumber Catalog

Performance Rating

LUMBER & MILLWORK

“ 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. SHGH is measured on a scale of 0 to 1; va l - 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

Double Hung Casement

Awning

Picture

Specialty

Patio Hinged Patio Gliding Sidelight

Entrance

& Transom

42 April 2011

March 2018 23