Energy Efficiency Basics

Today, there are established standards that make it much easier to see how various energy efficient windows and doors stack up against each other. When shopping for your windows and doors take the following factors into consideration.


ENERGY STAR is a program of the U.S. Environmental Protection Agency designed to recognize products that meet strict energy efficiency guidelines.


U-Factor correlates to the rate of heat transfer. The lower the number, the better a window is at keeping heat inside a building. The U-Factor is key in regions with cold winters. Just remember: the lower the U-Factor, the lower the rate of heat loss through a window.


Solar Heat Gain Coefficient measures how well a product blocks heat from the sun. In warm climates, the lower the number, the better. Here you want to keep heat out by choosing windows that reflect solar radiation. Less heat coming into the home means lower air-conditioning costs and a reduced carbon footprint. In cold regions, your windows can also help you take advantage of solar radiation, which is free heat that eases the workload of your furnace or other energy-powered heat source. A higher solar heat gain coefficient means a window will allow more heat to pass through.


Design pressure (DP) Rating measures the amount of pressure a door or window will withstand when closed and locked. Each DP rating also establishes other performance factors such as water penetration, air infiltration, structural pressure, forced entry and operational force. The higher the DP numbers, the better the performance. Look for the certified hallmark of the Window and Door Manufacturers Association.