The type of windows you choose for your home can have a dramatic impact on energy efficiency. Energy-efficient windows prevent heated or cooled air from escaping your home which helps lower utility bills.
Champion windows, sunrooms, siding, and practices meet all Energy Star manufacturing specifications and requirements. Energy efficient windows increase the value of your home and decrease your electricity bill.
U-factor measures the rate at which non-solar heat flows through a window, which is important because if heat can escape from your home in winter it will require more furnace runs to keep your house warm. Choosing windows with a lower U-factor will reduce energy costs because your heating bills will be lower in the winter.
To have a lower U-factor, manufacturers will use Low-E glass with a metallic coating or multiple layers of glazing. They will also use high-quality frames and sealants to reduce air leakage. When you see the ENERGY STAR label, it means that all of these elements have been carefully considered and combined to create an energy-efficient window.
In mixed climates like the North Central and South Central Climate Zones where it is necessary to rely on both heating and cooling, look for windows with a lower U-factor to help reduce your heating bills in winter and your cooling bills in summer.
The “E” in Low-E stands for emissivity, which refers to how much heat is absorbed or reflected by the glass. The lower the emissivity, the less heat is transferred through your windows and into your home.
These coatings can be made thicker or thinner to meet the needs of different climate zones and architectural styles. They also provide a variety of color and appearance options for the building interior.
In addition to lowering your energy bills, these coatings reduce interior glare, which helps you work more comfortably and sleep better at night. They can even protect your furnishings and fabrics from fading caused by harmful UV radiation.
Some manufacturers use a soft, thin application of the low-e coating in between the panes of double or triple-pane glazing. The coating faces the insulating airspace to minimize oxidation. Adding argon or krypton gas in this space adds additional insulating value and further reduces emissivity, which increases energy efficiency.
Low Solar Heat Gain Coefficient (SHGC)
The solar heat gain coefficient (SHGC) is the fraction of incident solar radiation admitted through a window, door, or skylight—directly transmitted and/or absorbed, and then released as heat inward. Windows with low SHGC ratings help reduce cooling loads in the summer by blocking excessive solar heat gains. Your home’s climate, orientation, and external shading will determine the optimal SHGC for your new or replacement windows.
Selecting the best windows for your climate is essential to energy savings. Energy Star qualified windows are rated based on four properties—U-factor, SHGC, Visible Transmittance (VT), and Air Leakage Resistance. These performance factors are also considered when choosing and installing ENERGY STAR qualified doors and skylights. ENERGY STAR labels include these performance ratings for easy comparison of products.
Energy Star Label
Replacing old windows with ENERGY STAR certified energy efficient windows, doors and skylights can lower your home’s energy bills and reduce greenhouse gas emissions. Look for the ENERGY STAR label to find products that meet strict energy efficiency specifications set by the Environmental Protection Agency (EPA). Many utilities provide financial incentives and rebates for homeowners who make energy efficient upgrades.
Every ENERGY STAR window, door and skylight is independently tested and verified to perform at levels that exceed guidelines for your climate zone. The NFRC energy performance rating shows the U-factor, solar heat gain coefficient, visible transmittance and condensation resistance.
ENERGY STAR qualified windows can be framed in wood, aluminum or vinyl. Typically, a wood frame is clad with aluminum or vinyl on the exterior surface to resist corrosion and provide low maintenance. Other framing materials are available as well. Many ENERGY STAR windows are designed with combination frames that have different materials throughout the frame and sash to provide optimal performance for your Huntsville AL home.