Start Your Project
1 (916) 244-7655
Energy Performance Testing, Certification and Labeling for Your House’s Windows and Doors
The National Fenestration Rating Council (NFRC) operates a voluntary program that tests, certifies, and labels windows, doors, and skylights based on their energy performance ratings. The NFRC label provides a reliable way to determine a window’s energy properties and to compare products.
The NFRC label can be found on all ENERGY STAR® qualified window, door, and skylight products, but ENERGY STAR bases its qualification only on U-factor and solar heat gain coefficient ratings, which are described below.
Heat Gain & Loss
Windows & Doors lose energy through the following;
- Direct conduction through the glass or glazing, frame, and/or door
- The radiation of heat into a house (typically from the sun) and out of a house from room-temperature objects, such as people, furniture, and interior walls
- Air leakage through and around them.
These properties can be measured and rated according to the following energy performance characteristics:
U-factor is the rate at which a window, door, or skylight conducts non-solar heat flow. It’s usually expressed in units of Btu/hr-ft2-oF. For windows, skylights, and glass doors, a U-factor may refer to just the glass or glazing alone. NFRC U-factor ratings, however, represent the entire window performance, including frame and spacer material. The lower the U-factor, the more energy-efficient the window, door, or skylight.
Solar Heat Gain Coefficient (SHGC) is the fraction of solar radiation admitted through a window, door – either transmitted directly and/or absorbed, and subsequently released as heat inside a home. The lower the SHGC, the less solar heat it transmits and the greater its shading ability. A product with a high SHGC rating is more effective at collecting solar heat during the winter. A product with a low SHGC rating is more effective at reducing cooling loads during the summer by blocking heat gain from the sun. Your home’s climate, orientation, and external shading will determine the optimal SHGC for a particular window, door, or skylight.
Air leakage is the rate of air movement around a window, door, or skylight in the presence of a specific pressure difference across it. It’s expressed in units of cubic feet per minute per square foot of frame area (cfm/ft2). A product with a low air leakage rating is tighter than one with a high air leakage rating.
Real Benefits of Replacing Your Windows Now
- Energy Savings – Since you have heard so much about replacement windows slashing your energy costs, let’s lay out the savings you can really expect. Windows are measured in U-values. This term can be confusing, but it simply describes the amount of heat the window conducts. U-values are the inverse of R-values which measure the amount of heat that is resisted. R-values are used to measure products like insulation. This means if you have an older home with single pane wood windows, they will have a U-value of approximately .99. Convert this into R-values and it equals R-1. If your walls are insulated with a standard R-13, then your windows are letting heat out of your house 13 times faster than your walls. Windows also lose heat because they usually leak air around the sashes. On average, windows represent an estimated 20% of a home’s overall air leaks. Upgrading your windows will ultimately increase the overall efficiency of your home and begin to see monthly energy savings.
- Comfort – Often windows are the first thing that comes to people’s minds when they think about air leaks. Although they account for only 20% of an average home’s overall leakage, they are some of the first ones you feel. And when the wind picks up, and the weather gets cold, they can have you reaching for the nearest blanket just to stay warm. Replacing leaky windows can make a major impact on your home’s comfort.
- Convenience – Is washing windows a challenge? If you install new double hung windows you can select a model with a tilt-in sash feature so you can clean both sides of your windows from inside your house. This saves you the hassle of hauling out the ladder or the cost of hiring a window cleaning company.
- Aesthetics – If you have old windows that you replace with bright, fresh new ones, I would bet my last dollar on the fact that you will have many friends and neighbors comment on how great they look. From both the inside and the outside, new windows make your home look newer and cleaner.
- Re-sale Value – According to a 2015 survey of cost versus value done by Remodeling Magazine, replacement windows have an 87.3% return on investment. Although this figure may be less in our current housing market, replacement windows will still yield a higher price for your home, covering a good portion of the cost you invested.
Door and window replacement are a smart investment in your home. Please get in touch with us today to get a free estimate of your energy savings.