The National Fenestration Rating Council (NFRC) energy performance label can help you determine how well a product will perform to help keep your home cool in the summer, warm in the winter and block out unwanted elements like wind, rain and ultraviolet rays.
By using the information contained on the label, builders and consumers can reliably compare one product with another, and make informed decisions about the windows, doors, and skylights they buy.
NFRC adopted a new energy performance label in 1998. It lists the Manufacturer, describes the product, provides a source for additional Information and included ratings for one or more energy performance Characteristics.
NFRC rates all products in two standard sizes so that consumers and others Can be sure they are comparing products of the same size. On the label, these Two sizes are listed as “Res” (Residential) and “Non-Res” (Non-residentail).
U-factor measures how well a product prevents heat from escaping. The rate of heat loss is indicated in terms of the U-factor (U-value) of a window assembly. U-factor ratings generally fall between 0.20 and 1.20. The insulating value is indicated by the R-value which is the inverse of the U-value. The lower the U-value, the greater a windows resistance to heat flow and the better its insulating value.
Solar Heat Gain Coefficient (SHGC) measures how well a product blocks heat caused by sunlight. The SHGC is the fraction of incident solar radiation admitted through a window, both admitted through a window, both directly transmitted, and absorbed and subsequently released inward. SHGC is expressed as a number between 0 and 1. The lower a windows solar heat gain coefficient, the less solar heat it transmits.
Visible Transmittance (VT) measures how much light comes through a product. The visible transmittance is an optical property that indicated the amount of visible light transmitted. VT is expressed as a number between 0 and 1. The higher the VT, the more light is transmitted.
There are several factors that make today’s windows more efficient than the older single paned windows. The material that makes up today’s windows has a lot to do with energy efficiency. For example, the majority of windows sold in The United States have a vinyl or wooden frame, dual paned glass, and special energy efficient coating called LoE2 and even newer LoE3.
Spectrally selective glazing is window glass that has been treated to allow the Visible spectrum of light to pass into a home but blocks the other spectrums- both infared (IR) and ultraviolet (UV).
Spectral selectivity is achieved by a microscopically thin, Low-Emisivity (LoE) Coating on the glass or on a film applied to the glass.
“LoE” is a term used by the window industry, which stands for “Spectrally-selective Low Emisitivy.”
Spectrally selective glazing screens out (or reflects) heat-generating ultraviolet and infrared radiation arriving at a homes exterior window surface while permitting most visible light to enter.
This type of glazing can transmit a high proportion of the visible solar radiation (sunlight), but screen up to 95% of the ultra violet radiation.
This results in a low transmission of radiant heat from the sun, and reduces the need to cool home interiors.
LoE insulates up to 100% better than ordinary glass, yet it’s practically invisible. Home occupants appreciate the clear view and natural light of LoE and the ability to sit in direct sunlight without becoming uncomfortably warm.
LOE increases the windows ability to reflect infrared radiation, which Reduces energy loss from a warm room, which means that heat is reflected back into your rooms when it’s cooler outside.
Windows with LOE coatings may cost 10 – 15 % more than traditional Windows, but their energy loss is reduced by 30-50%.
It has been proven that windows with a high solar heat gain, can account for more that 50% of air conditioning costs. LOE was engineered and designed to allow daylight to come through the window, but filters out the solar heat, and harmful UV rays.
For years LoE2 squared was the standard for energy efficient window. LoE2 is a double layer of Silver applied to the inside of the outside pane of glass. The Latest advancement in the glass industry is LoE3 cubed. LoE3 is a triple layer of Silver that lowers the windows SHGC (Solar Heat Gain) by 33% and blocks out 95% of the Ultra Violet rays. This means there will be less heat and damaging UV rays entering your home.
Double-glazed, or insulated, windows are the standard for window technology today. Basically, a double-glazed window contains two layers of glass combined together for greater energy efficiency.
Glass is highly conductive, which means single-pane windows let heat pour out of a room. By trapping air between two panes of glass, the thermal resistance Is more than doubled-a simple enough solution that the majority of windows in The U.S. is now manufactured with insulating glass.
Good quality, double-glazed windows are generally more expensive than single-glazed windows because of the complexity of manufacturing. You will Find that the insulation value they provide justifies the additional cost.
It becomes obvious that improvements need to be made because of the wear and tear over a long period of time to your home.
For most homeowners with homes over 20 years old, the following are typically on the list of home improvements projects.
Homeowners have choices to make when it comes to home improvement project. Replacing old windows can have an immediate impact on your energy saving efforts.
If you are making a list of home improvement priorities, window replacements may be the only improvement that can actually provide a return on your investment and have an impact on your budget right away.
With improved energy efficiency, you can reduce your electricity bills in summer and in winter months.
This means your electricity and gas bill will be lower than in previous years. You will also find that your home will have a more even temperature all year round, making your family more comfortable.
If you are in the market to purchase or replace windows, there are some Important questions to ask the prospective window contractor.
For your protection against unscrupulous contractors, it is important to get these questions answered before you sign on the dotted line.