Windows are one of the key elements to consider when looking to increase a home’s energy efficiency. Many factors come into play when choosing the right window from climate to desired conservation efforts. Spartan supplied Windows and Doors are energy-efficient solutions. That provide the maximum LEED category points.
Windows are one of the most high-tech products in residential construction. Since the early 1980s, the energy performance of typical windows has increased by more than 50 percent, the result of both improvements in glazing and in frame construction.
The National Fenestration Rating Council (NFRC) publishes the energy performance of certified window products, and in some states manufacturers are required to label their windows with the NFRC’s rating. These ratings are like the EPA mileage rating for cars—they may not provide actual energy consumption in a particular application, but are useful for comparison.
Maximizing thermal performance
The emergence of energy-efficient windows is a key part of a breakthrough in the overall design of houses and light-commercial buildings. Glazed surfaces no longer have to lose a lot of heat or feel cold in winter, so heating systems can be much smaller and less expensive.
Low-e glass coatings, which increase the R-value of standard double-glazing from 2 to about 3, are gaining in market share each year. The premium of 10 to 20 percent for low-e easily pays for itself in a few years in most applications. The added benefit is a warmer window surface that’s more comfortable to be near both in cold weather and in very hot weather. Double low-e coatings on suspended films are available in premium windows, and can increase the center-of-glass insulating value up to R-9.
By careful selection of low-e coatings, windows can be “tuned” to optimize the performance of a structure—balancing heat loss, solar gain, and visible light transmission through the glass. In hot climates, coatings that transmit less solar gain should generally be preferred. In cold climates, where solar gain can be beneficial in winter, glazing that transmits more solar energy is preferable on the south side of a building. On the east and west, less solar gain is preferable even in cold climates, because solar gain is greatest on these orientations during the summer, when air conditioning is likely to be used.
Use of an inert, low-conductivity gas in the space between layers of glazing is another way to improve thermal performance. Most low-e windows have argon gas fill. Some super-energy-efficient windows have krypton or a mix of argon and krypton between the glazing layers.
About window frame materials
Although standard for many years, aluminum windows are disappearing from most cold-climate markets. Vinyl frames are much better than aluminum in terms of thermal performance, but there are some environmental concerns associated with the production and eventual disposal of PVC (polyvinyl chloride). Vinyl windows vary greatly in quality. A particular weakness of vinyl windows is that vinyl expands considerably (more than wood or fiberglass) when heated by sunlight, and many consumers complain about weather-sealing problems over the life of the window due in part to this issue.
Wood windows are still the standard for energy efficiency. Vinyl or aluminum cladding adds value because of its low-maintenance qualities.
With any window materials, durability of the edge seals and spacers that separate the layers of glass is extremely important, as failure of this seal will cause condensation inside the window (fogging), and the loss of any low-conductivity gas fill.
SHOW ME THE MONEY
Spartan will utilize the latest software from AutoCAD to model the different outcomes of your window choices. The most important items to consider are the following:
Energy Savings—Energy savings can be substantial if you go green with windows. By simply replacing old, inefficient models with new ones, you can increase energy efficiency in your home by 30 percent or more.
Low E Windows—Low e coatings can prevent heat loss in winter and reduce heat from entering your home during the summer. Most importantly, low e makes windows much more comfortable all the time. In fact, the right low e coating (it will differ from climate to climate) can make such a significant difference when it comes to improving overall energy efficiency that adding a low e coating to your windows generally pays for itself in a few short years.
Low Conductivity Frames—Aluminum and steel window frames contribute to poor energy efficiency. Purchase wood, vinyl, or fiberglass window frames and opt for insulated frames where applicable.
Window Coverings and Landscaping—Exterior blinds, window awnings, and deciduous trees are all effective ways to reduce solar heat gain during the summer months. Tight fitting, insulated window shades will help trap heat inside during colder times of the year.
Reduce the Need for Artificial Lighting—The more natural light you can let in through windows, skylights, and design features like clerestory windows and light shelves, the less you’ll have to rely on expensive artificial light.