Energy Efficiency Can Be Enhanced

Between 25 and 50 percent of energy used in a home or business goes right out the windows & the glass doors... Literally.

That’s because, in most of these facilities, windows & sliding glass doors provide the biggest openings between ambient indoor air and the elements outside, and the biggest opportunity for valuable energy to escape.

Windows & Sliding Glass Doors are often the only protection against unwanted heat gain in the summer and heat loss in the winter. Modern window frames cut air infiltration down to almost zero and, when used with advanced glazing, can slash up to 40 percent off your heating and cooling bills.

As many property owners and managers are seeking ways to save on energy bills and reduce their impact on the environment, Bella Luna Services, Inc. can help by installing industry-leading Windows & Sliding Glass Doors.

As recently as 20 years ago, the windows in most homes held a single pane of glass. But for an average-size house, those same windows today can result in significant losses: Single-glazed windows in a cold -climate house would result in a yearly energy bill of about $800, and in a warm-climate house, the energy bill would be about $850, according to recent industry statistics. Recent reports reveal that today's high-tech double glazing would reduce annual energy costs in these same houses to about $450 and $500, respectively.

Most of those savings come from two techniques manufacturers use to make double glazing more efficient: low-e coatings and inert gases that fill the spaces between the panes. Low-e coatings were first developed to stop heat loss; newer coatings also stop heat gain where cooling is the key consideration. These coatings usually add 10 to 15 percent to the cost of a window.

Low-E Coatings: Low-emittance (Low-E) coating are microscopically thin, virtually invisible, metal or metallic oxide layers deposited on a window or skylight glazing surface primarily to reduce the U-factor by suppressing radiative heat flow. The principal mechanism of heat transfer in multilayer glazing is thermal radiation from a warm pane of glass to a cooler pane. Coating a glass surface with a low-emittance material and facing that coating into the gap between the glass layers blocks a significant amount of this radiant heat transfer, thus lowering the total heat flow through the window. Low-E coatings are transparent to visible light. Different types of Low-E coatings have been designed to allow for high solar gain, moderate solar gain, or low solar gain.

Rating Systems: A rating system developed by the National Fenestration Rating Council (NFRC) makes gauging the efficiency of a window quick and easy. A label on each window includes its U-value; its solar heat gain coefficient (SHGC), which tells how much heat it lets in; and its visible light transmittance. If you want to cut energy loss during the heating season, look for windows with low U-values. For optimal cooling, go with units that have a low SHGC but let in plenty of visible light.

You can avoid these ratings comparisons altogether by shopping for windows that carry the Energy Star label. Developed by the U.S. Department of Energy and the Environmental Protection Agency, the program tags the most energy-efficient windows. It also targets requirements to specific climates. Windows that meet these energy requirements are 15 to 40 percent more efficient than those that meet typical building codes.

Energy Star Windows: What Does the Rating Mean?

Although you have likely heard the term used before, many homeowners remain in the dark as to what choosing Energy Star windows truly entails. A joint effort of the EPA and US Department of Energy, an Energy Star rating can be given to a variety of products, ranging from kitchen appliances to siding, and use of these products can even earn you . Energy Star windows are rated on two features: U-Factor, which is a measure of how well it insulates heat, and SHGC, which is a measure of the fraction of incident solar radiation, basically meaning how much sunlight it lets through. Both are rated on a scale of zero to one, with zero meaning 100% effective and one meaning it does not insulate or protect at all.

Some of the features that make Energy Star windows more efficient and affect these ratings include:

• Low-E Glass
• Better Materials for Frames
• Gas Fills
• More than One Pane of Glass
• Steel, Foam, Fiberglass, and Vinyl Warm Edge Spacers

When you’re choosing Energy Star windows, it’s important to recognize that the criteria for Energy Star products vary throughout the four US climate zones. Florida is classified in the “Southern” zone, and our energy needs are “mostly cooling.” What this classification means is that our Energy Star windows must be extremely adept at cooling, but they may not necessarily be fit for use in Northern states, which also require protection from winter weather.

For replacement windows to have an Energy Star rating in Florida, they must have a U-Factor of no greater than 0.65 and an SHGC of no more than 0.40, meaning they must provide substantial protection against solar radiation, but they do not have to be especially effective at keeping heat in the home.

These requirements are in contrast with those for Energy Star windows in the Northern climate zone, which necessitate a U-Factor of no greater than 0.35 and can have any SHGC, meaning they must provide exceptional insulation of heat, but they can let any amount of solar radiation through.

In cooling-dominated areas, U-values of 0.75 and an SHGC of 0.40 or below are required. In heating dominated areas, U-values of 0.35 or below are required while there is no SHGC requirement. And in areas with mixed heating and cooling needs, U-values of 0.40 or below and SHGCs of 0.55 or below are required. (The determination for a heating-dominated climate means at least 70 percent of heating and cooling costs go to heating. In a cooling-dominated climate, at least 70 percent of heating and cooling costs go to cooling. In a mixed climate, at least 30 percent of heating and cooling costs go to each.)

Another program helps ensure that wood, vinyl and aluminum windows meet minimum structural standards. Developed by the American Architectural Manufacturers Association in conjunction with the National Wood Window and Door Association, this non-mandatory program puts windows through their paces with a series of performance tests. Windows that pass the tests are
granted a certification sticker.