Windows are the eyes of your home, providing sunlight and hopefully spectacular views. But if your windows are not very energy-efficient, the heat loss from them may be costing you in utility bills, besides feeling the uncomfortable chill of sitting beside such windows on a cold winter day.
But not to worry – with emerging technologies, there is a wide range of window choices that will match both the artistic tastes and energy efficiency aspirations of homeowners and architects alike. There are many aspects to consider when selecting a window and each one affects energy efficiency:
• Operator Type: This aspect refers to the physical design of the window. Windows are either fixed or operable. Traditional operable windows include projected or hinged types while sliding windows include double-hung, single-hung, and horizontal sliding. In contrast, fixed windows are not able to be opened, thus they are more energy efficient by being more airtight.
• Frame Types: The material used for the frame impacts the frame thickness, weight, and durability. Each characteristic impacts the thermal properties of the window. Some windows may use frame material that easily conducts heat, such as aluminum. Materials like wood, vinyl, or hybrids are much better at preventing heat transfer, however they will require more maintenance compared to aluminum.
• Glazing Type: Glazing seeks to reduce the amount of heat transmission especially via sunlight Glazing is accomplished via three different approaches. The first is by changing the chemical composition of the glass material. The second is by applying a coating to glaze over the surface. The third approach is to assemble various layers of glass. Low-emissivity coatings are becoming increasingly popular. Windows manufactured with this type of glazing typically cost about 10% to 15% more than regular windows, however, they reduce energy loss by as much as 30% – 50%.
• Gas Fills: This aspect of windows is closely related to glazing. When adding various layers of glazing, conductance of air between the layers is reduced to improve thermal performance. A common option for gas-fill is argon. The gas is inert, nontoxic, nonreactive, clear, and odorless, making it an ideal candidate as gas fill for windows with multiple layers of glazing.
• Spacers: The layers of glazing are held apart at designated distances by spacers. Warm edge spacers are becoming more prominent as manufacturers start prioritizing high-performance glazing.
Understanding every aspect of building a window is a true journey in energy efficiency. A U-factor is used to measure the efficiency of a window (sometimes R-value is used, which is the reciprocal of the U-factor). U-factor measures the rate at which heat flows through a window – the lower the U-factor, the slower is the heat transfer, hence the higher is the energy efficiency of that window. These values enable you to make an apples-to-apples comparison of energy efficiency when comparing different window designs.
Over the years, every component of the window has seen advances in technology, making windows more energy efficient. Once the least insulated portion of a home, windows continue to evolve and improve. New technologies have recently emerged in the form of evacuated windows and insulation-filled glazings.
• Evacuated windows seek to provide the perfect vacuum between glazing layers. With no gas to transfer heat, a vacuum is an ideal form of insulation.
• Insulation-filled glazings rely on highly insulating materials such as aerogel, honeycombs, and capillary tubes between glazings. The purpose of these materials is to diffuse light particles while trapping air.
Well-built windows provide insulation, driving down utility bills. Whether it’s the frame design or the gas-fill composition, each window feature is an important decision that will impact the energy-efficiency of your home for years to come. We would love to hear about how much your energy-efficient windows are saving you each month at firstname.lastname@example.org or 404-303-7280.