Installing energy efficient windows is essential when building an insulated building envelope. The ability of your home to keep cool air in during the summer months, and out during the winter, is key to making your home more efficient. Energy efficient homes save homeowners fistfuls of cash on their utility bills, and have the added bonus of helping to save our planet. That makes you a superhero, albeit a thrifty one.
Energy efficient windows are more expensive than conventional or double glazed windows. They will pay for themselves in no time, but you must select windows that best suit your needs. Deciphering the labels on your windows of choice will help. Labels provide information on the characteristics of the glass and the frame material. The label also provides you with the window’s energy performance data. The energy performance is expressed as a U-factor. The lower the U-factor value, the higher the rate of insulation. You can consult the Energy Star® chart for the ideal rating for your hometown. Generally warmer climes in southern and western Canada can use windows with a U-factor rating of 1.80 to 1.60. The colder central and northern areas need windows with U-factors of 1.40 to 1.20. Adding windows with an appropriate U-factor can save you 7 to 12 percent on your current energy costs.
Check your window labels to ensure that they are Energy Star® rated. This rating is necessary for you to receive a rebate from the government for the costs associated with installing a more efficient window system. These ecoENERGY rebates are provided as an incentive to homeowners to decrease energy consumption.
Your label will also give you a SHGC value. SHGC is the solar heat gain coefficient or the amount of solar energy that the window lets in. The lower the number, the less heat is allowed to pass into the home’s interior. Cold climates require windows with an SHGC range of 0.39 to 0.65. You can select windows with different SHGC values, depending on the direction the window faces, to maximise effect while reducing cost.
The AL rating refers to the rate at which air leaks from the window system. Choose windows with low AL ratings, preferably below 0.30.
Types of Windows
Double pane; you know these guys well — two panes of glass with a small air gap that slows heat transfer. You probably know their more advanced, gas-filled cousins too. These babies are filled with krypton or argon which provides more insulation. Modern advances have added window coatings to make ‘low-e’ windows. Low-e windows with solar coatings are also double paned and gas filled, but the coatings reflect heat back into the interior of your home. The coating helps to keep out summer sun while still letting the winter rays in. This is made possible by the different angles at which light hits the window in different seasons.
Using advanced green technology windows to reduce your bills will really make a difference. Replacing all your windows can be very costly. Consider doing only a few at a time. The coatings can be retrofitted to existing double pane windows at a reduced cost. If replacing your windows is out of the question, there are many cost-effective ways to making them more efficient. Retractable canopies and blinds will reduce heat during the summer, and can be retracted to let in the warmth of the sun during winter. Plant deciduous vines, shrubs or trees outside your windows. They will provide shade in the summer. In the winter they will lose their leaves and let the sun in. Caulk windows to prevent drafts and the loss of warm air. Everything you do to limit energy consumption will save you money and reduce green house gas emissions.