In days past, windows were responsible for a substantial amount of energy loss in a home. Single-paned windows with clear glass were the worst offenders, and fortunately, they are almost extinct in most modern homes.
Understanding the R-value and U-value of windows
In today’s market, many efficiency-boosting features are available from the high-quality window & door manufacturers. Toronto’s Neufenster windows for example recently introduced high tech European tilt and turn windows to the Canadian market that feature triple-pane glass. These windows, which come in a variety of styles and designs, maintain a high very R-value. The R-value is a measure of the window’s resistance to heat conduction. Higher R-values mean better energy-efficiency.
When shopping for windows, another factor to consider is the U-value. The U-value of a window is a measure of the heat transfer through the glass. In determining the U-value, technicians measure how much heat is lost through a window in one hour.
Most windows will have two U-values. One is a measure of heat loss through the glass, and the other is a measure of heat loss throughout the entire window and frame. The lower the U-value, the better the window is at reducing heat loss.
How to know if a window is energy-efficient
Double-paned glazed windows with insulation between the panes have become the new standard for windows in most homes today. While these windows offer a marked improvement over the older single-paned windows, designers and homeowners are now putting more effort into making homes more energy-efficient than ever before.
The double-paned glazed windows typically held an R-value of about three. New, high-efficiency windows have an R-value of five. The increase in the R-value from three to five can reduce heat loss by thirty to forty percent.
The goal for high-efficiency windows is to have them become as energy-efficient as the wall on to which they are installed. Most experts in the field of energy-saving in home and building designs feel that an R-value of five should be the new minimum, and companies that make windows should shoot for an R-value of seven.
The best windows for high-efficiency
- European windows—High energy costs in Europe have prompted the design of windows that maximize the natural resources of sun and air. European windows have to meet higher standards in both quality and energy-efficiency, and most are made to reduce the ecological footprint of the building in which they are used.
- Horizontal slider windows—The lack of complicated moving parts make horizontal slider windows some of the most energy-efficient windows on the market. The windows close tightly, blocking air and noise infiltration from outside. Insulation between the panes, and spacers used to insulate against the flow of cold air, help keep homes warmer in the winter and cooler in the summer.
- Casement windows—casement windows open fully, allowing more ventilation options than other types of windows. Many casement windows are now made with low-E glass, which is a microscopic layer of coating that reflects sunlight, reducing solar heat gain in the summer months. These windows also come with a non-toxic gas infill between the triple panes of glass. The gas acts as a powerful insulator, doubling the energy efficiency for a minimal extra cost.
- Picture windows—picture windows are fixed in place, without the ability to open or close. Because the seal is permanent and no part of the window moves, picture windows are among the most energy-efficient windows available. Double or triple-paned glass, with gas insulation between the panes, makes these windows perfect for letting in tons of natural light without sacrificing an energy loss.
- Sliding doors—these doors serve a dual function. They act as doors that give access to the outdoors but also function as a window offering a view and unobstructed natural light. With the proper coating, gas insulation, and high-quality weather stripping, sliding doors can also meet rigorous energy-saving standards.
Are high-energy efficient windows worth the cost?
Energy-efficient windows can make a dramatic difference in your energy cost, and most will pay for themselves many times over in energy savings. As homeowners become more ecologically aware, high-efficiency windows also add substantial value to a home.
A one-time federal tax credit is also available to homeowners who take steps to improve the overall energy efficiency of their homes. The tax incentive is meant to offer a more immediate offset of some of the cost-saving energy use in existing homes.
The energy used to heat and cool residences creates a significant environmental price-tag. Reducing the amount of energy consumed is better for the environment. Environmentally responsible consumers are drawn to measures they can take to save energy consumption, not just to save money, but to reduce the ecological footprint of their homes.