Are you looking to replace your old windows or install new ones and are not sure which product to choose? Today, homeowners have the luxury of choosing from a wide variety of window styles, shapes, sizes and materials that fit any budget. One important thing that you need to keep in mind when shopping for windows is that regardless of what product you choose, it should be energy efficient. These windows are not only environmentally friendly, but will also save you money during the heating and cooling seasons, while improving the comfort of your home. Understanding energy efficiency and its benefits will help you purchase windows that will be a perfect match for your specific needs.
What is an energy efficient window?
Depending on the temperature outside, heat is either gained or lost through the windows of your home. Ideally, a home should be well insulated, minimizing this heat gain or loss. Windows that are able to provide a sufficient level of insulation are considered energy efficient. When shopping for windows, look for the U-factor of each product- it measures the rate of non-solar heat loss or gain through the window. Low U-factors are most desirable, as these windows provide the best insulation and are the most energy efficient. When comparing products, keep in mind that the U-factor can refer to the energy efficiency of the glass alone, or the entire window (this would include the frame material and the spacers). In fact, most manufacturers now offer windows that have special low-E coating on the glass for improved energy efficiency, but many frames and spacers are actually not energy efficient and have a high U-factor. For example, aluminum windows are known to have poor insulation, while fiberglass windows offer superior insulation. You do not want to end up in a situation where you have purchased windows according to the U-factor of the glass and have neglected to pay attention to the material of the window frame itself.
Some windows are designed to not only be energy-efficient, but to also provide “free” heating for your home, by capturing and retaining solar thermal energy in the winter, such as Trombe-wall solar thermal windows. These liquid-filled “windows” can keep the temperature in your home at a reasonably “warm” level, without heat being on, even on a very cold winter day. However, these solar thermal windows are very expensive and the house design needs to be adjusted to avoid “overheating” during the summer months.
Benefits of energy efficient windows
Energy and Cost Savings
If you live in a region with a long winter season and you spend a lot of money on your heating bill, installing energy efficient windows will make a huge difference for your home and your pocket. During the cold months, windows that have poor insulation are the source of significant heat loss, discomfort and increased condensation. By installing windows with a low U-factor, you will have warmer window surfaces, reduced air leakage, and minimal condensation. As a result, you will end up feeling more comfortable inside your home, as well as realize significant financial savings on your monthly heating costs. For example, if you purchase thermally improved windows that have a none-metal frame, have a low-E coating and a low U-factor, you can save up to 25% on your heating costs.
Similarly, you will continue to save money during the summer. Poorly insulated windows are a major source of heat gain, requiring you to spend extra money to keep the AC running overtime, so that the house can be cool. New technology now makes it possible to have energy efficient windows with low-E coatings that reduce solar heat gain, without compromising the view or the amount of incoming daylight.
Reduced requirements for a heating/cooling system for your home
Real-world performance of tripple-pane windows vs double-pane windows:
The beauty and advantage of energy efficient windows is that they not only help lower the monthly heating and cooling costs, but also reduce the peak heating and cooling loads as well. Peak heating and cooling load is the maximum requirement for heating or cooling at one time. The particular peak requirement for your home determines the size of the furnace, heat pump, air conditioner that needs to be installed in your house for thermal comfort. Therefore, by reducing the peak heating and cooling load, energy efficient windows can actually enable you to install a smaller, more economical heating and cooling system in your house. This would be a particularly timely and financially beneficial solution for a home that is being newly constructed.
Increased comfort inside the home
Energy efficient windows can greatly improve the thermal comfort level of your home both during the heating and cooling seasons. During winter months, poorly insulated windows have a cold glass surface, which causes uncomfortable drafts, since the air next to the window is cooled and drops to the floor. Windows that have a low U-factor will have warmer glass surfaces and weatherstripping designed to seal tightly, leading to reduced air leakage and increased thermal comfort inside your home. In the summer, energy efficient windows will not get overheated since the low-E coating will protect the surface from being struck and heated by direct sunlight. Thus, the home’s interior space will also be at a comfortable temperature rather than steaming hot from the incoming solar radiation.
Reduced Condensation and frosting
One of the biggest issues associated with older windows that have poor insulation is condensation and frost, which collect during the heating season. This causes mold and contributes to rotting of window frames if they are made of wood. Energy efficient windows take care of this issue, because they have warmer glass surfaces and special insulating frames. In general, as the U-factor of windows improves, there is a much smaller range of conditions where condensation will occur.
Improved Lighting and View
With energy efficient windows you will no longer have to resort to traditional solutions of tinted glazing or shades on your windows to reduce solar radiation during the cooling season. New window technologies will protect your home from unwanted heat without compromising the amount of daylight or the view from your windows. When shopping, look for products that have a spectrally selective glazing such as low-E coating, or high-performance tints.
Costs for energy-efficient options
Low-E and Argon are now pretty much a standard feature of most replacement and new construction windows, and Low-E is actually a requirement in many states. However there are “premium” features that will increase the cost of your windows – these include:
Triple Glazing, Insulated Frame, Insulated Spacer, Krypton Gas, additional exterior insulators on sashes.
All these additional energy-efficient features are usually found as upgrades to top-of-the-line windows, and not available on mid-range and low – end windows. On average, it will cost you about $50-70 per window to add most of these features, considering you are upgrading from a mid – range window. However, the exact cost depends on too many factors specific to a particular home. Use our replacement windows calculator to estimate the cost of your windows and energy efficiency upgrades.