The following information is an example of energy and cost savings for Boston and Phoenix. See the sidebar to the right for information on energy use for generic window products in your city or region.
Heating Season Savings
In climates with a significant heating season, non-energy efficient windows can represent a major source of unwanted heat loss, discomfort, and condensation problems. In recent decades, windows have undergone a technological revolution. It is now possible to have lower heat loss, less air leakage, and warmer window surfaces that improve comfort and minimize condensation. The graphs below illustrate the simulated savings in heating season costs associated with energy efficient windows for a typical house in a heating-dominated climate. The savings shown do not include possible savings from reduced air leakage. Depending on the condition of the old windows in an existing home, the savings can be higher if window replacement leads to long-term air leakage reduction.
Cooling Season Savings
In climates that mainly require cooling, non-energy efficient windows can be a major source of unwanted heat gain. In recent years, low-E coatings that reject solar heat without darkening the glass have undergone a technological revolution. It is now possible to significantly reduce solar heat gain and improve comfort while providing clear views and daylight. The graph below illustrates the simulated savings in cooling season costs associated with improved windows for a house in a cooling-dominated climate. The savings shown do not include possible savings from reduced air leakage. Depending on the condition of the old windows in an existing home, the savings can be higher if window replacement leads to long-term air leakage reduction.
Using a whole-house fan properly can lower heating and cooling costs, reduce indoor allergens, and freshen the atmosphere of your home. Whole-house fans work by moving hot air out through gables or vents and drawing cooler air in. Whole-house fans therefore don't work very well when the outdoor temperature is much higher than the indoor temperature or when the outdoor humidity is high. New products have temperature and humidity sensors to add comfort.