The following information is an example of energy and cost savings for Boston and Phoenix.

Heating Season Savings:

In climates with a significant heating season, windows have represented a major source of unwanted heat loss, discomfort, and condensation problems. In recent years, 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 graph below illustrates the significant savings in heating season costs associated with energy efficient windows for a house in a heating-dominated climate. In cold regions, this means that windows are no longer an energy loser to be avoided -- increasing glazing area with high performance windows can have little or no affect on total energy use.

Cooling Season Savings:

In climates that mainly require cooling, windows have represented a major source of unwanted heat gain. In recent years, windows 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 significant savings in cooling season costs associated with improved windows for a house in a cooling-dominated climate. In warm regions, this means that high performance windows can face into the sun if desired without great energy penalties -- although shading techniques remain important.