Window insulation can be approached in two ways: through the windows themselves and through window coverings. In this short guide, we’re going to offer an introduction to both of these methods and help you get a foundational knowledge of window insulation. Insulated windows are a powerful asset for every home, being useful in both cold and warm climates. In a warm climate, high-performance windows are particularly useful as the temperature climbs towards 100°F. Good windows help in keeping the inside temperature to a more comfortable level. U-factor The most effective insulating windows have a low U-factor, and a high R-value.