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While it might take several years for new windows to repay in energy cost savings, the further benefits in terms of additional comfort, decreased body heat radiation to cold glass, airflow, and enhanced performance may make the investment worthwhile to you. Having said that other energy improvements – including insulation, weatherstripping and caulking, air sealing, insulating duct work, and an energy audit – typically reduce energy usage and supply superior returns for the dollar invested. It’s thus extremely important that you do the simple home weatherization before replacing the present windows.

Performance Measures

The reduced the U-factor, the lower the amount of heat loss, and the greater the item is at insulating. U-factors typically vary from about 0.20 to 1.20. Start looking for windows that give the value for the complete window and not only the middle of the glass.

R-value: The R-value is a dimension of a product’s resistance to heat loss or conductivity – higher R-value substances are more energy efficient with increased resistance to heat flow and greater insulative values.

The lower the SHGC, the better the solution or window is at blocking unwanted solar heat gain, which can be important in hot summers.

The higher the VT, the more complex the daylighting. The visible light transmittance ought to be higher or over 60% to 80% if the focus is on daylighting.

Condensation resistance: Condensation resistance (CR) measures the resistance to the creation of condensation. Higher numbers mean the item is better at resisting condensation. The evaluation is optional.

Air leakage: Air leakage (AL) measures how much outside air comes into a house through a good or window. The lower the air leakage value, the better the window will keep air out if it’s properly installed. Window labels may not demonstrate the AL rating since it’s optional.

When choosing windows, consider the sort of window, or design. Each has specific characteristics that may influence air infiltration.

Awning windows provide excellent ventilation when opened. When awning windows have an excellent gasket around the window, and it’s closed and secured, this kind of window offers good protection against air infiltration.