FAQ
What causes condensation to form between the glass panes of double-hung windows?
Inter-pane condensation occurs when the perimeter seal of an Insulated Glass Unit deteriorates, allowing ambient humid air to penetrate the space between the lites. Once the desiccant material inside the spacer bar becomes fully saturated, moisture fogs the interior glass surfaces. This indicates permanent seal failure and the loss of insulating gas, requiring glass unit or sash replacement.
How much money will I save by upgrading old single-pane windows to modern units?
Replacing single-pane clear glass windows with ENERGY STAR certified Version 7.0 models typically cuts annual household utility bills by 12% to 13% nationwide. Depending on your home’s square footage, local energy rates, and regional climate, annual utility savings generally range from $100 to well over $500.
Can I claim a federal tax credit when replacing inefficient residential windows?
Yes. Under the Section 25C Energy Efficient Home Improvement Credit, homeowners who install eligible ENERGY STAR certified exterior windows and skylights can claim a 30% federal tax credit on the product cost, capped at a maximum of $600 per tax year.
Is it better to repair drafty windows with caulk and weatherstripping or replace them entirely?
If your window frames are structurally sound, plumb, and free of rot, replacing cracked weatherstripping, adjusting sash locks, and recaulking perimeter trim resolves minor air drafts cost-effectively. However, if the frames are rotted, sashes are severely warped, or double-pane seals have failed across multiple units, full window replacement is the only permanent solution for restoring energy efficiency.
What is the difference between U-factor and SHGC ratings on window performance labels?
The U-factor measures the rate of non-solar heat transfer through the total window assembly; lower numbers indicate better insulating capability against winter heat loss. The Solar Heat Gain Coefficient measures the fraction of solar radiation admitted through the glass; lower numbers indicate superior protection against summer heat gain.
