06/26/2026
AC running all day but your house is still hot?
Your HVAC probably isn't the problem. Your windows are.
THE REAL ISSUE:
Solar heat gain—sunlight passing through glass and converting to heat inside your home—accounts for 25-30% of residential cooling load (U.S. Department of Energy).
Your AC removes heat. But windows keep adding it—often faster than the system can remove it.
WHY AFTERNOONS ARE WORST:
South/west windows + peak solar intensity + hottest outdoor temps = your AC fighting a losing battle
It runs constantly not because it's broken—because it's outmatched.
WHY BLINDS DON'T FULLY WORK:
Solar energy passes through glass before hitting your blind. Heat is already inside. Blinds reduce intensity but don't prevent the heat from entering in the first place.
SYMPTOMS YOUR WINDOWS ARE THE PROBLEM:
→ Hottest rooms face south or west → Heat is worst near windows, cooler toward interior walls → Discomfort peaks in the afternoon → AC runs constantly but never quite catches up
THE DIFFERENCE:
Running AC harder = treating symptoms (removing heat already inside) Solar control at the window = treating the source (stopping heat before it enters)
Window film reduces the solar energy passing through glass, so your AC has less work to do from the start.
Stop cooling the sun. Start controlling it.
https://www.coolvu.com/blog/hot-house-with-ac-on-solar-heat-gain-windows/
