Your air conditioner works hard to cool your home, but poor insulation can undo much of that work. Understanding the relationship between insulation and cooling helps you make smart improvements that pay for themselves.
How Heat Enters Your Home
Roof (40-50% of heat gain)
The roof receives direct sunlight all day, making it the biggest source of heat infiltration. An uninsulated roof can be 20-30°C hotter than ambient temperature.
Walls (25-30% of heat gain)
West and east-facing walls receive direct afternoon and morning sun. Dark-colored walls absorb more heat.
Windows (15-25% of heat gain)
Single-pane windows and those facing the sun are major heat sources. Glass conducts heat efficiently.
Gaps and Cracks (5-10% of heat gain)
Air leaks around doors, windows, and through the building envelope allow hot outside air to enter.
Impact on AC Performance
For every degree of temperature difference between inside and outside, heat flows faster into poorly insulated spaces. This means:
- AC runs longer to maintain temperature
- Compressor cycles more frequently
- Electricity bills increase 30-50%
- AC wears out faster
Signs of Poor Insulation
- Hot spots on walls or ceiling
- AC struggles on very hot days
- Rooms heat up quickly when AC is off
- Significant temperature difference between rooms
Cost-Effective Improvements
- Roof insulation: Best ROI, reduces heat gain 40%+
- Window films: Cheap, reduces solar heat 30%
- Curtains/blinds: Block direct sunlight
- Weather stripping: Seal air leaks cheaply
Calculate Your Savings
Use our Insulation Impact Calculator to see how much you could save with better insulation, and BTU Calculator to right-size your AC for improved conditions.