A thermal camera is one of the quickest ways to see where a home is losing heat. Done right, a walk-through can point you to missing insulation, drafty gaps and poorly sealed doors and windows.
Pick the right conditions
- Temperature difference. You need a gap between indoor and outdoor air. A difference of roughly 15°F (8°C) or more works, and bigger is better.
- Avoid the sun. Sunlight warms exterior surfaces and hides real patterns. Scan early in the morning or after dark.
- Wind and rain. Calm, dry weather gives the clearest results.
Scan the inside first
Heating season is easiest: scan interior walls, ceilings and corners. Cold patches on a heated room's walls often mean missing or settled insulation, gaps, or thermal bridging through studs. Look closely at:
- Window and door frames
- Outlets and switches on exterior walls
- Ceiling and attic hatch edges
- Where walls meet the ceiling and floor
- Recessed lights
Then check the outside
From outdoors in winter, warm spots can show where heat escapes: around windows, under eaves, and near the foundation or sill plate. Take a visible-light photo of each spot too, so you know exactly what you were looking at.
Make a few safe tests
To exaggerate air leaks, some auditors run a bathroom or kitchen exhaust fan to slightly depressurize the house and then re-scan. Cold streaks that appear along edges usually point to infiltration.
Record and prioritise
Note each finding with a photo, thermal image, location and rough severity. Air sealing gaps and fixing obvious insulation voids are often the cheapest, highest-return fixes.
What equipment you need
A 256×192 camera is plenty for most homes. Both phone and handheld options work. See handheld vs phone cameras to choose, and use our buyer's guide for matching specs to the job.