Action first
Why is my room hotter than outside?
Short answer
Stored heat, sunlight through glass, equipment and weak ventilation can keep indoor temperature above the outdoor reading.
What to do
- ✓Open safe windows when outside is cooler.
- ✓Use a fan to help warm air leave.
- ✓Turn off internal heat sources.
- ✓Continue ventilation long enough to cool the building fabric.
Why it works
This advice follows UK Health Security Agency guidance and the underlying principles of thermal mass and internal heat.
Important exceptions
Safety, health, weather and the design of your home can change what is appropriate. Stop if an action makes conditions worse.
Related guides
Sources & evidence
Reviewed 2026-08-21
- UK Health Security Agency: Beat the heat: keep cool at home checklist ↗
Supports: Shading, ventilation, reducing indoor heat and protecting people at higher risk.
official guidance · Accessed 2026-08-21