Passive cooling starts by reducing heat gains. Night ventilation helps only when outdoor conditions allow stored heat to be removed.
Sun and internal gains
Assess glazing by orientation, external shading, occupants and equipment. Low winter heating demand does not guarantee freedom from summer overheating.
Night heat removal
Check temperature difference, available airflow, opening security, noise and outdoor air quality. During hot nights, the cooling potential can be small.
Thermal mass
Exposed heavy surfaces can buffer fluctuations, but stored heat must later be removed. Linings and finishes affect interaction between mass and room air.
MVHR and scenarios
Bypass is useful at favourable temperatures, but normal ventilation flow is not a high-capacity cooling system. Check heat-wave conditions, humidity and any active backup requirement.
Common mistakes
Windows left open through a hot day can add heat. Monthly average temperature alone cannot test peaks; coordinate shading and operating instructions with occupants.
| Item | Parameter | Check / result |
|---|---|---|
| Prevent | Solar gains | Shading |
| Buffer | Thermal mass | Exposed surface |
| Remove | Night air | Conditions and flow |
What this means for your project
Assess summer operation alongside architecture. If passive potential is insufficient, provide controlled cooling rather than promising comfort without calculation.
Sources and scope of review
Related reading
- Insulated Raft Foundation: When It Makes Sense
- Summer Overheating: Why Highly Insulated Homes Can Still Overheat
- Enthalpy or Sensible Heat Exchanger?