Needs power
A large fan in the ceiling that pulls cool night air in through open windows and pushes the day’s hot air out through the roof space. Night-flush cooling done by machine rather than by opening the right windows, which makes it work on still nights when the passive version does not.
One of 6 ways to meet Active cooling. Build 2/6, Upkeep 3/6, Efficiency not rated. Cost, carbon and footprint below are rated against those 6, not in absolute terms.
A ventilated roof space big enough to take the air it moves, windows that open, and outdoor air that actually goes cold at night. It also needs an insulated shutter, or the opening it cuts through the ceiling leaks heat all winter.
none
Every option in this sub-function, with the value on each axis and a note on what drives it (this solution highlighted):
| Solution | Build skill | Upkeep burden | Efficiency |
|---|---|---|---|
| Night-flush cooling | Basic | 2 | N/A |
| Evaporative cooling | Basic | 2 | N/A |
| Heat pump (air- or ground-source), reversible mode | Specialist | 8 | N/A |
| Night-sky radiative cooling | Intermediate | 4 | N/A |
| Ceiling fan | Basic | 4 | N/A |
| Whole-house fan | Intermediate | 5 | N/A |
Build skill and upkeep burden are proxies (lower burden = simpler to maintain); the efficiency column is this sub-function’s ranking, 1 = best. “N/A” where an axis isn’t rated here.
No build tutorial recorded yet.
No sizing or quantities: how much a technique yields, and how much a household needs, both depend on the build and the people, so the catalogue compares options rather than dimensioning them. It carries no bill of materials and no build sequence, and it is written for an oceanic, clay-soil climate (Normandy, France). Regulatory notes are indicative and need confirming locally.