Night-sky radiative cooling

Needs power

A surface facing the open sky loses heat by radiating it upward, and on a clear night it can fall below the air temperature around it. Circulating water or air past such a panel after dark carries that cooling into the house. It needs a clear sky to work: cloud reflects the radiation back.

One of 6 ways to meet Active cooling. Build 2/6, Upkeep 2/6, Efficiency not rated. Cost, carbon and footprint below are rated against those 6, not in absolute terms.

Cost: Medium
Upkeep: Occasional
Skill to build: Intermediate
Lifespan: As long as the panel and its circulation loop; the sky does not wear out
Embodied carbon: Low
Space / material use: Medium
Output timing: Weather/time-dependent
Skill to repair: Basic

What your site needs

A roof or ground area with an unobstructed view of the sky, and a climate with clear nights in the season you want cooling. Under the cloudy summer nights of an oceanic climate this gives back much less than it does in a dry one.

Inputs

none

Outputs

none

Ranking in its sub-function out of 6 alternatives

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.

Sources

Building America Solution Center, "Passive and Low-Energy Cooling" (Pacific Northwest National Laboratory / US DOE): cooling by "thermal radiation to the sky and outer space" at night

Tutorials

No build tutorial recorded yet.

What this page does not tell you

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.