Passive solar and natural cooling: Resources and labour

Ordinary materials, clever placement, and some water

What this tab covers The natural resources (land, water, materials, fuel or feedstock) and the labour needed to capture this energy, per unit, with the reason each is needed.

Passive techniques mostly use ordinary building materials arranged with care. The main exceptions are water for evaporative coolers and deep-water pipelines for seawater cooling. No per-unit job figures were found.

Natural resources

Resource	How much	Why it is needed
Thermal mass (masonry, concrete, earth, water)	20 cm of concrete masonry in the Zion Trombe wall, delaying heat by 8-10 hours⁶	Dense materials store much heat per degree, smoothing heat flows between day and night.
Glass	Transmits 84-95% of sunlight per pane¹	Admits sunlight while blocking the longer-wave infrared emitted indoors.
Water (evaporative coolers)	About 2,980-12,457 gallons (11-47 m3, calculated) a year for a 1,500 square foot New Mexico home; bleed-off adds 10-50%³	Cooling comes from evaporation; bleed-off flushes out minerals.
Air movement	20-40 air changes per hour for evaporative systems³	Large air volumes must carry heat away.
Deep cold water and pipelines (seawater cooling)	Intake about 900 m deep; USD 16.5-70 million per project⁵	Only deep water is cold enough to chill buildings directly.
Reflective coatings (radiative cooling)	About 97% solar reflectance⁴	Any sunlight absorbed would outweigh the small heat radiated to the sky.

Labour

Phase	How much	Skills	Why it is needed
Design	No figure in the sources used²	Architects and building-physics engineers	Orientation, windows and shading fix passive performance at the design stage.
Construction	No figure in the sources used⁵	Masons, glaziers, carpenters; marine engineers for seawater systems	Shading and thermal mass depend on careful building work.
Operation and maintenance	Evaporative pads flushed every 8-12 operating hours (auto-flush)³	Building users and maintenance staff	Pads clog with minerals; occupants must open and shade windows at the right times.

Sources

Solar Collectors (workshop lecture, W. Weiss, AEE INTEC) Centre for Renewable and Sustainable Energy Studies, Stellenbosch University, 2013
Buildings Decarbonisation Report: Summary, Cooling Energy Transitions Commission, 2025
Evaporative Cooling Systems (Building America Solution Center) Pacific Northwest National Laboratory / US Department of Energy, 2024
Passive radiative cooling below ambient air temperature under direct sunlight (Raman, Anoma, Zhu, Rephaeli and Fan, Nature 515, 540-544) Nature, 2014
Sustainable cooling: a deep dive into seawater air-conditioning solutions for the Caribbean World Bank Blogs, 2024
Trombe Walls in Low-Energy Buildings: Practical Experiences (Torcellini and Pless, NREL/CP-550-36277) National Renewable Energy Laboratory, 2004