In 2023, Princeton researchers tested radiative cooling, keeping a building 3.9°C cooler

In 2023, researchers tested whether a building could be cooler than the air outside while still relying on natural ventilation. The experiment used two insulated boxes in California to study how radiative cooling, thermal mass and temperature-driven airflow could work together without fans or mechanical systems. The test box had an uninsulated aluminium roof covered with a radiative cooling material. According to the study published in Cell, titled ‘Passive radiative cooling to sub-ambient temperatures inside naturally ventilated buildings’, the surface released heat towards the sky, while its underside absorbed heat from inside the box through natural convection. Differences between indoor and outdoor temperatures drove air through the ventilation openings, and thermal mass helped moderate the temperature. During the November experiment, the test box was 3.9°C below the prevailing outdoor temperature, while the reference box was 5.0°C above it. Despite an internal heat source, the test box also maintained nearly seven air changes per hour during the day.How did the cooling roof work with natural ventilationThe test box relied on temperature differences to move air instead of using...