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Gerrard, Kyle

University of British Columbia

Radiant sky cooling offers a sustainable solution for improving thermal comfort in semitransient public spaces, such as outdoor seating areas, open-air corridors, and transit stations. By optimizing the material spectral emissivity, it is possible to limit solar heat gains and emit strongly through the atmosphere to deep space to achieve a net-negative heat balance and cool a surface below ambient temperatures even in direct sunlight. This work explores the potential of radiant sky cooling to mitigate heat stress without using electricity or actively conditioning a controlled air volume. Through a 2-month field test of a full-size 4’x4’ custom radiant cooling panel this study was able to examine the efficacy of the Radi-Cool commercial radiant film product and calibrate thermal models for use in design planning. A Phase Change Material (PCM) was also synthesized and tested, then added to the underside of the cooling panel to explore the performance benefits of such a material in maintaining adequately low daytime temperatures. The performance of the cooling panel was also compared against a typical urban tree canopy to assess whether a cooling structure based on a similar panel could be a viable alternative to vegetation for decreasing the mean radiant temperature (MRT) experienced by an occupant. Results indicate that a PCM is an excellent candidate to enhance radiant sky-cooling due to its high thermal mass to weight ratio and ability to extend time in desired temperature ranges. The calibrated thermal model also allows the potential for designers to test better performing materials, different orientations and tilts, and assesses real-world factors such as surface fouling and convective losses. This work demonstrates that radiant sky cooling is a viable, low-energy intervention for enhancing the thermal experience in semi-outdoor environments, contributing to sustainable urban cooling strategies.

Text

2025-05-02

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/90956

Mechanical Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/