Dorit Aviv, Zherui Wang, Forrest Meggers, Aletheia Ida
A radiatively cooled translucent building skin is developed for desert climates, constructed out of pockets of high heat-capacity liquids. The liquids are contained by a wavelength-selective membrane enclosure, which is transmissive in the infrared range of electromagnetic radiation but reflective in the shortwave range, and therefore prevents overheating from solar radiation and at the same time allows for passive cooling through exposure of its thermal mass to the desert sky. To assess the relationship between the form and performance of this envelope design, we develop a feedback loop between computational simulations, analytical models, and physical tests. We conduct a series of simulations and bench-scale experiments to determine the thermal behavior of the proposed skin and its cooling potential. Several materials are considered for their thermal storage capacity. Hydrogel cast into membrane enclosures is tested in real climate conditions. Slurry phase change materials (PCM) are also considered for their additional heat storage capacity. Challenges of membrane welding patterns and nonuniform expansion of the membrane due to the weight of the enclosed liquid are examined in both digital simulations and physical experiments. A workflow is proposed between the radiation analysis based on climate data, the formfinding simulations of the elastic membrane under the liquid weight, and the thermal storage capacity of the overall skin.
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