Evolving from an indirect evaporative cooling system to a radiant-capacitive heating and cooling system for low-mass buildings

Abstract

The study shows the development of a novel passive cooling system parting from previous experience gathered with an Indirect Evaporative Passive Cooling System (IEPCS), originally employed in a low-income dwelling located in the hot-humid climate of Maracaibo, Venezuela. Using the design thinking approach, we optimized the original passive cooling system so as to curb some limitations observed in the IEPCS, and developed a novel passive cooling and heating system more suitable to refurbishment schemes of low-mass dwellings in tropical areas. We present comparative results from test runs in small-sized test cells for the subtropical climatic conditions of Curitiba, Brazil. The hydronic system operates with water circuits to and fro a thermal storage unit, a sky radiator/solar collector to radiant-capacitive modules indoors. Results showed that while both the roof-pond system and the radiative cooling system with indoor capacitive module provide stability to the indoor thermal environment, a somewhat greater thermal amplitude is observed in the latter, which is partly due to the difference in thermal mass between the two systems. Cooling output of the novel system was somewhat lower than that of an indirect evaporative system and dependent on atmospheric exposure conditions of the sky radiator. Heating output is given as a function of pumping duration. Cooling potential reached about 78 % of that of the roof-pond module, for test conditions with nocturnal sky radiative cooling and no water circulation from the storage tank to the interior during the day.