Experimental study of unglazed transpired solar collectors integrated with buildings in humid sub-tropics

Decarbonization of heating and cooling loads of buildings presents one of the unique challenges to achieve carbon neutrality in diverse climatic conditions. Although solar water collectors are one of the most commonly used solar thermal systems, solar air collectors are also gaining attention due to no risk of frost and lower environmental impact. Transpired solar collectors (TSCs) are an ideal solution to this pressing concern, which can be mounted on roofs and façades of existing and new buildings. This paper presents a longitudinal experimental study in a humid sub-tropics context to assess the thermal performance of building integrated unglazed TSCs under real-world conditions. The results revealed the following findings: (i) a wide spectrum of temperature variation is observed in relatively cold ambient temperatures; (ii) roof-mounted TSC improves thermal energy generation by 5 % to 18 % under varying climatic conditions; and (iii) 3–13 % higher thermal efficiency observed with variation of orientation of the TSC on a building. These advantages collectively contribute to the overall superior thermal performance and efficiency of roof-mounted unglazed TSCs, making them a preferred choice for harnessing solar thermal energy for building space heating.