Improved design of a building-integrated solar air heater with volcanic rock as thermal storage: A proof of concept with 3E analysis

Climate change has become a major issue in the present era, leading to unpredictable weather globally. Specifically, low-income households face many challenges due to severe weather disruptions. Space-heating issues under such conditions can be addressed by simply designed and fabricated building-integrated solar air heaters (BISACs). The present work presents an improved design of such a system integrated with inexpensive volcanic rock as a heat storage medium. The medium was uniformly filled in granular form beneath the system's absorber and along the side walls. The thermal performance of the proposed BISAC was assessed in natural convection mode during the cold months (November to February) in Moradabad, India. The results showed that the maximum exhaust air temperature reached about 38.5 °C, the thermal efficiency was 39.7%, the heat transfer coefficient was approximately 35.21 W/m 2 ·°C, and the overall heat loss coefficient was around 6.15 W/m 2 ·°C on a cold day in early January. The proposed locally designed, user-friendly BISAC can supply hot air for at least 13 h (after charging, for about 2.21h) during winter. Its cost is about $61, and the payback period is roughly 3.71 years. The environmental and economic analysis indicated that the system reduces CO2 emissions by approximately 0.64 tons annually, with an environmental cost of about $7.8 per year. The feasibility study suggests that the proposed BISAC can meet users' hot-air demands in winter and can be adopted by low-income households for space heating or drying, providing significant financial and health benefits for sustainability.