Thermal Analysis of Building Roofs with Latent Heat Storage for Reduction in Energy Consumption and CO₂ Emissions: An Experimental and Numerical Research

In green energy buildings, air conditioning charges can be lowered through careful planning of the building's envelope. This article investigates several strategically designed phase change material (PCM) roof envelopes for savings on air conditioning prices, CO2 emission abatement, and payback timeframes in hot-arid and warm-temperate climates, taking into account unsteady heat transfer characteristics, cooling, and heating degree-hours. This is accomplished by using six different PCMs-RCC (reinforced cement concrete) roof envelope cases (RCC roof with PCM layer on the outer side, RCC roof with PCM layer on the center (middle), RCC roof with PCM layer on the inside, RCC roof with PCM layers placed on the outside and center, RCC roof with PCM layers placed on the center and inside, and RCC roof with PCM layers placed on the outer side and inside) with three PCMs (FS29 (form stable mixture), HS29 (hydrated salt), and OM29 (organic mixture)). PCM thermophysical characteristics are experimentally measured. The analytical results are experimentally validated. In hot-arid and warm-temperate regions, the layer of PCM installed on the outside of the RCC with HS29 saved the most on air conditioning expenses, at 6.29 and 6.61 $/m2, respectively. They also reported the greatest carbon mitigation of 300.55 kg of CO2/year and 281.58 kg of CO2/year with the faster payback periods. PCM roof envelopes are the most energy-efficient option for green buildings.