Multi-dimensional performance evaluation of passive strategies for realizing energy-efficiency and sustainability in buildings of composite climate

Developing new buildings or renovating buildings are critical challenges for the coming decades, as we need to build heat-resilient buildings and combat building energy inefficiencies. The building sector in various countries is encountering an extensive increase in energy demand. Maintaining a comfortable indoor environment with an inefficient building envelope reflects substantial implications for building occupants lacking financial resources. In regions where extreme conditions are periodic and building owners cannot afford air-conditioning systems, passive retrofitting or the use of passive techniques in new buildings should be provisioned to reduce indoor air temperature. The comprehensive assessment of passive strategies will help broaden the perspective of passive building envelopes and assist in selecting practical solutions. This study integrates and compares the energy, economic, and environmental performance of PCM, insulation, and reflective paint, enabling a thorough understanding of utilization in buildings of composite climatic conditions, unlike previous studies emphasizing solely the thermal or energy performance without considering economic and environmental comparison. A comprehensive comparative analysis was conducted using temperature, energy, economic, and environmental-based indexes to highlight the advantages of incorporating different passive strategies. The maximum and minimum temperatures are 43.9 °C and 9.2 °C, respectively, while relative humidity ranges between 99 % and 10 % in Raipur. The study validates the numerical analysis through experimental monitoring of ceiling surface and indoor air temperature in four small-scale test rooms. Three rooms incorporated insulation, reflective paint, and PCM in the roof, while one served as a reference room. The energy analysis based on the studied passive strategies yields substantial annual energy savings of 8 kWh/m2 to 37.7 kWh/m2, which can result in 2.5 to 8 kgCO2eq/year/m2 carbon emission reduction. The cost-benefit analysis uncovers the minimal payback period of 0.9 to 4.4 years except PCM and the minimal return period highly dependent on building utilization time. In conclusion, this research established that individual integration of insulation and reflective paint offers a cost-effective, practical, and sustainable solution for realizing green buildings in composite climatic conditions.