Thermal Performance Assessment of Nano-Enhanced Phase Change Material-Based Building Envelopes for Tropical Climatic Cities in India

Abstract

The manuscript aims to assess numerically the thermal performance of building envelopes (integrated with nano-enhanced phase change material) for the tropical climatic cities in India during the hottest months of May/June. A building envelope of size 5 m (Length) × 4 m (Width) × 3.5 m (Height) integrated with a 25 mm thick Rubitherm phase change material layer on its walls and roof is considered for the analysis. The numerical model is developed using the Design-Builder software by considering the dissimilar Indian climatic zones (composite, hot-dry, and warm-humid) and buildings of the different Indian cities (Delhi, Ahmedabad, and Chennai). The goal is to reduce the peak temperature in the buildings of these cities. The maximum solar intensity for these cities is found between 11 AM to 1 PM for the hottest month, May/June of the year, which is very high (22 kW) in Delhi, followed by Chennai (20 kW), and then Ahmedabad (18 kW). The phase change material stores heat during the peak hours (daytime) and releases the same during the off-peak hours (nighttime) when integrated into the building envelopes. The results show that the building temperature was reduced by 4°C, 5.8°C, and 1.2°C for Delhi, Ahmedabad, and Chennai, respectively. The heat gain reduction from conventional buildings compared to the phase change material-integrated buildings of Delhi, Ahmedabad, and Chennai is 33.47, 35.59, and 26.14 kWh/m², respectively. The thermal enhancement ratio, which captures the building performance with and without using phase change material, is calculated as 0.988, 0.982, and 0.996 for Delhi, Ahmedabad, and Chennai, respectively. This confirms the significant role of phase change material in lowering the peak loads in Indian buildings.