Effect of PCM layer location on the building’s temperature distribution and thermal performance: A case study on tropical climatic cities in India

The building’s energy storage capability and passive cooling performance depend on the building envelope. This study focuses on selecting and positioning the Rubitherm PCM (RT-42, RT-35 and RT-31) layer on the roof and exterior wall of a building envelope. In this analysis, a building of size 5[Formula: see text]m (length), 4[Formula: see text]m (width) and 3.5[Formula: see text]m (height) is considered and its thermal performance is carried out using the design-builder Software (Version 7.0). Three different thicknesses of PCM layer (20, 25 and 30[Formula: see text]mm) are incorporated between the building envelope’s vertical walls and roof to lower the building temperature. Also, three different PCM layer locations are considered for the building envelopes; case 1 (PCM layer placed close to the interior), case 2 (PCM layer placed in the middle) and case 3 (PCM layer placed close to the exterior). The study emphasizes the development of a numerical model by considering the buildings of three Indian cities (Delhi, Ahmedabad and Chennai) and three Indian climate zones (Composite, Hot-dry and Warm-Humid) during summer (May/June 2021). The PCM have different melting points and are selected based on the city’s average peak monthly temperature (Delhi: [Formula: see text]C, Ahmedabad: [Formula: see text]C and Chennai: [Formula: see text]C). Delhi experienced the highest solar intensity (on 10th June 2021) at 22[Formula: see text]kW, followed by Chennai (on 9th May 2021) at 20[Formula: see text]kW and Ahmedabad (on 13th May 2021) at 18[Formula: see text]kW. The idea is to identify a suitable PCM layer location and its thickness in the building envelope based on the thermal performance and load modulation capacity of the PCM-integrated wall. In Delhi, Ahmedabad and Chennai buildings respectively, the wall’s inner surface temperature difference was [Formula: see text]C, [Formula: see text]C and [Formula: see text]C, respectively with and without using the PCM wall. The maximum heat gain reduction is obtained at about 12–17% for case 3 with a 25[Formula: see text]mm thick PCM layer in all buildings. Thus case 3 with a 25[Formula: see text]mm thickness PCM layer gave the best cooling performance throughout the day for all analyzed cities. This highlights the role of PCM toward the thermal performance and temperature dilation of the building envelopes.