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Integration of phase change material (PCM) in walls and roof of a building is done to augment human comfort at places where variation of local diurnal temperature of ambient air is extensive. An exhaustive tool to study on year-round thermal effect due to solar radiation falling on a building is generally required to identify the correct PCM and the portion of a year that warrants better thermal management. The transient behavior associated with PCM heat transfer through building roof and walls vary in accordance with location and orientation of the building and the prevailing seasons. Hence, it becomes necessary to carry out a detailed analysis with the integration of PCM layers and to collect information with suitable theoretical approach as experimental study on energy performance of a building is time-consuming and expensive. In this paper, a three-dimensional building model has been developed and analyzed using ANSYS FLUENT for performing CFD analysis for comparing two identical buildings with and without PCM located at Chennai. PCM was integrated in roof and walls of the building and analysis was carried out for different days of the year. A novel concept of PCM effectiveness index is introduced to measure the thermal performance due to PCM integration in building. This novel concept is useful for building engineers to measure the effectiveness of PCM integration and to select the correct PCM for thermal management in buildings at any location and time of the year.

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The thermal comfort of occupants is a necessary requirement for any building. The present pandemic demands us to opt for natural ventilation over air-conditioned spaces to reduce the spread of the infection. This work aims to prevent air-conditioner usage in a commercial building in India during daytime office hours while simultaneously enhancing the thermal comfort of the building occupants through natural ventilation/Phase Change Material (PCM)/insulation techniques. Four building configurations, such as Building A (conventional building with no PCM and no insulation), Building B (building-integrated with PCM), Building C (building-integrated with insulation) and Building D (building-integrated with PCM and insulation) were analysed for various locations using DesignBuilder software. From the results, it is understood that insulation integration is recommended for locations with average nighttime temperatures greater than 27°C, while PCM integration is recommended for locations with an average nighttime temperature less than 27°C during the summer season. Also, nighttime cooling of the building through an air-conditioner is necessary for all locations during summer to maintain adequate thermal comfort with natural ventilation in the daytime. Finally, an appropriate PCM/insulation technique is recommended for an office building located in each location that falls under each type of climate. Hence, the selection of PCM/insulation technique is to be made based on the specific site conditions.