Abstract
The residential sector of Pakistan is a prime consumer of energy. With the fossil fuel-dependent energy generation setup and an increasing energy supply–demand gap, Pakistan is headed towards an energy fiasco. Therefore, drastic measures are required to enhance the energy efficiency of residential buildings in Pakistan. The current study is aimed to numerically investigate the energy performance enhancement of residential buildings by integrating Phase Change Materials (PCM) in the building envelopes of five major cities of Pakistan having different climates. The numerical computations are carried out in open-source building-simulation software, EnergyPlus. Initially, fifteen suitable PCMs are evaluated for a single-room base case house. CrodaTherm24 having a melting temperature of 24 °C with a thickness of 40 mm is found to be the optimum PCM choice when it is placed on the inner sides of building envelopes. It is then integrated into typical single-Storey and two-Storey multi-zone residential buildings. For a single-Storey building, the average monthly energy saving of 44.9% is achieved in Islamabad, 35% in Karachi, 32% in Lahore, 35% in Peshawar, and 49.6% in Quetta while for two-Storey buildings the average monthly energy saving of 12%, 21.4%, 15.5%, 12.9%, and 13.5% are achieved, respectively. The economic feasibility of implementing PCM in building envelopes is evaluated through static and dynamic payback period calculations. The usage of PCM for energy efficiency enhancements of residential buildings is found to be economically feasible for Lahore, Karachi, and Peshawar whereas, it is unsuitable for Islamabad and Quetta.