A phase change material (PCM) based novel retrofitting approach in the air conditioning system to reduce building energy demand

Improvement in air quality and reduction of airborne diseases can be effectively achieved by inducing fresh air into the building. However, this challenges the building's energy consumption. As a proposed solution, the present study dwells into the use of phase change materials (PCM), a heat-based exchanger, as a retrofit with a Heating Ventilation and Air-conditioning system (HVAC), to extract thermal energy from fresh air and consequentially diminish the energy demand. Calcium chloride hexahydrate (CaCl2 & sdot;6H2O) is used as PCM, selected by TOPSIS method based on entropy weights. The energy saved in the augmented PCM thickness (from 20 mm to 100 mm) and added longitudinal fins (5 mm in width and 50 mm in length) is assessed in comparison to the standard HVAC systems utilizing R134a. For summers in composite climate, the HVAC system retrofitted with a heat exchanger with 100 mm PCM thickness 48 fin configuration achieved peak and average energy savings of 12 % and 9 %, respectively, when the system operated for 6 h. For PCM thicknesses of 75 mm, 50 mm, and 20 mm, the maximum energy savings were 6.64 % with 48 fins, 5.22 % with 24 fins, and 3.22 % with 12 fins, respectively. The study provides policymakers with energy-efficient and sustainable solutions for HVAC systems, which can reduce energy demand and help combat climate change.