Application and evaluation of phase change materials for improving photovoltaic power generation efficiency and roof overheating reduction

With the development of countries, concerns about global warming have increased. Many countries are taking steps to implement green building-related policies to reduce carbon dioxide emissions; however, these policies are generally applied to new buildings. Therefore, this study focused on the applicability of phase change materials (PCMs) and the optimal application method for educational buildings that have a long service period and are difficult to dismantle among existing buildings. The best application is focused on reducing the building energy demand. phase change materials were applied to address concerns regarding surface temperatures of the building. The passive element, phase change material integrated brick, was applied to the roof, while the active element was a phase change material packed into the back of photovoltaic (PV) panels. Five scenarios were considered in assessing these technologies. photovoltaic installation on the roof surface was assumed for all scenarios, except scenario 1. In scenario 3, the phase change material was applied to the back of the photovoltaic panel, and in scenario 4, a brick layer impregnated with the phase change material was added to the roof surface. In scenario 5, the technologies of scenarios 3 and 4 were applied in combination. As a result of the analysis across the five scenarios, a maximum annual cooling load reduction of 14 521.6 kWh was derived. The overall heating demand increased, with the maximum annual heating demand increasing by 7134.2 kWh. Electrical energy was produced by installing photovoltaic panels, and energy savings were achieved; the highest overall load reduction rate was 22.55%. The calculated shortest payback period was seven years, which is reasonable. Based on cost and energy aspects, scenario 4 is considered the optimal retrofit plan. These results suggest that significant cost and energy savings can be achieved through building renovation with phase change materials.