Impacts of Photovoltaic Façades on the Urban Thermal Microclimate and Outdoor Thermal Comfort: Simulation-Based Analysis

Abstract

Cities face the consequences of climate change, specifically the urban heat island (UHI) effect, which detrimentally affects human health. In this regard, deploying PV modules in urban locales prompts inquiry into the impact of energy-active building components on the adjacent thermal microclimate and human thermal comfort. A twofold simulation-based methodology addresses this subject: First, the implications of façade-integrated photovoltaics on the urban thermal microclimate are investigated using a case study in Munich, Germany. Secondly, a parameter study allows us to gain further insights into the relevance of several parameters on the microthermal impact. The simulation results show a daytime heating effect of photovoltaics on the mean radiant temperature of up to +5.47 K in summer and +6.72 K in winter. The increased mean radiant temperature leads to an elevation of the Universal Thermal Climate Index of up to +1.46 K in summer and +2.21 K in winter. During night-time, no increase in both metrics is identified—hence, nocturnal recovery as a key element for human health is not affected. Despite extended human exposure to thermal heat stress in summer, PV façades improve the annual outdoor thermal comfort autonomy by 0.91% due to lower cold stress in winter. The higher PV efficiencies and lower albedo of the reference building surface lower the heating effect. However, with the current efficiencies, PV façades consistently lead to heating of the surrounding thermal microclimate in summer and lower the outdoor thermal comfort.

Keywords

• urban thermal microclimate
• outdoor thermal comfort
• photovoltaic
• microclimate simulations
• mean radiant temperature
• universal thermal climate index