New building simulation method to measure the impact of window-integrated organic photovoltaic cells on energy demand

Abstract

Building integrated photovoltaics is an envelope solution that combines energy generation, net energy demand reduction, and aesthetics. Lighter and semi-transparent technologies made the integration of photovoltaic cells in windows possible, which could not be achieved with traditional silicon technologies. This article aims to propose a new method to measure building energy performance using parametric models, simulation, and the use of genetic algorithms, resulting in a more precise and time-saving process compared to regular methods. Three different geometries and six façade configurations were designed, window-to-wall ratio and orientation were set as variables to optimize energy demand reduction. The software used is Rhinoceros, alongside the plugins Grasshopper, Ladybug, Honeybee, and Galapagos, running all simulations and optimizations in a single platform. Galapagos performs the optimizations, an automatic process that required on average 600 simulations to find the optimal solution, while regular methods take up to 9,720 possibilities. Although the benefits from building integrated photovoltaics vary depending on building geometry and envelope configuration, a net energy demand reduction was achieved in all cases. Such values ranged from 6.76%, reached by low-rise buildings with one photovoltaic façade, to 24.04%, accomplished by mid-rises where all façades had window-integrated photovoltaics.