Benefits of passive solar shading devices in Swedish climate scenarios. Integrated daylight and energy study.

Abstract: Modern well-insulated and highly glazed buildings experience increased overheating, even in cold climates. Buildings hold the biggest share of the world’s energy use, and current climate crisis can exacerbate future need for cooling. The study strives to analyse passive solar shadings on a south-oriented façade, having predetermined that external and internal shadings’ main function is solar heat gain and glare protection, respectively. Integrated daylight and energy study of several external shading geometries, two window sizes, and two glazing types was carried out using Radiance, Daysim, and EnergyPlus within Grasshopper, and involved preparation of daylight-driven lighting schedules, and glare-driven internal blinds schedules – further applied to annual energy simulations. Comparative nature of the study allowed to evaluate thermal and visual performance of fixed external shadings in Swedish climates, hinting that louvered overhangs may be preferable. The chief study finding highlights the gross impact of internal shading operation on overall building performance and indoor comfort. Furthermore, new climate-based performance prediction methods were developed. Those include external shading benefit index (ESBI) and internal shading benefit index (ISBI), the purpose of which is an early-design-stage recognition of critical periods in a climate year, for which a shading device ought to be foreseen, or a free cooling strategy utilised. The potential of the new tools is evident, and provided they are further developed, the methods are intended as a quick estimation of solar protection solutions, and a simulation-free blinds schedule preparation, offering eminent time-saving benefits for a design team.