Optimization of energy use for heating/cooling and lighting for a typical office room in a moderate climate

摘要

The energy use of an office building consists, apart from services, mainly of heating, cooling and lighting. Ideally, the building design minimizes the total consumption of (primary) energy. However, finding this optimum is not straightforward, since many design decisions have conflicting consequences on lighting energy use and energy use for heating/cooling.In this study, an optimization is performed for a south-facing single person office room in a moderate climate, with primary energy as the criterion. Optimization variables are the U-value of the opaque part of the envelope, the glazing-to-wall-ratio, the shading system, the glazing type and the thermal mass. The daylight availability is calculated using ray-tracing techniques in combination with the daylight coefficient approach. The solar heat gain coefficient of the shading devices is angle dependent and calculated using the WIS software. Building energy simulations are done with TRNSYS, resulting in yearly energy heating and cooling demands.In a first step, daylighting is not taken into account in the optimization. This results in an optimal design with high thermal insulation, low window-to-wall-ratios and a combination of an external and an internal shading device. Secondly, the optimization is redone accounting for daylighting. The results indicate that moderate window-to-wall-ratios, glazing with high visible transmittance and a double shading system ensure the lowest total energy use.