Impacts of occupancy on energy demand and thermal comfort for a large-sized administration building

Abstract

In the framework of various research projects at Hamburg University of Technology, a large-sized, non-residential building was investigated in a post-occupancy evaluation for several years. The building is designed as a lightweight construction with thermally activated ceilings, geothermal assisted heating and cooling, and partly manual ventilation. Thus, the users become part of the energy concept in terms of ventilation during summertime. The building's final energy demand is primarily covered by thermal energy from the ground for heating and cooling purposes. During winter, ground-coupled heat pumps characterize the overall electricity demand with seasonal fluctuations, whereas user-related electricity demands were comparatively constant throughout the year. User-related energy demands must be considered, since they were found to be a significant part of the electricity demand, especially for highly efficient office buildings, as this demand category accounted for around 50% of the total primary energy demand of the building considered, under standard conditions. As a counterpart of keeping thermal energy demands as low as possible, thermal comfort was maintained at a high level throughout the year, except for small limitations in winter due to the absence of humidity control, causing increased thermal discomfort at outside air humidity ratios beyond the desired indoor comfort zone. Furthermore, influences of manual user interventions on thermal comfort are considered. This study aims to contribute to a better understanding of the effects of user-related energy demands on the total energy performance of a building, and the interaction of fully-automated and manual building systems, with regard to thermal comfort.