Study on occupancy presence and heat use in a Norwegian office building

Abstract

Energy management in buildings is facing a great challenge in Norway due to the COVID-19 pandemic. The largest difference between the pre-pandemic and post-pandemic period is the occupancy pattern in non-residential buildings. However, existing research only discussed the energy use change by longitudinal analysis, and no related research has been conducted based on the measured occupancy data in the post-pandemic period. Therefore, to fill this research gap, a case study with an office building in Trondheim, Norway, was conducted in our work to compare occupancy presence, heat use, and their relationship before and after the pandemic by using data-driven methods. For occupancy presence, on the one hand, occupants’ presence rate was lower during the post-pandemic period compared with during the pre-pandemic period; on the other hand, occupants’ absence rate in the lunchtime was decreased during the post-pandemic period compared with during the pre-pandemic period. In addition, two typical occupancy presence patterns in workdays were given in our study, the normal-working day pattern and half-working day pattern. The half-working day occupancy pattern appeared when Norway faced the second wave pandemic and the government implements more restrictive measures. In terms of heat use, the heat use increased markedly in the post-pandemic period, with the largest gap in hourly heat use between pre-pandemic and post-pandemic on workdays increasing around 21%, and increasing around 31% on holidays. The minimum daily heat demand of this building during the post-pandemic period was much higher than that in the pre-pandemic period, with increasing around 46% (on workdays and increasing around 86% on holidays. Regarding to their relationship, a more significant correlation between the daily heat use and the daily maximum occupancy rate during the post-pandemic period was observed compared with that during the pre-pandemic period. This study indicates that the operation of the heating system of the case building may be inefficient in the post-pandemic period, and findings of this study could help engineers to optimize the operation mode of the heating system according to the change of occupancy pattern and achieve better energy-efficiency management in the post-pandemic period for similar type of building.