Experimental setup description and raw data from the micro-climate measurement campaign of the outdoor air temperature around an office building in Denmark during summer

Abstract

The local outdoor micro-climate induced by the presence of buildings can be significantly different from the outdoor conditions around weather stations located outside of urban areas. However, the latter conditions are often used to design buildings and size heating, cooling and ventilation systems. Such a mismatch can have a severe impact on the actual performance of building systems.To date, most of the micro-climate studies are based on numerical simulations and focus on the heat island effect in large urban areas subjected to heat waves. Consequently, there is a lack of experimental studies assessing the local outdoor micro-climate around buildings.To remedy that situation, the local micro-climate (outdoor air temperature) and the local weather conditions around a multi-storey office building used for teaching and research purposes at the university campus of Aalborg University, Aalborg, Denmark, during the summer of 2022.The results of this measurement campaign show that, depending on the orientation of the external building surface (South/North façade or rooftop), the distance from the latter and the weather conditions, the temperature in this air boundary layer can vary significantly and differ from the air temperature measured at nearby open fields or recorded by the local weather station. For instance, The gradient between the air temperature at 5 cm from the building envelope and at 200 cm from the building envelope is significant, especially in the case of sunny afternoons. On the South façade, temperature gradients have been measured at up to 3.4 °C and up to 13.6 °C on the building roof. On the North façade, however, no significant temperature gradient has been measured.Certain correlations can be observed between the temperature gradient on the building roof and the South façade and the wind speed and solar radiation.These results may help to validate and improve outdoor micro-climate numerical models, and adjust assessment, design and sizing methods for building systems affected by local outdoor air temperature around the building envelope.