Modelling the impact of building energy consumption on urban thermal environment: The bias of the inventory approach

Abstract

Building waste heat is the dominant contributor to anthropogenic heat that causes the urban heat island effect. Numerous studies have estimated the impact of anthropogenic heat emissions on the urban environment using the inventory (IVT) approach, but the assumptions of this method - equating building energy consumption to anthropogenic sensible heat emissions, can lead to over/underestimation of air and surface temperatures in the urban canyon. The building energy modelling (BEM) approach, considering the dynamic interaction between the outdoor microclimate and indoor environment, provides a reliable way to quantify the impact of building waste heat on urban climate. However, the temperature bias caused by the inventory approach has not been systematically investigated in the literature. In this study, we conduct simulations in Beijing for three building types (residential, office, and hotel) in four months (January, April, July, and October) to reveal the temperature biases by the IVT approach using the results from the BEM approach as the ground truth. Results show that the IVT approach overestimates the canyon air temperature (Tcan) in heating and ventilation months. The positive bias of daily maximum Tcan is >1°С in January and 2°С in October. In the summertime, the temperature bias by the IVT approach varies with the type and location of air conditioning (A/C). Daily mean Tcan is underestimated by up to 1.2°С when using window-type A/C, and is overestimated by up to 2.1°С when using water-cooled A/C at rooftop. The temperature bias is more evident in compact neighbourhoods with higher building surface fractions. Furthermore, it is found that the IVT approach causes overestimation of sensible heat flux and underestimation of latent heat flux in most of the studied scenarios, indicating a possible overestimation of urban heat/dry island in previous studies using the IVT approach. This study offers important insights into the building-microclimate feedback in the urban environment.