Impact of Building Structure on Heat Storage Flux Estimation: An Observational Case Study in Beijing

Abstract

The urban heat storage flux, QS, is one of the main drivers of the nocturnal urban heat island effect. However, the complex 3-D building structure makes observations and simulations of QS difficult. This study observes the 3-D surface radiant temperature (Ts) of a building in Beijing, China. The element surface temperature method (ESTM) and the half-order (HO) method are compared for QS simulation using Ts observations. The impact of building structure on QS and urban heat island intensity (UHII) are also studied. Results show the following. First, QS's simulated by ESTM and HO are nearly the same for walls. However, the HO method only needs one-layer exterior surface temperature, which has great potential for regional Δ QS simulation by satellite remote sensing data. Second, during the daytime, QS's of each facet are significantly different from each other. The maximum observed difference of QS is up to 452 W/m² between the roof and north wall in May 2019. Third, complete QS (QS, c) is calculated by each facet QS and area fraction. The relationships between UHII and both 2-D QS(roof QS) and 3-D QS (QS, c) are studied. QS is positively correlated with nocturnal UHII, and 3-D QS corresponds more closely to UHII with a larger Spearman's coefficient (p < 0.05). This study presents the effect of building structure on heat flux and could provide an insight for future QS and urban heat island (UHI) studies.