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

Abstract

The urban heat storage flux, Q S , 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 Q S difficult. This study observes the 3-D surface radiant temperature (T s ) of a building in Beijing, China. The element surface temperature method (ESTM) and the half-order (HO) method are compared for Q S simulation using T s observations. The impact of building structure on Q S and urban heat island intensity (UHII) are also studied. Results show the following. First, Q S '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 Q S simulation by satellite remote sensing data. Second, during the daytime, Q S 's of each facet are significantly different from each other. The maximum observed difference of Q S is up to 452 W/m 2 between the roof and north wall in May 2019. Third, complete Q S ( Q S,c ) is calculated by each facet Q S and area fraction. The relationships between UHII and both 2-D Q S (roof Q S ) and 3-D Q S ( Q S,c ) are studied. Q S is positively correlated with nocturnal UHII, and 3-D Q S 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 Q S and urban heat island (UHI) studies.