An indirect validation of convective heat transfer coefficients (CHTCs) for external building surfaces in an actual urban environment

Abstract

The convective heat transfer is an important component in the estimation of thermal balance of energy for arrays of buildings immersed in a turbulent boundary layer. This study proposes a novel cost-effective validation approach using targeted field measurements and numerical simulations as an alternative to the wind-tunnel and full-scale field measurement approaches that typically require significant human resources and instrumentation to develop convective heat transfer coefficient (CHTC) for buildings located in the urban environment. This study first introduces new CHTC correlations for regular arrays of cubic buildings. A field measurement is then conducted in an actual urban thermal environment characterized by the plan area density λp = 0.25. Afterwards, this urban thermal environment is numerically simulated using CHTC values for the specified λp and appropriate thermal boundary conditions. The results of the numerical simulations are compared with the measured air temperatures to indirectly validate the CHTCs for external surfaces of buildings. The results show that the difference between the simulated and measured air temperatures is small and typically within 5%. Furthermore, this study created a calibrated building energy simulation model to deploy newly developed CHTCs for building heating energy consumption calculations. Specifically, the energy simulations used both newly developed and commonly used CHTCs to analyze the influence of CHTCs on the heating energy simulation results. A comparison between the simulated heating and actual heating energy consumption shows that the developed CHTCs have a positive influence on the accuracy of the energy simulation results.