Numerical analysis of convective heat transfer coefficient for building facades

Abstract

The latest architectural trends demand an extensive use of glazed curtain walls running from building floor to ceiling. While glazing poorly controls the heat flow, it is important for viewing, daylighting, and solar design features. In order to evaluate building energy consumption accurately, knowledge of convective heat transfer coefficient (CHTC) distribution over the façade of the building is important. In this article, high-resolution numerical simulations that use three-dimensional steady Reynolds-averaged Navier–Stokes and energy equations are performed. Convective heat transfer coefficient values at the windward facade of five buildings, with rectangular floor plans, and heights of 3, 10, 15, 20–30 stories, have been produced. The influence of building height on CHTC distribution is investigated at Reynolds numbers ranging from 0.7 × 10⁶ to 33 × 10⁶, and a correlation equation as a function of building height and a reference wind velocity is developed. For example, as the height increases from 10.1 to 101 m in the study cases, the surface-averaged convective heat transfer coefficient on the windward façade increases by 55%. The high-resolution spatial distribution of convective heat transfer coefficient over façade of the tallest building indicates that the top-corner zone convective heat transfer coefficient values are higher by 24% and the base-center zone values are lower by 27% compared to the average CHTC value, implying the necessity for zonal treatment.