Convective heat transfer on leeward building walls in an urban environment: measurements in an outdoor scale model

Convection over the building envelope is a critical determinant of building cooling load, but parameterization of convection in building energy models and urban computational fluid dynamics models is challenging. An experimental investigation intended to clarify the heat transfer mechanism of a convective wall boundary layer (WBL) on a leeward, vertical building wall was conducted at the Comprehensive Outdoor Scale Model (COSMO) facility for urban atmospheric research. By comparing profiles of mean temperature and turbulent temperature fluctuation intensity we determined that the dominant regime of the WBL flow was turbulent natural convection. Continuous wavelet transform analysis was applied to detect intermittent turbulent natural and forced convection events in the WBL. Implications for parameterization of convective heat fluxes in urban areas are discussed.