Surface Convection Coefficients for Building Facades with Vertical Mullion-Type Protrusions

Abstract

Accurate knowledge of the heat transfer processes that take place at the external surfaces of a building is necessary for thermal modelling and for design purposes. Using a heated test plate fixed at the sixth-floor level to the wall of an eight-storey building, correlations are presented for the external convection coefficient, hc, as a function of wind speeds measured 1 metre from the test surface and 11 metres above the roof in the free stream. The effects of vertical mullion-type protrusions on the value of hc are measured for a range of protrusion heights separated by a fixed spacing, the geometries tested relating to facade configurations which are commonly found in British commercial high-rise buildings. Regression correlations are derived which may be used by designers and thermal modellers for the prediction of hc values for a range of typical building facades with vertical mullion-type protrusions.