The role of radiative-convective interaction in creating the microclimate of urban street canyons

An approximate sky view factor (SVF) has been developed, which is capable of estimating the mean rate of net longwave radiant energy loss from urban street canyons. Reduced scale models of typical canyon geometries were used in outdoor tests to verify the predictions of radiant fluxes obtained using the proposed SVF.Air-surface temperature differences from the scale models are used together with hypothesized within-canyon airflow patterns to determine some quantitative characteristics of the wind field in canyons. Simple correlations are proposed for the relationship between mean in-canyon and pedestrian-level flow speeds on the one hand, and the ambient (above roof-level) wind speed on the other hand. As expected, the height/width ratio of a canyon controls the form and magnitude of the flow within.

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