Effects of differential wall heating in street canyons on dispersion and ventilation characteristics of a passive scalar

► Various wall heating settings significantly affect ventilation of street canyons. ► Resistance to transfer of a facet scalar is dominated by the near-facet processes. ► The venting velocity and exchange velocity linearly increase with wall heating. ► Transfer of a scalar on a heated wall is much faster than that for a non-heated wall. ► Relative concentration fluctuations can reach 50% if windward wall is heated.