Convective heat transfer coefficient (CHTC) on the external building surface is an indispensable parameter for design purpose. A naphthalene sublimation method is introduced to measure the CHTCs on vertical external building surfaces of a dormitory building complex. After field measurement using this method, correlations are obtained for external CHTCs as functions of the local wind velocities, turbulence intensity, and top wind velocities. The shelter effect of buildings and turbulent effect in real urban environment are simply discussed. Finally, the comparison with other studies is given and the reason for these discrepancies is speculated as the width or surface topography of the measured wall.