Hot water at 50°c is routed from one building in which it is generated to an adjoining building in which it is used for space heating. transfer between the buildings occurs in a steel pipe ( 60 w/m·k) of 100-mm outside diameter and 8-mm wall thickness. during the winter, representative environmental conditions involve air at [infinity] -5°c and 1.5 m/s in cross flow over the pipe.