A new procedure for predicting the thermal comfort of people in naturally ventilated buildings is described. The procedure starts by obtaining, for each important wind direction, velocity ratios between points of interest inside the proposed building and the wind-measuring height outside. This is best done with a wind-tunnel test of a scale model of the building, but there are also published sources of such ratios. The ratios, plus building-induced temperature changes, are applied to a weather tape representing the site, in order to produce an hour-by-hour record of indoor climate. This record is used in a program simulating human thermal comfort. The program puts out the percentage of time, by season and by periods of day, that thermal comfort is expected in the proposed building. This information enables architects and engineers to make more rational decisions in designing naturally ventilated buildings.