A questionnaire was developed to measure human comfort in indoor environments. Based on principles of psychological measurement, it contains 39 polar-adjective pairs with responses being made on an 11-point certainty scale and transformed to normalized ranks for statistical analysis. Adjectives are chosen to measure perception of the six factors fundamental to human thermal comfort, plus other factors such as illumination that could affect feelings of wellbeing. Data were collected from three large university classes that met in one of two rooms on three different winter days. Responses were examined for validity by comparison with physically measured conditions and with checklists completed by a trained observer. Reliability (consistency) was examined by comparing responses for the same groups of students in the same room on different days and for different students in the same room on the same day. Few false or erroneous results were found.