Describes the instrumentation and measurement protocol used in ASHRAE research project RP-462, a field study of environmental conditions and occupant comfort in 10 office buildings located in the San Francisco Bay region. During the study 2342 visits to 304 participants were made during two seasons, collecting a full set of physical measurements and subjective responses at each visit. In addition, the project developed a laptop microcomputer-based thermal assessment survey that collected a substantial subjective data set in machine-readable form. Recommends the system for further use.KEYWORDS: Thermal comfort, research, USA, measuring, measuring equipment, instruments, monitoring, offices, analysis, microcomputers.