The proceedings are presented of a symposium which was held for the purpose of exploring new aspects of indoor thermal environments, caused primarily by the impact of energy conservation in new and existing buildings. Included in these proceedings are eleven formal papers which were presented by leading researchers in the field of thermal comfort and heat stress. Information was presented on a variety of approaches to determining human response to thermal environments. These included laboratory studies in environmental chambers utilizing instrumented human subjects, field studies involving surveys and questionnaires, mathematical modelling of humans, an analysis of some types of instruments used in assessing the quality of the environments, and a discussion of the relationships between productivity and the thermal environment.