Effects of various environmental grades on thermal comfort in semi‐outdoor spaces

Abstract The introduction of semi‐outdoor spaces to urban spaces and offices has increased in recent years. In previous studies, environmental grade has been defined as the level of control for the thermal environment set for an architectural space based on the use, where “semi‐outdoor environment” is an environmental grade division that exists as a gradation between indoors and outdoors. This study aims to clarify effects of various environmental grades on thermal comfort. Field surveys were conducted in five semi‐outdoor spaces in Tokyo from 9 to 25 September 2021, consisting of thermal environment measurement, questionnaires about thermal comfort and impression of surveyed spaces and real‐time sensation voting. By impression evaluation and comparison of the regression curves of standard new effective temperature (SET*) against percentage of “uncomfortably warm,” the surveyed spaces were classified into two categories: “outdoor tendency” and “indoor tendency.” The difference in thermal comfort for the diverse semi‐outdoor environment could be evaluated by the difference in spatial characteristics such as “sense of weight” of the top surface in addition to the difference in environment control. By regression analysis of real‐time sensation voting result using hierarchical Bayesian approach, environmental grade was clarified to affect the correlation between pleasantness/unpleasantness and air velocity.