Influence of environmental variables on thermal comfort and air quality perception in office buildings in the humid subtropical climate zone of Brazil

Abstract

This study evaluates the influence of environmental variables on users’ thermal comfort and air quality perception in the humid subtropical climate of Florianópolis, southern Brazil. A building with central air-conditioning system and three mixed-mode buildings, which alternated between natural ventilation and air-conditioning modes, were investigated. Statistical analyses were performed considering environmental data collected in situ between 2014 and 2016 – using microclimate stations, a portable thermo-anemometer and a CO2 analyser – and users’ subjective responses obtained by means of an electronic questionnaire. Results showed a direct influence of air temperature and humidity ratio and indirect influence of air movement on thermal comfort. In addition, thermal, air movement and humidity sensation, preference and acceptability affected thermal comfort and air quality perception, highlighting the importance of carrying out a complete assessment of users’ perception of the thermal environment. This work supports the use of the ASHRAE 55 adaptive thermal comfort model for mixed-mode buildings under natural ventilation operation. Based on the results obtained in this study, the use of hybrid ventilation strategy is recommended for energy savings due to reducing the use of air-conditioning and improving indoor air quality as there is a decrease in air pollutants level.