A real-world empirical investigation of indoor environment and workplace productivity in a naturally-ventilated office environment

Most studies on indoor environments and productivity in buildings have been conducted in controlled, static conditions often not representative of the real world, and have used self-reported assessments of productivity. This paper uses a case study-based, real-world approach to empirically investigate the relationship between the indoor environment and workplace productivity in a naturallyventilated office environment in central London. A range of environmental parameters (indoor temperature, relative humidity (RH) and CO2) were monitored continuously, alongside outdoor temperatures and RHs for six months covering both heating and non-heating periods. Transverse (BUS survey) and longitudinal surveys (Online survey) recorded occupant perceptions of their working environments, thermal comfort and self-reported productivity, while performance tasks were designed to objectively measure productivity over time in various environmental conditions. Statistical analysis of the data shows that mean indoor temperatures were more strongly correlated with mean outdoor temperatures in the non-heating season (May-July) when compared to the heating season (Feb-Apr), probably due to opening of windows. Indoor RH was found to be low (2500ppm, higher diurnal ranges, higher daily averages). Results from online surveys showed that productivity was reported to decrease when there was an increase in mean indoor temperature and CO2 levels. Negative but weak correlations were found between the performance task scores and CO2 levels. Insights from the study can be used to optimise indoor office environments to improve staff productivity