Personal control over indoor climate in offices : impact on comfort, health and productivity

A historical database was analysed to determine relationships between available and perceived control over the indoor climate on the one hand and effects on ofice workers on the other hand. The database contained questionnaire data from 1612 occupants that worked in 21 ofice buildings. For each building occupant indoor climate control was objectiied with a new (5-point scale) composite control index that referred to self-reported presence of operable windows and adjustable thermostats and to self-reported effectiveness of these two control types. Also some (composite) indices were constructed to objectify comfort perceptions of building occupants and the incidence of building related (sick building) symptoms (PSI 5). The two other outcome variables that were studied were related to self-assessed productivity and self-reported sick leave effects. The data were explored using a multilevel modelling strategy with occupants nested within buildings. In four separate models it was tested whether differences in personal control scores were related to differences in comfort, symptom, productivity and sick leave scores. The analysis revealed a signiicant association between the personal control index and the 4 outcome parameters (in all cases with a p-value of 0.001 or lower). Higher control scores were systematically associated with higher comfort scores, lower symptom incidence, higher productivity scores and lower sick leave effects. The database analysis results imply that when building occupants are provided with effective operable windows and effective adjustable thermostats they generally will be more comfortable and more productive (at least they themselves estimate to be more productive). They also will experience less sick building symptoms and will report in sick less often due to an inadequate indoor climate.