Based on almost 18 months of continuous direct measurements coupled with an electronic questionnaire, we have analysed the influence of indoor temperature and illuminance, outdoor climate parameters, thermal and visual sensation, clothing and season on the perceived productivity of office occupants. Using linear regression analysis, we have identified which of these variables have a significant influence on perceived productivity. From this we noticed that the observed variance in productivity is best expressed by either extreme or aggregated values of our driving variables (including indoor and outdoor temperature or thermal sensation), rather than by instantaneous stimuli. Our analysis also suggests that under warm conditions perceived productivity decreases by around of 10% compared to relatively cooler conditions. An assessment of the existence of a conjugate impact of these variables is also provided.