Can a naturally ventilated office outperform a mixed mode office? Pilot study on occupants' comfort

It is established that a mixed mode indoor environment provides the best for occupant comfort by augmenting the passive system with a mechanical system when and where required. However, the recent desperation for near zero energy environments, of which natural ventilation provides, warrants the need to explore the possibility of achieving this without sacrificing occupants' comfort. The purpose of this study was to investigate if a naturally ventilated building can outperform a mixed mode building in providing comfort for occupants. The Building in Use (BUS) questionnaire was used to carry out this survey on occupants' comfort in two office buildings in Auckland, New Zealand. The findings showed that occupants of the naturally ventilated office building were slightly more satisfied and comfortable than their counterparts in the mixed-mode office building for almost all the variables of comfort investigated. Thus, the results indicate that naturally ventilated office spaces can provide more comfort than mixed-mode office spaces, if well-designed. This finding suggests that the use of natural ventilation in office environments by designers and building owners should be encouraged. A limitation of this study is that it was carried out in the winter season. The winter season could have affected the results obtained. Also, the study was carried out on only two office buildings. As such, the results cannot be generalised to all office buildings in New Zealand. More surveys on ventilated systems are required for results to be generalisable.