Factors influencing occupants' blind-control behaviour in a naturally ventilated office building

An empirical study was carried out from Jan/05 to Apr/06 in a high-rise office building to reveal blind operation patterns and to investigate the variables driving blind usage. The positions of internal Venetian blinds of every facade were recorded on a daily basis. A subsidiary questionnaire survey was also carried out to understand the occupant's sensation and experience of their built environment. This paper reviews and extends current knowledge of the motivating forces involved by analysing actual blind occlusion against some potentially influential factors. The study reported aims to fill gaps in previous studies by addressing: an office building in its entirety (not just the offices towards a specific orientation), assessing larger offices as is typical (not single occupancy) and studying the building over a period of 16 months (not just several weeks or months). The work demonstrates the importance of solar altitude and solar radiation as the principal determinants of blind use. The seasonal effect is also very significant, when taking building orientation into consideration. The variation of the occlusion is located separately in a notable way according to how long the rooms are exposed to sunlight. Occupants' preferences for blind position are based on a long-term perception of sunlight and the built environment they are accustomed to. The study uses the logit analysis to predict the probability of blind lowering and raising actions: when solar radiation rises above 150 W/m(2), more blinds will be raised up than pulled down. Also, insights are reported about different behaviour patterns in non-office spaces within the building. (C) 2012 Elsevier Ltd. All rights reserved.