During the past three years, BRE has conducted winter and summer occupant surveys on satisfaction with environmental conditions in 23 buildings. These were a mixture of naturally ventilated and air conditioned buildings. The results presented in this paper are based on a secondary analysis of 5136 completed questionnaires. The aim of the analysis was to determine the effect of ventilation type and season on occupant satisfaction with key environmental parameters: thermal sensation, thermal comfort, humidity, air movement, stuffiness, air quality, lighting and noise.
Eight published post-occupancy surveys have focused on building services and energy performance, management, and occupant satisfaction in buildings of technical interest. All the buildings are relatively good; and two of them had unusually high occupant satisfaction: a sophisticated deep-plan air-conditioned office which demanded (and received) a high level of management; and a simple, low energy, largely naturally-ventilated medical centre, in which occupants were prepared to forgive some deficiencies in lighting, ventilation and summertime temperatures.
In recent years there has been a gradual re-emergence of the use of passive or 'low energy' ventilation and cooling techniques including mixed mode application. It is apparent that many clients developers and agents are reluctant to make a commitment to such 'low energy' buildings due to concerns, albeit unsubstantiated by hard evidence, that such buildings will provide acceptable comfort levels for occupants.
Unsolicited complaints from 23,500 occupants in 690 commercial buildings were examined with regard to absolute and relative frequency of complaints, temperatures at which thermal sensation complaints (too hot or too cold) occurred, and response times and actions. The analysis shows that thermal sensation complaints are the single most common complaint of any type and that they are the overwhelming majority of environmental complaints.
Forty subjects, 20 women and 20 men, were exposed to airflows from five different directions: horizontally towards the front, the back, and the left side and vertically upwards and downwards. The subjects were exposed to stepwise increased air velocities ranging from less than 0.10 m/s to 0.40 m/s at three temperature levels 20, 23 and 26°C. The results showed that airflow direction has an impact on perceived discomfort due to draught. At 20°C and 23°C, airflow from below was perceived as most uncomfortable followed by airflows towards the back and front.
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