The use of IR detectors to steer the ventilation is in principle an attractive approach for optimising the ventilation according to the occupants needs. In order to evaluate the performances under real conditions, one of the BBRI office buildings in Limelette (some 31 offices with in total 51 persons and a variable occupation load) was equipped with a mechanical supply ventilation system in which each terminal is controlled by an IR detector.
The need for auxiliary heating and cooling systems in European buildings is established on the basis of building physics and climatic conditions, emphasizing that cooling systems may not be needed in most regions if there are no large internal gains and the building envelope is well designed, through the use of bioclimatic design principles. Occupant attitudes and the consequences upon indoor environmental quality are also compared for the cases of actively and naturally controlled buildings.
Air quality in urban areas is often poor, creating problems for local buildings forced to ventilate with polluted air. Most of the pollution comes from traffic, with the worst periods during rush hours. What role can the automatic control of ventilation play in reducing the impact of pollutants?
In this paper a new strategy for controlling ventilation systems is described. The strategy provides fresh air at a flow rate proportional to an estimate of the rate at which occupants generate carbon dioxide. Thus, the ventilation rate is nearly proportional to the occupant density even under transient conditions. Properties of the new strategy are described, and the performance is compared to a concentration regulating strategy in a simulation. The new strategy is shown to respond faster to a change in the occupant density and to keep the concentration at or below a threshold.
Air quality, air flows in buildings, and ventilation are most important topics. Good air quality is however critically dependent also on other things than ventilation, e. g. source strengths, as is well known. The theme of our conference could also lead to the assumption that there is a simple connection between ventilation and air quality. As the public tend to see ventilation systems as responsible for bad air quality, it is important to state that there is no general criterion for good air quality possible to use in practice to control ventilation processes.
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