The use of indoor carbon dioxide levels is a good method for controlling indoor air quality in office buildings. The measured CO2 is used to determine the amount of outdoor air needed to purge air contaminants and to obtain the desired CO2 indoors. Two floors of a commercial building in Montreal were used in the study.
A literature search was performed to gain as much knowledge as was available on ventilation, indoor air quality sensors and demand controlled ventilation (DCV) strategies. Field data was gathered on the time and spatial variation of indoor air quality in houses. Appropriate designs were then developed. Design strategies are discussed elsewhere (1). Hour by hour simulations of the performance of several ventilation systems in various Canadian climates were done. Energy savings were then estimated for DCV and heat recovery ventilation with air to air heatexchange.
Simplified, physical models for calculating infiltration in a single zone, usually calculate the air flows from the natural driving forces separately and then combine them. For most purposes-especially minimum ventilation or energy considerations-the stack effect dominates and total ventilation can be calculated by treating other effects (i.e. wind and small fans) as perturbations, using superposition techniques. The stack effect is caused by differences in density between indoor and outdoor air, normally attributable to the indoor-outdoor temperature difference.
Air infiltration and ventilation has a profound influence on both the internal environment and on the energy needs of buildings. In most electrically heated high-rise residential buildings, in cold climates, during the peak winter conditions (below -18 deg C ambient temperature and above 15 km/hour wind velocity), the air infitration component contributes to heating load by 10 to 28 w/m2 - roughly 25 to 35% of peak heating demand. Any reduction in such uncontrolled air infiltration, without sacrificing indoor air quality, will have potential to reduce the peak heating demand.
This speech comprises a summary of two publications from the Swedish Council for Building Research (BFR); the knowledge survey "Buildings and Health" (BFR T4:90) and "Indoor climate and energy husbandry" (BFR G5:90). One central conclusion presented in both these publications is that the hygienic and climatic requirements are frequently neglected and that they must reassume a central position in the building and building management process.
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