Ventilation efficiency as a guide to design.

The concept of age, or residence time is applicable to characterize both how the supplied air or a contaminant is spread within an enclosed space and how quickly a contaminant is removed. Discusses the application of the concept toany enclosed space with air intakes and extracts. Establishes a direct relationship between the age concept, exposure to contaminants, and equilibrium concentrations. Treats different tracer gas techniques for measuring the age distributions and derived quantities. Gives different definitions of ventilation efficiency based on maximum concentration or average room concentration, and a definition of air diffusion efficiency. Presents results from measurements carried out in a mechanically ventilated two room test house, equipped in one case with one intake and one extract and in the other with one intake and two extracts.