Defines ventilation requirements for spaces intended for human occupancy and specifies minimum and recommended air quantities for the preservation of the occupants health, safety and well-being. Recommendations are given for different rooms in alltypes of building in terms of the outdoor air supply per minute. Also gives maximum concentrations of various contaminents. States that outdoor air requirement can be reduced if air is recirculated, purified or odour or gas removal equipment used, but in no case should be less than 5 c.f.m per person.
Suggests energy usage can be reduced by lowering the quantity of ventilation air. Reviews ASHRAE standards for minimum ventilation and air quality. Suggests changes in air conditioning design and the use of air purification equipment. Recommends further research.
Outlines the development of current ideas of effective ventilation from early 19th century when official (U.S.) requirements were unduly high due to misconceptions in health requirements. Examines current requirement.
Discusses how building ventilation is affected both by steady mean effect of air pressures and temperatures around and within the building and turbulent nature of the wind causing air diffusion through openings and cracks in the building envelope. Studies ventilation of an enclosure with a single opening subjected to turbulent impinging airstream. Derives simple theoretical models to assist understanding of physical phenomena causing air-flow through the opening. Compares these with results of experiments on a large-scale model, states need forfurther work on this problem.
Reviews the main mechanisms giving rise to natural ventilation of spaces with openings to outside air on one wall only. These are temperature difference, pressure fluctuation, mean pressure difference, turbulent diffusion and the "vane" effect. Derives expressions for the magnitude of the ventilation rates caused by each of these mechanisms. Reports wind tunnel studies of the ventilation rate in a small test chamber ventilated through one opening only. Air change rates were measured using a tracer gas.
Presents calculations of mean temperatures and relative humidities , shown graphically for three typical housing types assuming different heat and moisture inputs: 1) whole house uniformly heated with moisture from household activities uniformly distributed; 2) kitchen at constant temperature with high moisture emission rate; 3) unheated bedroom with two occupants assumed to be in thermalequilibrium with a room below at 15 c. Concludes that there is a certain critical amount of heat needed to give a relative humidity of less than 70% and thus avoid the danger of mould growth .