Briefly discusses wind-pressure on buildings. Derives equations for air-flow in a building without internal walls caused by wind pressure from perpendicular and oblique wind. Gives simplified method for calculating air flows inside a building with internal walls. Gives tables showing results of calculation of air flows for a building with two and three rooms. Discusses more complicated building types and gives results of calculation. Outlines determination of ventilation heat loss, air leakage of windows and doors.
Reports tests made to examine moisture problems in a flat roof of cold deck construction. Tests simulated the effect of normal, wet and very wet conditions below the roof with no ventilation of the roof. Found that without ventilation there is a substantial risk of moisture degrade and condensation problems. Roof was then ventilated at five air changes per hour and this was found to be effective in solving moisture problems. Suggests this as a minimum ventilation rate and that where it is difficult to provide ventilation in a flat roof, a warm deck design should be considered.
Explains method for calculating time dependences and average values of gas and particle concentrations in ventilated rooms, which permits determination of air pollution propagation in a room by means of given target functions. Applies method forvarious ventilation rates. Provides calculated example of determination of gas concentration occurring in a room with a leaky gas container. Illustrates representative time functionfor different pollutants.
Reviews the requirement in building regulations for cavity barriers in roofs. States need for providing ventilation in the cavities of certain forms of roof construction,particularly those with a continuous waterproof vapour barrier to avoid moisture build-up. Examines how adequate air movement can be provided in both new and existing flat roof voids, designed with or having installed cavity barriers.
The fundamentals of natural ventilation are discussed with particular reference to the ventilation of houses. The laws of flow are presented and typical values are suggested for the acting pressures and the size of openings through which flow canoccur. As an example of the application of the laws, the effect of wind and temperature difference on the ventilation of an exposed house is discussed, and the theoretical treatment is illustrated by experimental results.
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.