Unopenable, fixed windows have been widely used in high-rise buildings in Japan, but the energy crisis has forced a reconsideration of the merits of natural ventilation with openable windows. However opening windows inhigh-rise buildings, has the disadvantage that open windows causes air flow variation of a mechanical system due to stack effect.< Reports results of a computer simulation of this problem. Describes computer program to calculate air flows in a building. Describes example building, giving air leakage and HVAC system characteristics.
Fresh air requirements in individual rooms of an occupied house vary between 0.5 and 2 air changes per hour depending on the number and activity of the occupants. The most common method of ventilation control is by opening windows but measurements show that even quite moderate window opening results in air change rates greater than 2 air changes per hour throughout a house.< Reports measurement of the energy cost of window opening in a test house with a heat loss coefficient of 5 kWh/K day. Finds in a low energy house,controlled ventilation is essential.
Describes the use of mechanical ventilation coupled with heat recovery devices in residential buildings to maintain acceptable indoor air quality and conserve energy. Gives tables showing the energy saving possible with a heat exchanger.
Treats investigations in office building where 1) flow rates of supply air, return air and ventilation between main office area and adjacent rooms were measured with an anemometer. Return air rates remained constant but ventilation rates varied widely during measurement periods. 2) CO2 was used as tracer gas to determine ventilation rates in offices. Calculates alterations in gas concentrations in rooms adjacent to stairwell and changes in outdoor air concentrations. During air conditioning, ventilation rates in the room were 4-5 room air changer per hour.
Reports experimental investigation of moisture content of bathroom air during and after a shower. Describes test apparatus and procedure. Gives graphs of dry and wet bulb temperature, relative humidity and absolute humidity for various mechanical ventilation rates as functions of time. Gives results of measurements of tracer-gas decay rates for various mechanical ventilation rates. Presents theoretical model for calculations of moisture content in air in bathrooms and finds excellent agreement with experimental data.
A supply of fresh air is necessary in any dwelling to ensure a comfortable, safe and hygienic environment, but the heat loss to this air, during the heating season, may represent a substantial proportion of the total heat loss. This points to the need forgreater control of domestic ventilation, either by using a mechanical system or by better design for natural ventilation. This paper touches upon both of these possibilities. Gives simple method for assessing approximately the possible reduction in heat loss achieved by the use of a mechanical ventilation system.
With improved thermal protection of buildings proportion of ventilation heat loss has grown until it now accounts for 50% and more of total building heat losses. Since ventilation cannot be reduced below certain limits for comfort and hygenic reasons, selection of appropriate type of ventilation system is increasingly important to control heat losses. Describes characteristics and consequences for heat energy consumption and hygiene of constant ventilation and abruptly increased ventilation such as window opening etc.
Discusses toxic and flammable gases and vapours that lead to hazards in buildings. Examines trends in accidental deaths in the home in England and Wales from gas poisoning. Discusses influence of buoyancy on the dilution by ventilation air of accidental leaks of toxic and flammable gases and shows where buoyancy dominates layers can readily form. Presents theoretical results for controlling gas hazards in buildings by ventilation for a wide range of practical situations.
Describes the results of an investigation carried out to determine the rate of fresh air infiltration that is experienced during the winter in a modern air conditioned office building. Six different methods were employed to estimate the rate of infiltration through the building, four by direct measurement and two by calculation. The methods of direct measurement were,tracer gas decay, measured air flow through one floor, measured air flow through one air conditioning unit and measured change on power demand.
Describes measurements of air change rates using radioactive krypton as a tracer gas in a domestic house. Reports measurement of air change rates for a single room heated by either an open fire or a central heating radiator. Examines effect of opening doors and windows and rate of flow up chimney. Found with all the doors open very large airflows from heated downstairs roomsto unheated upper storey, causing large heat transfer to bedrooms: if bedroom doors were shut very little warming of bedrooms took place.
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