AIVC - Air Infiltration and Ventilation Centre

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mechanical ventilation

Influence of mechanical ventilation on moisture content of bathroom air.

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.

Natural infiltration routes and their magnitude in houses-part 1.

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.

Influence of the mode of ventilation of heat losses from buildings due to ventilation. Einfluss der Luftungsform auf die Luftungswarmeverluste von Gebauden.

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.

Ventilation in relation to toxic and flammable gases in buildings.

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.

Infiltration tests at Ringway House, Basingstoke

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.

Measurements of air movements in a house using a radioactive tracer gas

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.

Measurements of ventilation rates in houses with natural and mechanical ventilation systems

Describes measurements made to compare ventilation rates in six Belgian houses with both natural and mechanical ventilation systems using O2 and N2O as tracer gases. Ventilation rates were correlated with wind speed. Air leakage across individual components of the house was measured and from this the distribution of leakage areas calculated.

Savings through CO2 based ventilation.

Suggests many ways of reducing outdoor air admitted to a building. Notes importance of measuring minimum air flow to ensure adequate ventilation. Suggests measuring the concentration of CO2 in indoor atmosphere and using the results to control incoming ventilation. Describes simple and inexpensive implementation of the technique.

Airtightness and ventilation Tathet och ventilation

Describes measurements of airtightness and ventilation in prefabricated 'modulent' houses, 25 single-storey with habitable lofts and 8 single-storey, all with mechanical extract systems. Measurements used pressure method and tracer gas in houses with different airtightness, types of window, windproofing and facing materials. Possibility of presetting ventilation terminals and fans to achieve recommended airflows was investigated. Treatsrelationship between wind, temperature and airtightness. Notes number of shortcomings in ventilation system discovered during investigation.

Air infiltration and its effect in buildings. Rakennusten ilmavuotojen aiheuttajista ja vaikutuksista.

Points out that difficulty in calculating fortuitous ventilation in buildings caused by infiltration means that energy demand of a building contributed by it is scarcely ever known. Provides equations describing infiltration due to pressure differences, which in turn are caused by wind conditions, inside/ outdoor temperature differences and possible influence of mechanical ventilation systems. Describes computer program developed in Finland to calculate air infiltration. Demonstrates infiltration rates in houses.