AIVC - Air Infiltration and Ventilation Centre

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air change rate

Infiltration measurements in two research houses

Reports measurements of infiltration rates in two research houses in Minnesota under different wind, temperature and inside operating conditions using helium as a tracer gas. Suggests linear dependence of infiltration rate on temperature difference and wind velocity. Found infiltration rates varied from 0.1 to 0. 4 changes per hour

Measurement of infiltration in a mobile home.

Reviews methods of measuring infiltration rates. Describes tests made on a mobile home using carbon monoxide as a tracer gas and measuring the rate of decay. Concludes that infiltration rates depend primarily on whether or not the blowers for air conditioning or heating are turned on. Without blower the infiltration rate was of the order of 0.8 changes per hour, with the blowers it was 1.2 to 1.7. Reported linear dependence of infiltration rate on temperature difference but did not identifya dependable trend on the effects of wind.

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.

The fundamentals of natural ventilation of houses

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.

Air conditions of buildings and allowance for air penetration in calculation of the heating duty.

States that to calculate the ventilation characteristics of a building it is necessary to know the shape, planning and dimensions of the building, air leakage characteristics of all elements of the building, aerodynamic coefficients, wind velocity and internal and external air temperatures.

The effects of shelter on the natural ventilation and internal climates of simple animal houses.

Describes the ventilation of buildings by analogy with electric circuits and derives expressions for ventilation with and without flow through ducts in the roof. Finds that in general ventilation rate will vary linearly with wind velocity. Considers the effect of shelter belts on wind velocity and derives expression for sheltered ventilation rate. Suggests that eddy motion caused by shelters may be important. Gives measurements made on models in wind tunnels to show the affect on wind pressure of sheltering buildings at various distances.

An indirect method for measuring ventilation rates.

Describes a method for determining the rate of air change in a ventilated space using carbon monoxide as a tracer gas. Concentration of carbon monoxide was found by an infra-red analyser which proved to be very precise and sensitive and made it possible to carry out analyses in a short time. Air change rates were measured in a laboratory with open windows and with closed windows. Concludes that air change rates are greater with few large openings than with many small ones.

Air exchange in multi-storey buildings Wymiana poivietrza w budynkach wielokondygnacyjinych

Discusses the factors affecting air change rates in multi-storey buildings and derives expressions for the air infiltration through walls, windows and doors; air flow through gravity ventilation ducts; pressure pattern on the outside walls of the building and the "chimney draught" in the staircase. Derives mathematical model for calculating the air balance for a building with gravity ventilation ducts. Concludes that chimney draught (stack effect) has a large effect and that proper design of the extraction gravity ventilation system is very important.

Natural ventilation of dwellings

Reports measurements made in a flat in the Netherlands of internal to external temperature and pressure differences, wind speed and direction, position of windows and doors -whether opened or closed- and ventilation rates. Concludes ventilation rate can be predicted fairly accurately from wind velocity but energy consumption is not a linear function of wind velocity.

The measurement of ventilation rates using a radioactive tracer.

Reviews qualities desirable in a tracer gas for the measurement of ventilation rates in buildings. Reports experiments in which radioactive argon was used to measure the ventilation rate in a room. Results obtained agreed with simultaneous measurements using hydrogen as tracer. Suggests use of method for measuring ventilation rates in large buildings and use of krypton gas as an alternative to argon.