AIVC - Air Infiltration and Ventilation Centre

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ventilation rate

Inhabitant behaviour with regard to mechanical ventilation in France.

In France, most of the ventilation systems in dwellings now consist of exhaust vents linked up with a fan, and air inlets. A survey conducted by the CSTB shows that actual ventilation rates are frequently different from prescribed values and that a lot of problems encountered are related to occupant behaviour, - The duration of exhaust flowrate peak value was measured ; it was shown that this duration was dependent on the kind of command and its location in the room. - draughts through air inlets were a major concern. - a lots of air vents did not operate correctly because of fouling.

Concentrations of formaldehyde in modern dwellings with low ventilation rates.

Briefly deals with Finnish research into formaldehyde concentrations in modern dwellings. Describes materials and methods used by the Institute of Occupational Health in Finland to measure formaldehyde concentrations in more than 100 dwellings. Ventilation rates have also been measured in 35 rooms in 20 dwellings, and 46% have been below the minimum acceptable value of 0.5 ach.Where the ventilation rate exceeded 0.5 ach only 9% of the measured HCHO concentrations exceeded the limit value for old houses.

The loft as an air escape route.

Describes technique for measuring the volume of air leaving a house through the loft. Two tracer gases are used; nitrous oxide is released in the house and carbon dioxide in the loft. The mean concentration of N2O in the loft gives the volume of house air infiltrating the loft: and the mean concentration of CO2 gives the ventilation rate of the loft itself.< Gives two examples of the use of this technique and gives loft ventilation rate as a function of wind speed for one house.

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