TNO Research Institute for Environmental Hygiene have developed a mathematical model (based on an electrical analogue model) for deciding on the best ventilation system (natural v. mechanical) for a building while it is still atthe design stage. This model has been applied to an auction complex situated at Bleiwijk to deduce the best ventilation system for the building. Conclusions are that a natural ventilation system can be realized by placing ventilating devices exclusively in the roof.
The air tightness of buildings is part of an investigation performed by the State Research Centre of Finland. Regulations are being developed in Finland for the maximum allowable leakage in buildings. These can be stated as 0.2 ach/hr for residences, 0.1 ach/hr for low apartment buildings, and 0.2 ach/hr for high rise buildings. Tightness can be measured using a suitable fan connected to a board in a window or door opening, or by thermography.
In a modern residence with reduced air infiltration, a problem may arise if the fresh air requirement is left to natural leakage. The article discusses this problem, and describes techniques for measuring air leakage and typical results. The contaminants which define the need for ventilation are described and the case for controlled ventilation systems (and possibly heat recovery devices) is made. Areas for further research are recommended.
States that the reduction in energy losses due to reduced air infiltration is often overestimated because the effect of open windows is not taken into account.< Shows that the habits of airing are rather similar in some European countries. The proportion of windows open or ajar is inversely proportional to the indoor- outdoor air temeperature difference over a large interval of this temperature difference.< The proportionality constant seems to take a value that is independent of the building construction or the heating system of the residential building.
Measures air infiltration and tightness of Swedish houses using the tracer gas technique and the fan pressurisation technique. Uses a previously developed model correlating air tightness and infiltration to evaluate the performance of Swedish homes. Shows that it is difficult to achieve the recommended minimum ventilation rate according to the Swedish Building Code by relying on natural air infiltration. Most new homes do, however meet the Code's stringent air tightness requirements. A comparison with American houses show that Swedish homes are very tight.
Investigations in Denmark show that there are as many as 75 different compounds in indoor air in tight houses including toluene, xylene, and radon. The dust in homes contains a large number of allergically active ingredients, the most important being the dust mite, which occurs in bed clothes.< States that good air quality is therefore difficult to maintain with natural ventilation in new tight houses. If the hygienic demands of this decade increase the need for ventilation, mechanical ventilation seems to stand a good chance.
In dwellings and similar spaces with limited volume, dilution of indoor air contaminants may be insufficient. The concentration of contaminants in the inside air depends partly on the rate of emission into the room, partly on the ventilation and the concentration of impurities in the outside air. Sulphur dioxide, hydrocarbons, ozone and lead compounds occur in higher concentrations in the outside air, whereas nitrogen oxides, carbon monoxide, benzpyrene (from tobacco smoke), formaldehyde and dust have higher concentrations indoors.
Presents the latest results of air infiltration research in Finland. The aim is to increase the knowledge of the influences of air infiltration on energy consumption, ventilation and indoor climate. Briefly describes the principles of a calculation model for predicting the interconnection between airtightness and air change rate. Describes improvement of air tightness in Finnish buildings, with special attention to construction details. Discusses possibilities of draughtless and controlled fresh air intake through the building envelope.
Reports on a comparative study of residential infiltration as predicted by computer model and as measured in the Mobile Infiltration Test Unit (MITU) as well as in selected test houses, both occupied and unoccupied. Sensitivity analyses were also conducted on each parameter contained in the model against data obtained from MITU.
Characteristics of the ventilation in poultry buildings have been studied at the Hungarian Institute for Building Science. The pressure loss of the cross-building ventilation flow is determined for a section of a typical building and for two typical air inlet-outlet layouts. On the basis of velocity measurements the local hourly air change rates were determined in the cages and compared to the general air change rate in the building.
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