Using meteorological and physical data, a model simulating pressure and air mass flow distribution in buildings was produced using the method of non-linear networks. It was used to study wind and buoyancy effects on mechanically ventilated buildings. Contents include: natural ventilation in high rise buildings with and without air-handling equipment, a study of a hospital, and calculation of the annual heat load for ventilation.
Mathematical models for predicting indoor pollutant levels are being developed and compared with measured concentration in three residential dwellings - a relatively new townhouse constructed according to rigid energy-conservation guidelines,
Since 1970 measurements of air change rate have been carried out in about one thousand buildings by the Swedish Institute for Building Research (SIB). In this paper we present results from these measurements. The studied buildings are of various design and have ventilation systems of different types, natural as well as mechanical. The buildings include single family houses, row houses, and multi family residential buildings, erected between 1900 and 1982. The measurements have then been carried out using tracer gas (decay) techniques to determine the rate of air exchange.
Air infiltration typically accounts for a third of the energy loss in a heated building. The driving forces for natural air infiltration are wind and temperature differences. For a given combination of weather conditions the amount of air infiltration is determined by the character of the building envelope, mainly its airtightness. A useful technique in characterizing this housing quality is to measure air leakage. An air leakage standard for new construction has been in effect in Sweden since 1975.
A microprocessor system is being developed for occupancy related ventilation control of mechanical ventilation in Brunel University Library. The objective is to reduce space heating costs by decreasing the input of (cold) fresh air to the building below existing (heating season) levels, when the number of occupants in the building is sufficiently small to allow this. The occupancy levels can be measured in terms of CO2 level in the exhaust duct. The microprocessor control system is operational when linked to a CO2 monitor.
The air tightness of 15 detached houses was measured firstly immediately after erection and secondly after a period of 1.5 to 4.5 years. All the houses were timber framed ones, equipped with mechanical ventilation systems. Only two houses out of the 15 tested showed clear changes in air tightness. Thus the air tightness behaviour of the houses seems to be fairly constant.
This paper compares the conventional exhaust system with a supply-exhaust system with regard to the possible degree of control of the air exchange in the individual rooms. Ventilation efficiency and air exchange efficiency are defined and some examples show the local concentration, mean ventilation efficiency and mean air exchange efficiency for some simple ventilation schemes. Exhaust systems require a very tight building with small make up air openings. The ability of the different systems to avoid leakage out from the building of indoor air is also compared.
A survey of literature on the theory and practice of residential ventilation. The three main topics are ventilation needs, air movement in buildings, and the properties of ventilation systems. The ventilation need under winter conditions is estimated at 0.35 l/s m2 or, for a dwelling with kitchen and bath, 35 l/s. In fact, ventilation requirements are not constant but it is difficult to find a formula covering the various considerations.
Briefly notes the significance of ventilation heat losses for energy consumption. Notes the main sources of air pollutants in indoor air and the recommended fresh air rates per person for housing, for smokers and non-smokers. Notes the need for a well-sealed facade with mechanical ventilation and for judicious facade leakiness in the absence of mechanical ventilation. Notes the long-term need is for improved control of air infiltration. Notes briefly the AIC publication "Air infiltration control in housing".
A comparison of various ventilation strategies and their effect on air infiltration using a pair of experimental single family size houses. Discusses natural ventilation with and without ventilation grilles in the windows, centralized and decentralized mechanical ventilation. Concludes that mechanical ventilation is not economic at present energy prices.
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