Multizone infiltration requires extensive and complex information about the flow characteristics and pressure distribution inside the building, and thus has been too difficult to develop and to validate. By relying on lumped parameters for the description of air flow distribution in a building, a simplified model is produced. This paper describes the parameters and considerations involved in the development of the multizone infiltration model.
Buildings in cold climates must provide an indoor environment that is markedly different from that outdoors. The materials and components of the exterior envelope are subjected to large variations in conditions and greater demands are placed on the indoor environmental control system. Air pressure differences across building elements are augmented by buoyancy forces that influence air movement and indoor air quality. The potential for moisture condensation on and within the envelope is increased as is the danger of freezing in liquid systems.
Describes a reasonably accurate method for estimating air infiltration for engineers or energy auditors who are not specially trained in infiltration research. The method requires two steps: field measurement of the building properties, and calculation of the infiltration from weather data and themeasured properties. Fan pressurization techniques are described and how to use them to measure the air tightness of the building envelope, and the procedures required to make infiltration predictions with the Lawrence Berkeley Laboratory infiltration model.
This paper presents a simple method for estimating the total air change rate of a house with or without mechanical ventilation. The proposed method can be used to assess the effect of a mechanical ventilation system on total air change rates. It can also be included in existing simple computer programs forestimating heating requirements for houses. A calculation procedure is also presented for sizing mechanical ventilation systems for houses. This procedure can be used to estimate the forced ventilation rate required to achieve the desired total air change rate.
Measurement of air exchange rates, ages of air, and nominal and local ventilation efficiencies in large buildings is often complicated by the building size and compartmentalization, and by the presence of multiple ventilation systems. To allow characterization of the ventilation process in such buildings, a unique experimental system, that employs multiple tracer gases, is being developed at Lawrence Berkeley Laboratory. The tracer gases are sulfur hexafluoride and five halocarbons. The system is designed to be non-obtrusive, highly automated, and relatively easy to ins tall in buildings.
If the energy losses due to ventilation have obviously become an important problem since the energy crisis, there is still a lot to be done with respect to the behaviours. Previous research has given results about the share of venti lation losses i n the energy balance, and the rational reasons to introduce fresh air into the house. Annex VIII is specialized in the attitudes of the inhabitants, in their habits with regard to ventilation and even in their apparent irrationality.
Although infiltration of outside air across the envelope of a building has been considered of prime interest in relation to energy conservation and indoor air quality, it also important to understand the way in which air moves between zones within a building. A knowledge of the air movement pattern enables the transfer of pollutants or heat to be determined. In order to achieve this, a number of experimental methods have recently been developed, using either single or multiple tracer gases. (See, for instance, references 1,2,6,7,9) .
This paper reports the findings from tests undertaken in an untight, two-storey, brick-built detached test house. Different ventilation schemes were in use: natural ventilation and mechanical ventilation (both extract and balanced ventilation).
A multicell air flow computer program is used to determine the influence of 1) open windows and 2) closed internal doors on the ventilation rate of a semi-detached house. The changes in interzone air movement and room air change rates are also examined. Tracer gas field measurements used to validate the multicell program show good agreement with the predicted values. Results show that opening windows can alter significantly, not only the overall ventilation rate of the building, but also the individual air change rates in rooms.
Describes the measurement of air change rate and airtightness of a mechanically ventilated public swimming bath in Belgium. The relationship between airtightness and air change rate is outlined. Various methods of calculating the air leakage from the pressurization results are compared. Nitrous oxide was used for the tracer gas measurements, which were made both with and without the mechanical ventilation system working. The LBL model was used to calculate the air infiltration rate.
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