One of the main problems about air flows pattern studies remains the experimental validation of numerical codes developped for interzone air flow and polluant diffusion prediction. A few years ago, CETHIL developped a real scale experiment made of a 88m² dwelling built in our laboratory hall in a controlled climatic environment.
A branched connection is a single air flow passage connecting more than two zones. Its existence in a building has not been a critical issue for the measurement of air flows of single zones, as far as the validity or accuracy of the measurement techniques is concerned. However, with the ever increasing sophistication of building air flow measurement techniques --- which include tracer gas and multifan pressurisation techniques --- and the ever increasing use of them in multizones, it becomes increasingly desirable to examine the effect of branched connections.
This paper presents a new approach to determine the interzonal airflows of a multizone system using tracer gas measurements. In contrast to methods proposed earlier, the presented method does not use the mass balance as basis for the least squares problem but identifies the interzonal airflows as coefficients of the evolution equations for the concentrations. Therefore estimating the derivatives with respect to the time from measured data is avoided. Furthermore the concentration can be calculated at arbitrary points in time.
The methods available for the measurement of air infiltration and air movement in large industrial halls are restricted by the size of the building and the nature of the operations which take place within it. Single tracer decay measurements are the easiest to perform and this paper examines the possibility of extracting useful information from them. Using a multi-zone representation of the building volume, the properties of tracer decay curves are considered, and the ease of extraction infiltration and air flow data examined by means of simulations.
Seen from the AIVC Technotes 21 and 28, Ventilation Efficiency is still a complex concept. As well for measurements as for simulations. Two more or less separate terms are used: Ventilation Efficiency (-Supply Efficiency) and Ventilation Effectiveness (-Contaminant Removal Effectiveness). In thispaper is shown that the Multizone Ventilation Efficiency has a much wider range than Ventilation Efficiency within one room. In a single room efficiencies can be found for example up to 2 forvery good systems.
The International Energy Agency (IEA) task-sharing project "Air Flow Patterns within Buildings" was initiated in May 1988 for a duration of 3,5 years. Twelve nations contribute work and expertise and "share the task" specified in the project's objectives. This project and the AIVC belong to the same Implementing Agreement: The Energy Conservation in Buildings and Community Systems Program. As "Attachments" to the Implementing Agreement, they are called Annexes.
IEA Annex 23 has been established in order to attempt to resolve these difficulties in relation to multizone air flow modelling. These models are used to evaluate the air flow between individual rooms or zones as well as the rate of inflow andoutflow of air from buildings. This approach is especially important for evaluating the adequacy of ventilation, predicting pollutant transport and evaluating airborne heat transfer between zones. Such models therefore have vital applications in both energy and air quality related analysis.
One method of evaluating interzone airflow rates makes use of perfluorocarbon tracers (PFTs)(4). The PFTs are emitted at asteady rate by miniature permeation sources (the physical size is 7 mm diameter and 30 mm length) with a different PFT being
Mechanical equipment may influence the airflow between rooms in a number of ways: 1) There is the direct airflow through ducts using supplies and returns. This approach may be just a single pass system where supply air enters and exhaust leave
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