English

The airflow pattern and thermal comfort in a naturally ventilated classroom were predicted using CFD techniques. The CFD model for turbulent flow consists of equations for the conservation of mass, momentum and thermal energy and the equations for the k-E turbulence model, taking account of the effects of buoyancy and obstacles in the room. The thermal comfort was assessed according to the predicted mean vote (PMV) and predicted percentage of dissatisfied (PPD).

As part of the AIVC's technical programme, study has been performed on present and advanced ventilation systems. The first part of the study presents a review on demands for basic ventilation of residences and major design considerations forventilation systems. The second part is a review on ventilation systems advanced approaches divided into: air movement control systems; flow quantity control systems; ventilation heat recovery systems; alternative ventilation energy systems.Furthermore a system for the classification of ventilation systems is suggested.

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.

A mathematical model has been developed which will facilitate the prediction of infiltration rates within multi-zone buildings. The aim was to cater for: (i) significantly different temperatures in different parts of the building; (ii) flow paths at any height, including vertical connections between zones; and (iii) flow paths extending over large vertical distances. These aims led to the requirement in the associated computer program that the variation of pressure with height be accounted for independently within each zone of the building.

A new passive tracer gas method for ventilation measurements is described. The method utilizes passive tracer gas release from aliquid perfluorocarbon compound contained in a glass vial, equipped with a teflon membrane. Air sampling is also done passively by diffusion through a glass tube containing activated carbon. Quantitative analysis of trapped tracer compound is performed by solvent extraction and gas chromatographic separation using a liquid injection technique. Separation is done with a two-column system and quantitative analysis with an electron capture detector.

The possibility of unacceptable internal air pollution levels can cause concern at the design stage given the potential for cross contamination between building exhausts and ventilation intakes is there. The complexity of airflows around buildings, however, makes it extremely difficult to predict the contamination levels at the intake locations. This paper reports a wind tunnel technique using a model of a proposed building to determine the pollutant levels expected at various inlet locations due to the re-ingestion of noxious emissions from its two stacks.

Once the flow-pressurization characteristics of a building are known, the largest uncertainty in predicting air infiltration is the effect of wind shelter from nearby buildings. To study the effects of wind sheltering a large data set of hourly air infiltration and meteorological measurements were made for a row of test houses located on an exposed rural site. This configuration produces strong variations in wind shelter as the wind direction shifts from along the row to perpendicular to it.