English

A set of diagrams for estimating flow coefficients and exponents in the power law flow equation for cracks are presented. The diagrams are primarily intended for those who perform infiltration calculations by hand or by using a computer program for single and multi-zone infiltration and ventilation calculations. The error introduced by the estimation technique is compensated for by means of a correction coefficient with aspecific value in different pressure difference intervals. A computer program performing the calculations behind the diagrams is available for public use.

This paper is concerned with the application of air flow simulation in design. It describes the real world application - and the results of this with respect to building design improvement - of a building energy modelling system, ESP (RT) , which supports the analysis of coupled heat and fluid flow as encountered in a building andlor plant environment. The use of the system, and the design benefits to accrue, are demonstrated by elaborating two real world case studies.

This paper extends the integral mass balance approach to the remaining constant concentration technique. An integral formulation of the constant concentration problem is presented that accounts for the possibility of variation of tracer concentration. This approach leads, in principle, to data reduction strategies that may be expected to improve the accuracy of the constant concentration technique and that may be used to isolate those portions of a given constant concentration data set that are likely to be most reliable.

The evaluation of a code can be done by investigating two items: solving the correct equations and solving equations correctly and eficiently. An indoor airflow code VentAirI has been developed and is evaluated here. An evaluating procedure is suggested. The code is characterized by the standard high-Reynolds-number k-E model with wall function, the two-band radiation model and the SIMPLE algorithm. Test examples are: 1. A three-dimensional forced convection problem (Re=5000), 2. A natural convection problem (Ra=5 *10^10), 3.

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.