modelling

This paper is concerned with measurement of air and aerosol particle exchange efficiency in a single zone chamber. Aerosol particles and tracer gases were injected into the chamber and their concentrations were monitored as a funtion of time. The chamber was provided with supply and exhaust terminals which allowed various airflow and particle patterns (e.g. piston flow, displacement flow) to be investigated. The effect of airflow pattern on deposition rate of aerosol particles on the surfaces of the chamber was determined.

This paper presents a trial of applying a CFD package into an air movement study in an old English church. The possibility of adopting computational modelling in a complex shaped building has highlighted the problem encountered due to the large difference in scale between thermal elements and building enclosure. The results have demonstrated that there are still significant problems to be overcome in using CFD models in such situations.

As a result of the "Sick Building Syndrome" (SBS) the confidence of operators of office buildings into HVAC technologies has suffered a considerable drop. One of the most urgent questions before reconstructing or renovating old office buildings is, therefore, whether the air conditioning system to be installed will lead to increasing complaints on behalf of the occupants and how to prevent them. As for indoor air flows, one possibility is given by full scale model experiments leading to results which are very much like the future effective values.

Simulation is proving more and more important in building physics. Programs of different levels of complexity are today available for researchers and designers to model and plan buildings. But the accuracy of the output is not usually provided as a common result. This paper is a short summary of a dissertation [1] focused on the accuracy of the simulation outputs as a function of the accuracy of the input parameters.

Proper dimensioning of natural ventilation system for multi-storey buildings is a critical matter, because the air flow rate depends on many parameters as outdoor temperature, wind, distribution of air inlets and envelope air leakage, characteristics of outlets and cowls. The computer code GAILNE BIZONE predicts the ventilation rates in multi-storey dwellings equipped with passive stack ventilation system. Each level is treated as a two-zones configuration, but each zone is linked to the collective ventilation shaft of the building.

The paper summarises an approach to determining the equations governing the air flow through simple cracks subject to fluctuating pressures. To this end, an experimental arrangement has been developed that enables the laboratory simulation of fluctuating driving pressure signals. A standard straight crack was subjected to this signal, which fluctuates in both magnitude and frequency. An air control system permits a high level of fluctuating pressure control.

A fundamental objective of this report is to investigate the techniques used in the design and research fields for the evaluation of thermal and air flow simulations. The scope is restricted to the whole building rather than flow and heat transfer within individual structural elements (e.g. cavity walls). Considerable developments are taking place in the field of air flow and thermal simulation. Rather than present an in-depth study of these developments, this report concentrates on the rather more general aspects of the combined simulation.