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.

Building airtightness data are essential for design and model evaluation. An attempt has been made with the Numerical Database to compile data appropriate toinfiltration and ventilation studies. These cover the air leakage characteristics of building components, the characteristics of buildings themselves and data on wind pressure distributions. AIVC Technical Note 44 (Orme, Liddament, and Wilson 1994), contains detailed summary tables and graphs of the information stored in the computer Database, together with a complete list of references.

The main goals for this design tool are: - A powerful, but simple to use, technical and economic tool for selecting a ventilation plant. - Guide and control the consultants in accordance with the owner's economic preferences. - The long run extra cost, if one is forced not to follow the guidelines of the method is calculated in order to get the economic backgrounds for a decision. - Creating a key-value for the cost of ventilation that can be understood by engineers and people with economic education. The three most important parts of the selection of this design tool are: 1.

In many design cases, energy as well as occupant comfort are the relevant criteria which are studied using computer simulation programs. Comfort evaluations cover air quality, thermal, visual and acoustical comfort. For all these individual aspects, specific simulation programs are available today, but very few programs allow for the integrated evaluation of several or all relevant parameters. The more, heat transport, ventilation as well as lighting are physically coupled and therefore must be integrally modelled in the simulation process.

The monitoring of the performance of domestic ventilation systems is quite a complex exercise. A wide variety of parameters must be taken into account in order that a suitable assessment of performance may be made - in many cases, insufficient data is collected. Even when the data has been collected, it is often the case that comparison of results from different studies is made very difficult due to variations in the treatment and presentation of the data.

This paper discusses four concepts that have been found useful in improving estimates of ventilation rates in residential buildings. These concepts are improved methods for describing leakage distribution and wind pressures: 1. Separation of large, well defined "local" leakage sites from the background building leakage. 2. Changing surface pressure coefficients to account for the effect of upwind obstacles. 3. Making wind pressures (in terms of pressure coefficient and wind shelter) continuous functions of wind direction. 4.

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.

A new multizone airflow and contaminant dispersal model CONTAM93 is described, along with a demonstration of its application in a study of ventilation and contaminant control in single-family residential buildings. While CONTAM93 is based on existing theory of network airflow analysis and contaminant dispersal, the model employs a unique graphic interface for data input and display. The interface uses a sketchpad to describe the connections between zones and icons to represent zones, openings, ventilation system components, and contaminant sources and sinks.

A measurement system is described to record the movement in a room of neutral density balloons or bubbles, and thus the movement of air in that room. It is based on photogrammetric analysis of coincident video recordings made from several view points. Under laboratory conditions, the system was found capable of measuring position to an accuracy of +/-3cm over a range of 8m, andof measuring 3-D velocities to better than +/-0.05 m/s. The system was usable under field conditions, and could be operated in an occupied building. The largest space tested was approximately 30x15x10m.

The paper describes the application of a new tracer gas technique for studying ventilation. The technique is called the homogeneous injection technique, since it relies on the continuous injection of tracer gas in all parts of a zone-divided ventilated system, with tracer injection rates, which are strictly proportional to the zone volumes. The steady state concentrations of tracer gas in the different zones are proportional to the local mean ages of air.