modelling

A Moisture Admittance Model, which takes into account absorption and desorption, has been developed to simulate moisture behaviour in dwellings. The model has been integrated with the BREEZE computer model used to simulate air and contaminant flow. Simulations from the combined model have been compared with predictions using the Louden model and with measurements of vapour pressure taken in a test house. The Louden model tended to over-predict experimental values but there was reasonable agreement between the MAM-BREEZE model results and measured values.

Passive stack ventilation systems have been used for a number of years throughout the world. They were specifically mentioned within the 1995 revision of the Building Regulations for England and Wales as a means of compliance. BRE Information Paper 13/94 gives recommendations for the design of duct systems within dwellings that place restrictions upon the number and severity of bends that may be used. These restrictions limit the scope for the use of passive stack ventilation within dwellings.

The work described in this paper is aimed at predicting the local values of the ventilation eflectiveness parameters of large industrial buildings by a technique which involves the use of computational fluid dynamics and multizonal modelling. A modelling technique is described and applied to a typical modern industrial building equipped with both, mixing and displacement ventilation systems. The results of modelling each of the above systems are presented and discussed.

This paper reports on the use of BRE's domestic ventilation model, BREVENT, to predict subfloor and whole house ventilation rates in a BRE/DoE test house. Before the model could be used though some minor adjustments were necessary because one of its underlying assumptions was that the subfloor temperature was equal to the external temperature. Temperatures measurements over a number of months showed this assumption to be false and so an extra stack term was introduced into the model. However, the overall difference this makes is still quite small, only a few percent at most.

Train tunnels and subways are an interesting field of ventilation. Trains move air through tunnels at rates of 600 m³/s (over 2 x 10^6 m³ per hour) which is much more than flow rates in buildings. Air pressures can vary up to some 3000 Pa leading to air velocities in the range of 10 to 50 m/s. This can lead to unsafe situations and thermal discomfort. The development of high speed trains causes more concern for better tunnel design. Modern stations often house small shops and restaurants, that require lower air velocities for thermal comfort.