The external facade of a nine storey office building has been reclad with a ventilated cavity structure with a length to height ratio greater than forty. As there is little published information regarding the likely air flows within such cavities a research programme has been set-up to investigate the ventilation and energy performance of this structure. This paper will address the cavity air flows through both theoretical and full scale measurements.

A literature review shows that the actual trends to prediction of air flow in multizone buildings are not only due to economical reasons but mainly to indoor air quality, acoustical and thermal comfort improvements. During the last decade, almost fifty models have been developed in eight countries [1]-[4]. Except some models the analysis of interaction between HVAC systems and building infiltration is seldom studied [5].

A small test room has been built which is five times smaller than the so called Annex-20-room. Different kinds of tracers have been used for visualizing of flow patterns. Velocities, concentrations and mass transfer coefficients have been measured. The measuring instrumentation is based on thermal anemometry (hot wire probes) and a special ammonia-mass transfer method, respectively, in order to estimate the heat flux coefficient at the walls.

This investigation is concerned with the determination of velocity pressure loss-factors for HVAC system components using tracer-gas techniques. Experimental work was carried out using an HVAC system and k-factors for various components such as bends, branches, contractions, expansions and orifice were determined. Results were compared with measurements made using a pitot tube and values given in the CIBSE Guide and ASHRAE Handbook. The performance of different types of filters used in HVAC systems was also examined.

A branched connection is a single air flow passage connecting more than two zones. Its existence in a building has not been a critical issue for the measurement of air flows of single zones, as far as the validity or accuracy of the measurement techniques is concerned. However, with the ever increasing sophistication of building air flow measurement techniques --- which include tracer gas and multifan pressurisation techniques --- and the ever increasing use of them in multizones, it becomes increasingly desirable to examine the effect of branched connections.

Building air flow is directly related to the building energy consumption and indoor air quality. As buildings become increasingly air tight, air flow through building background cracks becomes more important, and can account for up to half of the total building air infiltration. However, background leakage is not well understood, due to the lack of appropriate measurement methods. The multi-fan guarding zone or deduction technique provides a means for testing background leakage distributions, an important parameter for characterising the background leakage.

One of the main problems about air flows pattern studies remains the experimental validation of numerical codes developped for interzone air flow and polluant diffusion prediction. A few years ago, CETHIL developped a real scale experiment made of a 88m² dwelling built in our laboratory hall in a controlled climatic environment.

Spillage of combust ion products from open f lued combust ion appliances represents a source of indoor air pollutants which can cause danger to health. Air extract fans are installed in kitchens in order to remove moisture and cooking smells, but the room depressurisation which they create is a potential cause of spillage. A series of experiments was therefore set up to determine the fan flow rate and internal/external pressure difference at which spillage first occurred in different open flued gas and oil boilers.

The greenhouse effect is one of those topics in environmental politics which are currently worldwide at stake. There are several national concepts aiming at the diminution of CO2-emission in order to lessen the greenhouse effect. One of these concepts is the CO2-reduction programme of the Federal Republic of Germany. With this resolution, passed on November 7th, 1990, Germany's Federal Government aims high: national carbondioxide emission is to be cut back by 25 per cent by the year 2005.

The house dust mite inhabits bedding and soft furnishings in homes. It is implicated as a major cause of allergic asthma. Maintenance of indoor humidity below a level of 7 g/kg inhibits the growth of the mite population. A pilot survey was carried out by EA Technology in cooperation with the Building Research Establishment to investigate the effect of mechanical ventilation with heat recovery (MVHR) both on indoor humidity and mite abundances.