A laboratory for the study of residential attic performance under natural conditions has been constructed. In one of the test cells, with a flat ceiling, white shingles, and venting devices at the soffit and ridge, measurements were taken of air flow through the plane of the ceiling. A ceiling "hole" was constructed in the otherwise tight ceiling, consisting of a PVC tube, an anemometer and a direction sensor. Data were collected for a six-month period.

The heat loss associated with the external fabric of a building has been greatly reduced by the increased levels of modem insulation, but heating losses associated with cold external air flowing into a building via leakage points in the external facade are still a major problem. Some ventilation is necessary but a detailed knowledge of this leakage would enable the major heat loss routes to be blocked. A crack has been studied which has hot air of a known temperature and flowrate passing over it.

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.