This paper gives an overview of duct leakage issues in Europe. A literature review indicates alack of ductwork air tightness measurement data in the member states. However, based on afew papers and above all on a field study on 22 duct systems in France, we conclude that theventilation and energy use implications of leaky ducts are large and merit furtherexamination. To this end, we have started the SAVE-DUCT project (1997-1998) aiming atstudying the potential implications of a tight air duct policy at the European level.

Trouble shooting air distribution problems in mechanically ventilated offices often has to be carriedout in limited "after hours" periods. The method of applying a pulse of tracer to the fresh air supplyhas been found to be too time consuming to map the local mean age of air over complex floor plans.In response an automated gas chromatograph has been developed to make air change efficiencymeasurements in real time using the method of homogeneous emission.

This paper presents the results from the monitoring of a low energy building, namely, the Portland Building University of Portsmouth - UK) during February and July 1997. The BMS Research Group at the University of Portsmouth has instrumented the building so that its performance can be compared with the predictions obtained at the design stage. The Building has been operational since July 1996 and the monitoring exercise commenced in January 1997. Sensors monitor air temperature, air relative humidity and slab temperature in selected areas of the building.

Perceived barriers restricting the implementation of natural or simple fan assisted ventilationsystems in the design of new office type buildings and in the refurbishment of existing suchbuildings have been identified in seven central and north European countries with moderate orcold climate: United Kingdom, Belgium, The Netherlands, Switzerland, Norway, Sweden andDenmark.The barriers were identified in an in-depth study with structured interviews based onquestionnaires among leading designers and decision makers: architects, consultant engineers,contractors, developers, owners and governme

This investigation is part of project NATVENT TM, a concerted action of nine institutions of seven European countries under the Joule-3 program. It aims to open barriers that blocks the use of natural ventilation systems in office buildings in cold and moderate climate zones. The choice to apply natural ventilation in office buildings is very arbitrary; it depends very much on the personal preference of the architect or taken for budgetary reasons, even sometimes not considered at all.

The air flow in a Passive Downdraught Evaporative Cooling (PDEC) tower has been modelled using a Computational Fluid Dynamics (CFD) code. Water is injected into dry warm air and the interaction between the water and the air is represented using a particle transport model. This models the transfer of mass, momentum and heat between the water particles and the air in addition to predicting individual particle trajectories.

Air flow through doors, windows and other large openings constitutes a major factor inbuilding ventilation. However, due to the complexity of the physical processes involved,relevant physical phenomena are not yet fully understood.The paper presents data obtained from five consecutive experiments concerning air flowthrough a large opening (door) connecting two rooms (volumes 28.3 m and 38.1 mrespectively) with different air temperatures.

Checking models of thermal behaviour or ventilation of a room can be performed in specialtest cells. At EMPA a ventilation test chamber with several experimental facilities has beendesigned and built. The inside wall surface temperatures of the chamber can be controlledusing a software model which simulates the thermal behaviour of a real wall. As a test case aheated office room was calculated with TRNSYS and compared with measurements made inthe chamber.As an example of checking ventilation models the validation of a CFD-model of ahorizontally pivoted window is presented.