In occupational hygiene the common practice is to use dilution ventilation (MIXVENT) which ideally requires perfect mixing. Increasingly, however, displacement ventilation (DISPVENT) is being applied; ideally this involves fresh air displacing contaminated air without mixing. Keeping MIXVENT as a reference the approach of intervention was used to estimate the potential of DISPVENT for improving environmental conditions in a garment sewing plant. Air exchange efficiency of MIXVENT came to 49%. DISPVENT improved the efficiency to a level of 57%.

The first part of this paper describes a detailed study of the flow of aerosol particles through large openings and the second part describes deposition characteristics of aerosol particles in a single-zone chamber lined with different types of materials, e.g. aluminium foil and carpet. Tracer-gas and aerosol particles were injected into a naturally ventilated room and their concentrations with time were monitored. The room was fitted with a number of windows which allowed examination of single-sided ventilation.

The use of sulphur hexafluoride (SF6), nitrous oxide (N2O) or carbon dioxide (CO2) as tracer-gases have been examined for the measurement of airflow in a two-zone environmental chamber. A series of measurements were carried out to examine airflows through a doorway under natural convection, forced convection and combined natural and forced convection. Results were compared with those predicted using the MULTIC computer program.

This paper is concerned with measurement of airflow in ducts using an active (pumped) sampling system. The system is capable of sampling tracer gases using either tubes packed with adsorbent or sample bags. A perfluorocarbon tracer (PFT) was injected into the ducts using thermostatically-controlled heating blocks. The samples were collected and analysed using a thermal desorber/gas analyser system. Laboratory and field testing of airflow in ducts was carried out. A large office building was studied for measurements of ventilation rate, ventilation efficiency and air quality.

Computational fluid Dynamics (CFD) is a powerfizl tool for analysing problems of air movement and has been increasingly widely used in applications in buildings. The emphasis has often been on its development as a replacement for the experimental approach, however, further work is needed to develop confidence in applying CFD to problems of air flow in buildings.

Ventilation is necessary to insure acceptable indoor air quality as well as to protect the building itself against damage due to condensation Ventilation rates however, must not lead to excessive energy consumption In order to comply with these requirements of hygiene, comfort and energy savings, French regulations stipulate that the ventilation of dwellings has to be general and continuous and achieved by specific systems by which fresh air is provided to the dwellings.

Designing a comfortable inside climate for office buildings to operate within comfort limits (PMV+/-0.5) requires a flexible operating strategy. Two systems a VAV and a VHV are identified and compared to each other. Dynamic simulation techniques are used to obtain an optimal design, based upon comfort conditions not temperatures. The control strategies are optimised to minimize energy consumption while controlling the HVAC system to remain within comfort limits in the occupied zone.

The issue of energy consumption assessment is a complex one. Sophisticated simulation software whilst providing detailed predictions of the thermal performance of buildings, cannot be claimed to have an appropriate level of user friendliness for widespread application. On the other hand, simple software packages for the assessment of thermal transmittance cannot adequately deal with such factors as occupancy pattern and weather variations. In an attempt to fill the middle ground, the concept of energy rating has been developed.

In the framework of a CEC demonstration project on humidity controlled ventilation, detailed measurements are carried out in 18 apartments in Namur, Belgium.The paper gives a brief description of the building, of the airtightness of the apartments and of the ventilation provisions. The largest part of the paper deals with the major outcomes of the study.

Within the framework of demonstration and industrial pilot projects in the energy sector supported by the Commission of the European Economic Communities, an important experiment has been dedicated to the HYGRO-ADJUSTABLE NATURAL VENTILATION (Contrat EE/166/87/FR). The experiment took place on three sites: Les ULIS (France), NAMUR (Belgium) and SCHIEDAM (the Netherlands).