A number of studies have shown that approximately 1 in 10 hospital in-patients will acquire a nosocomial infection (NI) '*).These infections are associated with significant mortality rates, and have a large economic impact on health care systems. A Department of Health (DoH) study estimated that in acute care hospitals in England 950000 lost bed days and financial costs off 111 million (1986 rates) were associated with NI '3).Through the use of ultraviolet germicidal irradiation (UVGI) lamps it ii possible to achieve a high degree of pathogen disinfection.

The fractional collection efficiency (FCE) tests of a commercially available two-stageelectrostatic precipitator (ESP) have been performed for six flow rates. The tests covered theparticle size range from 0.018-1.2micrometer using two types of test aerosols, NaCl andenvironmental tobacco smoke (ETS). Measurements were performed by means of twoScanning Mobility Particle Sizers (SMPS) and the Aerodynamic Particle Sizer (APS).

Models are presented for describing the performance of room air cleaners in removing pollutants from indoor air, particularly the levels of removal that can be achieved in practice. Controlled levels of pollutant were generated in a room environmental chamber, and the performance of a commercial room air cleaner was assessed according to the models. The room environmental chamber was operated in static (sealed) or dynamic (ventilated) modes.

A general trend in intelligent buildings is the decentralization of environmental controlsystems. Decentralized environmental control systems have many advantages over centralizedsystems. In order to filly utilize a decentralized control system, the control zone should becompletely individualized so that one occupant can feel free to adjust the air volume andtemperature without being concerned about affecting the comfort of other occupants. Afurniture integrated air distribution control system can provide highly individualizedenvironmental control.

The performance of a hybrid air-conditioning system which utilises wind-induced cross ventilation is investigated. The characteristics of flow and temperature fields are examined using CFD simulation under various conditions of inflowing outdoor air i.e. air temperature, air exchange rate and width of the opening for cross ventilation. In this simulation, the room air controlling system (VAV system) which is used to keep the task zone at a target temperature is reproduced through changing the supply airflow rate of the air-conditioning system.

Air recirculation in the new office and laboratory building of the Norwegian Institute for AirResearch was discovered and characterised from a leaking sulphur hexafluoride cylinderstored in the garage. The garage/staging area was located at the far end of the right wing ofthe three-storey building, and was used for loading/unloading of equipment and for storage ofequipment and compressed gas cylinders. Sulphur hexafluoride tracer was detected in thecorridor on the ground floor right wing leading to the central reception area.

As a result of the recent resurgence in tuberculosis incidence, there has been increased interestin using ultraviolet germicidal irradiation (UVGI) of room air to reduce exposures toinfectious agents. This paper presents results of experimental studies investigating how airmixing and ventilation influences the efficacy of UVGI for inactivating airborne bacteria.Tracer gasSFGand tracer particles generated by nebulization of a- salt solution were injected into a full-scale room. The particles simulate an aerosol carrying an infectious agent generated by persons coughing or sneezing.

In apartments of Korea, exhaust-only hood system is commonly installed for kitchen ventilation. However, as to resident's increasing complaints recently due to poor indoor air quality and hood noise, a careful review regarding kitchen ventilation system came to be in need. This paper presents a research that was conducted to improve ventilation problems in the existing kitchen of apartments. For this purpose, a field test has been carried out to examine the effect of range hood's exhaust airflow rates, and makeup air inlet's settings on kitchen ventilation efficiency.

This presentation deals with the problem of achieving stable microclimate in old buildings ofSt Petersburg - such as churches, museums and palaces. Characteristic traits of such buildingsare rather thick envelops which as a rule accumulate large quantities of heat or cold. Themajority of these buildings are equipped only with central water heating and are naturallyventilated.Experimental study of microclimate in buildings of this kind proves that during cold season(with average temperature -10C) the relative humidity there will be about 30-35% and less.

The paper presents the results of the tests of two-zone airflow pattern forming in a room with displacement ventilation where various heat sources and various airflow rates were tested. The position of the interface layer between the zones was determined experimentally - on the basis of tracer gas concentration measurement and on the way of calculation - on the basis of the plume model above a point heat source complemented with experiment. The following heat sources were used: a plume simulator, a desk lamp, a computer, a round plate and a human body.