English

The design of natural ventilation systems - the configuration and sizing of system components - assumes one of two generic forms: the nasty form based on thermal comfort criteria or the nice form based on specified airflow rates. The nasty form demands consideration of the complex coupled interaction of a building's airflow and thermal systems - a difficult and often intractable challenge. The nice form, on the other hand, is quite tractable, yet it is commonly approached using interactive and approximate techniques.

In residential buildings, air-conditioners are usually operated in intermittent mode. Thisintermittent mode may complicate many aspects of indoor environments. Indoor humidityexcess is a major problem, since humidity excess is associated with biological pollution andformaldehyde emission. This paper reports our monitoring of indoor air temperature andrelative humidity in a real life building in the hot humid Hong Kong climate. These monitoredresults indicate that, in residential buildings, occupants habits in using windows for naturalventilation exacerbate indoor relative humidity excess.

Many HVAC systems built in the time between 1960 and 1980 have now reached the end oftheir lifetime and require retrofitting. When HVAC retrofits are performed in connection withbuilding renovation, there is often a potential for reduction of thermal loads. The questionwhether a renovated building should have an airconditioning plant or free ventilation oftenrevolves around arguments of energy consumption and investment. However it is not takeninto account that there can be no thermal comfort in many cases of cooling loads and outdoortemperatures.

In recent years, increasing importance has been placed on energy efficiency in residentialbuildings. This has resulted in tighter buildings, which raises concerns about the amount ofventilation required to provide acceptable indoor air quality. Relatively few studies have beenconducted on multifamily buildings, where the multiple zone interaction makes testing andanalysis difficult. In order to address this problem, detailed testing of air flows, pressures, andtemperatures was done at three electrically-heated multifamily buildings in the U.S.

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.

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.

Classrooms in New Zealand schools are mostly low rise buildings with natural ventilationdesigns, sized for summer cooling. This study has investigated winter ventilationperformance in twenty-four classrooms in twelve primary schools in the Wellington region.Its purpose has been to provide baseline data on the effectiveness of existing naturalventilation, along with approximate pollutant profiles on which to base new mixed modeventilation designs.

The goal of this study was to investigate the effectiveness of stand-alone modular airpurification systems in improving air quality in dental practices and certain hospital andlaboratory environments. As air pollutant make-up and concentration may vary significantlyin different indoor enviromnents, the air cleaning technologies utilised should be optimisedfor the pollutants targeted in a particular environment. Reduction of mercury vapours andformaldehyde were examined because of their importance for indoor air quality in dentalpractices.

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.

A currently unresolved problem in building design in the paradox between increasing demand for good thermal insulation, and the requirement for ample levels of ventilation, to maintain a healthy indoor environment. A possible solution to this problem is a supply air 'ventilated' window. An experimental set-up has been designed to test the performance of the window under various conditions. The behaviour of the window is shown, and the factors affecting it's performance discussed.