English

The impact of an ozone generator air cleaner was investigated in a full scale test chamber. Test results demonstrate that, where styrene is present, air cleaners increase indoor levels of formaldehyde, oxygentaed organic compounds, ozone and nitrogen dioxide.

Experiments with an air-handler and electronic air cleaner (producing ozone) were operated in a Canadian house to analyse ozone indoor levels for different air change rates and outside ozone levels. Continuous operation of air cleaner increases indoor ozone levels by up to 9 ppb, which may push indoor ozone levels higher than outdoor guidelines figures.

A test protocol for the determination of fractional filtration efficiency of electrostatic precipitators was developed in order to determine the changes in efficiency of these appliances in real life, due to reduced corona discharge from the ionizing wires, and to define an accelerated laboratory method reproducing the real life vapor deposition process leadiong to the coating of the wires.

The performance of two gaseous air cleaners in a single test room was measured for toluene. The effectiveness is between 82 and 94%. Numerical simulations were performed with CONTAMW software to predict indoor air quality. The comparison with experimental results is good.

Sixty pubs were investigated in the UK to measure environmental tobacco smoke (ETS) concentrations in smoking and non-smoking areas. The ETS sampling equipment is described. A statistical exploitation of the results shows that the status of the zone has a big influence on its ETS level: ETS concentration in smoking areas is higher than in non-smoking areas, but ETS exposures are significant in the non-smoking parts. Results also show that the effect of the ventilation system on the ETS concentration is not significant in such pubs.

Fiberglass duct interior liners with and without biocides were submitted in an environmental chamber during 15 days to high air humidities, moisture and nutrient. Conclusion is that liners with biocide reduce microbial growth under high humidity as long as they remain dirt free and dry. Impermeable smooth liners show better performance than liners with porous or rough surface.

A big airport hangar for planes (177x37x92 m) was studied using CFD in cold season conditions. Without nozzle jets for air supply, severe temperature stratification occurs. With nozzle jet fans (17 m/s - 11000 m3/h), the average temperature in the occhupied zone is increased of 2 C.

A questionnaire about the perception by HVAC systems designers of indoor air quality problems, already used in the USA in 1993 on a group of 60 designers, was submitted to 32 Polish HVAC designers. Results of both surveys are compared. No big difference appears concerning the perception of the role of ventilation, but Polish designers show less knowledge about other factors having an impact on indoor air quality (emission from building materials, air quality perception,...).

Numerical simulation (CFD code) was used to optimise the design of the ventilation system of a large underground bus terminal complex near Seoul (Korea). The analysis of air flow patterns and parameters such as NOx and CO concentrations (from diesel engines of 19 buses) allowed to suggest and study modifications of design (change in airflow rates and grilles locations). Changes improve indoor air quality as the mean residual life time of contaminated air decreases.

This paper analyses through CFD simulation results the removal effectiveness in an office cooled by a chilled ceiling combined with either mixing or displacement ventilation. For passive pollutant sources, both systems provide similar air quality. For active pollutants and when a large volume of all fresh air is supplied, displacement ventilation has better performance.