Central Europe is, especially in the residential sector, a region using mainly hydronic systems with static heat transfer surfaces, which operate noiselessly and with slow air movements. Cooling is - as yet - not required. This implies that air-heating systems are not very common in Austria. However, new improved building standards may change this situation, because the specific heat load is significantly reduced. In the building sector, both energy savings and a reduction in C02 emissions can be achieved relatively quickly.
Research scientists at the BRE and De Montford University have carried out tests examining the performance and operation of stack ventilation systems in auditoria.
Macroscopic flow numbers relating to the jet momentum of air diffusion terminal devices are studied in this paper. Diffuser jet momentum, jet momentum number and jet momentum ratio are reviewed in the literature. New expressions for jet momentum ratios and jet volume numbers are proposed for specifying the mean room air speed in mechanically ventilated enclosures. The proposal is validated against experimental data from seven sites under fifteen operating flow conditions. Two macroscopic flow numbers correlate with the measured mean air speed in the room.
To investigate the effect of ventilation on indoor radon (222Rn), simultaneous measurements of radon concentrations and air change rates were made in 117 Danish naturally ventilated slab-on-grade houses built during the period 1984-1989. Radon measurements (based on CR-39 alpha-track detectors) and air change rate measurements (based on the perfluorocarbon tracer technique; PFT) were in the ranges 12-620 Bq m-3 and 0.16--0.96 h-1, respectively. Estimates of radon entry rates on the basis of such time-averaged results are presented and the associated uncertainty is discussed.
An extensive survey has been carried out in 52 underground car parks in Hong Kong focusing on carbon monoxide concentrations in the air. So far as short term health effects are concerned this compound is generally regarded as the most important chemical species from car exhausts. Its presence can be used to quantify air pollution, and give an indicator of the air quality in car parks. The sites were sampled during peak hours. This report presents the results and analysis of the carbon monoxide levels measured.
Trees, displacement ventilation and the use of thermal mass all played their part in giving the Green Building of the Year Award to the Ministry of Defence. Ewen Rose gets under the skin of the winning building.
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