ventilation

Aerodynamic phenomena affecting the ventilation process, such as aerodynamic mixing, generation of secondary and slightly turbulent flows, roof contours, infiltration and convection and their connection with geometric parameters of the object and energy expenditure for ventilation are analysed.

Ventilation is widely used to help maintain acceptable indoor pollutant concentrations. In this paper, the relationships between ventilation rate and indoor concentration are examined by the use of mass balance models and measured data. It is shown that the pollutant source strength and pollutant removal by processes other than ventilation can have a large impact on the indoor concentration and that maintenance of a typical ventilation rate does not ensure an acceptable indoor concentration.

Plastic track detectors LR-115 and CR-39 were used to estimate the concentration of radon-222 and its daughter products (218Po, 214Po) in a room by recording tracks of their alpha-particles. Although the ventilation rate is the main factor th

The effectiveness of range hoods and window fans in removing indoor pollutants is considered. Tests were conducted in a two-room test space with an infiltration rate less than 0.1 hr-1 using sulphur hexafluoride as a tracer gas. Range hood te

Looks briefly at current research into developing techniques for measuring and predicting natural ventilation and infiltration rates in buildings.

Describes the technique employed, including the mathematical model as well as results from a validation test using an experimental chamber. The model assumes an exponential decay of the tracer gas concentration. The precision of the analytical procedure is estimated at better than 9%, while the error of the measured ventilation rate of the test chamber was 5%.

A tracer method was developed for the evaluation of workplace ventilation. Nitrous oxide or freon was used as the tracer. The concentration of the tracer gas was measured with an infra-red analyser. The versatility of the tracer technique for industrial hygiene applications was improved by the use of a microcomputer for data calculation, display and storage. Three applications are presented: 1. determination of the capture efficiency of a local exhaust hood, 2. the evaluation of the air leakage of a room, and 3. measurement of the local ventilation rates in a large industrial plant.

A reduction of infiltration and ventilation rates by a mere 1% would reduce annual US energy costs by about 300 million dollars. Infiltration and ventilation activities are an important part of the comprehensive energy conservation research policy of the US Department of Energy. The starting point for this policy is an analysis of how energy is used in buildings, starting with an examination of the buildings themselves. Summarizes US research and future activities.

This paper discusses the situation in the Netherlands with respect to air tightness of dwellings and reflects discussions about this in the Dutch Standard Committee on Air Tightness of Buildings. Results of measurements and calculations are given and the considerations of different groups in thediscussion are included. Finally an attempt is made to produce a model for the prediction of air flow rates, infiltration losses and seasonal gas consumption on the basis of air leakage measurements.