Air-to-air heat exchangers were evaluated as a method of maintaining indoor contaminant concentration levels below acceptable levels. A mathematical simulation of air infiltration and indoor contaminant generation was used todetermine the distribution of contaminant concentrations at various average intervals including hourly and yearly. Both spot generation such as from unvented combustion, and diffuse sources, such as from materials, were considered for four contaminants, nitrogen dioxide, carbon monoxide, carbon dioxide and formaldehyde.
Air infiltration rates are important in determining greenhouse heating requirements. Design recommendations usually suggest one to two complete air exchanges per hour under calm conditions. Tests made in 10 commercial ranges showed no greenhouse in excess of one exchange per hour, with one as low as 0.34 per hour, and an average of 0.56. However, additional tests at CSU showed marked variation, depending upon greenhouse size and heating methods, as well as type of structure and outside wind velocity.
A water vapour mass balance technique that includes the use of common humidity-control equipment can be used to determine average air infiltration rates in buildings. Only measurements of the humidity inside and outside the home, the mass of vapour exchanged by a humidifier/dehumidifier, and the volume of interior air space are needed. This method gives results that compare favourably with those obtained with standard methods using tracer gas.
The multiple tracer gas technique of I'Anson et al. has been improved, in order to increase the rate at which samples can be taken. Using parallel gas chromatographic separation columns and an electron capture detector, it is now possible to take an air/tracer gas sample every thirty seconds in the case of a two-zone ventilation and air movement test. Rapid sampling enables a new,simplified analysis of the air movement between two connected zones to be employed. This analysis derives ventilation rates and intercell airflows simultaneously.
This paper reports on measurements of air change rate in dwellings during occupancy. The occupants were shown to exert a considerable influence on the total air change. The air change rate for occupied dwellings is, on average, 3-4 times greater than the air change rate in sealed dwellings (with air escape valves, doors, windows, and ventilation system closed). The measurements also reveal a tendency for higher air change rates in mechanically ventilated dwellings than in naturally ventilated dwellings.
This paper presents a simple method for estimating the total air change rate of a house with or without mechanical ventilation. The proposed method can be used to assess the effect of a mechanical ventilation system on total air change rates. It can also be included in existing simple computer programs forestimating heating requirements for houses. A calculation procedure is also presented for sizing mechanical ventilation systems for houses. This procedure can be used to estimate the forced ventilation rate required to achieve the desired total air change rate.
A multicell air flow computer program is used to determine the influence of 1) open windows and 2) closed internal doors on the ventilation rate of a semi-detached house. The changes in interzone air movement and room air change rates are also examined. Tracer gas field measurements used to validate the multicell program show good agreement with the predicted values. Results show that opening windows can alter significantly, not only the overall ventilation rate of the building, but also the individual air change rates in rooms.
Describes the measurement of air change rate and airtightness of a mechanically ventilated public swimming bath in Belgium. The relationship between airtightness and air change rate is outlined. Various methods of calculating the air leakage from the pressurization results are compared. Nitrous oxide was used for the tracer gas measurements, which were made both with and without the mechanical ventilation system working. The LBL model was used to calculate the air infiltration rate.
This report describes tracer gas measurements and pressurization tests made on two low-cost houses about one year after their construction. The influence of wind speed on the ventilation rate was found to be significant, whereas stack effect was found to have no significant influence. Infiltration rates of 0.24 and 0.34 h-1 were found. These values are very low for Belgian dwellings. A pressurization and depressurization test was performed for each house at pressure differences between 5 and 150 Pa. The ageing effect was found to be quite substantial.
Presents a detailed description of the measurement technique and apparatus used to measure the air change rate in the Spencer St and Linford low-energy houses in Milton Keynes, UK. An automatic air infiltration rig using nitrous oxide tracer gas constant decay was used. Air leakage was also measured by pressurization for the Linford houses and some from the neighbouring Pennyland project.
Login