In this paper, we investigate the potential of an aerosol-based technique to significantly reduce the leakiness of residential air distribution systems (ADS). The first part is dedicated to a short review of theoretical analyses of particle transport and deposition in an ADS as well as particle removal in the leaks. The purpose of this review is to pre-determine the ranges of the flow rates, pressure differentials and miscellaneous characteristics of the particles that would allow plugging of the leaks in a relatively short time.
A computer program has been developed to predict the wind pressure coefficients Cp on facades and roofs of block shaped buildings. The program is based on fits of measured data, including wind shielding by obstacles and terrain roughness. Main advantages of the program are: - it needs no expertise of its users on wind pressures; - the input is simple. It exists of building and obstacles coordinates and orientations; - generating Cp values for ventilation model calculations needs no separate action.
There is an increasing concern at the possible health effects of fine suspended particulate (aerosol) upon human health, particularly in the urban environment. Aerosol infiltrating indoors may arise from transport, power generation and natural sources. Aerosol also arises from indoor sources, through cooking processes for example, and from animal dander. In zones within a building, within which the air is reasonably well-mixed, the levels of aerosol will depend upon the ventilation rate and the rate of deposition on indoor surfaces.
A study was set up to compare the effectiveness of passive stack ventilators (PSV) with mechanical extract fans (MEF) in providing adequate ventilation in UK homes. New build and refurbished homes with PSV and MEF were identified and questionnaires posted to 3000 households of which 1223 were returned. The survey showed that in homes installed with a PSV system, only 7% of those in the kitchen and only 8% of those in the bathroom were reported as blocked up. There were also few cases in which the MEF was blocked up or disconnected: 1.5% in kitchens and about 5% in bathrooms.
This paper describes the new indoor environment research facility recently constructed at the Institute for Research in Construction, National Research Council Canada. This facility allows full-scale testing and physical modelling of office space lighting, thermal comfort, indoor air quality, airflow and contaminant-flow patterns, ventilation, acoustical characteristics, and occupants' reactions to these parameters. The facility consists of a test room, approximately, 12 m by 7 m by 2.74 m high, with adjustable interior partitions.
So as to better understand and predict IAQ problems, the velocity field and distribution of local mean age of air were determined experimentally with three-dimensional anemometry and decaymode tracer gas measurements inside a classroom. We also performed 3-D numerical simulations of the velocity field in this room, using a CFD code. The time dependent concentration decay of tracer gas was simulated using the previously determined flow field in the pollutant transport equation. Relatively good agreement was found between the simulated and experimental concentration decay curves.
Disadvantages and advantages with different heating and ventilation systems in modern housing have been discussed during many years in Sweden. The discussion has intensified for modem low energy houses, where the use of forced air heating has increased during the last fifteen years, mostly in one-family houses. In many articles and the general debate diverging opinions have been presented concerning the thermal comfort, the air quality, the ventilation and the energy use in modern one-family houses with forced air heating.
Nowadays it is rather common with demand controlled ventilation in public buildings and offices. The purpose of demand controlled ventilation is to adapt the ventilation to the varying needs of the occupations. In dwellings it is rather unusual with demand controlled system. The main reason for that is the high investment cost for the system. The outdoor air used for ventilation in dwellings is therefore not effectively used. For example in a mechanical exhaust ventilation system 50 % of outdoor air is leaving the house without being used of the people.
The installation of packaged heat recovery ventilation (HRV) systems has recently become common practise in new homes in Canada. Despite improvements in product quality and reliability, HRV systems are only capable of providing safe, continuous, efficient and effective ventilation if homeholders have a understanding of the basic operation and maintenance procedures and the system's interaction with other house systems. Furthermore, homeholders must be able to perceive the value of HRV systems if they are expected to operate them.
The work concentrated on estimating the effects of building leakages and terrain parameters on the air infiltration. The analysis was performed mainly using a multi zone airflow model Movecomp with which the building and its ventilation system could be described in detail. The computations were performed for a flat in a 418-storey building. The highest infiltration occurred in an untight two-facade flat in open terrain. The calculations gave valuable information on the effect of the location of the leakage.
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