The ventilation of a large room is often achieved by supplying inlet air from a small side-wall mounted opening. The velocity distribution in a typical room with a small circular inlet opening close to the ceiling is described. The supplied air forms a wall jet below the ceiling which is easy to describe in terms of velocity distribution, entrainment, etc. The jet is deflected at the end wall opposite the supply opening and the resultant flow in the lower part of the room - the occupied zone - has a rather complicated structure.
Reviews the papers on air infiltration and ventilation research presented at the ASHRAE annual meeting held in Honolulu, Hawaii, in June 1985. The twelve most significant papers on multizone infiltration and air leakage are discussed at length and other infiltration-related papers mentioned. Authors' abstracts for the twelve symposium papers plus seven technical papers are presented.
Several infiltration models treat the complexity of air flows in multizone buildings, but most of them are written as research tools and are not generally available or user-friendly. Professional engineers and architects are in need of a simplified multizone infiltration model. This paper describes the first step in Lawrence Berkeley Laboratory's development of a multizone infiltration model for calculating the air flow distribution of a building without using any iteration procedure.
Reduction in air leakage rates due to weatherization of homes can be determined by fan pressurization and tracer gas techniques, but only the latter gives the results under normal occupancy conditions. Assessment of such rates measured before and after weatherization must consider their dependence on wind speeds and inside-outside temperature differences.
The Brookhaven air infiltration measurement system (BNL/AIMS) uses a family of four passive perfluorocarbon tracer sources and miniature passive adsorbent samplers to inexpensively but very effectively tag individual zones within multizone buildings with uniquely discernible tracer vapors.
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 requirements for the reduction of humidity. Required air change rates for hygiene and moisture removal for various rooms are given. Air flow rates are calculated for natural ventilation with closed windows, hopper windows and controlled ventilation. Ventilation by window opening is discussed. Gives examples of the transfer of moisture within a building, and the main reasons for ventilation, with particular emphasis on moisture removal. Lists danger of condensation on various building elements, causes and remedies. Advises on ventilation measures.
In this paper a hypothesis is set up for explaining the discrepancies between the relatively high acceptable air velocities found during many earlier climate chamber tests, and the much lower acceptable velocities found under many practical circ
Based on the age concept, the performance of the following three principle ventilation schemes have been monitored (supply air terminal - extract air terminal), ceiling-ceiling, ceiling-floor, floor-ceiling. All systems used only air for both heating and cooling. Contaminants with both greater, less and approximately the same density as air were released at a point source. The tests were both carried out in an empty room and with a person (heated mannekin) in the room.
The indoor air quality depends on several different factors. One is the air flow or air movements within the building and through its external walls. These flows are governed by the type of leakage openings and the pressure differences across the walls and the air terminal devices. The pressure differences are caused by wind, thermal and fan forces. Mathematical models can be used to calculate the different air flow rates. A simple example is used to demonstrate magnitude and consequences of this air leakage for two different ventilation systems.
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