In this paper the author analyses the different weaknesses of the HVAC systems in case of air contamination by a deliberate pollution of the inducted air due to vandalism, terrorism or any other motives.To prevent that danger he gives some advice about HVAC installation :A safe air intake is necessary, but the intake grille for ventilation must be inaccessible from outside the building and its position at ground level unsuitable.Air dampers must have effective sealing and be closed in the event of a bioterrorist attack.Recirculation systems can be contamined too from a source within the bui
Variable Air Volume system use VAV boxes that serve open areas for five or more occupants, each zone is controlled with a single space temperature sensor. But VAV zone control strategies remained the same for the last years, so the designers have to consider that system : it provides a high quality environment for occupants, it permits the use of a smaller air-distribution system that is low cost and does not compromise building comfort or operating efficiency.
In that study, Volatile Organic Compounds levels found in two tropical office buildings are analysed. The concentrations have been measured under different conditions of ventilation (normal occupancy with ventilating system working, and with the ventilation system shut down).
On account of Volatile Organic Compounds (VOCs), large proportions of workers suffer from eye and respiratory discomfort or headaches. In a small-scale painting process, efficient ventilation system must be provided for human health. In this study, ventilation characteristics of toluene have been analysed in a room of a small-scale painting process with various exit locations with different suction velocities at the exits.
The author gives practical advices in the design of local exhaust ventilation system (mainly hoods) to capture the contaminant and general ventilation systems to dilute the offending chemical contaminant to acceptable effects. The effect on local environment is studied too.
Air tighness of ventilation network is very important, so the manufacturers have developped sets of new sealed fittings. These new equipments have been tested in CETIAT laboratory. Results show good performance in term of air tighness and installation time.
The new French regulation about energy performance of buildings (RT 2000) specifies airtighness criterion for ventilation network. The author gives a methodology to measure the overall airtighness of ventilation installations on site. Examples based on a school and an apartment building are given.
Current approach for design and installation of mechanical ventilation systems in houses is described in the framework of Canadian building codes and standards, which contain requirements about air change rates, air distribution, sound level, interference with other systems or building envelope.
Results of on site measurements in office buildings relative to the performance characteristics of five ventilation networks are presented. The poor air tightness is responsible for defects and bad performance.
This paper investigates, using CFD simulation, the influence on energy and comfort of the position of small openings for air exchange between rooms in ventilated and air-conditioned rooms of highly airtight houses. Measurements of velocities and temperatures were operated in a Japanese house with floor heating and central air conditioning system providing some fresh airl. Results agree with these of CFD calculations. Calculations were used to search for the optimal position of small ventilation openings between rooms.
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