The airflows of rooms are different with the ventilation methods, indoor heat sources distribution, as well as room structures themselves. To understand the features of indoor airflows, engineers and researchers use laboratory tests, CFD techniques and field investigations to probe into the essences of indoor air movements. At present, CFD methods are widely used in predicting space air distributions because of lots of well-known advantages. On the basis of long-term research work, the 3DFLOW codes were developed, which is based on the standard three-dimensional ?
This paper describes a study of reduced performance of mechanical exhaust systems in 42 Dutch houses after several years of operation. It also describes the effect of reduced ventilation on air quality and the perception and use of the ventilation system by residents. The guanine contents of dust samples taken from the sleeping room were determined to assess the risk of allergy.
A CO2 level of 1000 ppm is very often used as reference for control and design of ventilation flow rates in buildings. This level is well accepted in practice, and is thus normally not given any further considerations. To retain 1000 ppm CO2 in a room with fully mixed flow conditions, a flow rate of 7 liters/sec per person must be supplied. In many countries, national regulations and standards prescribe flow rates for comfort ventilation that are significantly higher than 7 l/s.
Fan is a source of noise in ventilation and air conditioning systems. The article provides information about noise emission from different types of fans and the ways to attenuate it, using different types of silencers, including passive and active silencers, or combination of both.
In this study the performance of a double-skin façade in an office building equipped with a hybrid ventilation system was analyzed. The hybrid ventilation system studied was based on a low-pressure mechanical exhaust system and demand control of ventilati
This article aims at precising the difference between Underfloor air distribution (UFAD) and Displacement Ventilation (DV) systems, though they both use supply air delivered into a room or space from an access floor.This article presents each system with its different way of working in applications for commercial buildings.
The model estimations aimed at identifying the most important parameters that determine air change rate along with predicting the indoor radon concentration to be expected in new Dutch dwellings under different ventilation conditions.Measurements were compared to the model estimations. To increase infiltration and thus to decrease radon concentation, opening the air inlets and inside doors proved to be efficient.
Up to now, the use of a single HVAC unit to handle ventilation along with mechanical cooling was the aim of designers : it permitted to curb the cost of a building's mechanical system. In this article the author suggests a new design approach to treat the ventilation air and to manage the latent cooling load for the building. It consists in "splitting" the building's total cooling load with a DOAS. This approach allows each component of the HVAC system to do what it does best.
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.
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