The performance and effectiveness of any ventilation and cooling strategy depends largely on the method of air distribution and heat removal system. The consequences of poor air distribution and cooling systems are draughts, air stagnation, large temperature gradients and radiation asymmetry. These factors are the chief cause of the occupants' dissatisfaction with their thermal environment, and are major contributors to the so-called 'sick building syndrome'. Cooled ceilings combined with displacement ventilation, sometimes known as 'comfort cooling', has gained popularity in recent years.
In this study, we have tested more than 80 silencers of different sizes (from O 250 to 1250), length, insulating thickness and with or without central pod. The attenuation, measured at several velocities between 0 - 8 m/s, was compared to some literature estimations and has shown strong differences. They induce that literature estimations should be used only in the same conditions they were made and, not too widely, as it is currently done because real knowledge of the influence of parameters is lacking.
A wind tunnel study was carried out to investigate the airflow through courtyard and atrium building models. Ventilation strategies resulting from the use of different atrium roof pressure regimes (positive pressure and suction) were examined and compared with the performance of the open courtyard. The model buildings were monitored both in isolation and in idealised urban environments of varying group layout densities. The effect of wind direction was also observed.
A computational study had been carried out on hot and cold air interaction across the door of an urban transport vehicle. The studies show that within 20 s after the door is opened all cool air beside the door of the vehicle would flow out when the amb
The efficiency of a kitchen ventilation system is usually determined by its ability in heat and effluent removal. The main part of a ventilation system is the hood, with its face (or capture) velocity. Heat generation associated with the cooking process is the main factor that affects the thermal comfort. The heat removal capability is studied under different capture velocities so as to determine the minimum requirement for efficient removal of heat and effluent.
A systematic analysis of recently constructed dwellings in the Flemish Region has been undertaken within the SENVVIV-project (1995-1998). In total 200 dwellings have been examined in detail. The study involved various aspects: energy related building
Filters used for general ventilation are mass produced and tested by type at rated airflow rate in order to determine the evolution of the pressure drop and the efficiencies during an artificial and shortened clogging process. For filters of better quality it is necessary to evaluate the efficiency concerning fine dust: the traditional atmospheric dust spot efficiency method is now being substituted with an innovative method which allows one to determine the fractional efficiency versus the particle diameter within a 0.2 divided by 3 um range.
Infiltration has traditionally been assumed to affect the energy load of a building by an amount equal to the product of the infiltration flow rate and the enthalpy difference between inside and outside. Results from detailed computational fluid dynamics simulations of five wall geometries over a range of infiltration rates show that heat transfer between the infiltrating air and walls can be substantial, reducing the impact of infiltration.
Simulations have been performed to investigate the performance of intelligent algorithms for control of indoor air quality through natural ventilation strategies whilst simultaneously meeting the requirements of thermal and visual comfort. The proposed control algorithms are founded on the knowledge base of the building physics and support the control of natural ventilation through control of the window opening, whilst simultaneously controlling the lighting, heating and cooling systems of the building.
Similar to supply air jets in mixing ventilation this paper describes a comprehensive flow model for displacement ventilation derived from the integrated Navier-Stokes differential equations for boundary layers. A new test method for low velocity diffusers in displacement ventilation is developed based on this new flow model. Contrary to jet flow, it is shown that the only independent variable in the new model is the buoyancy flux.
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