Overnight free cooling in buildings brings potential benefits that have been known for some time. This study investigates those benefits when used in conjunction with an under floor air delivery system (UFAD). A detailed study using CFD was undertaken for a building in an airport in the UK with under floor air conditioning system and mechanical ventilation providing fresh air. Results show the energy consumption and peak cooling loads reductions when using night time cooling with outside air during the cooling season.
Advantages of floor supply and floor return systems (UFAD: under floor air distribution systems) are described. They are presented by the author as being capable of better performance (thermal comfort, indoor air quality) than floor supply and ceiling return system. They also offer flexibility and ability to allow individual control.
Variations in heat source positions in a room bring changes in the ventilation effectiveness. Those changes are studied using experimental data and CFD results. Results show that a good ventilation effectiveness can be achieved when the contaminant and the heat source are located close to the zone containing the exhaust opening.
The concentration of fungal spores is higher in the crawl space than inside houses. Domestic mechanical exhaust ventilation systems may create air flow between crawl space and base floor through leaks. This study used data from eight buildings to develop a model providing relation between indoor and crawl space fungal spores concentrations. Results show that the correlation between the fungal spores in the crawl spaces and indoors depends on the size range of microbe species.
In an air-conditioned office building in Singapore, 3 different filtration systems have been evaluated under similar fresh air intake and ventilation rate conditions (electrostatic filtration, electrostatic filtration with chemical adsorption, and media filtration) . Chemical and microbial contamination levels under different filtration strategies have been monitored.
A method for analyzing the thermal and lighting radiations in offices building has been developed. It enables the simulation of complicated lighting environments composed of a combination of artificial lighting and solar radiation, in ventilated and air conditioned offices.
This paper describes a method for the determination of optimal indoor conditions, using three parameter indexes: PMV (predicted mean vote) for thermal comfort, CO2 concentration for indoor air quality and cooling/heating load for efficient use of energy. A performance index of the HVAC system is calculating by adding square errors between actual and desired values. It is then minimized to find optimal indoor air conditions.
This paper deals with the simulation of air flow pattern in an office in Singapore (22.5 m x 84 m) with a typical day environmental conditions. Thermal comfort and indoor air quality audit, as well as ventilation measurements are used for validation of the simulation results.
In 2 tropical countries such as Singapore and Indonesia, the perception of thermal comfort is different for people according to their living standards. The higher the standard of living is, the better comfort in living environment is required. A comparative study has been conducted with subjective and objective measurements.
Two methods have been used for measurement of natural convection flows in a narrow vertical channel of which one wall is heated : a hot wire anemometer adapted to measurements in flows where temperature gradients exist (two hot wires with different overheat) and a method for attaining bulk flow information in boundary layer flows. Results from these two methods are compared.
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