Roof thermal performance is one of the most important factors for achieving indoor thermal comfort in a tropical house designed for natural cross ventilation. This study, based on field study data, discusses roof design strategies for a hot-humid climate by investigating the impacts of roof thermal performance on indoor thermal comfort in a naturally ventilated house. Conventional roof design for tropical houses mainly focuses on the roofs day-time thermal performance for limiting solar heat gain through the roof structure.
The transmission of SARS in high rise residential buildings in Hong Kong has highlighted the importance of indoor environmental quality. One of the important parameters that requires investigation is natural ventilation. The air change per hour (ac/h) of living rooms was studied in two newly constructed vacant tall buildings in Hong Kong. The aim was to benchmark the air change rate of high rise residential buildings. The scope of the work covered the measurement of air change rate in living rooms under both natural ventilation and air conditioning operation.
Convective heat and mass transfer through large internal openings play an important role in the aero-thermal behaviour of buildings. These phenomena become even more dominant in the case of naturally ventilated buildings. The three-dimensional zonal model of coupled heat transfer and air flow calculations ZAER (Zonal AERial model) has been extended to enable predictions of variations in temperature distributions and airflows between and within rooms subjected to natural convection.
Indoor microbial exposure has been implicated in various adverse health effects. This study aimed toexamine the effects of ventilation efficiency on indoor/outdoor (I/O) levels of airborne microbes in homes with natural ventilation, a predominant type adopted by most residential buildings in Taiwan where high microbial concentrations have been reported. Environmental investigations were conducted in 44 homes. Indoor and outdoor airborne bacteria and fungi were collected using a Burkard sampler with Trypticase Soy agar and Malt Extract agar in a flow rate of 10 L/min.
The airflow rate of a building ventilated by wind is usually predicted by using the wind pressure coefficients obtained for a sealed building and discharge coefficients based on measuring the airflow characteristics through an opening in a sealed chamber (chamber method). This can result in the underestimation of wind driven flow through large openings located on opposite sides of a room. In this paper, the discharge coefficient, based on the chamber method, and the actual condition of cross-ventilation are calculated and compared with each other by means of stream tube analysis.
This paper attempts to look at the unsteady flow pressure on the blade tip in order to quantify the inception of instability of an axial-flow ventilation fan. A test rig was set up to measure the unsteady static pressure near the rotor blade tip region by mounting several transducers on the outer casing. The data sampling system was configured for acquisition and post analysis. The measurement results showed that, as the throttle was closed, the flow disturbance appeared firstly at the rotor inlet.
Effective planning of building ventilation, whether passive or mechanically assisted, requires detailed information about external air temperature. This paper presents experimental evidence from Adelaide, Australia, that demonstrates substantial intra-urban variations in air temperature, whose magnitude changes across the urban space and as a function of time.
Natural ventilation, as a medium for air exchange between the indoor and outdoor environment, is known for its functions of providing outdoor ‘fresh’ air and removing indoor air pollutants. In this study, the minimum outdoor air ventilation rate required to maintain radon concentration at an acceptable level was determined.
The advantage of conventional personalized ventilation (PV) is to considerably improve the fresh air percentage near PV air terminal devices (ATDs). However, the distribution of the fresh air percentage is very uneven in the field. Occupants are confined to their working zones in order to obtain good inhaled air quality. Ceiling mounted PV can overcome the disadvantages of conventional PV, although the fresh air percentage is lower than that of conventional PV near working zones.
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