In natural ventilation systems, fresh air is often provided through opening of windows, andthere is a wide range of possibilities with regard to selection of window type and position inthe facade. Different window types have quite different characteristics and thereby differentimpact on the thermal comfort conditions in the occupied zone. The thermal comfort is alsovery dependent on the selected natural ventilation strategy, the outdoor conditions and theavailable pressure difference across the window opening.
This paper presents an experimental study of natural ventilation induced by combined forces of thermal buoyancy and opposing wind in a single-zone building. Experiments demonstrated that for a certain range of buoyancy strength and wind speed, two different stable ventilation modes and thus flow rates exist for a fixed building geometry at given buoyancy and wind strength. In these situations, the final ventilation mode and the ventilation flow rate are dependent on the ventilation history of the building.
Kakegawa City Hall, completed in March 1996, contains a sixstorey high glass-walled atrium integrated into the open-plan main office areas via stepped terraces. To save energy while still providing a comfortable indoor environment, the type of HVAC system adopted required careful consideration. Frost prevention fans normally used for tea plantations were installed on the terraces to blow warm air downwards during the heating season. Transferring air from the ventilation windows in the office spaces to those in the upper parts of the atrium also achieved effective natural ventilation.
A programme of work involving the measurement of ventilation rates, air velocities and temperatures has been completed within a naturally ventilated auditorium in the Queens Building, De Montfort University. Measurements have been recorded for 'winter', 'mid-season' and 'summer' conditions, and average occupancy levels.
This British Standard gives recommendations on the principles which should be observed when designing for the natural ventilation of buildings for human occupation.
Split-duct roof ventilators or windcatchers are used to provide both supply and extract ventilation to the spaces which they serve. However, buildings are often erected in conditions where there is no prevailing wind direction. An investigation into four and six segment windcatchers to determine their relative performances under different wind conditions was undertaken using scale models in a wind tunnel. Conclusions indjciate that six segment windcatchers have a more predictable, reliable performance in uncertain or variablewind conditions.
Using the wind pressure difference method to estimate the cross ventilation potentials of a building at a particular site, the appropriate wind frequency data at the building site are important (Aynsley et al, 1977, Su, 2001). This study investigated wind frequency data available from the data recording site at Auckland airport and discusses how to obtain the building site wind frequency data from the original wind frequency data recorded from such sources.
The results of numerical simulation on the effects of solar chimney and underground cooling system for ventilation and heating in the new building of Faculty of International Environmental Engineering Kitakyushu University, Japan are described. It was found interesting to see the air flow rates with and without the effects of wind during the cooling period and air temperature during the heating period due to the solar chimney.
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