When buoyancy forces, wind forces and envelope heat losses interact in a naturally ventilated building, the behaviour of the flow rate as a function of these parameters can be quite complex. This paper derives the equations for the flow rate in a two-zone building where one zone is above the other, and where each zone has a high and a low opening.
Unsteady wind effects can be important in natural ventilation, but their treatment requires knowledge of instantaneous surface pressure distributions which are extremely difficult to obtain. The paper describes a theoretical investigation aimed at determining the effects of unsteadiness and, perhaps more important, the conditions for which it may be worth accounting for them in the design process. For generality the study uses nondimensional parameters. The effects of unsteadiness on both mean and instantaneous flow rates are covered.
This paper describes the fluid mechanics of natural ventilation by the combined effects of buoyancy and wind. Attention is restricted to transient draining flows in a space containing buoyant fluid when the wind and buoyancy forces reinforce one another. The flows have been studied theoretically and the results compared with small-scale laboratory experiments. Connections between the enclosure and the surrounding fluid are with high-level and low-level openings on both windward and leeward faces.
One sixth of the total energy consumed in Taiwan is for building operation, mainly for summer cooling. The energy consumed for summer cooling can be greatly reduced if naturalventilation can be exerted in Taiwanese urban apartments. To explore the feasibility ofapplying stack ventilation in urban apartments during warm season of Taipei, this studyexamines the ventilation volume induced by the combined wind and stack effect in a twostory building.
Particle characteristics in indoor environments are strongly related to the characteristics ofoutdoor particles. The aim of this work was to investigate how submicrometre particle numberconcentration changes with the distance from a road.
The aim of this study is to illustrate the importance of the effects of wind turbulence on airchange in buildings. Using two simple configurations, tested over a short period, twoapproaches are compared.The tests are performed using m experimental house which is filly exposed to the wind.
Air flow patterns and temperature distribution within courtyard have been studied. Wind and thermally driven flow have been thoroughly analysed as a function of the depth to width ratio (Aspect ratio) as main parameter. CFD results show a quite similar behaviour regarding to velocity profiles for all the cases, though temperature profiles are highly affected by dimensions of the courtyard. The whole study can be extrapolated to urban canyons, where air flow patterns are quite similar as a result of having the same geometry.
In 1984 the municipality of Frederikshavn in northern Jutland, Denmark initiated a project for the climatic design of a new housing area. The site is particularly exposed to strong winds all the year round and one of the major tasks was to design the overall building site and the buildings so that major improvements in the exterior wind environment were achieved. Furthermore the design brief from the municipality called for an overall climatic design, where low-energy solutions were combined with consideration of the exterior environment near the buildings.
The relationships, in courtyards, between wind flow pattern and temperature distribution have been studied. Thus, in the first part of this study a dimensionless temperature based on the exchange of heat by convection is defined. Then, using the ratio of depth to width (Aspect Ratio) as the main parameter, we are able to explain the curious behaviour observed. Finally, courtyards are divided into several zones in order to separate the different heat sources in each one, allowing us a stratification study.
The performance of a glazed solar chimney for heat recovery in naturally-ventilated buildings was investigated using the CFD technique. The CFO program was validated against experimental data from the literature and good agreement between the prediction and measurement was achieved. The predicted ventilation rate increased with the chimney wall temperature. The effects of solar heat gain and glazing type were investigated. It was shown that in order to maximise the ventilation rate in a cold winter, double or even triple glazing should be used.
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