A computer model for predicting natural ventilation in buildings by solar chimney alone is presented. The simulations are based on the solution of the 3-D steady laminar conservation equations of mass, momentum and thermal energy with an appropriate set of boundary conditions. The equations are discretized using a finite difference formulation and solved by the Marker and Cell (MAC) scheme. Indoor airflow fields and temperature distributions are discussed with respect to human comfort at the living level, 1 m above floor.
The evolution of the temperature profile in a warm room driven by a natural ventilation flow which develops when the room is connected to a cold exterior by two openings at different vertical heights is explored. With the openings at the top and base of the room, we find the classical displacement ventilation regime provides a leading order description of the flow. With openings at the centre and top of the room, the ventilation is hybrid, with the lower part of the room being well-mixed, and the upper part being stratified by an upward displacement ventilation flow.
This paper presents an innovative roof design. The roof is designed in response to the Tropical climate of Thailand with respect to human thermal comfort. It is composed of a combination of CPAC Monier concrete and transparent tiles on the outer side, air gap and another combination of gypsum with aluminum foil board and translucent sheets on the house side. It has two functions in operation: In daytime the roof acts as a solar chimney and induces natural ventilation. The transparent tile provides not only ,sufficient daylight for housing but also help in increasing the ventilation rate.
With the purpose of evaluating validity of the application of CFO on the problems of cross-ventilation, numerical simulation was performed, using standard k- E model and two types of modified k-E models which improve evaluation accuracy in production term of turbulence energy, and also using LES, and the results were compared with those of the corresponding wind tunnel experiment. As a result, it was found that the defects of the model characteristic to the standard k- E model could be improved to a certain extent by application of the modified models.
Solar energy air-collectors installed on the sun-oriented building facades can be used for improving natural ventilation of adjacent rooms. The basis of the physical process is an unbalanced buoyancy force arising from the temperature difference between ambient and the air inside the room. Although difficult to control due to the variability of the climatic conditions, these devices can be used as means of reducing the need for conventional energy to provide indoor air conditions within acceptable limits required by health and comfort considerations.
For the academy Mont Cenis in Herne, Germany, a large microclimatic glass envelope (72m x 1.80m x 15m) with separate buildings inside the envelope, a concept for the natural ventilation was put up and a program for the control of the motor driven windows in the facades and in the roof was developed. To comprise the influence of wind speed, wind direction and the temperature difference between the envelope and the environment, numerous CFD-calculations were carried out on the base of a wind tunnel test and dynamic thermal calculations.
Architecture and engineering journals have been increasingly attentive to innovative non-residential buildings designed with operable windows. Such buildings may rely exclusively on natural ventilation for cooling, or may operate as mixed-mode, or "hybrid" buildings that integrate both natural and mechanical cooling. Architects who want to incorporate natural ventilation as an energy-efficient feature need to collaborate closely with mechanical engineers.
The present paper refers to the numerical prediction of air velocities and temperatures inside single-sided naturally ventilated buildings and more specifically the special case in which air from the external environment is brought into the building through single-directed openings. The work is focused on the physical procedures governing air movement during the single-sided natural ventilation.
Analytical solutions are derived for calculating natural ventilation flow rates and air temperatures in a single-zone building with two openings when no thermal mass is present. In these solutions, the independent variables are the heat source strength and wind speed, rather than given indoor air temperatures. Three air change rate parameters α,β and γ are introduced to characterise, respectively, the effects of the thermal buoyancy force, the envelope heat loss and the wind force.
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