English

An existing computer model for dynamic hygrothermal analysis of buildings has been extended with a multizone airflow model based on loop equations to account for the coupled thermal and airflow in natural and hybrid ventilated buildings. In water distribution network and related fields loop equations have been widely used to resolve the flow of water and other fluids. In the field of natural ventilation the loop equation method have rarely been used in spite of its quality.

A full-scale test room is used to investigate experimentally and numerically the velocity and temperature fields in the case of a mechanical ventilation. Detailed fields are measured for three cases of ventilation air temperature: an isothermal case, a hot case and a cold case. The experimental data are used to test two turbulence models: a first order k-ε turbulence model and a second order RSM turbulence model. The RSM model predicts the temperature and velocity fields better than the k-ε turbulence model.

house is a dominant factor for animal welfare. There are threshold values or recommendations for the most important climate parameters. Temperature, humidity, CO2 and NH3 gas concentrations, germs, dust, odour and air flow velocity have to be observed. Unfortunately the necessary ventilation of livestock buildings leads to emissions, too. So an important aim is to develop ventilation systems that produce: 

Traffic–related pollutant has been recognized as an air pollution hot spot due to its large emission rate and great health impacts for the exposed population. In the present investigation, a computational fluid dynamics technique is used to evaluate the effect of traffic pollutions on indoor air quality of a naturally ventilated building. The transport of street-level nonreactive pollutants emitted from motor vehicles into the indoor environment is simulated using the RNG k-ε model of the turbulent flows and the pollutant transport equations.

The aim of the present study was to determine the applicability of a genetic algorithm for the optimization of daylighting systems, as well as the requirements for the lighting simulations to be used. Furthermore, by testing the daylighting performance of a building's facade when several parameters are allowed to change simultaneously, the results were used as a complement of previous parametric studies. The goal of the optimization was to maximize energy savings by reducing visual discomfort while maintaining good daylight penetration.

An extended top of the roof can induce the upflowing wind which flows close to the wall and in this way it increases the intake airflow rate in the air gap. A model was set up to save energy with the consideration of a suitable thickness of the air gap and a suitable length of the extended top. The Computational Fluid Dynamics (CFD) was employed to simulate the wind field in the ventilated roofs with extended top and the cases were carried out according to Changsha’s climate parameters in China. The results show that the extended ventilated roof works very well in summer.

Quantification of natural ventilation rates is an important issue in HVAC system design. Natural ventilation in buildings depends on many parameters whose uncertainty varies significantly, and hence the results from a standard deterministic simulation approach could be unreliable.

The buoyancy-driven natural ventilation of a room with large lower and higher level openings is investigated by both theoretical analysis and CFD simulation. Pressure-based formulae are developed for the prediction of the height of neutral plane and airflow rate, and three different flow modes are identified according to the position of the neutral level: (I) when the neutral height is at intermediate level of the lower opening; (II) when the neutral height has no intersection with openings; (III) when the neutral height is at the intermediate level of the higher opening.

Assessments based on CFD snapshots of stable conditions within strongly transient domains do not address many aspects of performance associated with occupant interventions, control actions or changing climate. Such domains (e.g. double skin façades) are characterised by transient flow patterns due to changing weather patterns, actuation of dampers intermittent opening of façade windows and operation of building environmental systems. Importing boundary conditions from whole building simulation is an improvement but it discounts the impact of the flow predictions on the building domain.

A mathematical model for simulating airflow in solar channel of the insulated Trombe solar wall system is proposed. It is assumed the glazing is isothermal and the solar heat absorbed by the wall is transferred to  the air in the channel with a constant flux by natural convection. The mass, momentum and energy  conservation equations are discretized and solved using the finite difference control volume method. An experimental study of solar chimney was used to validate the proposed mathematical model.