Thermal and environmental simulation of buildings

Abstract

The purpose of most buildings is to provide a comfortable and healthy indoor environment for the occupants. As a result of increasing energy prices in the last decades, much effort has been done to reduce the cost arising from mechanical and natural ventilation of buildings. This often involves lowering the outdoor air intake. At the same time, many new pollution sources have been introduced in the buildings. These issues are important if we take into consideration that today the majority of the people spends more than 90% of their time indoors. In this work will be presented a physical and mathematical models to study the three-dimensional turbulent air flow patterns with thermal buoyant effects, the heat transfer, including radiation between walls, the gas contaminant trasnport and the most air transport into mechanical or natural ventilated spaces. the calculations made use of a numerical procedure, which solves the three-dimensional equations for the conservation of mass, momentum, thermal energy and air contaminant transport. The turbulence is modelled by the k-e model and thermal radiation by the discrete transfer method. To validate the mathematical model, the predictions results were compared with experimental data for two different scales - full scale office room and 1/4 laboratory scale model. A physical modelling technique, based on dimensional analysis, was used to derive the physical properties of the laboratory model, designed to provide similarity with the room. The simulation of the air contaminant distribution, the thermal and the air flow patterns in an office natural ventilated room (prototype and model) was performed