English

Symmetry is not a sufficient condition for the design of a ventilated room to generate two-dimensional airflow. Three-dimensional effects were observed in a symmetrically designed 3m x 5m x 8.5m test mom having a 0.019m slot inlet opening height under the ceiling in the one end wall. The ceiling jet velocity profile measured in the symmetric plane agreed well with the jet models for two-dimensional !low, but large differences were found out of the symmetric plane.

The flow in a ventilated room will not always be a fully developed turbulent flow. Reduced air change rates owing to energy considerations and the application of natural ventilation with openings in the outer wall will give room air movements with low turbulence effects. This paper discusses the isothermal low Reynolds number flow from a slot inlet in the end wall of the room. The experiments are made on the scale of I to 5. Measurements indicate a low Reynolds number effect in the wall jet flow.

The aim was to develop a simple dynamic model for predicting air exchange caused by short time single-sided ventilation and necessary window opening time in classrooms. Tracer gas measurements have been made in a full-scale room. The comparison indicates that the model can be used when rough estimates of air exchange are of interest.

This paper shows that under certain conditions, multiple solutions for the flow rate exist in a natural ventilation system, induced by the non-linear interaction between buoyancy and wind forces. Under certain physical simplifications, the system is governed in steady state by a non-linear algebraic equation or a system of equations. Three examples are given here: a single-zone building with two openings, a channel with two end openings, and a two-zone building with two openings in each zone. Analytical and numerical solutions are presented.

This study investigated the sources and concentrations of volatile organic compounds (VOCs) including formaldehyde in the air of a new office and conference centre building. The building is naturally ventilated, and was designed to demonstrate a number of innovative approaches to environmental design. Occupant surveys have shown a high level of occupant satisfaction with the indoor environment.

Epidemiological studies suggest that cooking with gas leads to an increase of air pollutants and may enhance symptoms of respiratory diseases. However, little experimental data are available concerning the emission of pollutants due to different cooking processes. The goal of this study was to investigate the influence of cooking under standardized conditions on the indoor air quality. A model kitchen was built and three different gas stoves and one electric stove were included in the study. Two different menus were prepared with different settings of the ventilation rate of the exhaust.

In dwellings ventilated by extract ventilation there are common complaints of cold draught caused by the supply air entering the room through openings close to the windows. This paper reports on studies of unconventional ways to distribute the supply air in order to minimise the risk of such problems. Experiments have been done where the supply air device is located in the hall of an apartment. The ventilation efficiency in the rooms adjacent to the hall has been studied with open and closed doors. The behaviour of gravity currents has also been studied in scale models.

Air may be pre-cooled using thermal mass before it is supplied to an occupied space. One option is to pre-cool the air in a basement space and exhaust the air at high level through stacks. However, the thermal forces that determine the direction of airflow, including heat gains in the occupied space, thermal mass cooling and the external air temperature may counter each other, and result in flow reversal.

In many cases natural ventilation is used to ensure an acceptable indoor environment. However it is difficult to design a building for acceptable ventilation rates and indoor comfort without the proper tools or guidelines. The passive building simulation tool Building Toolbox was extended with natural ventilation models for the design of natural ventilated buildings. The simulation tool was verified with actual measurements during three case studies to ensure its integrity and to illustrate its applicability in this field.