English

A number of new techniques have been developed in recent years, by various researchers, to assist in the sizing and positioning of natural ventilation openings. These may be of considerable assistance in the natural ventilation design process, while still allowing architectural freedom. This paper reviews some of the available techniques. The complexity of the configurations accounted for by the procedures ranges from two openings with the indoor air at a uniform temperature to a technique that allows for multiple openings throughout a multi-zone structure.

As the climate in the Nordic countries is cold for several months a year, windows are crucial parts of building envelopes. The current trend to reduce the heat losses by building- components has resulted in many modifications of the design work of windows in order to improve the thermal performance and the indoor climate. The improvements of window constructions have resulted in a higher surface temperature on the inner pane and considerably lower downdraught, which in turn has created an opportunity to introduce unconventional design of the heating and ventilation systems.

In displacement ventilation the airflow pattern in a room is mainly guided by the convection flows from the heat sources present in the room. This implies that the air in the breathing zone mostly comes from the lower parts of the room, where the air often is less polluted by pollutants originating from persons or electrical appliances present in the room.

Wall-mounted air conditioning systems including window-type and split-type air conditioners are widely used in Asian countries. However, these systems blow cold air directly into the working space perpendicular to the mounted wall and may make people affected by these air conditioners experience discomforts such as draught and uneven temperature distribution. Now a wall-mounted air conditioning system is expected to effectively implement the displacement ventilation system for space cooling and cold draught avoiding.

For indoor thermal environment engineering and heating system dimensioning, naturally ventilated spaces impose difficulties due to the interaction of indoor and outdoor air flows and due to their variation in time and space. Thermal building simulation models basically assume mixed air flow conditions in the individual zones, but are able to dynamically model the building masses and the heat exchange between them and the zone air.

There are many ventilation and air conditioning systems, having their own set of advantages, disadvantages and applications. Inadequate control on ventilation rate for the case of natural ventilation system can lead to indoor air quality problems or excessive energy loss, while mechanical system is often expensive for the installation, operational and maintenance costs.

The characteristics of a hybrid air-conditioning system, utilizing natural and mechanical ventilation, is investigated in an office setting. The characteristics of the indoor environment are examined with CFD(Computational fluid Dynamics) simulation under various conditions of incoming outdoor air. The control of the room air conditioning system (VAY system) is included in the calculation through changing the supply air volume to keep the task zone's temperature at a target temperature.

An isothermal air curtain for isolation of smoking areas in restaurants was designed, built and evaluated in a test facility using oil-smoke visualisation and tracer measurements. The test facility was a ventilation test room set up as a small restaurant, with tables, chairs, person simulators (cylindrical heat sources) and balanced mechanical ventilation. Fresh air was supplied in the non-smoking section of the room, exhaust air drawn from the smoking area, and the air curtain was attached to the ceiling between the two sections.

A three dimensional computational fluid dynamics (CFO) analysis has been used to predict airflow patterns in laboratory fume hoods. The simulation includes bypass fume hood primary operational features including the top and bottom bypasses, front airfoils, and rear slotted baffles. The study included the effects on the fume hood airflow of sash height changes, an operator positioned outside the fume hood, and equipment within the main fume hood chamber.