The study concerns the ventilation of a parallelepiped shape room by means of several systems whose supplying and extracting methods differ, so the different thermic conditions applied to limits. To qualify the efficiency of each of these systems in relation with the various current criteria, we carried out measurements by means of a tracer gas, both with a transitory and a permanent flow. At the same time, numerical simulations were carried out by means of a CFD code which solves the equations of the fluids mechanic, material and heat transfers associated with flows.

The comparison of the performances of ventilation systems must take into account different issues. For indoor air quality, different kinds of pollutant sources have to be defined. To make an evaluation of the results, the best approach is to consider the people exposure. Four generic pollutants are taken into account : rooms components or furniture, human metabolism, cooking activities, passive smoking. As the definition of the unit for each pollutant is free, it is useful for their comparison to press them on a common "normalised" basis.

The performance of mechanical ventilation systems has been checked in several innovative residential houses in the frame of Swiss research as well as pilot and demonstration projects. This paper gives a list of performance criteria for the ongoing comparison and evaluation of these mechanical ventilation systems. For some criteria, target values are proposed. In the second part, this paper shortly describes four residential buildings with mechanical ventilation systems where such evaluations were performed and highlights interesting design features and results from the measurements.

The paper will discuss problems connected with incorporation of stochastic factors into deterministic models of indoor air quality. Three different methods: a quasi dynamic multi-zone modelling with generating of input data time series, multi-zone modelling based on the theory of stochastic differential equations, Monte-Carlo simulation with independent random generating of stochastic parameters, will be shortly presented. Described methods are compared on the base of computer simulation of CO2 concentration in simple two compartment office.

Low emitting building materials have contributed to the reduction of indoor air contaminants, and in many countries gas ranges and gas cookers are rarely used. As a result, in buildings located in urban environments, a considerable part of the contaminants in the indoor air may originate from the outdoor air. In urban areas buildings are exposed to high concentrations of a large number of contaminants, especially during traffic peak hours.

A naturally ventilated three level office building has been used to study basic stack ventilation configurations and the interaction between ventilation and the subsequent cooling of the building structure in summer. The research was performed in the framework of a European project on passive cooling of buildings and the objective was to validate simple ventilation algorithms and to give an experimental basis to design guidelines for night cooling techniques.

This paper presents the special needs and difficulties concerning cooling and ventilation of the SwissMetro high-speed ground transportation system. SwissMetro is based on four complementary technologies: a complete underground infrastructure, a partly evacuated tunnel system to reduce the aerodynamic drag of the vehicle with a maximum speed between 400 and 500 km/h, linear electric motors and a magnetic levitation and guiding system. Due to high internal and external heat loads permanent cooling and air-conditioning of the vehicle is required.

In response to complaints about poor air quality in bus termini, the Hong Kong Government is considering imposing legislative control over ventilation system design and operation of bus termini in Hong Kong. However, there are, as yet, no relevant air quality criteria and ventilation system design guidelines for Hong Kong. In this paper, measured air quality data for 5 semi-enclosed bus termini are reviewed. This provides a picture of the prevalent air quality in bus termini.

AIOLOS is a project partly financed by the European Commission, DG XVII for Energy, within the frame of the ALTENER programme. The purpose of the project is the creation and dissemination of educational material on the use of passive ve~ltilationc ooling systems and techniques as applied in buildings. All information will be coupled with the problems of passive solar heating, daylighting and visual comfort. The project is oriented to South European but also North European countries with moderate climate presenting cooling problems.

This study is done by order of a Finnish air cooler manufacturer and it is founded to a master's thesis of the same subject matter. The company produces e.g. unit air coolers with electric fans and so the aim of the study was to reduce draught problems caused by cold air jets.