English

A condition often assumed when designing a naturally ventilated building is where air enters at low level and leaves at high level due to the stack effect. It then follows that, at upper levels, the air may be relatively 'stale' since it has previously passed through the lower storeys. An analogous situation may arise when wind is blowing, in which the air entering through the windward face becomes stale as it passes through the building to the downwind sections. It is not well understood how ventilation may, in reality, be affected by this.

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.

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.

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.

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.

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.

Adequate ventilation with the "right amount of air, to the right place and at the right time" are important factors for achieving a good indoor climate. Thus it is of prime importance that the ventilation system is working properly. Using traditional methods, it is a very time consuming, and some times even impossible, task to balance ventilation systems to achieve correct air distribution. In most countries the growing concern about Indoor Air Quality has resulted in Building Codes demanding increased ventilation rates.

The aim of this study was to compare the radon levels at workplaces and in homes located nearby. Homes (number of 57) and partly or fully underground workrooms (number of 55) have been studied at the four workplaces in southern Finland and one workplace in northern Finland. Radon concentrations both at workplaces and in homes seemed to be at the same level in the same district. The mean radon concentration in workrooms was 406 Bq.m³, and in homes concentration was 398 Bq.m³.

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.

The present paper presents results from measurements of outdoor airflow rates and air change rates carried out simultaneously with measurements of the indoor concentration of carbon dioxide (CO2 ) . The measurements were made both under controlled laboratory conditions and in the field. The field experiments were performed in a conference room, an assembly hall and an office room, and the laboratory investigation was carried out in a 19 m³ test chamber.