The results presented here supply values for the room ventilation efficiency of a number of configurations covering as many as possible of the ventilation systems encountered in actual practice. The study is based on experimental results and numerical simulation. Using a few configurations experimented-on, simulations were performed using CFD code, which in particular allowed the reliability of calculations to be checked. The simulation tool was then used in such a way as to arrive at results that could be applied in practice.

Concentrations of indoor air contaminants are normally calculated by assuming that they fullyfollow airflow paths in a room. This assumption is also used to predict the local residence timeof contaminants in a room, which may further be used to characterise the ventilation effectiveness.In this paper, a different methodology has been adopted, in which indoor airborne particles do notalways follow the main airstream induced by the ventilation system. Dispersion of particles ispredicted by a drift-flux model.

Existing infiltration and exfiltration calculation methods are mainly based on the stationaryapproach, where long term mean values are used for wind input data. The real wind speed is,however, varying continuously with time. Because the process of the crack flow is non-linear,using mean wind speed values will give erroneous results for the air flows.

This paper presents an analysis of different possibilities of representing mass transfers in zonal models. In this aim, formulations derived from the Navier-Stokes equations or from Euler's theorem are obtained. The models which result from them and empirical models are compared so that to define the best compromise between simplicity, accuracy and easy convergence.

The series connected heat exchangers - configured either as an arrangement of gas-gas,gas-liquid or liquid-liquid heat exchangers- are widely used in the process industry andair-conditioning where they can be found in a variety of heat (cool) recovery, in heating andcooling applications.

The purpose of this research is to give an overall prospect of the performance of 4 kinds of ventilation systems for dwellings using numerical simulation under various conditions. The total number of combinations of various parameters for the calculation is 174. Calculations for pollutant concentration, humidity and condensation, interior pressure and airflow rate, heat energy by ventilation, etc. are performed hourly through the heating season.

This paper deals with the interzonal air movement in a building, throughhorizontal openings, under natural convective conditions. These airflow phenomena areinvestigated experimentally, through a series of experiments in the stairwell of a full-scalebuilding, using tracer gas technique. The resulting time-dependent concentration evolutionoffers a means of analyzing the flow field. These cases are also simulated by a CFD code, thatuses the finite-volume method and incorporates a low-Reynolds k-E two equation turbulencemodel.

This paper will present a general approach that may be used to solve natural ventilation designproblems typically addressed at the preliminary design stage - How wide should windows beopened in a given building for wind-driven cross ventilation on a moderate summer day? Howshould a ventilating monitor be configured to mitigate internal and solar gains on the samesummer day?

Evaporative cooling is an interesting alternative to conventional compressor refigerationsystems for air-conditioning. However, the use of evaporative cooling presupposes all-airsystems and is, to a large extent, limited by ambient conditions as well as the settled demandson the indoor climate. High outdoor humidity levels have a great influence on the supply-airtemperature achievable, i.e. cooling loads possible to meet. One way to reduce the influenceof these limitations is to use desiccant cooling, i.e. to dehumidify the ambient air before theevaporative stages.

In the present paper a model for steady-state thermal analysis of ventilated and unventilated light rook is proposed. The aim of the work is tostudy the influence of thermo-physical and geometric parameters of the roof and boundary conditions (solar radiation) on the entering heat flowand the temperature distribution within the roof structure.