English

Since reduction of ventilation rates in dwellings for economical reasons, it has been necessary to study whether this reduction had not been done to the detriment of indoor air quality. Several means of investigating were developed: experimental tests are indispensable but usually expensive that is why numerous research centres choose to model the thermoconvective fields in rooms.

The energy saving practice of stopping ventilation systems at night may reduce the daytimeair quality. Sorption phenomena where pollutants absorbed at night are reemitted during theday and the general slower removal of pollutants at the reduced average ventilation rates willcontribute to the deterioration of air quality at intermittent running systems. The purpose ofthe study was to investigate the impact on construction product emission during the day fromreduced ventilation rates at night. Experiments were performed in three small-scale chambersof Climpaq type with dilution systems.

The overall objective of the present work is to evaluate the performance of three turbulence models, with a view to predicting characteristics of airflow within an anisothermic cavity. The standard K-c. model, the Renormalisation Group model (RNG) and the Reynolds stress model (RSM) are used in conjunction with the Fluent code. The accuracy and the relative performance of the three models are evaluated by comparing their numerical results with experimentally obtained data. This comparison is made for the constant flow rate of a twodimensional turbulent mixed convective airflow.

Convective transfers mainly determine the energy and mass balances which regulate the micro-climate inside a greenhouse. Air flow and temperature patterns induced by natural ventilation through greenhouse roof openings are only considered here. Flow visualizations were performed on a half scale test cell simulating the absorption of solar radiation at the floor surface of a single-span greenhouse. Temperature and air flow patterns were observed in a steady regime i) with a single sided roof vent and ii) with two symmetrical one.

The role of metallic surfaces is not only to save energy in winter and in summer by separating the inside and the outside. New and inexpensive ways of collecting solar energy for internal heating, new ways of ventilating, heating and cooling through the fabric elements are described. Two very significant prospects are : radiative cooling by metallic surfaces and enhancement of indirect daylighting by optimised ceilings. The subject of the European CURES program is to promote these new technologies by simulating and testing them.

Air flow patterns and temperature distribution within courtyard have been studied. Wind and thermally driven flow have been thoroughly analysed as a function of the depth to width ratio (Aspect ratio) as main parameter. CFD results show a quite similar behaviour regarding to velocity profiles for all the cases, though temperature profiles are highly affected by dimensions of the courtyard. The whole study can be extrapolated to urban canyons, where air flow patterns are quite similar as a result of having the same geometry.

Over the last decades, a great importance has been given to thermal insulation, in technological designing of building envelope. Lately, a basic requirement of indoor air quality, strictly related to ventilation control strategies, has been highlighted. Then, it is necessary to evaluate correctly, during the design phase, the air permeability of enclosures through validated methods, to assess new technologies through laboratory tests on prototypes and finally to verify real performances through on-site testings.

Indoor and outdoor concentrations of various pollutants were measured in a naturally ventilated building in the West End of Edinburgh during and after the period of the Commonwealth Heads of Government Meeting (CHOGM) to assess the effect upon indoor pollution levels of the closure of some streets in the city. The relationships between indoor and outdoor air qualities in respect of traffic-generated pollutants were studied and the building's relative attenuation of external pollution levels investigated.

Achieving optimized partial improvements of the indoor climate may often be better than to know all optimal levels. The purpose of this study was to investigate the relative importance of temperature, noise, draft and window area. 30 heat-acclimatized subjects participated in 10 exposures in single person climate chambers. Each exposure lasted three hours. During an exposure, the subject was free to optimize the operative temperature at a link to either draft, noise or window area. For each pair of parameters, three linear links were tested.

The use of tracer gas is of great help in measuring airflow rates and detecting shortcuts in air handling units, and is essential for ventilation efficiency measurement. However, the planning of experiments, that is choosing tracer gas injection locations and air sampling locations, is not straightforward. Moreover, the mathematics used for interpretation are quite complex, and require elaborate calculations. Therefore, a measurement protocol and the corresponding interpretation algorithms are being developed and implemented in a user-friendly computer program.