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In Asian countries under sultry climatic conditions includingJapan, natural ventilation and cross-ventilation at nighttime give very good effects on the improvement of physical conditions of the residents and on the coolingof the buildings in intermediate and summer seasons.However, a densely populated urban area such as Tokyo, sufficient ventilation flow rate may not be necessarily maintained because the distances between neighboring houses are shorter and also because of the problem to keep privacy of the residents between the windows, which are positioned face-to-face on wall surfaces.

Considering that natural ventilation is a climatic factor,a renewable alternative, as well as an important source of comfort, it seems to be relevant to consider its great potential when applied to architecture, taking into account economical and environmental gains. It is difficult to think about studying air circulation without mentioning the north Africa vernacular architecture and its ability to create the best solutions to increase the ventilation without any energy consumption, therefore, adopting passive cooling.

This document aims to present the progress and the outcome of the research on double skin façades that is being carried out within the European ‘BESTFACADE’ project. Double skin facades have become an important architectural element in office buildings over the last 15 years. The demand for natural and hybrid ventilation in commercial buildings is increasing due to growing environmental consciousness while at the same time energy consumption for buildings has to be reduced.

In hot and arid climates, evaporative cooling appears to have significant potential to provide thermal comfort and reduce the energy loads of summer season. These regions used wind towers as means to reduce energy consumption of air conditioning systems.However, the cooling potential of wind towers techniquewas investigated in real exiting building in Ouarglacity of Algeria (hot and arid climate); Measurements have been performed under two conditions with and without evaporative potential.A mathematical model of wind tower has been developed and validated using the measured data.

Presently the assessment of the thermal behaviour and the energy efficiency of naturally ventilated double skin facades (DSF) is only possible by using complex simulationtools, which allow inter-connections between fluid dynamics, energy balances and optical transport mechanisms. The performance assessment of mechanicallyventilated DSF is slightly easier but still requires simulation tools.

This study documented that houses in the southeastern United States built on typical wall ventedcrawl spaces possess the following characteristics: 1) liquid water, water vapor and associatedmoisture issues, 2) mold spores, 3) measured holes between the crawl space and living space, 4)measured transmission of mold spores from the crawl space to the living space.

This paper outlines the Australian Standard 1668.2: 2002 ETSHI risk methodology and extends it to give a means of calculating the numerical death risk from exposure of specific age/gender groups to defined Environmental Tobacco Smoke, (ETS) exposures.Acceptable risk exposure is discussed (with numbers) and actual mortality statistics are presented for comparison.A smoking permitted office situation is analysed and some conclusions are drawn.This paper (and the underlying research) was not funded by pro or anti tobacco interests.

For the prototype of the local air conditioning of the working places named PERMICS(Personal Microclimate System) the air velocity and turbulence intensity at horizontal air inlets were analyzed. The velocity field was visualized with smoke. Based on findings from visualization the measurements were made with new technology of the hot-wire anemometer named HW3D-ED. Experimental analysis has been supplemented by a numerical simulation of the velocity field on the air terminal device and in the breathing zone using a commercial CFD package, software PHOENICS.

The Single Coil Twin Fan (SCTF) system is a newly developed air-conditioning and air distribution system that aims to deliver enhanced IAQ as well as save energy. The fundamental principle of this system is based on demand ventilation and demand cooling, which is achieved in the individual occupied zones through localized temperature and carbon dioxide sensors positioned in the respective return grilles. The conditioning of the two air streams is achieved by a single compartmented cooling coil, which provides ease of control of the chilled water flow through the coil.

The present communication forms part of the conclusions to emerge from the research project-Development of a methodology for the estimation of ventilation efficiency in residentialhouses- financed jointly by the Spanish Ministry of Education and Science and by ERDF, andcarried out from 2003 to early 2006.The aim is to present the results obtained for ventilation efficiency in systems of hybrid ventilation for houses, which is about to be implemented in Spanish legislation.