Computational fluid Dynamics (CFD) is a powerfizl tool for analysing problems of air movement and has been increasingly widely used in applications in buildings. The emphasis has often been on its development as a replacement for the experimental approach, however, further work is needed to develop confidence in applying CFD to problems of air flow in buildings.

Ventilation is necessary to insure acceptable indoor air quality as well as to protect the building itself against damage due to condensation Ventilation rates however, must not lead to excessive energy consumption In order to comply with these requirements of hygiene, comfort and energy savings, French regulations stipulate that the ventilation of dwellings has to be general and continuous and achieved by specific systems by which fresh air is provided to the dwellings.

Designing a comfortable inside climate for office buildings to operate within comfort limits (PMV+/-0.5) requires a flexible operating strategy. Two systems a VAV and a VHV are identified and compared to each other. Dynamic simulation techniques are used to obtain an optimal design, based upon comfort conditions not temperatures. The control strategies are optimised to minimize energy consumption while controlling the HVAC system to remain within comfort limits in the occupied zone.

The issue of energy consumption assessment is a complex one. Sophisticated simulation software whilst providing detailed predictions of the thermal performance of buildings, cannot be claimed to have an appropriate level of user friendliness for widespread application. On the other hand, simple software packages for the assessment of thermal transmittance cannot adequately deal with such factors as occupancy pattern and weather variations. In an attempt to fill the middle ground, the concept of energy rating has been developed.

In the framework of a CEC demonstration project on humidity controlled ventilation, detailed measurements are carried out in 18 apartments in Namur, Belgium.The paper gives a brief description of the building, of the airtightness of the apartments and of the ventilation provisions. The largest part of the paper deals with the major outcomes of the study.

Within the framework of demonstration and industrial pilot projects in the energy sector supported by the Commission of the European Economic Communities, an important experiment has been dedicated to the HYGRO-ADJUSTABLE NATURAL VENTILATION (Contrat EE/166/87/FR). The experiment took place on three sites: Les ULIS (France), NAMUR (Belgium) and SCHIEDAM (the Netherlands).

Under-estimating the ventilation flow rate results in increased sanitary risks and damage to the existing building structure. Over-estimating ventilation flow leads to energy waste. In this context, a number of approaches have been designed to determine indoor air quality indicators. The aim of these is to compare comfort and sanitary quality in different atmospheres. This document presents four air quality indicators developed by three French teams and one Danish team.We examine the strengths and weaknesses of each design, plus their specific areas of use.

The importance of natural ventilation, typically restricted to residential buildings application, is rapidly increasing also within the commercial buildings. This is mainly due to the energy savings expected from a reduction of the use of the forced ventilation. Moreover, the remote control of the indoors, provided by means of the intelligent buildings features, allows an easier management of the environmental quality. Furthermore, the indoor air quality is also directly affected by the air exchanges obtained by natural ventilation.

Increases in the levels of thermal insulation required in the walls and roofs of houses in the U.K. in recent years have meant that heat losses through floors now assume greater significance, as a proportion of the total heat loss from a dwelling. To effect further reductions in the energy consumption of houses, the thermal performance of floors needs to be examined to assess the most cost effective insulation strategy.

The number of smokers differs mainly with age, sex, education, profession, and cultural background. The change in habits from the 2nd World War till today in form of increasing number of female smokers and decreasing number of male smokers is significant. The smoking of tobacco causes pollutants in the form of volatile organic compounds, particles, and carbon monoxide. Many of the pollutants are carcinogenic. In some cases the concentration of specific tobacco smoke related pollutants in room air may be higher than the maximum allowable concentration.