Up to now, the use of a single HVAC unit to handle ventilation along with mechanical cooling was the aim of designers : it permitted to curb the cost of a building's mechanical system. In this article the author suggests a new design approach to treat the ventilation air and to manage the latent cooling load for the building. It consists in "splitting" the building's total cooling load with a DOAS. This approach allows each component of the HVAC system to do what it does best.

In France, air quality in working areas is a matter of preoccupation for both the industry and the welfare state, that is in charge with the application of the rules and regulations in that field. The Labour Legislation and the Institution of Prevention, bring advice and assistance to the companies and final users.20 practical guides dealing with ventilation are listed at the end of the article.

Three experiments aiming at improving the atmosphere in industrial premices are described in this paper. The working conditions of the staff have been improved along with an amelioration of the process and quality of fabrication.The third example proves that a well adapted technical approach allows the improvement of working conditions coupled with an energy control.

A heatlhy environment at work has become a real preoccupation. It began first in offices but now it exists in industry which was reluctant up to now in spending money for it, because the output responsibles were not convinced that such an investment could bring an output gain. A loss of productivity can depend on the ambiant temperature for example.

The technical literature very often refers to the international standard ISO 7730. That reference seems to have been accepted too quickly several years ago, without consulting the experts of the profession and without a real critical examination.Now we are facing a difficult situation because the profession recommends (and it is right) temperatures that are lower of several degrees to the ones advised by the standard. Furthermore, an important number of concrete researches demonstrate the very big uncertainties of the data the standard relies on. A serious warning is necessary.

Today the term of comfort includes the different aspects of indoor air quality, thermal, acoustical and visual comfort.Standardisation working groups have already worked in those different fields, and some standards already exist but it will certainly take several years to adapt them according to the countries and continents. Anyway environmental quality is a subjective perception and depends on many interactions. The aim is to insure comfort to the majority of people, but a personal adaptation of the user will always be necessary.

The notion of comfort is not easy to define. As it relies on elements partly subjective, a statistical approach of the user requirements is necessary.In order to reach the optimum reduction of the causes of discomfort, the profession in charge with the indoor air quality has adopted a certain number of rules that working groups of standardization try to improve and complete.

In this paper the author analyses the different weaknesses of the HVAC systems in case of air contamination by a deliberate pollution of the inducted air due to vandalism, terrorism or any other motives.To prevent that danger he gives some advice about HVAC installation :A safe air intake is necessary, but the intake grille for ventilation must be inaccessible from outside the building and its position at ground level unsuitable.Air dampers must have effective sealing and be closed in the event of a bioterrorist attack.Recirculation systems can be contamined too from a source within the bui

A numerical investigation has been made on the effect of thermal and mass buoyancy forces on the development of laminar mixed convection between vertical parallel plates with uniform wall heat and mass fluxes. Some parameters such as velocity, temperature and concentration are presented and their incidence on heat and mass transfer between the plates is discussed for both positive and negative values of the buoyancy ratio. Results and discussions are presented.

A study on the effect of air temperature on productivity was carried out in telecommunications offices with an observational approach in call centre 1 and an intervention approach in the second call center by installing cooling units.The study shows that the productivity can be reduced by 5 to 7 % when the indoor temperatures increase.