The assessment of human exposure to airborne contaminant is an important issue in building design. The physiological significance of such exposure and technical means to minimise such risks have long been known in literatures. (1, 2, 3) In recent years, computational works have increasingly been seen used as design assessment tools as an alternative to site measurement and wind tunnel tests.
A client was pleased with the performance of a recent building designed and built with low energy objectives on the "mixed mode" principle. When the time came to build another building he appointed the same design and construction team and challenged them to suggest cost effective improvements to the environmental features of the original building. The team developed a "shopping list" of potential energy use reducing features that included chilled slabs, which could be cooled by both a cooling pond and mechanical refrigeration. Fortuitously the site had sufficient space for a cooling pond.
Recently, the need to control environmental tobacco smoke {ETS) in restaurants and bars has increased. In Finland, a new law prohibiting ETS states that non-smoking areas must be established and the dispersion of tobacco smoke to non-smoking areas must be prevented. Employees' exposure to ETS must also be limited in restaurants to a reasonable level. In this new situation the existing instructions for designing ventilation in the hospitality industry are inadequate.
Although the REEXS-principle Reinforced Exhaust System) has been the object of numerous investigations, who found substantial improvements compared to ordinary local exhaust ventilation hoods, it is far from being generally accepted and used. A Swiss team consisting of researchers of the ETHZ (Swiss federal institute of technology), the EMPA (Swiss Federal Laboratories for Materials Testing and Research) and the company Sulzer Infra have started a project for further investigations of REEXS hoods in the frame of the COST G3 action Industrial Ventilation.
In June 2000 ASHRAE's Standard Project Committee on "Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings", SPC 62.2P, recommended and the Board of Directors approved ASHRAE's first complete standard on residential ventilation for public review. The standard is an attempt by the Society to address concerns over indoor air quality in dwellings and to set minimum requirements that would allow for indoor air quality and energy efficiency measures to be evaluated.
This paper describes the development of a hybrid conditioning system that creates a comfortable indoor environment in a building. The operation of a variable-volume displacement conditioning system and a radiant cooled floor have been optimized to reduce the building load. Control strategies were developed that optimize energy consumption and contain moisture levels within specified limits. The development of conditioning-only occupied zones is shown and how the overall energy consumption is reduced. Its application in a large airport is described.
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