The example below illustrates some of the energy-efficient design process and its incorporation into an overall facility design. The example describes the energy-efficient design of a research institute specializing in the development of special-purpose microelectronic components.
A central plant with constant airflow rate was chosen for the air conditioning of the multi-story building. At the entrance of each story, the HEPA filters are grouped centrally in easily accessible compact filter boxes according to zones, so that monitoring and maintenance work can be carried out, without need to enter the research rooms. An air distribution system, which is designed so that later modifications can be made without difficulty, conveys the supply air to custom-designed clean air distribution elements. The size and arrangement of the distribution elements, the direction of airflow and the airflow velocity are exactly tailored to the individual requirements of each workstation. In some cases the apparatus is protected by the use of horizontal unidirectional flow, in others by vertical unidirectional flow.
The workstations are thus isolated from the surroundings by the use of the principle of spot protection. The remaining room areas of the laboratory are air conditioned merely by spill-over flow from the clean zones, and additional supply air devices have not been necessary. This allows both the desired room air conditions to be maintained and an air cleanliness corresponding to cleanliness Class 10,000 according to US Federal Standard 209D, to be ensured—at no additional cost as far as air engineering is concerned.
The velocity of the air emerging from the clean air distributing elements was set individually within the range 0.25 to 0.4 m/s (~50 to 80 feet per minute) and is subsequently kept constant by means of automatic air volume control devices.
Minimization both of the spatial extent of the area protected by unidirectional flow and of the flow velocity are (sic) therefore used to keep down the airflow rate to the very minimum possible. [Schicht, 1991]
