The first step in energy-efficient air filtration design is to determine accurately rather than estimate the filtration required for the laboratory's process needs and for safety. Close attention to filtration efficiency will result in significant energy use reductions over the life of the facility, especially when the optimization of the filter's final pressure drop is calculated.
The next step in designing energy-efficient filtration is reducing pressure loss in filter systems by selecting filters with the lowest pressure drop available, usually those with deep, extended surfaces; underrating filter bank(s) by sizing for reduced volume compared to the rated filter volume; and designing the filter bank for a low face velocity of no more than 300 feet per minute (100 feet per minute is best for energy-efficient design). The Micro-Electronics Facility Efficiency Workshop (1995) points out that, "...since filter life is inversely proportional to the square of velocity, cutting velocity in half can extend filter life by a factor of four." Some High-Efficiency Particulate Air (HEPA) filters cause less pressure drop than the filters typically included in conventional supply systems; HEPA filtration does not necessitate large pressure drops.
The features described above will cost more than conventional designs partly because of their requirements for increased duct size and filter area. However, these recommendations are usually shown to be cost effective when life-cycle cost analysis is done.