The unidirectional design is available typically in one of the three major configurations:

(1) Clean work stations, (2) Tunnel design and (3) Open bay design.

1. Clean Work Stations are used for localized areas and involve the use of hoods with

HEPA filters. These find quite a use in laboratories and research centers. These offers energy efficient operation as only small volume is provided with desired class cleanliness level rather than the whole area.

2. Tunnel Design incorporates HEPA filters in ceilings instead of hoods. Similar to clean work stations, this arrangement too, provide localized cleanliness with a difference that the cleanroom space is partitioned from rest of the area and HEPA filters are mounted on ceiling. This arrangement is suitable for modular spaces typically between 11 and 14 feet wide. Wider tunnels experience too much or turbulent flow. The advantage of a tunnel is reduced HEPA filter coverage and ease of expanding additional tunnel modules into unaffiliated areas. The disadvantage is they restrict new equipment layouts as processes change, and products change.

3. Total Clean-Room (open bay design) strategy involves open bay designs that typically use HEPA filters in the entire ceiling and returns in the floor. The design is suitable for large areas up to 50000 sq ft construction with interior walls placed wherever production processes dictate. These rooms are more costly to build and maintain but do provide flexibility for change as new products are introduced and production equipment or processes are improved