When a college in Maryland began planning for its new Science Center, they not only placed an emphasis on optimized energy savings, but also needed to keep an eye on first costs. Energy recovery was a no-brainer, but since the air handling units were serving laboratories in addition to classrooms and offices, cross-contamination of the airstreams was a concern. Then when the Architect wanted to look at placing the air handling units on the roof instead of in a mechanical room as a cost savings measure, their real challenge to design an effective heat recovery system within those parameters began.