The LA school district is the largest school district in the country. As such, they have to provide for a large amount of student education. Times of construction or renovation required the design and manufacture of some 350 portable classrooms. Two MARVAIR units are to be saddle-bagged onto the exterior of each classroom in order to condition the interior. Unfortunately, the Return Air duct for the unit has to be facing directly into the classroom and this causes a noise problem. Recent study has shown that noise levels above NC30 in classroom environments can lower student's efficiency, some even suggest NC25 for certain learning situations. With the higher noise levels created by the MARVAIR unit, the classrooms will not make ideal learning environments for the students.