Wall diffusers, where the diffuser itself and the plenum box is placed in the wall or in a skirt, is used in combination with - or as an alternative to ceiling diffusers. When the wall diffusers are used in combination with ceiling diffusers, the ceiling diffusers will typically be used for supply air and the wall diffusers for exhaust air. If the entire ceilings area has to be freed for ex. other installation needs, or because there isn’t a suspended ceiling in the room, there is great advantage in using the wall diffusers for both supply air and exhaust air. That way you can avoid visible duct mounting in the room itself, and instead you get the possibility of placing air ducts in the corridor, hallway or other similar places.
In order to supply air to comfort zones, diffusers with an adjustable jet pattern or a built-in function to ensure the Coanda effect against the ceiling. That way too much velocity is avoided in the occupied zone.
More about VAV Diffusers