Abstract: An air diffuser comprising a base and first, second, third and fourth side walls extending from the base to form a hollow shell. At least one of the side walls includes a plurality of bores therein forming multiple discharge tubes. The base and side walls form a plenum into which conditioned, pressurized air is supplied. The conditioned air is discharged from the plenum through the tubes in columns. Screws or other fastening devices may be used to secure the hollow shell to a surface. The multiple discharge tubes are each spaced from the surface and have longitudinal axes oriented in angular relation to the surface for entraining ambient air from above and below each column of air being discharged for mixing of ambient air with each column of the discharged conditioned air.