A modular office panelling system has been improved by providing an air circulation arrangement of selectively cool or remove heat from a particular area defined by the panelling system. Fans are provided in removable panel cover portions which can advantageously be secured in the office panelling system in the same manner as fabric covered removable cover portions. Thus, the air circulation arrangement may be provided as an original specification or added as a retrofit in the field. The interior of the panel is also used as a large inlet plenum whereby the flow of air into the panel is at a slow velocity.