A universal access port includes a specific size opening that is formed through a wall of a conditioning enclosure and located at a specific distance from a floor or mounting surface. The opening is preferably rectangular in shape, but other shapes may also be used. When not in use, the universal access port is covered with a sealing panel. Insertable devices may be efficiently inserted and removed from the universal access port. A perimeter of the insertable device is sized to be sealable inserted into the universal access port. Each insertable device preferably seals with an exterior and interior wall of the conditioning enclosure. Some insertable devices include fixturing devices, windows, manual manipulation devices, junction devices, hinged access doors, wire access devices, temperature modifying devices or air circulation devices.