Apparatus having a protective envelope, use thereof, and method for operating a room region

An apparatus comprising:

• a protective envelope enveloping and surrounding at least one room region which directly adjoins a floor area, the protective envelope separating the at least one room region from an environment surrounding the protective envelope;
• at least two layers including a first layer and a second layer separated by a spacer layer that spaces the first and second layers apart, the spacer layer being traversed by flow in a longitudinal direction through the spacer layer;
• at least one flow unit fluidically connected to the spacer layer;
• the first layer is permeable to flow, is mounted closest to the at least one room region and has a permeability to flow in the range from 500 to 49,000 m3/m2/h, the first and second layers are formed from only at least one material for directly enclosing a clean room of ISO classes 1 to 9 according to DIN EN ISO 14644-1:2016-06;
• that the protective envelope has an outlet area to which a sterilization unit is attached;
• and
• the at least one flow unit has an internal pressure formed inside the spacer layer which is greater than an inner room pressure formed inside the at least one room region which is greater than an ambient pressure in the environment surrounding the protective envelope.