Considerations of Designing the Ventilation of Defensive Underground Structures

Nowadays, due to hostile threats, most critical and important structures are built                           underground. Being underground and the camouflage and concealment of these structures                     impose certain limitations and conditions on their mechanical installations that are never                 considered for other buildings. The appropriate design of mechanical installations of                        underground structures with the passive defense approach for normal and critical conditions are so indispensable and sensitive that in case they are designed inappropriately, not only their                           vulnerability will not reduce but also an underground structure can be turned to a mass cemetery in this regard. Because these installations are easily detectable and vulnerable and also the most important part of an underground structure. This article intends to transfer the experience of its writer regarding design considerations of ventilation and cold and warm facilities of                        underground structures with the passive defense approach, particularly the camouflage and              concealment issues. The ordinary methods of air conditioning and the advantages and                     disadvantages of each are investigated and then taking the whole technical and economical and passive defense issues into considerations, the appropriate cold and warm and ventilation system of a typical underground structure is suggested. Finally, the executive solutions to prevent the entrance of smoke and contamination to the personnel assembly area and also solutions for the camouflage and concealment of fans and also exhaust air shafts, are explained. The said               executive solutions have been already employed in various projects and their performance has been approved which due to their confidentiality nature, their technical details are excluded.