The roof has one circular roof fan at the left, and a rectangular box at the other.
Presuming that the manufacturing area was was adjacent to JM's offices (on the left) the left-most circular fan vents the manufacturing area. Heres the fan : http://lenr.qumbu.com/steampics/160521_fans_01.jpg ( 7 pixels) And a small car (6 feet wide). http://lenr.qumbu.com/steampics/160521_fans_02.jpg (10 pixels) That gives the diameter of the fan as about 50 inches. Here's a 32,000 CFM roof fan that fits (49 inch outside diameter) : http://www.industrialfansdirect.com/IND-FA-R-B/LFI-RD42T3750CM.html Conclusion : allowing for heat loss through the ceiling, 1MW can be safely dissipated by a fan of this size.
