Underground Garage

This study was created for an architect in Santa Monica California who was, in 2016,  designing a large residence to be built near Dodger Stadium. The garage is 49,000 square feet. Calculations show it needs just over 36,000 CFM. The first draft of the design uses a huge Greenheck axial fan that takes over 10,000 watts for its 15 HP motor. There are over 300 feet of custom ducting with sizes ranging from 14 inches by 28 inches up to 20 by 80 inches with 6 tapered transitions along the lengths. Added to that are 8 big 40 inch by 18 inch grilles. 

Below shows what happens if  5  Tornado TP500s are used. The electric power drops from 10,000 watts to 2525 watts and the ventilation without power is increased from zero to over 10,000 cfm due to gravity and wind power alone. This also eliminates all the horizontal ducting and uses 20 inch vertical ducts to  the EP500 units on the roof. 

Performance is also improved with the 36 inch TP900. Only 3 are needed at 14,000 CFM each for over 42,000 CFM under power and the free air gravity flow is double or triple that of the 500s. 

Note this is an excellent plan for a garage with no building on top. And since the vertical ducting is just 20 inches diameter it is possible that ducting through rooms might be affordable.