Considering this question is regarding a machine shop located in a pole barn, it is possible that this question should be asked in Commercial Forum. If not--
I have installed walls, ceiling and insulation (r-17 spray foam 2.5", plus r-13 cavity in walls and r-30 in ceilings) in my pole barn where I plan on operating a machine shop. The barn was erected in two separate adjacent sections. The interior of the south section is 38 x 30 with 9' ceilings and the north section is 31' x 31' x 12'. The south section has an insulated metal entry door and an insulated 10 x 8 overhead door on the south wall, one 2 x 4 double pane window on the west wall and an insulated metal door in the north wall(common between the two sections). The north section has an insulated 12 x 10 overhead door in the north wall. Exterior temperatures were figured for 46725 zip code. I used 50% relative humidity for my calculations not knowing if this is appropriate for the intended usage.
It is possible that the north section will not require constant HVAC and I am wondering if there is a way to size the furnace for the entire building, but only heat one half consistently with occasional heating of the other section to economize on HVAC operating cost, without causing the furnace to short cycle? Perhaps this isn't a good idea to begin with!
I have attempted to calculate proper furnace sizing using HVAC calculation software available online, but the software is designed for residential application, therefore I have come to realize that there are some inputs not available that would be included in commercial applications that might alter my overall results such as lighting, activity and air quality. The difference in BTUs when figuring the common wall as an exterior wall is 5000.
Any advice before I proceed will be greatly appreciated!