Climate/RH Control Casework

I've been asked to give input on an exhibit proposal involving display and possible international travel of objects that are very sensitive to levels of relative humidity that differ from their current home level. I've designed and built casework for small objects such as panel paintings that was well sealed and tended to have little problem maintaining a constant rH, but this show may need individual conditioned spaces to 30 cubic feet ( .85 cubic meter) or larger.

My question to the group is how large a volume have people found it reasonable to condition by using passive methods such as silica gel. It is a given that the casework will be designed with impermeable surfaces and proper gasketing, and the rH differential is likely to be in the range of 20-30%.

I am aware of active electromechanical systems, but the cost and logistical problems are leading us to trying to design a simple system that could work. Any ideas are greatly appreciated.

Jamie Hascall
Chief Preparator
NM State DCA
Exhibits Central
Santa Fe