Yes of course if you have a big collection it would maybe make sense to adapt the whole room. Most museums handle it like that.
Before i bought my boxes i had most of my items at home and needed to check the humidity twice a day. Since my house has on average 35% humidity i was hanging wet towels to upkeep the needed 50% on a daily basis. This went on for an half a year or so and was a real pain in the a**.
Someday i really got fed up, the whole situation was just ridiculous so i went and asked the -kunsthistorische museum- in vienna how they coop with this issue. They were very friendly and came up with that passive solution for me.
If your items are already behind a display case you can still use the passive system. Just leave a bowl with the buffer-material inside and make sure the display cases are tight. The sealing gaskets costs around 4 euro per meter and is easily retrofitted.
Sometimes you may see mysterious little boxes inside the display cases when you visit the museum next time. This is nothing else than the humidity-buffer.
With 'active systems' which control the humidity and temperature i havent delved into. So i sadly cant tell prices or which companies to go for nor do i have any longtime experience. Besides of the running costs, like all electrical appliances, if there is current involved, those products tend to brake up after some time. Imho if you are not a museum or an super high-tier collector its not worth it.
As soon as my display cases are finished i will post every important technical detail so you can rebuild them or let a glazier recreate it. I have visited the austrian treasure chamber now several times and studied nothing else but the show cases just to be able to reverse engineer them. HAHAHAHA
furthermore information (in better english )about the actual problem.
http://www.nga.gov/content/ngaweb/co...e-temp-rh.html
http://www.nga.gov/content/ngaweb/co...e-temp-rh.html
kind regards
Andi