Humidity control

[Mike Crisp]

Dear All,

My university is building new accommodation for our department which
includes the GAUBA herbarium, and air conditioning is going to be limited
by cost.  There is little doubt that we will have temperature control, but
humidity control is under question.  I have read that specimens should be
kept in a relatively narrow humidity range (around 50%) because if too
moist they rot, and if too dry they become brittle.  I have vetoed
evaporative cooling because of the high humidity that it creates.
Refrigerated air conditioning is the alternative but it tends to run at low
humidity (<<50%).  Is this likely to be a problem?

Yours Sincerely,

Mike Crisp