Since I am not a technician, my only experience with this subject is
hearing that one should try to keep the room at a constant temperature
and humidity for the benefit of both the piano and the reproducing
player mechanism.

Living in the Chicago area, I use an indoor humidifier in the winter
and usually keep the doors and windows closed year round.  Outdoor
temperatures in the winter can get down to ten below zero or so.  Are
there guidelines (e.g. percent indoor relative humidity) to attempt to
attain, particularly in the winter months?

Also, our home tends to heat up during the day in the winter (without
heat) because we have floor to ceiling windows facing direct sunlight
which radiate the heat.  Sometimes I must turn on the air conditioning
in winter to cool it down.

Would it be "certain death" for the piano if I opened the windows and
let some cold fresh air in?  Any technical advice other than to move to
a warmer climate?

Rich Lazar