Humidifiers in collections storage areas

Stephanie Gowler <sgowler [at] library__in__gov> writes

>Our main archives stacks area (approximately 22,000 square feet)
>suffers from extremely low relative humidity during the dry winter
>months. I'm still trying to determine if it will be possible to
>lower the temperature in this area of the building (it's a steady
>68-70 deg. F year-round); in the meantime, I'm investigating
>alternative ways to regulate the RH. ...

HVAC systems not only filter, heat, cool, humidify, and dry the air
- they also bring in fresh air and exhaust stale air. Some newer
buildings sense CO2 levels and automatically adjust the rate of air
exchange, but older buildings generally do not have this technology,
and their air exchange rates are fixed. My understanding is that air
exchange rates are almost never adjusted, although I'd be happy to
be proved wrong.

The rate of air exchange is determined by standards and based on
estimated occupancy. They are set when the HVAC system is initially
commissioned, and often never revisited. I was in one university art
gallery with an air exchange system that was permanently set up for
opening nights, where a crowd of hundreds might gather in the
gallery. However, the gallery in reality was permanently very
sparsely populated, Though the gallery was nearly deserted for most
of the time, the fresh air supply was permanently set for occasions
that might total 24 hours of heavy occupation each year (based on
six receptions at four hours each). The mechanical system was
oversized and hard to control for the other 364 days of the year.

You may have more (perhaps much more) air exchange in your stacks
than you need. If so, this will overwhelm any natural buffering the
books themselves might offer, and will demand the use of larger and
more energy hungry humidifiers. Although stand alone humidifiers may
help, it is important that you continue to talk to your building
managers and include them in your efforts. The savings on
humidification energy, maintenance, and humidifiers may be well
worth the effort or cost of having someone look into your HVAC
system before you invest.

Jerry Shiner
Keepsafe Microclimate Systems
800-683-4696


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