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Subject: Temperature control

Temperature control

From: Michael McHugh <mmchugh<-a>
Date: Wednesday, December 7, 2005
Joachim Huber <joachim.huber [at] prevart__ch> writes

>According to the engineers, the HVAC-System is designed to work at a
>constant temperature of 20 deg. C and constant relative humidity of
>55%. The system will work fine at this setpoint up to an outdoor
>temperature of 26 deg. C. But on very hot days the outdoor
>temperature will be well above 26 deg. C and the museum is urged to
>run its galleries theoretically at higher indoor temperature up to a
>maximum of 26 deg. C (outdoor 32 deg. C, which according to German
>building standards is supposed to be the maximum temperature for
>this region). The question is how quick the temperature should be
>allowed to rise within short periods (hours/day). Assuming that the
>climate control won't break down ;-) : what is the difference in
>risk between keeping the temperature down to 20 deg. C as long as
>possible and then having a sharp increase vs. rising the temperature
>over a longer time period following the outdoor temperature. ...

Assuming that the current HVAC system cannot tolerate the stress of
keeping a constant temperature on very hot days, is there anything
that can be done architecturally to prevent the heat buildup on
these days? Can the translucent glazing be shaded or covered? Can
the space directly below the glazing be vented to prevent heat
buildup? (This should be discussed with the HVAC engineers because
it will affect the humidity levels).

Dramatic/frequent temperature swings are more of a problem than
elevated temperature or humidity for short periods (a heat wave).
Can collection storage areas be kept at a constant temperature and
humidity while gallery temperatures are allowed to fluctuate?
Sensitive items could be stored seasonally.

Perhaps the Museum could use climate controlled cases for
particularly sensitive artifacts.

Dataloggers could be used to identify microclimates within the
Museum (temperatures may fluctuate more on upper levels and near
entrances). Some artifacts are more sensitive than others. Working
closely with the curator may identify display strategies that will
minimize risk.

Michael McHugh, AIA
LEED Accredited Professional
E. Verner Johnson and Associates
Museum Architects and Planners
222 Berkeley Street,  Suite 1350
Boston, MA 02116
Fax: 617-437-1272

                  Conservation DistList Instance 19:30
                Distributed: Thursday, December 15, 2005
                       Message Id: cdl-19-30-004
Received on Wednesday, 7 December, 2005

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