Hi Charlie,
How are things in Norfolk?
(I lived in Williamsburg for many years).
The most important environmental variable to keep stable is the relative humidity - it has sometimes been a practice in some institutions that do not have humidity control in their HVAC to swing the temperature to keep the RH more stable. Usually the temperature point is established for staff and visitor comfort. In just about every case (other than tin artifacts) conservators will favor colder conditions as that retards chemical deterioration and biological activity (including mold and mildew).
It really depends on what objects or art you have and where you have them.
If you have metals, ceramics, and stone objects in good condition then they can accommodate a wider range of temperature and RH conditions. If you have ivory, bone, wood, textiles, paintings, or paper based objects then you need to be more diligent about keeping a stable RH - and objects with mixed media that combine organic and inorganic materials can often suffer more damage because the wood may swell and shrink and that iron rivet or screw does not.
If you have objects primarily in exhibit cases then you can micro climate those to maintain RH and buffer any large fluctuations by good case design and with the use of silica gel.
It sounds like to may need to do an institution-wide analysis of energy consumption. There may be even greater savings found in changing out non-exhibit lighting to low consumption bulbs and fixtures, and in looking at what is turned on when the memorial is closed. There is also the issue of how well the building is insulated and so looking at energy loss is probably an even bigger issue - often infrared thermal imagers are used to survey structures to detect when you may have areas of heat loss / gain - so you would know from that if windows are a prime area to focus on, for example. By doing this kind of analysis you then can formulate a plan to attack the issues specifically instead of just guessing what may actually lower consumption and cost over the long term.
Again returning to your temperature - I really don't see a 2 degree modification as a huge issue in general - but so much depends on how your relative humidity is doing and in the specifics of the spaces where you have your collections.
Cheers!
Dave
David Harvey
Conservator
Los Angeles, CA
On Thu, Dec 11, 2008 at 7:18 AM, Charlie Knight
<[log in to unmask]> wrote:
I have a question regarding keeping a constant temperature/RH in exhibit areas. Our main museum is housed in a mid-19th century Court House (2 floors) and currently we keep the temperature between 68-72, usually right at 70, although some galleries run much higher temps than others. However, we have been instructed by our Dept Head (we are a City bureau) to reduce our energy consumption to cut our costs - obviously lights can be turned off when we're not open, but the temperature controls must remain on for the welfare of the artifacts on exhibit. So my question is would there be any harm in lowering our temperature by two (2) degrees, for a target range of 66-70?
Charlie Knight
MacArthur Memorial
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