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We have been telling our clients to keep their collections at 70° F @ 50%rH per current standards. Recently I have seen discussions about modifying those to 65° F @ 45% rH.

In an effort to be more energy conscious and address climate change concerns some clients are wondering if they adjust their HVAC settings to conserve energy during off hours, what deviation from ideal settings is safe? We maintain data loggers on site with their collections and can monitor changes by the hour. I have been looking for studies on this and have not come up with anything yet. Any input would be greatly appreciated.

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Dennis Callahan
Callahan art & Associates
Chicago IL
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Hello Dennis,
This is a fair question but not one that can be resolved with a quick answer. It depends on the contents of the collections, both in materials and structures, and on characteristics of storage hardware, and item level containers, if any. The current literature is very active in discussing these issues but does not lead to simple conclusions, especially for anyone who has not followed developments over the past decade. I suggest you contract a conservator specializing in preventive conservation to review the situation and make recommendations. It is possible that local extra protection for most sensitive items might permit broader changes to specifications but that requires expert review and judgement. Preventive conservation specialists can be found through the American Institute for Conservation at Find a Conservator

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Robert Waller PhD
Protect Heritage Corp.
Ottawa
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Original Message:
Sent: 05-06-2020 09:19 AM
From: Dennis Callahan
Subject: Temp / rH settings for collections

We have been telling our clients to keep their collections at 70° F @ 50%rH per current standards. Recently I have seen discussions about modifying those to 65° F @ 45% rH.

In an effort to be more energy conscious and address climate change concerns some clients are wondering if they adjust their HVAC settings to conserve energy during off hours, what deviation from ideal settings is safe? We maintain data loggers on site with their collections and can monitor changes by the hour. I have been looking for studies on this and have not come up with anything yet. Any input would be greatly appreciated.

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Dennis Callahan
Callahan art & Associates
Chicago IL
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Dear Dennis,
I will echo Rob's response that there are a lot of factors that go into setting appropriate environmental targets.  The field has been moving away from a simple 70/50 recommendation but it replaced with a lot more nuance than merely substituting another set of numbers. For a good overview of the topic you can check out the page on Environmental Guidelines on the AIC wiki.  If you don't want to wade through the whole wiki page just download the Crack Warp Shrink Flake article by Pam Hatchfield that is linked on the page.

There is also a good bit of research on sustainable environmental practices.  One good place to start is some of the resources out of the Image Permanance Institute  https://www.imagepermanenceinstitute.org/research/sustainability.html
Best,
Rachael

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Rachael Arenstein
A.M. Art Conservation LLC
rachael@amartconservation.com
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Original Message:
Sent: 05-06-2020 09:19 AM
From: Dennis Callahan
Subject: Temp / rH settings for collections

We have been telling our clients to keep their collections at 70° F @ 50%rH per current standards. Recently I have seen discussions about modifying those to 65° F @ 45% rH.

In an effort to be more energy conscious and address climate change concerns some clients are wondering if they adjust their HVAC settings to conserve energy during off hours, what deviation from ideal settings is safe? We maintain data loggers on site with their collections and can monitor changes by the hour. I have been looking for studies on this and have not come up with anything yet. Any input would be greatly appreciated.

------------------------------
Dennis Callahan
Callahan art & Associates
Chicago IL
------------------------------

Dennis,

I highly recommend this free PDF book from the Smithsonian: Proceedings of the Smithsonian Institution Summit on the Museum Preservation Environment (see below). In the book there is a guide to discussion and exercises regarding the preservation environment: "A Guide to Discussions and Exercises Regarding the Preservation Environment: Determining and Implementing Your Institution's Optimal and Sustainable Preservation Environment." Every institution will have different expertise, different operating conditions (building, HVAC etc.). No one solution is best for every institution.

One of my greatest concerns is the lack of experience people have with acquiring and analyzing their data. Data loggers will have variations in measurement (even when calibrated!); their data may be based on air return systems where air from different rooms is mixed together; parts of a single room will have variation.  This means that staff from different departments have to invest some time working together to understand their building and how data collection may be representative of the range of micro environments that can exist. When we talk about set values and ranges the reality is we are really talking about a wider range of values.

https://scholarlypress.si.edu/store/museum-studies-art/proceedings-smithsonian-institution-summit-museum-/

Best wishes,
Tiarna

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Tiarna Doherty
Ph.D. Student
University of Delaware Graduate Programs
Fairfax VA
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Original Message:
Sent: 05-06-2020 09:19 AM
From: Dennis Callahan
Subject: Temp / rH settings for collections

We have been telling our clients to keep their collections at 70° F @ 50%rH per current standards. Recently I have seen discussions about modifying those to 65° F @ 45% rH.

In an effort to be more energy conscious and address climate change concerns some clients are wondering if they adjust their HVAC settings to conserve energy during off hours, what deviation from ideal settings is safe? We maintain data loggers on site with their collections and can monitor changes by the hour. I have been looking for studies on this and have not come up with anything yet. Any input would be greatly appreciated.

------------------------------
Dennis Callahan
Callahan art & Associates
Chicago IL
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