Lee,

Almost every conservator who I know recognizes that when setting HVAC
standards for historic buildings and structures that the stability of
the architectural artifact is equally if not often more important that
its contents.

I believe that this philosophy is reflected in the New Orleans charter
on Historic structures that in part of the APT (Association for
Preservation Technology).

There are no absolutes in HVAC standards because the system has to
operate and perform in context with the outdoor environment. The
seasonal conditions in North Dakota and Phoenix are very differnet
from yours in Virginia and thus that has to be reflected in suggesting
system parameters. Usually what is done in an region like yours in
Virginia with distinct seasonal variations is to ramp .or slowly
increase or decrase the system's set points over a period or weeks so
that the relative humidity set point is slowly acclimated to a higher
setting going from spring into summer. What will adversely affect RH
sensitive collections the most (and they are usually organic media)
are very rapid changes in relative humidity, greater than 10% to 20%
in a 24 hr. period, for example. Sometimes when an historic building
uses an older HVAC system, it can be managed by altering the
temperature to maintain a more stable RH. The RH is much more
important to the stability of the building and the collections, the
temperature is much more important for visitor and staff comfort.
Again, as in almost all historic site and museum endeavors, some
compromises are always hovering on our shoulders.

Also the parameters depends on the nature of the historic structure
and the type of collections within it. Most historic sites and
buildings have mixed collections and furnishings, but some have been
turned into more focussed exhibits, such as the Barnes near
Philadelphia, that contains predominantly fine art paintings.
It is very common for historic structures in colleges and universities
to be used to house what are more traditional museum exhibits. Perhaps
others on the list who are familiar with that situation can comment on
how the environment is managed in those circumstances.

Since you are in Orange, Virginia, I will suggest that you contact two
former colleagues of mine when I lived and worked out there at
Colonial Williamsburg. Contact Robert Self, the Architectural
Conservator at Monticello. Also, I would suggest contacting Dr. Thomas
Taylor.
, manager of architectural collections and architectural conservator
at Colonial Williamsburg. . Both of them are very helpful and they can
also put you in touch with their HVAC engineers in their facilities or
operations departments for more specific information on their systems
and set points.

Cheers!
Dave

David Harvey
Conservator
Los Angeles, California, USA

On 10/27/05, Lee Langston-Harrison <[log in to unmask]> wrote:
> Hi all:
>
>
>
> I know this subject comes up often, but I need a quick answer from staff
> in historic houses (made of brick and plaster) that deal with
> environmental conditions and their house as an important "artifact."
> This goes to curators and conservators who have (or are considering)
> HVAC systems.
>
>
>
> What compromise do curators and conservators make with regards to
> historic/original objects vs the house's needs vs the public's comfort?
>
>
>
> In houses that have HVAC systems, what are the "standards" we should try
> to maintain?  What is too high a humidity?  Too low a humidity?
>
>
>
> What is too high a temp? Too low a temp?
>
>
>
> What is the acceptable rate of change?  How "flexible" can your RH and
> temp be within your historic structure?
>
>
>
> My historic house is undergoing a grand renovation, and we are
> installing state of the art HVAC and environmental monitoring systems.
> I am concerned about the range of   So. I poise the age-old question,
> again.
>
>
>
> Could you historic house folks or building experts weigh in here?
>
>
>
> Thanks!
>
>
>
>
>
> Ms. Lee Langston-Harrison
>
> Curator
>
> James Madison's Montpelier
>
> P.O. Box  911
>
> Orange, VA 22960
>
> 540-672-2728, x421 (o)
>
> 540-672-7366 (f)
>
>  <mailto:[log in to unmask]> [log in to unmask]
>
>
>
>
>
>
>
>
>
>
> =========================================================
> Important Subscriber Information:
>
> The Museum-L FAQ file is located at
> http://www.finalchapter.com/museum-l-faq/ . You may obtain detailed
> information about the listserv commands by sending a one line e-mail message
> to [log in to unmask] . The body of the message should read "help"
> (without the quotes).
>
> If you decide to leave Museum-L, please send a one line e-mail message to
> [log in to unmask] . The body of the message should read "Signoff
> Museum-L" (without the quotes).
>
>


On 10/27/05, Lee Langston-Harrison <[log in to unmask]> wrote:
> Hi all:
>
>
>
> I know this subject comes up often, but I need a quick answer from staff
> in historic houses (made of brick and plaster) that deal with
> environmental conditions and their house as an important "artifact."
> This goes to curators and conservators who have (or are considering)
> HVAC systems.
>
>
>
> What compromise do curators and conservators make with regards to
> historic/original objects vs the house's needs vs the public's comfort?
>
>
>
> In houses that have HVAC systems, what are the "standards" we should try
> to maintain?  What is too high a humidity?  Too low a humidity?
>
>
>
> What is too high a temp? Too low a temp?
>
>
>
> What is the acceptable rate of change?  How "flexible" can your RH and
> temp be within your historic structure?
>
>
>
> My historic house is undergoing a grand renovation, and we are
> installing state of the art HVAC and environmental monitoring systems.
> I am concerned about the range of   So. I poise the age-old question,
> again.
>
>
>
> Could you historic house folks or building experts weigh in here?
>
>
>
> Thanks!
>
>
>
>
>
> Ms. Lee Langston-Harrison
>
> Curator
>
> James Madison's Montpelier
>
> P.O. Box  911
>
> Orange, VA 22960
>
> 540-672-2728, x421 (o)
>
> 540-672-7366 (f)
>
>  <mailto:[log in to unmask]> [log in to unmask]
>
>
>
>
>
>
>
>
>
>
> =========================================================
> Important Subscriber Information:
>
> The Museum-L FAQ file is located at
> http://www.finalchapter.com/museum-l-faq/ . You may obtain detailed
> information about the listserv commands by sending a one line e-mail message
> to [log in to unmask] . The body of the message should read "help"
> (without the quotes).
>
> If you decide to leave Museum-L, please send a one line e-mail message to
> [log in to unmask] . The body of the message should read "Signoff
> Museum-L" (without the quotes).
>
>

=========================================================
Important Subscriber Information:

The Museum-L FAQ file is located at http://www.finalchapter.com/museum-l-faq/ . You may obtain detailed information about the listserv commands by sending a one line e-mail message to [log in to unmask] . The body of the message should read "help" (without the quotes).

If you decide to leave Museum-L, please send a one line e-mail message to [log in to unmask] . The body of the message should read "Signoff Museum-L" (without the quotes).