This event has ended. View the official site or create your own event → Check it out
This event has ended. Create your own
View analytic
Friday, May 30 • 2:30pm - 2:50pm
(Exploring Sustainable Preservation Environments Session) RH Guidelines: The Risk of Rigidifying an Option

Sign up or log in to save this to your schedule and see who's attending!

It is understood within the conservation community that no single RH range is optimal for all objects. It is difficult to know what the safe RH range is for any specific object, and it is even more difficult to provide a wide variety of RH environments based on individual needs. Therefore, it was necessary to determine a general RH condition that provides a low-risk environment for the overwhelming percent of collections on open display and in storage.

In the absence of precise information on RH-related risk, the trend was toward the implementation of a relatively narrow RH range. Over the last two decades, there has been a reevaluation, based on research regarding object response to RH and a greater concern about the negative consequences of providing tight RH control, in terms of monetary cost and impact on the building envelope.

Recently, there has been further pressure to accept a wider RH range in order to accommodate inter-museum loans between institutions that could not meet the narrower RH range preferred by many lending institutions. In addition, a wider RH range is now being considered as a potential "new" guideline for museums because of energy savings benefits.

This has resulted in the consideration within the general museum community for a new RH guideline, allowing for an annual RH range of 40-60%, with limits for allowable RH drift within this range. This guideline is also in line with the ASHRAE Museum recommendation for "A" Class RH control.

The purpose of this presentation is two-fold:

First, it is important to assess if there is an increase in risk to collections as a result of expanding the acceptable RH range, particularly from 55% to 60% RH at the high end, and to evaluate the degree of risk relative to the benefit of operating at the expanded RH range. Existing data on material behavior, and operational consequences when using a set-point of 55% RH with an allowable drift of 5% will be examined.

Second, it is essential to understand how a new guideline may be interpreted and how it will impact museum environmental system design and operation. So much depends on one's understanding of a "guideline". Is it a "recommended practice that allows some discretion or leeway in its interpretation, implementation, or use" (businessdictionary.com), or is it "a principle put forward to set standards or determine a course of action" (collinsdictionary.com)?

Ultimately, there is a tendency to oversimplify a complex subject such as risk. It is not an exact science, and there is a danger in rigidifying a recommendation so that it reads like a requirement. It is correct that an excessively restrictive RH guideline that prohibits the loan of objects which are at low risk under broader RH conditions should be reconsidered. At the same time, broadening the acceptable RH range must be carefully considered so that it does not result in a similar rigid adherence, without sufficient regard for potential negative consequences.

Session Moderator(s)
avatar for Michael Henry

Michael Henry

Engineer/Architect, Watson & Henry Associates
Michael C. Henry, PE, AIA, is Principal Engineer/Architect with Watson & Henry Associates. He consults on sustainable environmental management and building envelope performance for preventive conservation of museum collections. He consults throughout the United States and in Cuba, Mexico, Brazil, Rwanda, Tunisia and India. Michael is Adjunct Professor of Architecture in the Graduate Program in Historic Preservation at the University of... Read More →


Steven Weintraub

Principal, Art Preservation Services, Inc.
Steven Weintraub (MA in Art History 1975, Certificate in Conservation 1976, NYU; BA, Colgate University) is Institute Lecturer at the Conservation Center (NYU), where he offers instruction in the Preventive Conservation course with Dr. Hannelore Roemich. Trained as an objects conservator, Mr. Weintraub is now in private practice specializing in the consultation, research and product development for the museum environment. He also lectures in... Read More →


Paolo Dionisi Vici

Associate Research Scientist, Metrpolitan Museum of Art
Paolo Dionisi-Vici is an Associate Research Scientist at the Department of Scientific Research of the MMA since 2009. He holds a PhD in Wood Science and his past activities deal with the monitoring of important wooden objects in Europe. He is mostly interested in designing self-powered miniaturized measurement systems and he succesfully installed some of his customized solutions in different exhibiting locations. He is part of the team that is... Read More →

Friday May 30, 2014 2:30pm - 2:50pm

Attendees (152)