Volume 17, Number 3 .... September 1995
Two reviews of the Symposium "What are Appropriate Standards for the Indoor Environment", June 23, New York, NY
June 23, 1995, New York City, NY
The Indoor Environment Symposium, subtitled "What are appropriate standards for the indoor environment?" to re-evaluate recent environmental recommendations (allowable ranges of temperature and relative humidity) released by the Conservation Analytical Laboratory (CAL), Smithsonian Institution was held at the Conservation Center, Institute of Fine Arts, New York University (NYU), in New York on June 23, 1995. The Symposium, organized by Norbert Baer, a Professor at NYU and Paul N. Banks, a Professor of School of Library Science at the University of Texas, Austin, started with Prof. Baer describing the reason for calling for the Symposium. There were a total of 10 presentations, all invited by the Symposium. Each speaker was given 30 minutes for presenting his or her respective view.
Session I was dedicated to four presentations of the heavily debated research results which produced the recommendation by CAL that is described in their article titled "The Determination of Allowable RH Fluctuations," in the WAAC Newsletter, Volume 17, Number 1, January 1995. The presentation titled "Determination of Allowable RH Fluctuations", by Marion F. Mecklenburg, the Senior Research Scientist at CAL, explained research objectives and described theoretical background of the mechanics (elasticity and plasticity, relationship between stress and strain) of art materials subjected to temperature and relative humidity changes. Charles Tumosa, Senior Research Scientist at CAL, described changes of material properties, such as stress-strain curves for various RH in elastic and plastic regions, yielding stresses of art materials with RH variations of old woods vs. new woods and high equilibrium RH vs. low equilibrium RH. Effects of temperature of glass transition temperatures of various materials were also discussed. Tumosa then presented a graph of their operational cost of maintaining climate control systems at specific ranges of RH, a result of their building survey, from a least controlled building, Silver Hill (25% RH) at $1-2/sq. ft., to a tightest controlled building, HMSG (2-3%) at $5.5/sq. ft., with more detailed discussion on those two extreme cases.
David Erhardt, the Senior Research Chemist at CAL, then presented RH range requirements from a variety of art materials from the chemical reaction point of view. (The presentation was the same as the material he provided at the IIC Congress, Ottawa in 1994). Mark H. McCormick-Goodhart, the Photographic Scientist at CAL, concluded CAL's presentation by providing results of the case study using storage of photographic materials, particularly photographic gelatin. He described the high cost of RH controls associated with low temperature storage chambers and offered a low cost solution which is to place the objects in micro-environments of sealed plastic bags.
In Session II, titled "Environmental Management Tools", Donald K. Sebera, the Principal of Conservation Science Services, presented the use of the Isoperm method for rating an environmental condition for storage of paper which he developed in 1988 while he was at the Library of Congress. He described his approach to estimate chemical damage to paper in the presentation titled "The Storage Environment: The Use of Isoperms in Estimating Environmental Effects; Providing a Preservation Environment". The method estimates longevity of paper in a given storage environmental based on the rate of chemical reaction with respect to a standard condition which is 20 degrees C and 50% RH.
James Reilly, the Director of Image Permanence Institute at the Rochester Institute of Technology, then discussed an approach of estimating the amount of damage to papers using Preservation Index (PI) and Time Weighted Preservation Index (TWPI) in his presentation titled "New Technologies for Environmental Assessment and Preservation". PIs and TWPIs are evaluated from temperature and RH variations from the ideal storage condition. Sample conditions were discussed using temperature and RH records collected at the attic and basement in a residential building.
William P. Lull, the principal at Garrison/Lull, presented "Valuing Environmental Improvements Using Environmental Management Tools". He described a typical HVAC system and some design improvements which will allow improved performance without significant modification costs by understanding the present system and selecting appropriate technology depending on the range of temperature and RH requirements. He presented a case study using one of his past projects in which he used the PI ratio to estimate damages to stored objects to justify cost of mechanical improvements.
After an hour lunch break, Session III, which presented case studies, proceeded. In the first presentation, titled "Twenty Years of National Environmental Guidelines and Their Implementation in Canada," Stefan Michalski, Senior Conservation Scientist at the Canadian Conservation Institute, discussed his 14 year old environmental recommendation of a range of 20% RH that was based on swelling factors of woods which is published in the wood industry's Handbook. The data were measured in experiments and research conducted in the 1930's. He expressed the importance of the conservators' observation for identifying construction flaws in the object before deciding on the allowable RH variation. Although one can assume ranges of damage risks on objects for ranges of RH variations, the over-all risk management is of greater importance. He concluded by expressing that the major problem is over-generalization.
The next speaker, Adrienne Thomas, the Assistant Archivist at the National Archives, presented a report on the allocation of various spaces, air handling systems, and environmental requirements for the new National Archive building titled "Environmental Considerations for Archives II, the New Facilities of the National Archives in College Park, MD."
James R. Druzik, Conservation Scientist at the Getty Conservation Institute, made a presentation titled "Research in Support of the J. Paul Getty Museum and Research Facilities," as the final presentation of the Symposium. He presented a three-part review of GCI environmental research: 1) ten years of indoor-generated and outdoor-generated pollution air pollution research; 2) cost savings issues of reducing the relative humidity control in modern HVAC equipped buildings; and 3) the collaborative research between the GCI and the Shelburne Museum to monitor and document the efficacy of simplified approaches for the environmental control for historic buildings. In the GCI's cost vs. RH control study, Druzik noted that the study found small cost benefit when the RH control was relaxed from plus or minus 2% to plus or minus 7%. However, given the multitude of the CAL's findings on the Smithsonian Institution museums where a reduction in RH control proved to have a large cost benefit, Druzik remarked that the GCI would re-examine the mathematical models and extend their earlier investigations to wider ranges of RH control like those cited by CAL.
After a short break Session IV, Round Table and Discussion, was held after additional short remarks by the above presenters and Paul N. Banks and Steven Weintraub, the President of Art Preservation Services. Then the speakers responded to questions from the audience.
The basis for CAL's environmental recommendations seems too narrow. It lacks consideration for objects with variations in constructions materials, workmanship, material compositions, and state of conservation. Also, risks of damage should increase as the requirements for environmental conditions relax. Each object is unique in construction and value. The requirement should be set with these factors in mind, not from limited and simplified material test data.reviewed by Shin Maekawa
The Symposium entitled "What are appropriate standards for the indoor environment?" took place at the Institute of Fine Arts of New York University on June 23rd, sponsored by the Conservation Center and organized by Norbert Baer and Paul Banks. The topic was actually limited to relative humidity and temperature, with no discussion of air quality. Because of the recent press release from the Smithsonian Institution on their research on the response of materials to the environment, the symposium was in essence an opportunity for conservators and others involved with the issue to hear and see the results for themselves and to present other points of view that some in the field consider to have been left out of the Smithsonian work.
Some seventy people attended the session, many who are themselves active in the field and were drawn by the controversy; others, including collections managers, curators, and collections administrators, were present to listen and learn. For those of us who had been unavoidably pulled into the controversy over the press release, one priority was to find out to what degree the hard research data supported the claims the press release seemed to be making (that, for example, ordinary air conditioners control RH well enough to protect collections), and to what extent it supported our current understanding of the behavior of collections we had observed.
The conclusion reached by many of the listeners was that the press release was not very relevant to the actual research, and that the scientists involved had reached conclusions that are similar to observations made over long periods of time by conservators: that it is vital to avoid the extremes of relative humidity for all sensitive collections, that colder is better, drier is often better, that rough equilibrium is better than large swings in RH, and that 50% plus or minus 2% is neither particularly beneficial nor worthwhile.
There was substantial disagreement about the primacy of the allowed fluctuation in the total picture, which must include system design and cost. In Smithsonian buildings, the cost per square foot of buildings with the 50% plus or minus 2% specification was reported as over $6, whereas those with wider tolerances had much lower associated costs. Other speakers pointed out examples where an allowed fluctuation of plus or minus 2% resulted in costs only slightly higher than $2 per square foot, the figure that is generally applied to any climate-controlled building. They further noted that the equipment, and thus installation costs, necessary to maintain either amount of fluctuation would be the same.
Although there was no time during the discussion to deal with the issue directly, it seemed to many discussing the matter over lunch and during the reception after the sessions that major costs and limitations on humidity control are based on issues other than the degree of allowance specified. In order to add substantial humidity, a building needs vapor barriers, which add to the costs of construction. At the high RH end, energy required by reheat systems is the major contributor to high cost; these requirements are the same no matter what the specifications of any system. For those who deal directly with clients, introducing vapor barriers and reheat are major issues; the question of allowed fluctuations seems relatively unimportant.
A basic objection to the Smithsonian research and the conclusions drawn from it is that real objects are much more complex than the single materials tested. Smithsonian speakers acknowledged this, and agreed that certain very sensitive objects will need microclimates. There was little or no disagreement, in fact, and several other similar matters met with clear agreement.
One new item from the symposium was the work done by Don Sebera on what he calls isoperms. This term refers to pairs of temperature and RH levels that will result in the same projected length of life for a particular material. On a graph with temperature across the bottom and RH along the left side, isoperms are shown as curved lines which illustrate the choices that can be made for environmental parameters of a particular material to provide a given useful life. The Committee on Preservation and Access (1400 16th Street, NW, Suite 740, Washington, DC, 20036-2217, 202/939-3400) can provide reprints of his article entitled "Isoperms: an environmental management tool" from June 1994. The article is available from them for $10.00 (half- price for more than 10 sent to the same address). The graphs as he presents them are very helpful in figuring out environmental control strategies, and will probably provide a greatly improved way of explaining conservation concerns to engineers and architects.reviewed by
Timestamp: Thursday, 11-Dec-2008 13:02:34 PST
Retrieved: Wednesday, 21-Feb-2018 11:01:37 GMT