The Abbey Newsletter

Volume 20, Number 4-5
Sep 1996


The New Museum Climate: Standards & Technologies

NEDCC's Conference at The Museum of Fine Arts, Boston April 25-26, 1996

by Millie O'Connell

(Millie O'Connell is a preservation consultant to NEDCC.)

The conservation community gathered at Boston's Museum of Fine Arts on April 25 & 26, 1996, for a two-day conference on "The New Museum Climate: Standards and Technologies." Presented by the Northeast Document Conservation Center (NEDCC) and the Museum of Fine Arts (MFA), this meeting attracted 170 conservators, curators, architects, administrators, and facilities managers from the northeast region and beyond. It was funded in part by the National Endowment for the Arts and the Massachusetts Cultural Council. Distinguished speakers discussed changing standards and new developments, and described their personal efforts to control the environment for museum collections.

Stefan Michalski, Senior Conservation Scientist at the Canadian Conservation Institute (CCI) in Ottawa, sounded the bugle of practicality in his presentation, "Changing Standards for Environmental Control." The needs of small museums have forced CCI staff to become more practical in their recommendations for climate control by taking the broad spectrum of collections needs into consideration. Maintenance of the commonly-recommended levels of 50% RH and 70° F with minimal fluctuation has proven difficult and impractical for many institutions. The fact that various artifact types respond differently to the same climate conditions further complicates decisions about climate control and makes it important to understand the vulnerabilities of various materials. As a result, CCI staff no longer prescribe a single magical and simple standard.

A practical and cost-effective approach for institutions with mixed historical collections is to strive for conditions that average plus or minus 20% RH. However, even a single event of plus or minus 40% RH can produce "small to severe risk" to collections and must be avoided at all costs. Reliability of existing climate control equipment is paramount.

In general, CCI staff describe potential risks and let the client decide how this information fits into the total collections management picture. Thus, the need to protect collections from fire, theft, and improper handling might well take budgetary preference over an attempt to maintain stringent climate control. In the same way, protection from light damage might well be a more serious concern for some fine arts museums than is strict control of relative humidity.

For further information on CCI's research into the effects of temperature and relative humidity, I refer you to the speaker's article, "Relative Humidity and Temperature Guidelines: What's Happening?" in the CCI Newsletter, No. 14, September 1994, a copy of which was distributed to conference participants.

Barbara Mangum, Chief Conservator at the Isabella Stewart Gardner Museum in Boston, addressed the subject "What Do Collections Really Need?" She described the conditions that prompted her museum's current $8 million environmental control project. From its inception, the Gardner Museum's collections, especially panel paintings and wood sculpture, have been endangered by marked fluctuations in relative humidity. Loud cracking noises were described in early letters from Isabella Stewart Gardner to Bernard Berenson. Since that time, two incidents of 100% RH caused mushrooms to grow in the courtyard. Condensation on all surfaces combined with dark conditions facilitated mold growth.

The attempt to gain control over the environment at the Gardner Museum began with a careful study and gathering of data by an environmental engineer. Environmental monitoring demonstrated a relative humidity range of 18% to 84%, with temperatures in summer frequently above 90° F. Staff conservators kept a building diary and produced condition surveys for hundreds of fragile artifacts. The effect of unstable environment through the years was very evident in damage to lacquered objects, veneer and cane furniture, gilt wood, panel paintings, and enamels. Paint has blistered, leather wall panels have cracked, wrought iron has corroded, and stained glass has been damaged by high heat from the sun. Not even stone has been exempt from damage, with stalactites forming.

Gardner Museum staff members continue to work with environmental engineers in their quest for relief from erratic and extreme environmental conditions. The proposed environmental control system will include gaseous filtration, and will cost $5 million. The cost of climate control will increase from $1/sq. ft. to $2.50/sq. ft., but the difference will serve to protect valuable collections from future damage.

James Reilly, Director of the Image Permanence Institute (IPI) in Rochester, New York, presented "Research Applied to Planning: Isoperm Diagrams and IPI Environmental Research." He reviewed the process of evaluating temperature and relative humidity conditions, which involves data gathering, data interpretation, and action planning.

Data gathering typically takes place with one of these instruments:

  1. a recording hygrothermograph (described as labor-intensive, requiring frequent calibration, providing only a short-term view);
  2. dataloggers (which are usually more accurate, but require facility with computers); or
  3. built-in sensors (where data extraction is not easy, and facility with computers is a must).

Data interpretation includes an examination of environmental damage, which can include

  1. mechanical damage (such as warping, shrinking, swelling, cracking, caused by humidity that is either too high, too low, or with changes occurring too fast);
  2. biodeterioration (such as insects and mold, caused by interaction of temperature and relative humidity); and
  3. inherent chemical decay or natural aging (here the material reacts with itself at a rate determined by temperature and relative humidity).

The question then arises as to what to do with data, once it has been gathered. Ideal data analysis predicts the occurrence and severity of biodeterioration and mechanical damage, quantifies the rate of chemical decay, and is understandable by managers. While computers cannot analyze mechanical damage or biodeterioration, they can analyze chemical deterioration through the laws of kinetics and reaction.

IPI has developed two tools that simplify the process of interpreting temperature and humidity data and determine their effect on chemical deterioration. The first is the Preservation Index (PI), a table of predicted lifetimes for organic materials at specific temperatures and relative humidities. Because climate conditions in any storage environment change over time, the Time-Weighted Preservation Index (TWPI) was developed to measure the cumulative effect of changing conditions in a particular storage area. The TWPI is an average of changing PI values, with more weight given to bad conditions than to good conditions. PI and TWPI values are given in years, making it easy to compare the quality of various storage areas or to argue that climate conditions need to be improved in order to extend the lifespan of collections.

A newly developed Preservation Environmental Monitor (PEM) stores temperature and relative humidity data and calculates PI and TWPI. Data is logged and displayed, and can be stored for up to five years. Developed by Randall Wirt, this instrument will soon be field tested. Because it was funded with grant money, the technology will pass to the public domain.

Richard Kerschner, Conservator at The Shelburne Museum, Inc., in Shelburne, VT, discussed his first-hand experience with "Managing Climate Control in Historic Structures." Kerschner has faced the challenge of improving conditions in 33 museum buildings, representing a wide range of building types. He uses conventional HVAC systems only in buildings that will not themselves be damaged by modified environmental conditions. He employs humidistatically controlled heating to reduce dampness in buildings that are closed for the winter, using a humidistat instead of a thermostat to activate heat when humidity rises to a dangerous level. In summer, air is circulated and ventilated from buildings when outside air is drier than inside air; this equipment is controlled by humidity or dew point sensors. Other low-cost practical steps the Shelburne Museum has taken in order to direct moisture away from buildings include installing gutters and downspouts, upgrading storm drains, dredging a pond, and improving drainage of dirt roads. Reference was made to Kerschner's article, "A Practical Approach to Environmental Requirements for Collections in Historic Buildings," JAIC 31(1992): 65-76, which was distributed to participants.

Arthur Beale, Director of Objects Conservation and Scientific Research at the Museum of Fine Arts in Boston presented a talk on "Evaluating and Improving the Existing Environment" at his institution. The oldest part of the building was opened in 1909 and the newest in 1981. Slightly more than half of the 544,000 square foot structure is climate-controlled with the goal of 50% RH (plus or minus 5%) and 72 degrees F (plus or minus 2 degrees).

A central chilled water plant that serves most of the climate-controlled areas dates from 1981. It has been expanded to serve more than just the newer parts of the museum and updated with such features as direct digital controls. The remainder of the systems that truly control climate are nine stand-alone units. Most are less than a decade old and serve areas housing climate-sensitive objects such as musical instruments, textiles, and ship models. Still other areas are served by a combination of independent air-conditioning and humidification units. A number of display cases in the "heat only" parts of the building are fitted with either active or passive systems that control relative humidity to some extent.

Decisions regarding system selection often come down to choosing a solution to a finite problem that may represent higher operating costs, but will have substantially lower capital installation costs. Often the choice is between doing the project with stand-alone equipment or not doing it at all. Sometimes decisions are determined by the difficulties of locating new ductwork and plumbing in an old structure, or getting sufficient electrical service to remote parts of the building. Another complex comparative cost factor centers on steam generation for adding humidity. The MFA's stand-alone systems use Nortec steam generators which produce between 10 and 100 pounds of steam per hour depending on their size. They are equipped with a disposable plastic cartridge where dirt, scale, and minerals in untreated tap water are trapped.

Like many older museums in cold climates, the MFA faces major costs trying to upgrade climate control systems to maintain higher relative humidities in the winter because appropriate insulation in walls and windows, thermal breaks, and moisture barriers are missing. Because necessary modifications to the building envelope can become a very significant part of the overall environmental improvement costs, other alternatives are often sought. The most successful alternative used by the MFA is microclimates, either exhibit or storage cases, located on inside partition walls and in galleries without exterior walls.

The MFA uses two Kennedy-Trimnell units-Ralph Trimnell's version of the relative humidity control module-serving two very large cases of Chinese wooden furniture and lacquerware. Twenty-five such units have been sold in the United States; they cost about $10,000 and control 3,500 to 4,000 cu. ft. of cases in average applications. The unit has a compressor and humidistat located outside the case it is controlling. It senses the RH of the room in which the case is located and modifies the airstream into the case to add or remove moisture to achieve the desired RH in the case. It uses silica gel as a buffering column. The humidistat following the silica gel in the airstream senses and activates either a steam generator to add moisture or cooling compressor to remove moisture. The unit also has an automotive-type air filter.

Beale described a new humidity control system developed by Steven Weintraub of Art Preservation Services, New York City (212-988-3861), that utilizes Arten silica gel in high impact styrene trays, covered with a spunbonded permeable polyester fabric called Reemay. It can be equipped with connectors and tubing that allows up to twenty trays to be put together and connected to a portable reconditioning system.

The MFA continues to utilize Arten silica gel trays as buffering material in tightly sealed cases in non-climate-controlled galleries. Following Beale's talk, MFA staff conducted a tour of the museum's environmental bowels for the interest of conference members.

The second day of the conference began with the presentation, "Large or Small, New or Old: Systems Options for Environmental Control," by Ernest Conrad, President, Landmark Facilities Group, East Norwalk, CT (203-866-4626). Once again, the day started on a practical tack. Conrad presented a classification system that divides structures into groups with similar thermal characteristics. Three climate categories-uncontrolled, partially controlled, and climate controlled-each have two sublevel classifications. Combined with information about occupancy limitations and the kinds of collections each group might house safely, these classifications are useful in developing preservation approaches for particular buildings.

Uncontrolled Climate

1. No mechanical devices: Type 1 structures include covered bridges and Greek temples where environmental conditions equal the outdoors.

2. Ventilation only: Type 2 buildings include barns that are enclosed for weather protection. While heating and cooling systems are not possible, ventilation with propeller fans can reduce temperature.

Partially Controlled Climate

3. Heating & Ventilation: Type 3 buildings include house museums which can be heated and provided with exhaust ventilation. These buildings might be masonry structures or those made of wood framing and siding. Windows would be single glazed, with no insulation. Humidistatic heating is good to use for buildings in this category.

4. Basic HVAC: Type 4 structures have ducted systems of heating and cooling and include masonry buildings or those with composite framing, plaster walls, and insulation capability.

Climate Controlled

5. Climate control with drift: Type 5 buildings are designed and built as humidified structures. They have ducted HVAC systems with humidification capability.

6. Special constant environments: Type 6 buildings have been designed specifically to accommodate environmental needs of collections, and include vaults, storage rooms and specialty cases.

Conrad noted that only Class 5 buildings satisfy human comfort needs year-round. He also stressed that because buildings are often combinations of these classification groupings, their treatment is not as clear-cut as one might think. Conrad's unpublished paper presented at the AIC conference in June 1996, "Balancing Environmental Needs of the Building, the Collection, and the User," was distributed to conference participants and states his position more fully.

M. Brigid Sullivan, Chief Conservator, Collections Conservation Branch, Northeast Cultural Resources Center, National Park Service, in Lowell, Massachusetts, presented a paper on "Environmental Monitoring for Operating Efficiency." Her talk included the following points:

Warren Young, Director of Engineering Services, Museum of Fine Arts, Boston, spoke on "Getting the Best from Facilities Staff and Systems." He noted that by working together over recent years, the museum's facilities and conservation departments have almost become one regarding their work for the collection. Facilities staff work in the building day and night and sometimes become aware of problems affecting collections when conservators and curators are absent. The facilities' call list includes conservators and curators. Good communication and documentation are of great importance.

The MFA spends $1 million on electricity annually and uses half a million gallons of oil each year. Half the oil is used in summer to dehumidify. Energy conservation is a constant battle. Warren Young's quote of the day: "Nobody ever calls me to say that the environment in the storage area is excellent."

Anne Hawley, Director, Isabella Stewart Gardner Museum, Boston, addressed the subject "Juggling Priorities: Making a Commitment to Environmental Control" in her talk, while Patricia Jacoby, Director of Development, Museum of Fine Arts, Boston, spoke on "Finding Funds for Environmental Improvements."

Hawley stressed the fact that the conservation community needs to be political in order to become effective. Theatrical techniques work well to inspire donors, for example, demonstrating worm holes in paper, fabric deterioration, veneer lifting, etc. In the same vein, the Gardner Museum did the most visible piece of its environmental project first-glazing and waterproofing the courtyard skylight-in order to inspire other donors to contribute.

Creating an environment for conservation includes campaigning for the objects. Conservators at the Gardner Museum have actually treated objects in the galleries so that visitors can observe. Hawley emphasized that long-range planning efforts must involve conservators.

For her part, Jacoby encouraged an appeal to donors' emotions: what if these objects were no longer around? She encouraged managers to divide environmental control into logical and fundable pieces and to be creative. In-kind support is popular in the corporate world. Boston Edison services have saved the MFA $700,000.

Before federal budget cuts, both women used to spend a lot of time at NEA or NEH. They now devote their energies to trustees and overseers as sources of funding. Cultivating donors should be an educational event, not just a social event. Contributors want to learn, not just party. The National Center for Nonprofit Boards in Washington (202/452-6262) offers useful workshops for board members.

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