אקלים עבור אוספים - סטנדרטים ואי ודאויות

ניל מקמנוס


Nov. 7 – Nov.9  2012

Pinakothek der Moderne, Munich


The conference "Climate for Collections – Standards and Uncertainties" was supported and made possible by four major initiatives and institutions: The EU-funded research project Climate for Culture, the Doerner Institut, the Bayerische Staatsgemaldesammlungen as well as by the Verband der Restauratoren e.V. (VDR) Germany's professional association for conservators.

The conference aimed to discuss many issues facing museum professionals; standards, high energy bills, complex air-conditioning equipment, alternative climate control strategies, climate change and the effects of inappropriate indoor climate on cultural heritage. The subject of the conference centered on the question: "What is known and what is not known about suitable environmental conditions for heritage collections?"

Three core factors were given by the conference organizers as the driving force for the meeting at this time. Firstly the work of the Climate for Culture initiative; concerning damage and risk assessment, damage functions and determination of tolerable ranges for environmental parameters. Secondly the global need to save energy and to reduce the carbon footprint. And lastly the initiative and influence of the Bizot group, the International Group of Organizers of Large Scale Exhibitions, for a redefinition of internationally accepted museum conditions. This initiative has caused major concerns within the conservation community.






Opening Remarks


First Panel Discussion


The conference program included with 34 half hour presentations and additional discussion sessions packed into the three day period.

Notable lectures of a particular interest to me were given by:

  • Boris Pretzel; Head Scientist, Victoria and Albert Museum, "If only we knew… knowledge or wishful thinking"

The speaker discussed the V&A's environmental position and the surprising fact that quite a few of the galleries in the museum are not air-conditioned, supported by many years of environmental monitoring and analysis of the objects on permanent display within these galleries. His conclusions were that the current standards are too rigid, simplify and ignore uncertainty. "We should take what we think we know and be critical about this knowledge". "We should stop using standards as a crutch when we don't know enough, guidelines are better".

  • Lukasz Bratasz, "Allowable microclimatic variations in museums and historic buildings: reviewing the guidelines"

He presented a review of the guidelines and museums and conservators usage from the start point of Gary Thompson's 1978 publication, "The Museum Environment", through the ASHRAE Handbook from 1999 to the current European standard EN15757 from 2010. He proposed we need to accept a tolerable damage criterion and accept the low risk levels. This is the current case with light; "light means access" = "access means damage". The same can be applied to the environment particularly RH.

He stressed that no museum in the world can honestly say that they have AA (ASHRAE) standards in every space within their museum. He proposed the current Class B (ASHRAE), 50% +/- 15% RH are safe for most objects, and pointed out that the body of scientific research indicates that this is a safe level.

When dealing with objects that have lived their lives outside the museum environment (in churches or historic houses for instance) we should maintain the historic average levels. This is the concept of object acclimatization; the object can be even at risk if it is moved from an uncontrolled environment to classic museum conditions.

  • Edgar Neuhaus, "A Critical look at the use of HVAC Systems in the Museum Environment"

The speaker is an independent environmental consultant engineer with specific experience in the museum and collection storage sector, a specialization severely lacking in Israel.

He emphasized the risks to collections due to poorly maintained, unstable and incorrect HVAC systems installed within museums.  By the use of thermal photography he showed the difference within gallery rooms due to poor system installation; localized heating/cooling of artworks due to proximity to vents and/or poorly insulated walls. His recommendations were the greater use of conditioned showcases and museum zoning.

  • Stefan Bichlmair, "The Moving Fluctuation Range"

The speaker examined how we analyse environmental data over short and long term periods. He pointed out the differences in results that were obtained using only daily averages rather than a sliding 24 hour schedule (showing the max/min ranges). He encouraged us to use all the available data when calculating averages.

  • Robert Child, "The Influence of the Museum Environment on Pest control"

Robert Child's talk described the different activity stages of museum insect pests and how this relates to the building temperature. He made general recommendations to lower the temperature, lower the RH, increase monitoring, improve identification and address IPM issues.

  • Jeremy Linden, IPI, "Field-tested Methodology for Optimizing Climate Management"

The speaker talked about IPI's (Image Permanence Institute) collaborations with different Museums and collections to aid them in improving their environmental conditions. How do we achieve sustainability without sacrificing preservation? To affect this change we need to talk to the administration.

We need to redefine the goal - define the best possible preservation conditions with the least consumption of energy that is sustainable for the long term. Improvement can often be made without major capital investment but should be linked to the infrastructure and capabilities of staff and the institution. It is not a one-time project, sustainability and preservation issues need to be constantly reassessed and this involves data gathering within the museum and of the localized outdoor climate measurements.


Many other talks focused on the issues faced by European Historic houses, their display environment, cost and sustainability and simple and passive systems to keep the RH within a broader but safe bandwidth of 40-60% RH. This was often achieved by allowing the temperature to fall, in Winter, much below generally accepted visitor comfort levels and only provide slight conservation heating to control the RH levels. The speakers who gave presentations on these issues were: Nigel Blades, Stefan Bichlmair, Henk Schellen, Charlotta Bylund Melin, Kristina Holl, Melanie Eibl and Andrea Luciani.

Sustainable and passive environmental control systems, and building design used for museum storage facilities were discussed in talks presented by Morton Ryhl-Svendsen, Peter Bartsch and Marta Leskard.

Object analysis, modeling and risk analysis damage functions were presented by Paul van Duin, Naomi Luxford, Henk Schellen, Paul Lankester and Michal Lukomski.

Stephan Michalski, Andreas Schulze and Jesper Stub Johnsen each gave talks around the subject of standards; why we have them, how they are created in the EU, how we should use them (guidelines not facts), the effect of incorrect application of standards and risk analysis.

Each day ended with a lively debate in which professionals in the audience gave their own thoughts on the day's presentations. Thursday's discussion was particularly strong on the topic of "energy efficiency & sustainability" with the following important points made:

  • "Energy efficiency vs. beneficial conditions for objects"
  • Facility staff should be trained to maintain systems to be pro-active not reactive.
  • Use of passive systems like shading.
  • Visitor comfort levels (18-20C), are they really necessary?
  • Saving money should not be at the sake of saving the collection.
  • Dehumidifying is more expensive than Humidifying.
  • Cooling in summer months more expensive than heating in winter.
  • Low seasonal fluctuations leads to large savings.
  • Do not let the "outdoors in", circulate the internal air and maintain a reasonable winter temperature.

Conclusions proposed by the conference working group:

The conference's closing discussion was delivered by Jonathan Ashley Smith, who presented the conclusions of the conference working group's meeting earlier that day.

  • Honesty.
  • You can’t argue from the particular to the general. Meaning you can’t take your experience of the particular reaction of one object and apply the results to be representative of a whole group.
  • You can’t argue from the general to the particular. Testing, modeling and real time observation on groups of objects can only at best provide guidelines. Definite standards cannot account for the variance in every object in every location.
  • It’s not a sin to allow +/- 10% RH variation.


Additional conclusions proposed in the general discussion:

This was an interesting and healthy discussion that took place after the conclusions presented by Jonathan Ashley Smith, summarizing many of the positions proposed by the various lecturers, institutions and audience members:

  • Stable RH means a stable object, (mechanically/physically)
  • RH control is important, and not necessarily expensive. A reasonable statement when describing Humidification and de-humidification by independent dehumidifiers. De-humidification during cooling within HVAC systems has high energy consumption.
  • Temperature control is less important, and expensive. Very much dependant on the material, obviously the long term preservation of photographic and audio-visual material extremely dependant on low temperatures.
  • Historic RH more important than an arbitrary set point or standard. True especially for cultural material housed in non-museum collections (historic houses, churches, etc).
  • Ventilation according to need. Unnecessary ventilation in a controlled museum environment is expensive to maintain, exterior air should only be brought in to provide minimum human comfort. Control air exchange rate.
  • Far greater energy savings can be made in other areas of museum activity, but these are probably beyond your control.
  • Material response time is important, and dependant on size, thickness and composition. Use buffered storage enclosures.
  • Maintenance and cleaning of HVAC systems is important and can save money.
  • Build better museums and storage facilities.
  • New air-conditioning machines and systems are more efficient and can save money.
  • Allow permits to shade buildings.
  • Mechanical damage by RH is cumulative, in the same way as chemical damage by light.  We must understand that organic objects have a finite life span and plan our environment to how we expect that usable life time to be.
  • Conservation erases the climatic memory of an object. Treatments on site or in the studio such as re-tensioning canvases, resetting and gluing furniture joints and aqueous treatments of paper items removes the elastic memory of an object which lived its life in an uncontrolled or partially controlled environment. Professional conservators should know to consider their treatments in relation to the environmental location the object will be returned.
  • Who can affect the changes? The point must be proved to museum management and facility staff. Get them on your side. Often the cutting cost and sustainability are strong arguments but they should not be at the expense of the collection involved.
  • 14C – 25C is a reasonable temperature span to aim for. This does not mean short term fluctuations between this bandwidth are acceptable; rather we should aim for a sliding seasonal temperature between these outer limits throughout the year.
  • Main cause of damage to objects is the interaction with users.


I would add these further personal conclusions in the context of the Israeli museum community:

We should class all accredited Israeli museums by the ASHRAE museums classification system. This would simplify and make the inter-museum loan process more transparent; loans between similarly classed museums could be put into effect more easily. Institutions lending to museums with a lower classification will know what to realistically expect when setting environmental control levels for their particular objects. No longer should museums hide behind tight environmental restrictions to deny loan requests, when the real reluctance to approve the loan lies elsewhere. ICOM or the Ministry of Culture should head the drive to ensure compliance and honesty between the accredited museums.

Looking back over the past twelve years that I have been working as a conservator with Israeli collections we have yet a lot of work ahead of us improve the preservation of our cultural collections on a National level. Many small accredited museums with static displays could essentially be categorized as historic house museums. Most of them have a very open environmental envelope and its control should be managed accordingly. Many operate partial air-conditioning systems; cooling in the Summer and heating in the Winter only during periods when the museum is open and only for the comfort of staff and visitors. What is clear that a partially operated, poorly maintained, unstable and incorrect HVAC system can cause more damage to a collection than simple maintenance of the RH within reasonable levels. Initiatives such as the now closed Conservation Center in Jerusalem were badly managed as the objects that were conserved returned without real consideration of the environmental, storage and display conditions of the parent museums. As conservators we have to share the responsibility that items that have been conserved in the past have sometimes failed once returned to their original environment. Money would have been better spent on improving display, storage and environmental systems.


Neill McManus

Book & Paper Conservator