Climate is what we expect, weather is what we get.
(Mark Twain, 1835-1910)
This quote from Mark Twain, written at the turn of the century, could no better sum up the circumstances in which we find ourselves today. The rapidly growing public appetite for cultural heritage experiences is both a boon and a burden. The boon is self-evident but the burden in part can be seen in our expectation of comfort – it’s the climate we expect. In my observation working in the sub-tropics, visitors to museums, galleries and libraries don’t just have a cultural experience in mind, they are also seeking cool respite and on hot summer days they come in droves.
Recent statistics from the Australian Bureau of Meteorology are sobering – 2015 was the fifth warmest year on record and the summer of 2015/16 recorded the hottest sea surface temperatures on record; 2016 was the fourth warmest year on record; 2017 was the third warmest year on record whilst in Brisbane the annual mean temperature was the hottest recorded. Australia has a diverse climate and I know there are regions that experience bracing cold, it is just hard for me to imagine because I live in Brisbane and it is just getting hotter.
That is why I thought it would be a good idea to talk to Cobus Van Breda, who lives and works in Tasmania, in the cool temperate zone. I was keen to speak with Cobus who responded to the Collection Environment survey on behalf of the Tasmania Museum and Art Gallery (TMAG). In the following interview he explains the approach that TMAG has implemented to manage the museum climate for a range of buildings and collection materials, using the Heritage Collection Council (HCC) Guidelines for Environmental Control in Cultural Institutions (2001) and the AICCM Interim Temperature and Relative Humidity Guidelines for storage and display conditions (2014) as TMAG’s preferred references.
AP: In your response to The Collection Environment survey, on behalf of the Tasmanian Museum and Art Gallery, you indicate that the Heritage Collections Council Guidelines for Environmental Control in Cultural Institutions (2001) is used as the reference for the control of the display and storage environments. How long has TMAG been using non-conventional, wider temperature and relative humidity parameters?
CVB: At the Tasmanian Museum and Art Gallery we have been using the Heritage Collections Council Guidelines since 2003 for all but three of our storage and display areas: our temporary exhibition galleries (because loan agreements insist on 50±5%RH, 20±2°C); our Prints & Drawings Store (50±5%RH, 20±2°C, as the store contains European Portrait Miniatures on ivory) and our Photo Cool Store (35±5%RH, 15±2°C with high air filtration, as the store contains a range of photographic materials and some decorative silver). While most objects can be safely stored within the wider parameters of the HCC Guidelines, highly hygroscopic materials, such as ivory portrait miniatures, are still stored in the tighter 50±5%RH, 20±2°C range, and unstable material such as photographic media and some metals are stored in low temperature, low RH.
I remember as a student in 1991 listening to the late Colin Pearson (one of the authors of the above guidelines) give a very sobering lecture on environmental control. In my memory it is the road to Hell is paved with good intentions lecture. Essentially it was the sad tale of installing an expensive (as they all are) HVAC system into a retrofitted or purpose built museum in the tropics so as to display and store all the collection in the ‘ideal conditions’ of 50±5%RH, 20±2°C on a daily basis. Then the inevitable breakdown and/or lack of recurrent funding to run it, and the inability to ventilate a building specifically designed or retrofitted to reduce air exchange, essentially creating a humid hotbox and widespread damage to the collection.
The issue is summed up well on page 6 of the HCC Guidelines by Pearson:
Air-conditioning is very expensive to install and maintain, and unless high quality (and therefore price) systems are used, air-conditioning can often cause more damage than no air-conditioning. There is unfortunately a neurosis that without air-conditioning, museum, gallery, library and archival collections will rapidly deteriorate. This is not the case. It is more important to have a stable environment than specific levels of temperature and relative humidity, and this can be achieved by careful building design.
I am sure many of you, particularly those who have been involved in redevelopments, have observed that Australia is fortunate in that many state and local institutions are not infrequently the recipients of generous capital grants for improvements. Unfortunately problems arise when recurrent funding cannot sustain what the capital grant was used for. Our display and storage buildings, which cover three campuses and include structures from as early as 1815 to the 1980’s simply cannot nor need to be fitted with HVAC plant to meet the tight parameters of 50±5%RH, 20±2°C on a daily basis. The HCC Guidelines has so far proved to be a practical and nuanced aid.
AP: What temperature and relative humidity parameters were in use before TMAG moved to the HCC Guidelines and how did TMAG implement the change? I am interested to know if it was a gradual change in conditions. Were others involved such as Facilities Management and an HVAC agent or contractors? Did the institution engage in a trial period?
CVB: The building which houses our temporary exhibition galleries (with HVAC) was built in 1966. The current HVAC system in the temporary exhibition galleries was first installed in the 1990’s and has been upgraded ever since to meet the ideal conditions of 50±5%RH, 20±2°C on a daily basis. The other 80% of our galleries pre date 1900 and prior to 2003 were simply considered outside any guidelines.
AP: Can you describe any seasonal observations you have made regarding the use of wider environmental parameters? Have you observed temperature and relative humidity data patterns recorded internally as the seasons change? Human comfort is an important consideration for facilities managers, has this been an issue?
CVB: We are fortunate that Hobart has a cool temperate climate with an annual temperature range of -3 to 40°C and an average RH of 55-60%. Over the last 15 years we have monitored all the other non-HVAC controlled spaces (that is over 80% of our display galleries) and with the invaluable help of the Facilities Manager, improved the building fabric – such as insulation and closing off gaps, enclosed or glazed where possible to buffer vulnerable objects, and over winter introduced low level heating for visitor comfort and to reduce the RH. In most of our galleries this has kept us within the HCC guideline parameters for a temperate zone, most of the time. Winter, because of the heating can sometimes be on the dry side, and summer, if temperatures are high and it is wet can be on the humid side. Our experience has proven that enclosing objects in cases or glazing two dimensional works (paintings) tends to stabilise their RH to around 50%.
Our Colonial Gallery is an interesting example. The gallery is on the first floor of a masonry building constructed in 1900. It is about 8 x 26 metres with close to 6 metre high ceilings. Since its construction it has been the gallery in which our most significant paintings and objects have been displayed. We have over twenty years of thermohygrograph readings for this space which relies solely on the building fabric and portable oil heaters in winter. The greatest problem noted over the last twenty years has been the occasional ingress of dust (the roof is tiled) in windy weather and on one occasion suspected infiltration of cement dust from a construction site across the road, which required immediate careful removal. Following our redevelopment in 2013 the roof was better sealed, greatly reducing the dust issue. Over the last twelve months the average summer temperature was 25°C and 50%RH, winter 20°C and 45%RH. The maximum daily temperature fluctuation was 4°C and 15%RH. To my knowledge there has not ever been any noted damage to any object in this gallery due to the environment. We have also noted that it can take up to 6 hours for major and rapid external changes in RH to filter up to this gallery.
We still however have some spaces within our display areas that require further modification, mostly this relates to finding the right level of heating in winter so as to not reduce the RH too far. Some spaces are also just not suitable for some objects.
AP: In the survey you indicate that TMAG refers to the AICCM Interim Temperature and Relative Humidity Guidelines for loans from the TMAG collection. Results from the survey indicate that over 50% of respondent organisations request the conventional, narrow environmental parameters for cultural heritage material on loan. As a conservator working for an institution that has implemented wider environmental parameters for display and loan, how do you reconcile these different approaches in your practice?
CVB: We still require the conventional tight guidelines from borrowing institutions but we will also assess their environment for suitability if they cannot meet them. This question perhaps comes to the heart of the matter for me. My colleagues and I will not refuse a loan on the basis that the borrowing institution cannot meet 50±5%RH, 20±2°C on a daily basis alone. This is not what a thinking professional should do, and would be hypocritical if the object was in fact currently within our own institution on display or stored in an environment of 18-24°C and 45-65%RH. We will work with our registration colleagues and each of us within our speciality will assess the object and the risk after finding out as much as we can about the environment at the borrowing venue. On occasions we have set up our own thermohygrographs or data loggers to do this. Sometimes modifications are necessary, such as glazing the object or specifying display within an appropriate case. Sometimes the environment is just not suitable and the answer will be no. Usually however a solution can be found because we want people to see and enjoy our collection.
AP: In the survey you indicate that TMAG has a main storage area for mixed collections and a general cold storage. Could you please describe the parameters used for cold storage and what materials are housed in this store?
CBV: In 2003 TMAG obtained a 3,500 square metre storage facility from the National Archives of Australia. Two thirds of that storage space was essentially a large, well-insulated box that we have modified with a ducting system controlled to recirculate 90% of the air, with capacity to warm it (but not cool it). The inlet ducts are set to close if the outside RH rises above 55% or the temperature is above 21°C. This has proven to be a very efficient and suitable store for a large part of our collections without the complexities and costs of a HVAC system.
In 2007 we modified a vault to create a cool store operating at 35±5%RH, 15±2°C with high air filtration. These parameters were chosen to give maximum practical benefit to the storage of a range of photographic materials without seriously compromising their enclosures (frames, daguerreotype cases, albums). At these levels it is also possible to safely remove the object without condensation forming on its surface. The vault is also used to store decorative silver and some other metals.
Money, both capital and recurrent, saved from unnecessary work to our big insulated box which is very suitable for the majority of objects is better directed towards a more complex cool store needed for a small but vulnerable part of our collection.
