Temperature and Relative Humidity (RH)

Controlling the temperature and RH of collections spaces are critical to preventive conservation of collections. Maintaining appropriate levels can care for collections in a cost effective, passive, and sustainable method. Reducing energy use is important as both a mitigation and adaptation method for cultural collections – bringing down costs, lowering emissions as well as engaging and contributing to sustainability. Balancing visitor needs and expectations is also an important consideration.

A method to reduce energy use has been to safely expand the limits of temperature controls – meaning less use of the HVAC air conditioning systems that are very energy heavy. AICCM guidelines now state temperature between 15-25 degrees in both temperate and tropical climates, however RH needs to remain relatively consistent with only changes of 10%, between 45-55% in temperate climates and 50-60% in tropical climates with the set point one of the most critical elements of climate control. Further details on different climates and set points for different geographical climates can be found on the AICCM Environmental Guidelines page.

Besides climate control systems other strategies can involve more passive methods, and it is important to keep accurate measures of the climate over time to understand the collection spaces and comparing them with fluctuations to the external temperature to understand how the building, and different areas are responding.

Much can be learnt from the building and architectural industries – looking at sustainable passive cooling and heating systems within buildings. This can require changes to the building envelope so is very important as part of the planning when new buildings are created, or alternatively, going back to re-insulate. This can also involve a mixing of traditional techniques of controlling temperatures and appropriate buildings for the climates, which will often have not relied on electricity, with modern needs.

Another method is to only target certain materials or objects for more intensive controls through microclimates. For example, very fragile materials that are known to deteriorate sharply in certain conditions can be isolated in containers with stable conditions and monitored more closely.

Simple building maintenance is also important, for example ensuring there are no leaks from plumbing systems or that door draughts are reduced, are simple and cost-effective ways to maintain consistent environments.

Switching energy sources to solar panels or other renewable sources onsite is something that has been pursued by multiple Australian museums.

References and recommended reading

AICCM Environmental Guidelines (2019) aiccm.org.au/conservation/environmental-guidelines/

AMaGA National Standards for Australian Museums and Galleries (2016) amaga.org.au/sites/default/files/uploaded-content/field_f_content_file/nsfamg_v1.5_2016.pdf

ICOM-CC (2014) Environmental Guidelines ICOM-CC and IIC Declaration icom-cc.org/332/-icom-cc-documents/declaration-on-environmental-guidelines

Member case studies

In 2011 a number of conservators and collection managers were asked ‘what do you see as the challenges and opportunities for conservators as they deal with the likely relaxation in environmental guidelines for collections?’. aiccm.org.au/network-news/aiccm-national-newsletter-no-118-july-2011/

Amanda Pagliarino discusses the current work being done at QAGOMA to implement environmental settings that are adapted to the use and capacity of their different storage and exhibition buildings and the collaborative work undertaken to implement this more widely through loan programs. blog.qagoma.qld.gov.au/climate-for-galleries-an-evolution-in-thinking/


As one of the Ten Agents of Deterioration, light damage initiates cumulative and irreversible material degradation making it a significant consideration in the protection of heritage objects and collections. Reducing light exposure is the most commonly used method of prevention as given by lighting guidelines and standards utilised within preservation environments.

Applying rigid schemas for display can however be problematic for equitable access and inefficient use of museum resources in frequent rotation of displays.

Lighting levels of objects on display impact visitor experience including safety and viewing comfort in addition to the rates at which the objects undergo colour fade and other detrimental consequences of photodegradation. Finding balanced and sustainable approaches relies on management practices that promote shared responsibility and consider the value of access and use of heritage to current audiences as well as those in the future.

The sensitivities of individual objects to light vary depending on factors that include previous exposure to light, substrate interaction, particle size, and colourant concentration (Tse 2019, p. 337).

Additionally the composite nature of many heritage objects benefit from a more tailored approach to protection from light rather than generalised categorisation of materials.

Tse promotes microfade testing (MFT) to determine the lightfastness of a given material in order to more accurately assess sensitivities to light. Customising lighting plans for collections with known light sensitivities can therefore provide a better foundation from which to calculate acceptable exposure times.

Practical methods of reducing UV radiation are applying UV filters to windows where objects are exposed to natural light and placing UV filters on artificial lighting sources. It is also prudent to monitor lux and UV levels with light/UV meters regularly.

As photochemical degradation is aggravated by high temperatures, relative humidity and oxygen, placing objects in micro-climates within anoxic environments may provide an alternate option for sustainably safeguarding heritage materials. (AK October 2021)

References and recommended reading

Ashley-Smith, J, Derbyshire, A & Pretzel, B 2002, ‘The continuing development of a practical lighting policy for works of art on paper and other object types at the Victoria and Albert Museum’, in R Vontobel (ed), ICOM-CC 13th Triennial Meeting, Rio De Janeiro, 22–27 September 2002, James & James, pp. 3–8.

Brokerhof, A, Kuiper, P & Scholten, S 2018, ‘Spread or Sacrifice: Dilemma for Lighting Policies’, Studies in Conservation, vol. 63, no. sup.1, pp. 28–34.

Cuttle, C 2007, ‘Light-induced damage to object’, in Light for Art’s Sake: Lighting for Artworks and Museum Displays, Butterworth-Heinemann, Oxford, pp. 39–49.

Ford, B & Smith, N 2011, ‘Lighting guidelines and the lightfastness of Australian indigenous objects at the National Museum of Australia’, in J Bridgland (ed), ICOM Committee for Conservation, 16th Triennial Conference, Lisbon, 19-23 September 2011, James & James, pp. 1–13.

Ford, B 2011, ‘Non-destructive microfade testing at the National Museum of Australia’, AICCM Bulletin, vol. 32, no. 1, pp. 54–64.

Ford, B & Smith, N 2011, ‘The development of a significance-based lighting framework at the National Museum of Australia’, AICCM Bulletin, vol. 32, no. 1, pp. 80–86

Saunders, D & Kirby, J 1996, ‘Light Induced Damage: Investigating the Reciprocity Principle’, in ICOM-CC, 11th Triennial Meeting, Edinburgh, Scotland, September 1-6, 1996, James & James, pp. 87–90.

Tse, Season 2019, ‘Microfade Testing for Heritage Institutions: A Canadian Experience’, Studies in Conservation, vol 64, no.6, pp. 337-351.

Vincent L. Beltran, JD & Maekawa, S 2012, ‘Large-scale assessment of light-induced color change in air and anoxic environments’, Studies in Conservation, vol. 57, pp. 42–57.

Bruce Ford 2013, ‘Breaking the rules: light-exposure risk assessment and micro fading’, Cultural heritage conservation science and sustainable development: Experience, research, innovation. International conference in the frame of the 50th anniversary of the Centre de recherche sur la conservation des collections – CRCC, Paris, 23 May, Published on 6 December 2013, viewed 10 September 2009. www.youtube.com/watch?v=c59HGiHE9SQ