Session 9: Preventive Conservation (David Thickett and Rob Thomson)

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Session 9, the last session of the fourth day of the IIC Congress covered Preventive Conservation, a crucial subject indeed, after different perspectives on remedial conservation were dealt with in the previous days. The session allowed for a nice overview of three topics: controlling the climate in historic interior spaces, managing light radiation, and vibration monitoring and mitigation. It was interesting to see the range of solutions that were developed across various institutions in the UK. There was a lively discussion in the chat during the live presentation as all of the primary authors were available to answer questions. 

The first two talks of the session were a great pairing as they both reviewed heating and dehumidification methods for controlling the environment in historic buildings. Minimizing energy use for sustainability were also highlighted in these talks. The topics of sustainability and applicability were highlighted by Sarah Staniforth, who moderated the Q&A session.

The first talk titled, ‘Comparison of Environmental Control Strategies for Historic Buildings’ was presented by David Thickett (image 1). David vividly compared methods for controlling relative humidity levels- some built in and some portable that can be added to existing historic spaces. Beyond measuring the environment and weighing these against the IPI risk indices, energy use measurements were also taken for comparison with the effectiveness of the environmental control methods.  

The second speaker, Rob Thomson, in his paper, ‘Heating or Dehumidification? Maintaining Appropriate Relative Humidity Levels in Historic Buildings Containing Museum Collections’, focused on simple strategies applied in three charming properties of the Historic Environment Scotland (image 2). These strategies focused on humidistatic heating vs. dehumidification, but not air conditioning as it was not suitable for these locations. Thomson also discussed the humidity ranges they were trying to achieve based on the individual needs of each location.

The topic of dehumidification came up as a theme from the morning’s regional live session “Uncontrolled Environments.” Staniforth asked for further discussion around the use of dehumidification taking into account climate change. The takeaway from the talks and discussion during the Q&A session was that dehumidification is quite effective, can be tested at a low cost, and has the added benefit of filtering pollutants from the air. However, both heating and dehumidification are needed. Fortunately renewables can be used for conservation heating, which can make it carbon neutral. Air conditioning is the most expensive of methods and as was indicated by Thomson, can’t be installed in many historic locations. Essentially, one system does not fit all. Fortunately we have the results from these studies to help us in making decisions as the methods discussed can be applied across the world. Choosing the right environmental control system for historic sites involves understanding the particular needs of each location.

Find out about the following talks by checking out the other Session 9 blog posts.


Carlos Izurieta is a senior student of conservation and restoration of paintings and sculptures at Universidad Politécnica de Valencia, Spain.

Samantha Springer specializes in sculpture and variable and is the Owner and Principal Conservator of Art Solutions Lab in Portland, Oregon, US.

Priyanka Panjwani is a conservation architect and design professional based in Mumbai, India.