St Vigeans sculptured stones, Angus

Rob Thomson, 15.10.2014
The benefits of temperature and humidity controls
Two stone cottages in the village of St Vigeans in rural Angus are home to 38 carved stones, which once stood on an old church mound to broadcast early messages of Christianity. The museum and its collection is cared for by Historic Scotland.

In 2011 the museum went from being open to the public to a “by appointment only” system. This presented an opportunity to save energy as the building no longer needed heating to comfort levels. However, relative humidity still needed to be controlled.

In July 2012 we installed a humidistat to control the existing electric heaters. The collection is reasonably robust so we chose a higher-than-normal relative humidity of 75%.

A temperature boost button was also installed to heat the building for four hours at the press of a button. The effectiveness of this system was confirmed by installing temperature and relative humidity data loggers in the museum.

Considerable amounts of energy have been saved. For example, the year before installation our energy use was 9,056 kilowatt hours, but 2013 we had reduced this by 55% to 4,100 kilowatt hours. The cumulative savings since the installation in July 2012 have been £1,300.

The equipment cost £500 and took an electrician and conservator half a day to install. This is a fast payback and a notable reduction in Historic Scotland’s carbon footprint.

Rob Thomson is a freelance preventive conservator