Analysing the energy consumption of conservation heating systems at the National Trust

Conservation heating has become the main method of controlling relative humidity in historic houses of the National Trust and many other organizations. In recent years the Trust has begun to focus on its carbon footprint and ways that it can use energy more efficiently in all its activities. This article describes work the Trust is undertaking to evaluate energy use of its conservation heating systems. The research focuses on three case study properties to understand their conservation heatingenergyuse in termsof the spaces controlled and to compare their efficiencies with external benchmarks. The article further describes the development, testing and application of 'conservation heating degree days' as a method for estimating the energy demand of conservation heating systems from simple environmental data.