Improving the energy efficiency of the UK housing stock is important both to meet carbon emission reduction targets and to reduce fuel poverty. For this reason, domestic properties are frequently retrofitted with energy saving measures. This study looks at how the energy consumption, thermal properties and internal temperature of 14 dwellings change as a result of a solid wall insulation (SWI) retrofit. A decrease in heat transfer coefficient of 111(-7)(+6)% was calculated for 2 dwellings, which is slightly lower than the previously modelled value of 18%. However, many houses displayed evidence that the full benefit of SWI was not being realised as, for example, energy savings were offset with increases in internal temperature. Future retrofit schemes should therefore consider supplementing the changes in fabric with increased guidance for the occupant. Crown Copyright (C) 2018 Published by Elsevier B.V. All rights reserved.