Energy performance of Scottish public buildings and its impact on the ability to use low-temperature heat

•A well-functioning space heating system can operate below 70 °C for 98% of the year and below 55 °C for 71% of the year.•The performance gap between measured and calculated energy use is widening across building age groups, with a clear increase for post-1980 buildings.•Pre-1980 buildings can operate with supply temperatures below 70 °C for 96–99% of the year and below 55 °C for 67–71% of the year.•Building envelope improvement, whilst recommended, is not a pre-requisite for using low-temperature supply in pre-1980 buildings.•Post-1980 buildings could have limitations in respect of using low-temperature heat under windy conditions.