The headline news out of Scotland is that all new built homes will be required to meet a Scottish equivalent of the Passive House standard as of January 2025. This tectonic shift in policy reflects Scotland’s determination to cut emissions and meet its climate goals while also reducing fuel poverty among those living in new social housing.
However, years before Scotland began to seriously consider this requirement for newly built homes, the Scotland Futures Trust (SFT)—a non-department company owned by the Scottish Government that works with the public and private sectors to finance and support infrastructure projects within Scotland—had made a similarly dramatic, albeit more complex, shift in policy. This policy applies to new schools and was instituted after research conducted by Edinburgh City Council’s sustainability division showed that some relatively new schools were performing as poorly as schools from the Victorian era, or indeed even worse. Finalized in March 2020 and known as the Learning Estate Investment Programme (LEIP), the initiative incentivizes reductions in energy consumption and emissions for newly built schools while also improving indoor air quality (IAQ) for students and teachers. It realizes each of these objectives by tacitly encouraging schools to be built to Passive House standards.
Identifying a Gap in Performance and Air Quality
A persistent scourge of the construction industry, the performance gap— defined as the disparity between the anticipated energy use of a building as modeled and the actual use once it is built— arises due to a multitude of factors that can be difficult to resolve. The dominant reasons for the gap are uncertainty of specifications during modeling, poor operational practices, and unanticipated occupant behavior, according to a 2016 paper published in Frontiers in Mechanical Engineering. The paper estimates that the three issues have an estimated effect on energy use ranging from 20-60, 15-80, and 10-80%, respectively (see Table 1). Other contributing factors identified in the paper include unanticipated changes to design made during construction, poor commissioning, and substandard construction practices.