Monitoring of completed buildings often identifies significant gaps between the predicted and actual energy use of buildings. This is referred to as the ‘energy performance gap’. To date, most research on the energy performance gap has focussed on non-domestic buildings; this paper presents a case study from the UK domestic sector. Monitoring equipment was installed in six identical flats located in a new-build apartment building. The actual energy used during the first year of occupation is compared with the design stage normative Standard Assessment Procedure calculations as well as seven transient DesignBuilder models produced by a cohort of seven MSc Architecture students. As six identical flats were investigated, the paper provides a unique opportunity to develop an energy use distribution on the monitoring side of the energy performance gap. The work demonstrates that the energy performance gap is evident in the domestic sector