The introduction of energy performance certificates in Scotland has been thrown into confusion after it emerged that separate government-backed energy rating software can produce radically different results for the same building

The two approved applications are the dynamic simulation model (DSM) and the simplified building energy method (SBEM).

Software producer Integrated Environmental Solutions (IES) said a hospital tested with both approved packages got an E rating under the SBEM system and a C with DSM.

David McEwan, UK manager of IES, said: “It’s only a matter of time before people say: ‘Why should we get an E when we could move up two grades?’”

Public buildings in Scotland have had to display EPCs since 4 January.