A case study of the assessment of a London office block for an energy performance certificate is available at www.bsjonline.co.uk

Swan House, a seven-storey building dating from 1989, achieved an E rating. The assessment, carried out by Power Efficiency, looked at the building envelope, air permeability, boilers, glazing and metering.

Recommendations detail how energy efficiency could be improved to provide potential cost savings of £14,000 a year and achieve a D or even C EPC rating.