Tel: 01380 736920 | Email:
Oil Boilers, Biomass Boilers, Solar PV, Air Source Heat Pumps, Hot Water Cylinders

SAP and Boiler Efficiencies

SEDBUK (Seasonal Efficiency of Domestic Boilers in the UK)

SEDBUK has now been replaced, but initially it was developed by the Government alongside boiler manufacturers, under their ‘Energy Efficiency Best Practice Programme’. It was designed as a fair basis for comparisons of boiler energy performance when installed in a typical domestic situation in the United Kingdom.

Building Energy Performance Assessment

In August 2014, the boiler efficiency support resources that were held on the SEDBUK website were relocated to the Building Energy Performance Assessment support website ( This is designed to support UK building energy performance assessments that are produced using the National Calculation Methodologies for energy rating buildings (NCMs), such as SAP. To search the boiler efficiency database click here.

Standard Assessment Procedure (SAP)

To determine boiler efficiencies, a ‘Standard Assessment Procedure’ more commonly known as SAP, is used. SAP is the Government’s standard method for energy rating in the United Kingdom. SAP ratings enable the comparison of energy efficiencies and demonstrate the likely effect of improvements to a property in terms of energy use.

SAP 2009 focuses on improving the accuracy of the way the efficiencies are worked out. It incorporates a key revision over the previous 2005 procedure, in the assumed carbon emissions per kWh of oil used by the boiler. It may appear that the efficiencies of boilers reduced with SAP 2009, but it is important to understand that the new methodology gives a more realistic estimate of the average annual boiler efficiency when installed in typical conditions, based on evidence from recent independent testing and field trials.