|The Government's Standard assessment Procedure (SAP) for the
energy rating of dwellings changed on the 1st July 1999. As
of this date, SAP 98 became the energy rating method approved
by the DETR for building regulation purposes. One of the main
changes is the introduction of the 'Boiler Efficiency Database'.
The Boiler Efficiency Data File is published as part of the
DETR's Boiler Efficiency Database scheme. It holds data on
domestic boilers, gas and oil fired only, current and obsolete,
for the purposes of carrying out SAP energy ratings.
Although other data is included, the most important item
of information in the Boiler Efficiency Data File is the SAP
seasonal efficiency for each boiler, which may now differ
between boilers of the same type if calculated by the SEDBUK
method (see section 2) introduced in SAP 1998. Where SEDBUK
figures are not available the SAP seasonal efficiency will
be type efficiency, as given in Table 4b of SAP 1998.
SEDBUK (Seasonal Efficiency of Domestic Boilers in the UK)
is a new method for calculating the seasonal efficiency of
central heating boilers, developed and agreed with boiler
manufacturers. Its purpose is to identify differences in efficiency
between different boilers in such a way that they are recognised
and treated fairly in the SAP. The new method uses efficiency
test results already obtained by manufacturers to demonstrate
compliance with the European Boiler Efficiency Directive,
so does not require any additional testing to be carried out.
The development of the SEDBUK method allows SAP to recognise,
for the first time, the seasonal efficiency of individual
makes and models of boilers rather than just types of boiler.
The method is described in Appendix D of the Government's
Standard Assessment Procedure for Energy Rating of Dwellings
(1998 edition), which is published on behalf of DETR by BRECSU
and available from the BRECSU Enquiries Bureau (phone 01923
664258). The attribution of a SEDBUK value to individual boilers
is expected to influence boiler purchases such as local authorities,
social housing landlords, and others who are alert to the
need to raise SAP ratings and improve energy efficiency.
The Boiler Efficiency Database holds information both on
current boilers, which by law have to comply with minimum
energy efficiency values, and obsolete boilers, which do not.
There are three efficiency category calculations
1. SEDBUK based on certified data: Efficiency has been calculated
by the SEDBUK method from the results of standard tests defined
in the Boiler Efficiency Directive. The results of the standard
tests must have been certified by a suitably qualified Notified
Body (i.e. an independent test house deemed competent under
European rules for boiler testing) Subject to verification,
the database manager will calculate seasonal efficiency in
accordance with the SEDBUK method and create an entry in the
2. SAP default: Efficiency has been taken from SAP 1998 Table
4b, based on boiler type. It has not been calculated from
test results pertaining to this particular boiler. Entries
in this category are admitted to the database on a temporary
3. Estimated : Efficiency has been taken from SAP 1998 Table
4b, based on boiler type. Entries with efficiency category
3 are for obsolete boilers only, which usually do not comply
with the provisions of the Boiler Efficiency Directive.
In the absence of declared manufacturers data, an indicative
seasonal efficiency taken from Table 4b should be used. However
if declared manufacturers data are available, these should
be used in preference.