SEDBUK & Boiler Efficiency


Boiler efficiency A-rated explained diagramWorcester’s Greenstar condensing boilers are at least 90% efficient, meaning that they turn 90% of the fuel they use into heat.

The official rating for boiler efficiency is the ‘SEDBUK’ scale. SEDBUK stands for ‘Seasonal Efficiency of a Domestic Boiler in the UK’.

Greenstar condensing boilers achieve the highest possible efficiency category – SEDBUK Band ‘A’.
 

What is a condensing boiler?

The term ‘condensing boiler’ refers to the fact that the boilers produce condense from time to time.

Condensing boilers use heat from exhaust gases that would normally be released into the atmosphere through the flue. To use this latent heat, the water vapour from the exhaust gas is turned into liquid condensate.

In order to make the most of the latent heat within the condensate, condensing boilers use a larger heat exchanger, or sometimes a secondary heat exchanger.

Due to this process, a condensing boiler is able to extract more heat from the fuel it uses than a standard efficiency boiler. It also means that less heat is lost through the flue gases.

What is SEDBUK?


The SEDBUK rating was developed under the UK Government’s ‘energy efficiency best practice programme’ with the co-operation of boiler manufacturers, including Worcester. It provides a basis for fair comparison of different models of boilers.

The SEDBUK rating is the average annual efficiency achieved in typical domestic situations. It takes into account sensible assumptions about climate, control, pattern of usage and other similar factors.

The rating is calculated from laboratory tests together with other important factors such as boiler type, fuel used, ignition type, UK climate, boiler water content and typical domestic usage patterns. So, for estimating annual fuel running costs SEDBUK is a better guide than laboratory test results alone.

The boiler’s performance is scored, enabling the boiler to be placed in a banding system using a scale from ‘A’ to ‘G’. ‘A’ rated boilers are the most efficient.
 

Condensing Boiler Regulations

Building regulations that have come into force since 1st April 2005 state that any replacement or new gas or oil boiler must be a condensing boiler. Rare exceptions can apply.

SEDBUK was developed under the Government's Energy Efficiency Best Practice Programme with the co-operation of boiler manufacturers, and provides a basis for fair comparison of the energy performance of different boilers.

SEDBUK is the average annual efficiency achieved in typical domestic conditions, making reasonable assumptions about pattern of usage, climate, control, and other influences. It is calculated from the results of standard laboratory tests together with other important factors such as boiler type, ignition arrangement, internal store size, fuel used, and knowledge of the UK climate and typical domestic usage patterns.
 

BAND SEDBUK RANGE
A Above 90%
B 86-90%
C 82-86%
D 78-82%
E 74-78%
F 70-74%
G Below 70%

For estimating annual fuel costs SEDBUK is a better guide than laboratory test results alone. It can be applied to most gas and oil domestic boilers for which data is available from tests conducted to the relevant European standards. The SEDBUK method is used in SAP.
 

There are not many band G boilers around, most old cast iron boiler are between D-F.


The SEDBUK Development Project

The purpose of the project was to develop a method for calculating seasonal efficiency for individual central heating boilers to use in the UK Building Regulations, Part L (Conservation of Fuel and Power).

The project took place over a period of three years, during which a theoretical seasonal efficiency model was developed for simple boilers and then adapted to include other types. Experimental data obtained from detailed laboratory tests on over 20 different boilers, supported by data from field trials in 99 homes, was used to validate the theoretical assumptions. This allowed fuel usage data (termed "signature") to be related to efficiency test results supplied by manufacturers.

The work was carried out for BRECSU on behalf of the Department of the Environment, Transport and the Regions, with BG Technology as the main contractor to provide technical expertise. At each stage the findings were debated and agreed by members of the boiler efficiency project team, who represented:-


 
Energy Efficiency

To help you find other related information, the energy efficiency website gives general information, and provides a large range of links to other more specific energy efficiency sites.

Click here to visit the energy efficiency web site.



Information and guidance on heating systems in general is also available on the site, as well as assistance to find installers and suppliers.

 

 


You can search the DEFRA database to find the efficiency of your current boiler.  Boiler Efficiency Database
 

Advantica (formerly BG Technology)

BRE (Building Research Establishment)

CBF (Condensing Boiler Forum)  

DEFRA (Department for Environment Food & Rural Affairs
FAERO (Federation of Authorised Energy Rating Organisations)

MODUSSE (Manufacturers of Domestic Unvented Supply Systems Equipment)  

OFTEC (Oil Firing Technical Association for the Petroleum Industry)

SBGI (Society of British Gas Industries)

WMA (Waterheater Manufacturers' Association)