SAP 2005

Dunbrik flues & chimneys with appropriate secondary heating
help meet the SAP Target CO₂ Emission Rates

Effect of using flued appliances on SAP Emission Calculations

Domestic properties have to meet Target CO₂ Emission Rates (TER) using a Standard Assessment Procedure (SAP).

By including secondary heating with a flue or chimney in your house designs you can reduce the CO₂ emission rate for SAP purposes, enabling other design features to be relaxed whilst still complying with Building Regulations Part L. This occurs because the SAP calculations for a house without a secondary heating appliance assume that an electric fire is used, and these have a high CO₂ emissions rate.

Dunbrik flue and chimney systems used with stoves, open fires or gas fires help meet the CO₂ emissions target.

BSRIA Sample SAP Calculations

Dunbrik commissioned BSRIA, the leading UK test house, to calculate the SAP CO₂ emissions for various types of flued secondary heating appliances compared with the default electric fire.

In 6 out of 7 scenarios, the CO₂ emissions were lower using a flued secondary appliance than the default electric fire. This means that other design features could be relaxed and still comply with Building Regulations. The only exception was with a particularly inefficient gas-fired secondary heating appliance.

The full report can be viewed at dunbrik.co.uk/documents/bsria_report_11-10-07.pdf or a copy obtained from Dunbrik on 01924 373694.

Note: Assumptions used in the Standard Assessment Procedure (SAP)
For all dwellings, the SAP calculations assume that 10% of the heating is from a secondary heating appliance.
If the house design does not include a secondary heating appliance, SAP assumes an electric room heater will be used. SAP uses a high emission factor for electricity.
If the house design includes a secondary heating appliance, the SAP calculation uses the efficiency of the actual appliance and emissions for the fuel type used. The emission factor for gas or wood is much lower than that for electricity.
For the purpose of the SAP worksheet a chimney, such as the Dunbrik A1 chimney system, is described as having a minimum 200mm diameter liner and a flue, such as the Dunbrik gas flue block system, is described as having less than 200mm diameter.