ECO3 Alternative methodologies


Publication date

Industry sector

Supply and Retail Market

Scheme name


For each ECO measure a supplier notifies to us, it must provide the associated ECO savings. Under ECO3 there are four ways to score measures:

  • Deemed scores
  • SAP/RdSAP (DHS only)
  • Demonstration actions, innovation measures, and monitored measures
  • Alternative methodology.

DHS measures

Where SAP/RdSAP do not contain a methodology for calculating the savings for a particular DHS measure, a supplier may apply to us for approval of an alternative methodology to calculate savings. DHS measures cannot be scored using either deemed scores or the innovation and monitored measures routes, but they can be a demonstration action.

Other measures

Generally, non-DHS measures are scored using deemed scores. Where there is no deemed score for a measure, a supplier may apply to us for a new set of deemed scores or an alternative scoring methodology. Suppliers should also consider whether the demonstration action, innovation measure or monitored measure routes could be applicable.

Applying for an alternative methodology or new deemed score

Applications must be made by an obligated energy supplier. Suppliers should contact us if they wish to make an application. For further information on alternative methodologies see Chapter 5 of the ECO3 Guidance: Delivery document.

Approved alternative methodologies and deemed scores

Once an application is approved for an alternative methodology or new deemed score it will be published below, and can be used by any supplier.

Fuel cell mCHP

We have approved an application for a new deemed score for 'fuel cell mCHP' (micro-CHP) in ECO3. 'Fuel cell mCHP’ can be selected as a post-main heat source for boiler measures in v1.6 of the main deemed scores matrix and is classed as a renewable heating measure. The same rules apply to 'fuel cell mCHP' as all other renewable heating measures installed under ECO3.

Time and Temperature Zone Control

In March 2021, we approved an alternative methodology application for a new Time and Temperature Zone Control (TTZC) measure type in ECO3. The new TTZC measure type can be selected in v1.7 of the main Deemed Scores Matrix. The guidance note sets out the requirements for claiming the TTZC deemed scores.

HMO bedsit premises

In September 2021, an alternative methodology application was approved for a new scoring method for measures installed in bedsit premises within ECO3. The guidance note sets out the requirements for using the scoring method.