After you have completed an implementation, you may calculate the energy savings and corresponding energy savings certificates (ESCs) that result from the implementation. This involves the following two step process:

Step 1: Calculate your energy savings from your implementation using the relevant equation for the calculation method

Your Accreditation Notice sets out which calculation method you are permitted to use, and any conditions which apply to the use of that calculation method. You must ensure that you:

  • use the correct energy savings equation for your method (check the ESS Rule to determine which equation to use)
  • meet all the requirements of the ESS Rule for using that calculation method
  • comply with your conditions of accreditation (these are mainly set out in the Accreditation Notice but may also include conditions advised in writing by the Scheme Administrator).

Further information on each calculation method is set out in the relevant Method Guide.

Step 2: Convert the energy savings for an implementation to ESCs

Once you have calculated the energy savings, you can determine the number of ESCs that can be created by applying Equation 1 of the ESS Rule. Equation 1 converts savings to ESCs by applying the relevant certificate conversion factor to the savings. Note for electricity savings you must also apply the regional network factor.

This image shows ESS rule equation 1, as described in the above paragraph

Important things to know:

  • Certificate conversion factors are specific to each type of eligible fuel and are set out in clause 33 of the Electricity Supply Act 1995 and clause 37A of the Electricity Supply (General) Regulation 2014 (Note the certificate conversion factor for Gas has changed – see the TESSA Latest Info page for details).
  • The number of ESCs you create must be rounded down to the nearest ESC. However, when you register certificates, you may apply the rounding to the sum of the savings from one or more implementations so you only apply the rounding once.
  • While you may calculate the number of ESCs yourself, this step is performed automatically by TESSA using the energy savings for each implementation (as calculated in Step 1). From 14 April 2023, TESSA will also apply the regional network factor to electricity savings to calculate the number of ESCs from an implementation in accordance with Equation 1. For more information, see Registering certificates.