ECO4 Supplier Data Dictionary
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This document provides information to assist suppliers in completing the ECO4 notification templates for projects and measures. It contains a description of every field on the templates, the acceptable data that may be entered in those fields and the circumstances under which this data should be included. Suppliers should only use the most recent version of the dictionary and templates.
The project and measure notification templates are also available on this page.
A list of changes in each version of the dictionary document is found in the summary of updates published below
Main document
[ECO4 Supplier Data Dictionary v2.0 [PDF, 381.81KB]
](https://www.ofgem.gov.uk/sites/default/files/2025-08/ECO4-Supplier-Data-Dictionary-v2.0.pdf)
Subsidiary documents
[Project notification template v1.1 [CSV, 875.00B]
](https://www.ofgem.gov.uk/sites/default/files/2023-05/Project%20notification%20template%20V1.1.csv)
[Measure notification template v1.1 [CSV, 490.00B]
](https://www.ofgem.gov.uk/sites/default/files/2023-05/Measure%20notification%20template%20V1.1.csv)
[Summary of Updates to ECO4 Supplier Data Dictionary v2.0 [PDF, 111.04KB]