Transport Infrastructure Ireland’s (TII) Biodiversity Metric Tool was released in December 2025. The release of an Irish metric marks an important shift towards assessing and accounting for biodiversity losses and gains on major infrastructural projects in Ireland. Our Ecology team has experience advising on minimising loss, enhancing existing features, and maximising biodiversity both on and off-site, from the design to post construction stages of a project. Previously, the team has used the Uisce Eireann’s metric, and the DEFRA (Department for Environment, Food and Rural Affairs) metric, which is statutory in England, to calculate any losses or gains in biodiversity. The TII Metric is similar to the DEFRA metric but specifically designed for Ireland and uses Irish habitat classifications and has certain other adaptations for the Irish environment.
Use of the TII Metric is required on all new TII road, greenway and light rail projects. It is not currently mandatory for non-TII projects, but where DEFRA or other Metrics are currently being used on a voluntary basis, this new guidance may provide an Ireland specific alternative.
Since the release of the TII metric, our Biodiversity Net Gain (BNG) specialists have been busy reviewing the associated Technical Report, and the User Guide and are looking forward to testing the new metric on relevant projects. The metric has recently been published, and we anticipate that there will be challenges associated with its application and likely revisions necessary to ensure it achieves its aims. However, having an Irish metric to quantify biodiversity and to account for losses and gains is a step in the right direction. Without such a mechanism, there is no clarity and/or consistency in measuring changes.
MKO notes the intention for this Metric to be used in association with, and in addition to, the environmental and ecological assessments that currently exist (EcIA and EIA). It will be used as an accounting mechanism, rather than the sole method of ecological assessment. The use of a biodiversity metric can be of value to project proponents in that it provides clear and quantifiable measurement of any gains that are achieved as a result of mitigation or enhancement measures applied.
MKO welcomes the new TII Biodiversity Metric and also welcomes the actions in the TII Biodiversity Plan including: ‘Strive to achieve a net gain for biodiversity on all new projects by 2030’ and ‘Establish the biodiversity baseline of the entire TII network using the biodiversity accounting metric’. If this new Irish Metric is found to be effective (through trial, error and revision if necessary), and if it is used in conjunction with the continued requirement for ecological assessment (EcIA and EIA), it has great potential to facilitate BNG as defined by CIEEM (Chartered Institute of Ecology and Environmental Management) in its briefing paper on Biodiversity Net Gain in Ireland (2024) ‘as designing developments in a manner that leaves biodiversity in a better state than before. This is achieved by avoiding impacts on ecological features of high value, minimising unavoidable impacts, enhancing the value of existing features, and providing new ecological features that were not previously present.‘