Updated IEMA guidance: What's changed and how it impacts development

As the spotlight intensifies on sustainable development, the updated Institute of Environmental Management & Assessment (IEMA) guidance: Assessing Greenhouse Gas Emissions (GHG) and Evaluating their Significance gives some much-needed clarity to developers looking to determine the effects of their project on climate and the benefits of mitigation.

Our climate change specialist and proud co-author of the new guidance, Tom Dearing, shares his thoughts and breaks down the updated guidance to summarise some of the key points.


What's changed?

A new edition of the leading guidance document for assessing greenhouse gas emissions in Environmental Impact Assessment has been published. The main changes are:

  • a new scale for significant and non-significant effects, based on a development’s GHG performance relative to a net zero and 1.5°C aligned reduction trajectory;
  • a greater focus on up-front mitigation, which can differentiate development projects with significant or non-significant effects.

IEMA’s guidance was first published in 2017 and has been widely followed as good practice for this area of EIA. It firmly established the principle that GHG emissions are cumulatively significant, with assessing and mitigating them being a core part of EIA for development projects.

A challenge has been differentiating the significance of emissions between projects and drawing Environmental Statement conclusions that decision-makers can apply consistently. This guidance update is timely, tackling the challenge with a net zero aligned methodology.


How important is the timing of the GHG guidance update?

A lot has changed since 2017. The UK has adopted a net zero target, COP26 in Glasgow brought renewed public attention to leadership in this area and the IPCC’s emerging Sixth Assessment Report underscores again the severe consequences of not staying within a rapidly diminishing global carbon budget.

In this context, the sustainability of development projects comes under close planning, legal and public scrutiny. GHG mitigation and the EIA process must be robust and draw clear, evidence-based conclusions.

It can be hard to distinguish the significance of emissions between developments of different types and scales. A projects impact might be small on a national scale but cumulatively could undermine the UK’s net zero goal. Methodological clarity on how to assess and communicate this, in a way that embeds a proportionate level of mitigation, is needed now more than ever.

Green trees next to commercial building - sustainable building

Can a clear approach be created?

Methods for calculating GHG emissions are well established. But one of the biggest current challenges has been finding the best way to create a clear methodology that acknowledges the importance of every tonne of CO2 emitted while usefully communicating to developers and decision-makers the impact of different developments with different levels of performance.

The new guidance offers a more detailed, descriptive scale that aligns more closely with EIA practice. The significance of different levels of COemissions will be described from: beneficial, to negligible, minor, moderate, and major adverse effects.

Each description relates to the rate of emission reduction needed to achieve an applicable trajectory towards net-zero, whether at a sectoral or economy-wide level. And in turn, this helps support our contribution to stay within a 1.5-degree compatible global carbon budget.

What is the overall goal of the update?

To encourage good design and support emissions mitigation. And by doing this, having an assessment practice in place that can reward good development performance by bringing that clearly to a decision-maker’s attention.

Who does the guidance help?

It’s aimed at the needs of decision-makers and developers, those who will apply this guidance on a project. It’s also hugely beneficial to our own needs, as the people writing environmental service chapters, for methodological clarity.

What is the whole-life carbon assessment, and does the guidance cover it?

Whole Life-Cycle Carbon (WLC) emissions are the carbon emissions resulting from the materials, construction and the use of a building over its entire life, including its demolition and disposal.

A WLC assessment provides a true picture of a building’s carbon impact on the environment, and the new guidance covers this. It calculates whether it can reach a conclusion about the net lifetime effects of developments and where operational benefits may compensate for some of the construction stage impacts.

And why this is so vital for the future?

"It’s a simple breakdown: to be able to shape developments in a way that reduces or avoids GHG emissions is absolutely paramount. And to communicate the outcomes of this through EIA in a clear, concise way that high-quality development can be differentiated and supported through is crucial".


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