Opening the Rochdale Envelope

Opening the Rochdale Envelope

Immersed in the world of offshore wind a decade or so ago I came across a mysterious concept, that of the Rochdale Envelope. My colleagues seemed to view it as important and I knew I needed to know more, particularly about the implications it may have for my projects; so here is what I learned.

The Rochdale Envelope stems from an actual planning application in that town where the developer worked alongside planners to provide adequate detail to allow an informed decision, whilst leaving enough design flexibility to allow the scheme to remain responsive to new developments and opportunities.

The Rochdale Envelope has since become codified in the Planning Inspectorate guidance underpinning offshore developments and has rapidly become the norm in the UK and beyond as countries around the world look to learn from the UK offshore wind experience

From the developer’s perspective being ‘flexible’ has great benefits, especially when scoping the Environmental Impact Assessment to capture all likely significant effects. Turbines are twice as large as a decade ago and more powerful machines still are lined up to follow. This rapid advance means specifying dimensions such as tip height in advance can backfire as new and better machines emerge; it can stifle innovation, adversely affect project economics and ultimately increase the cost of electricity to the consumer.

Developers nearly always ‘scenario map’ major projects; traditionally using best, worst and middle case scenarios to apply the various factors to the project model. Project parameters may include turbine size, electrical infrastructure, cabling and so on. ‘Rochdale’ took this further and integrated the changing nature of wind farm design into account.   

Organisations generally aim to develop projects responsibly; designing them around known issues such as migrating birds and sea mammals. By also paying close attention to stakeholder comments and concerns, allowing them to guide the project, objections can be removed and mitigated allowing the scheme to evolve.  Of course, manifold stakeholders on an offshore project, which may cover hundreds of square miles of seabed, seldom agree on what may or may not be a ‘best case’ and compromises need to be made. The industry tries to be collaborative; the introduction of design ‘chills’ and design ‘freezes’ gives stakeholders the opportunity to make meaningful contributions at crucial points in the project’s development: stakeholder engagement is clearly governing the design and development of UK offshore wind.

Rochdale envelope activities carried out by the developer are time consuming and resource intensive. Stakeholders may also find it hard to review differing versions of the same project before making an informed response

The Rochdale envelope is a proven and useful device for enabling shifting project parameters to be assessed and agreed prior to submission of planning applications. Where issues are encountered, the early and agreed drafting of binding planning conditions are tailored to the project and agreed by the various parties. Results indicate the process to be effective and one of the reasons the UK offshore industry is flourishing and acknowledged as an energy sector and UK economy leader.


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