On 13 November 2008, the Planning and Energy Act 2008 received Royal Assent. The Act enshrines the 'Merton rule' in law and should not be confused with the Planning Act and Energy Act which have both also recently received Royal Assent.


The Merton Rule (launched in 2003 through Merton Council's Unitary Development Plan) set out that 10% of the energy used in new, non-residential developments above a threshold of 1,000sqm must come from on-site renewables, such as wind turbines or solar panels. It also gave local planning authorities the power to include reasonable policies requiring development in their areas to comply with energy efficiency standards that are more stringent than those under the energy requirements of Building Regulations. 

Since its introduction, around 20 local authorities have implemented the rule and over 150 local authorities are in the process of adopting it. It was hoped that the policy would be extended to residential properties and become incorporated more broadly. However, developments last year temporarily weakened the Rule.

'Planning Policy Statement 22' published in 2004 lent support to the Merton Rule. However, the 2007 policy statement, Planning Policy Statement: Planning and Climate Change - Supplement to Planning Policy Statement 1 did not incorporate the targets. There was no longer a requirement that either a certain proportion of energy must come from low-carbon or renewable sources or that the energy production be on-site. Instead, planning authorities were encouraged to 'provide a framework that promotes…renewable and low-carbon energy generation'.


The Act changes the position. Introduced to Parliament on 5 December 2007 as a Private member's Bill, the Act gives local planning authorities in England and Wales the power (not a duty) to include, in their development plan documents, policies that impose reasonable requirements regarding the proportion of on-site and near-site renewable energy and other low carbon energy that must be used in developments.

The Act does not specify the proportion of renewable or low carbon energy to be required but commentators expect it to be around 10 - 15%.


The Act may have implications for developers, who have in the past expressed concern about the Merton rule. However, it should be noted that the requirements and policies that the local authorities have the power to impose under the Act must be 'reasonable'. No guidance as to what may be reasonable is given, although section 1(5) states that policies implemented under the Act must not be inconsistent with relevant national policies.