The Merton Rule affects major development projects

The 'Merton Rule' is the ground breaking planning policy, pioneered by the London Borough of Merton, which requires the use of on site renewable energy to reduce CO2 emissions in the built environment. Most local authorities have followed Merton's lead, which now affects planning permission for all new major development projects throughout the UK.

The Merton Rule was developed and adopted in 2003. Its impact was so great that most councils in England have now implemented it, it has become part of national planning guidance and led to the Zero Carbon Buildings policy.

Merton Council has been working closely with other authorities, professions and industry to embed the Merton Rule. This work is not only leading to big CO2 reductions, but it is helping to create an industry that can respond to the needs for affordable renewable energy.

The Merton Rule is a prescriptive planning policy that requires new developments to generate at least 10% of their energy needs from on-site renewable energy equipment. The most commonly accepted threshold is 10 homes or 1,000 m2 of non-residential development. This is the accepted definition by local (and regional) planning authorities, academic institutions, trade and professional bodies, and the development, construction and engineering industries.

The Merton Rule covers sustainable energy for all buildings – Not just homes

The Merton Council website states that: "Very importantly, the Merton Rule encompasses all buildings and not just homes. As the huge number of planned houses gets built they will be accompanied by new schools, supermarkets, shopping, malls, office blocks, leisure centres, etc, and it is essential that these heavy energy users also play their part in contributing to the Government's renewable energy and climate change strategies and targets."

Towards Zero Carbon - providing sustainable energy

Following the publication of Planning Policy Statement 22 (PPS22), Planning Guidance on Renewable Energy, the London Borough of Merton was the first to formalise the government’s renewable energy targets in its adopted UDP, setting the target for the use of on site renewable energy to reduce annual CO2 emissions for all new major developments in the borough by 10%.

The first project to comply with the Merton Rule – ten light industrial units – was completed in June 2005 at Willow Lane, Mitcham, using micro turbines and solar photovoltaic panels to meet the requirement.

Croydon were quick to follow Merton's lead, and their first project designed to reach a '10% target' was completed in July 2005.

North Devon chose to demand 15% CO2 reduction from renewables and Kirklees Council have proposed that by 2011, 30% of energy consumption in every one of its new buildings will have to be from renewable sources. This is a trend that has drawn increasing interest from local authorities across the UK. Councillor Andrew Cooper, Kirklees Council cabinet member for housing and property, said: "We are effectively setting our own version of the building regulations for renewable energy in Kirklees and this will impact on every residential home, every children's centre and every school we build. This policy ensures a new high standard for buildings in the future and that future is green".

Mr Cooper also mentioned that Kirklees Council took into account the expected increases in the price of gas and oil and with new buildings needing to last for at least 50 years, renewable energy will save costs in the long-term.

Planning and Renewable Energy

Over 325 of the 390 local authorities in England have followed a Merton Rule by adopting pro-renewables planning policies within Unitary Development Plans (UDP) or Supplementary Planning Documents.

In 2008, the government published its central planning guidance Planning Policy Statement – Planning and Climate Change – PPS1 that requires all UK local planning authorities to adopt a "Merton Rule" policy.

Adrian Hewitt – the man responsible for making the Merton Rule a mainstream mantra in planning policy – has moved on from Merton Council. His thinking has also moved on from the need to require developers to incorporate renewable energy to the need for post occupation evaluations and the need to monitor the energy performance of buildings in use.

What are the renewable energy options?

With this background all developers need to consider their options for on site Renewable Energy. The merits of different renewable energy technologies will tend to vary with the location and intended use of each building.

ICAX is able to offer a high carbon offset by using Interseasonal Heat Transfer which links the most successful renewable technologies – solar thermal heat collection is summer and ground source heat pumps to extract heat in winter – with Seasonal Thermal Storage in the form of a ThermalBank.

The ICAX integration of Interseasonal Heat Transfer has been widely recognised, and IHT was chosen by Merton Council itself for its new Acacia Intergenerational Centre: ICAX provides sustainable energy to Merton Council.

Code for Sustainable Homes has been influenced by The Merton Rule

The government’s Code for Sustainable Homes plans to require all new residential developments to be zero carbon by 2016 (where the net CO2 emissions resulting from ALL energy used in the dwelling are zero or better). The code is more stringent than the Merton Rule, so it is likely to supersede it in the residential sector.

The Carbon Reduction Commitment (CRC) is a proposed mandatory cap and trade scheme in the UK that will apply to large non energy-intensive organisations in the public and private sectors. The scheme is currently under consultation and is expected to start in April 2010.

Energy Performance Certificates (EPCs) are now required whenever a building is built, sold or rented. The certificate provides ratings from 'A' (the most energy efficient) to 'G' (the least). The average up to now has been 'D'.

Criticism of The Merton Rule

The London Borough of Merton was the first local authority in the UK to include a policy in its Unitary Development Plan requiring ‘all new non-residential development above a threshold of 1,000m2 to incorporate renewable energy production equipment to provide at least 10% of predicted energy requirements’.

There was initial opposition to the policy from Government Office London and the Office of the Deputy Prime Minister (ODPM) over concerns about its legalities under the Town and Country Planning Act and enforcement of renewables through Building Regulations. Merton formed an alliance with environmental and other organisations to explain the benefits of the Merton Rule and was instrumental in persuading the Government to confirm in Planning Policy Statement 22, both the legality of such policies, and its desire to see other boroughs emulate them.

Some have criticised The Merton Rule for its focus on introduction of a Renewable Energy requirement and have suggested a change of emphasis towards higher insulation standards and lower energy consumption would be a more cost effective way to reduce carbon emissions.

Others have highlighted the "Liability problem": Developers are reluctant to invest larger capital sums on renewable energy when the revenue benefit (of lower annual running costs) goes to the occupiers of buildings after completion.

Cost Effective Renewable Energy

It has been generally accepted that renewable energy technologies should be adopted in spite of the additional costs involved. Interseasonal Heat Transfer is the advent of cost effective renewable energy.

The spirit of The Merton Rule

The spirit of The Merton Rule lives on in recent government legislation in the form of the Renewable Heat Incentive which provides a clean energy cashback to generators of Renewable Heat and the Feed-In Tariffs which provide cashbacks for on-site generation of green electricity.


See also: The Carbon Reduction Commitment (CRC) which is a mandatory cap and trade scheme that applies to large UK organisations from April 2010 in the public and private sectors.

See also: Energy Performance Certificates (EPC) which are required whenever a building is built, sold or rented. The certificate provides 'A' to 'G' ratings for the building, with 'A' being the most energy efficient. The current average rating is 'D'. This is part of the Energy Performance of Buildings Directive, which all EU member states must adopt.

See also Sustainable energy.

See also Renewable Heat Incentive