Merton London climate rule

Posted on March, 01 2012

Climate mitigation by Merton Rule

Climate mitigation by Merton Rule

London borough Merton established a climate-change mitigation rule that all new buildings reduce CO2 emissions a minimum of 10% through the use of renewable energies. The strategy, now widely known as the Merton Rule, has led to investments in small renewable energy sources and energy-efficiency in buildings. It is so successful that it has been copied by around half of local authorities in the UK.

Keywords: climate change, mitigation, Merton Rule, renewable energy, buildings

Carbon emissions are an important component of the ecological footprint. In 1997, the Kyoto Protocol was established as the first major international agreement aimed at lowering GHG emissions. To decrease the emissions various combinations of policy instruments and technologies have been used by nations, communities, and businesses. Some have not been so successful, while others have made real progress in lowering emissions. A good example of a successful approach is the Merton Rule.

In 2003, the London borough of Merton proved itself to be a leading community for responsible action on climate change. It did so through an innovative rule: all new buildings were required to have a minimum 10% reduction of CO2 emissions via use of renewable energy (see also Barcelona, Berlin and Seattle). While a 10% reduction of CO2 emissions is far below what is required for climate-change mitigation, the design of the mitigation strategy is potentially very important.

Fines for failing to comply
Compliance is required as part of the planning consent process with the municipality. Failure of a building developer to meet the 10% reduction target leads to a fine. The 10% reduction is measured by comparing a Merton Rule building’s CO2 emissions to what they would have been if no renewable energy technology had been used.

In order to know how much CO2 a building would be responsible for if not using renewable energy, the Building Research Establishment has created Energy Use Benchmarking Guides. These guides were created by measuring the energy consumption per sq m of a normal building, then converting that energy measurement to carbon emissions for the whole building. To create a comprehensive guide, this has been done for several different types of buildings (e.g. buildings with spacious floor plans, buildings with many small rooms). The Merton Council uses a sophisticated real-time energy monitoring system to ensure that CO2 reduction targets are being met by all new buildings.

Success rule widely copied
One important outcome of this policy is that developers in Merton have enhanced the renewable energies market by investing in small wind turbines, ground source heat pumps, biomass heating, solar water heaters, and photovoltaic technologies.

The Merton Rule not only encourages the use of renewable energy sources. It also encourages the construction of energy-efficient buildings. This is because a building that requires less energy overall, will also need less renewable energy in order to reach the 10% reduction target. So the more energy-efficient a building is, the less money a developer will have to spend on technology to supply renewable energy. This is leading developers in Merton to design solutions to maximize the energy-efficiency of buildings. It also means that Merton Rule buildings have a smaller ecological footprint than their conventional counterparts.

The Merton Rule has been so successful that it has been adopted, in one form or another, by around half of local authorities in the UK. The British government has stated that it expects all planning authorities to put in place policies similar to the Merton Rule.

International Energy Agency (IEA) and Organisation for Economic Co-operation and Development (OECD), 2009, Cities, towns & renewable energy: yes in my front yard, Paris: OECD/IEA

Peter Newman, Timothy Beatley, Heather Boyer, Resilient cities: responding to peak oil and climate change, Washington, DC: Island Press, 2009

Merton Council,

Text by: Aaron Thomas

Merton, London
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Map Merton
Merton, London
© Jim Linwood