Decarbonising Southwark District Heating Plantrooms


The Mayor of London’s Energy Efficiency Fund, managed by Amber Fund Management Limited, has provided £7 million to the London Borough of Southwark to support a highly innovative project to provide low carbon heat to over two thousand homes in the borough by drawing heat from the London Chalk Aquifer using water source heat pumps.

The heat pumps improve local air quality by replacing the existing gas boilers, which used to emit harmful NOx and particulate matter.

Southwark had commissioned a feasibility study of five of its district heating estates by CalfordSeaden with specialist input provided by ICAX on the hydrogeological assessment side. As a result of the feasibility, two sites were discounted leaving three estates that were deemed technically and financially viable for decarbonisation – Consort, Newington and Wyndham.

All main contractors on Lot 3 of the Southwark Major Works Framework were invited to attend an information day and site visit which included background information on the projects and the chance to see aquifer based water source heat pumps in action at the Balanced Energy Network at London South Bank University.

Water source heat pumps have been installed in Southwark to three community housing estates – serving 2,175 homes – to provide base load heating in place of the gas boilers which were previously used. The gas boilers have been retained in case they are needed to provide resilience on the coldest days of the winter.

The ICAX heat pumps were designed to provide a high temperature flow to the building so that the existing heat distribution systems did not need to be refurbished. This saved time and avoided disruption so that the retrofit could proceed with no disturbance to the people living in the buildings.

Carbon Emissions Intensity

ICAX Heat Pumps installed in Southwark plant rooms

These 600kW heat pumps, like all other heat pumps, emit no carbon dioxide on site. Because heat pumps avoid the need for combustion they also issue no nitrogen dioxide, nor sulfur dioxide or any other gas or particulate matter in Southwark.

Heat pumps use electricity which may be generated from renewable electricity or from fossil fuel sources. The CO2 released at power stations is sometimes attributed to use of electricity for heating to imply that use of heat pumps is not entirely low carbon heating. However, the electricity generated for the National Grid has a dramatically reduced carbon factor now that coal fired generation is largely phased out and wind generated electricity is making an increased contribution.

The electricity supplied to the heat pumps in Southwark can take advantage of Demand Side Management algorithms to match the use of electricity to times of excess supply where this can be achieved without compromising the heating or cooling requirements in the building.

ICAX Heat Pump Southwark

The Electrification of Heat

The electrification of heat opens up opportunities not only to balance the national grid, but also to use demand side response techniques at the local level to balance local energy supply and demand.

The heart of the network is the efficient use of renewable energy based on the recycling of heat drawn up from the London aquifer to heat buildings on the community network in winter.

Heat pumps are used to transfer heat to buildings in winter instead of generating heat afresh when needed by burning fossil fuels. ICAX has developed heat pumps which can deliver high temperatures so that they can be used at the heart of the community heating system to deliver heat to buildings on a Fourth Generation District Heating Network.

Balancing the supply and demand for heat through the seasons is mirrored by balancing the supply and demand for electric power by shifting some of the demand from times of peak consumption (by day) to times of excess supply (by night).

The Energy Trilemma

Energy Trilemma

The London Borough of Southwark is accepting the challenge from government to address the Energy Policy Trilemma:

  • by using heat networks
  • by using heat transfer instead of combustion
  • by accelerating the electrification of heat
  • and by employing "demand response" to focus on using off-peak electricity and reduce peak electric demand.

Demand Response

Demand side response can be used to shift the timing of electric demand from hours of peak demand to times of surplus supply. DSR requires a bi-directional energy grid to signal when prices are low to trigger additional use (and to signal when prices are high to inhibit use).

Urban Air Quality

Southwark is also addressing the growing problem of air pollution: the water source heat pumps will provide heating without employing combustion or releasing any gasses on site.

Balanced Energy Network

The water source heat pumps installed in Southwark follow on from the successful Balanced Energy Network installed at the London Southbank University. Like the award winning BEN project, the Southwark Housing project:

  • is a retrofit installation
  • is designed by ICAX
  • draws heat from the London Chalk Aquifer
  • uses high temperature heat pumps from ICAX
  • is in the London Borough of Southwark


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Ground Source Heat Pump Association