Case Study

Enfield

Kensa alongside ENGIE delivered England’s largest shared ground loop array heat pump system.
  • LocationEnfield
  • Completion DateFeb 2020
  • 2019 District Heating Project of the Year (H&V News Awards)
  • 2020 Best Tall Building Retrofit or Refurbished Project (Tall Buildings Conference & Awards)
  • Over 400 flats over 8 x 12 storey tower blocks
  • Tenants' bills are reducing from an average £800 per year to an average £350
  • Estimated 773tCO2 saved
  • Featured in the Mayors of London’s Climate Action Week programme 2019
  • 100 boreholes ranging from 197-227m deep across 2 sites
  • Replacing electrically powered underfloor heating

Kensa and ENGIE delivered England’s largest shared ground loop array heat pump programme replacing electric heating in Enfield Council tower blocks, all in under one year, with tenants remaining in their flats.

Eight tower blocks with a total of 400 flats in the London borough of Enfield had their inefficient electric underfloor heating replaced with What is a Ground Source Heat Pump?Ground Source Heat Pumpsground source heat pumps. Each flat received an ultra-quiet Kensa ShoeboxProductShoebox heat pump along with a hot water cylinder. The heat pumps were connected to district heating in the form of 16 shared ground loop arrays serving the 8 tower blocks.

The award-winning district heating scheme saw a total of 100 boreholes drilled, ranging from 197-227m deep across the 2 sites. The boreholes were connected to the tower blocks via underground header pipes and riser pipework running through the stairwells providing a source of heat to 402 flats.

The tower blocks were previously heated by electrically powered underfloor heating which was powered directly from Enfield Council’s landlord supply. Tenants previously had no control over their heating which meant that they often had to open windows to try and control the temperature. With no metering provision tenants had to pay a fixed monthly fee to cover their heating regardless of how much heat they required. Therefore many tenants were pushed into fuel poverty with typical annual heat costs of £800-£1,100 per flat. This led Enfield Council to have major concerns about the health and wellbeing of their tenants.

Enfield Council comments:

This is an eco-friendly system that has enabled residents to save between £450-700 a year in heating costs at a time when household budgets are being squeezed. This project is good for residents and good for Enfield.

The latest readings suggest the flats are using less overall energy for heating and hot water than calculated. Electric consumption shows that heating bills are in the region of £200-£250, with the highest still only coming in at £450/year for a top-floor flat.

Dr. Matthew Trewhella, Director at Kensa, comments:

One of the great strengths of this system type is its flexibility and scalability. Shared ground loop systems can be featured in developments of just two properties (micro-district) whilst this project clearly demonstrates how the concept can be scaled up to much larger systems.

Simon Lacey, Regional Managing Director for ENGIE’s Places & Communities division, comments:

One of the key reasons this project has been a resounding success is that all parties have a shared vision which centres on improving lives, and we have worked collaboratively to achieve this goal for the residents of Enfield. We’re delighted to have been recognised for taking a proactive approach in tackling fuel poverty and hope to replicate this model across the country, so more people can live in sustainable homes without breaking the bank.

Benefits to tenants:

  • Each flat received the ultra-quiet Kensa Shoebox ground source heat pump and a hot water cylinder.
  • Warmth and flexibility was restored as tenants now have control over their own heating and hot water.
  • As the heat pumps were connected to each flats own electrical supply, tenants now only pay for the heat they actually use via their electricity bills.
  • Heating and hot water costs for each tenant has reduced to £350-400 per year due to the high efficiency of the heat pump (300%)
  • Projected heating and hot water cost savings are £400-700 per year for each flat (30-50% savings), but recent readings suggest bills of £200-£250
  • Equating to £9 million in collective lifetime bill savings over the nominal 40 year system lifetime.
  • Allowing many to no longer live in fuel poverty as tenants health and wellbeing is improved by being able to heat their flat properly
  • Minimised running costs and maximised comfort

Benefits for the client:

  • With the added upfront investment from the ECO grant, Enfield Council are set to recover the capital costs for delivering the heating solution
  • Excellent value for money that no other heating technology can compete with and allows Enfield Council to sustainably re-invest into further energy-saving projects.
  • The properties EPC ratings have improved by 8 points on average

Benefits to society:

  • Heating replacement will save 773tCO₂ per year. This may increase even more as the electrical grid decarbonises.
  • Ground source heat pumps are non-combustion devices which is a great advantage to London’s air quality improvement campaign.

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