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Case Study
20 Fenchurch Street 

Visiting one of London's most iconic buildings, also known as "The Walkie-Talkie," on its Green Team Meeting day was a truly insightful experience. It was exciting to see property managers, tenants, and businesses all in one place, sharing their energy-saving wins through the Go Dark Project and other green efforts.

March 2022 - February 2023

Location: London


1 year achievements

2nd Place



Energy savings

13,425,498 kWh

largest gross savings

£ 2,272,298


Building characteristics


100,284 m2

total area 



Construction completed


37 floors

(plus three-story "sky garden")


Electricity supply (100% Renewable energy), Roof-mounted PV, BMS, HVAC, DHW system (Domestic Hot Water)

Building Systems


422 bicycles, 19 motorcycles parking spaces 


Ocupational density

1 person per 10m2

BREEAM Excellent (80.2%),


Top actions

Management and behaviour

  • Conducted green team meetings to boost awareness and discuss the sustainability agend​a

  • GWS Tenant and Simmtronic specialists conducted assessments and maintenance to enable energy adjustments on individual floors​

Minor technical and re-programming

  • Initiated Project “ Go Dark”– (Switching off lights from 11pm to 5am), saved 785,000 kWh in July and August compared to 2019​

  • Adjusted and reset the lighting dimmer by 40% in the lobby area and switched off exterior lights.​

  • Started LED Lighting replacement programme by conducting a lighting review of the emergency staircase, B1, B2, and back of house (replaced approx. 1,140 Lights)​

  • Implemented boiler switch off procedure which switches off the boiler when the external temperature exceeds 28 °C​

  • Adjusted BMS setpoints in the building to control and manage the energy consumption of the building better ​

  • Implemented Cooling tower variable set points procedure by using outside wet bulb temperature proxy to achieve maximum efficiency during summer


Don't just take it from us

What Savills say

Savills logo.png
"We were extremely excited to participate in the CUBE Competition. Gamification provided an added incentive to participate competitively on the very important issue of energy conservation. We were proud to be the highest gross saver across the whole competition, and to have showcased our innovation and hard graft in making savings. Our occupiers and landlord were equally as proud of 20 Fenchurch Street’s collaborative achievement."

- Sean Harlow, Head of Engineering at 20 Fenchurch Street, Savills

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