10-12 Downing Street, London

10downingstreetlarge10-12 Downing Street is a building complex that includes number 10 Downing Street, the locale of British Prime Ministers since 1735. It houses some 150 workers, two homes and a suite of presentation and ceremonial staterooms.

The building is undergoing a phased modernisation and refurbishment programme, which is its first since 1963. Exactly 50 years on from that last refurbishment, much of the building’s structure and services are in need of renovation, repair and replacement.

Under the programme, the 300-year-old grade 1 listed building’s display energy certificate (DEC) rating has improved from E to D since 2009, and energy use is published in real time on the Number 10 website.


  • BREEAM version: BREEAM In-Use
  • BREEAM In-Use asset and building management rating: Very Good – 4 Star Score:
    Part 1(asset): 62.12%,
    Part 2 (building management): 56.73%
  • Building size: 6631 m2 floor area


BREEAM_RecognitionSustainability in Downing Street is largely driven by government-wide targets for improvement. The Prime Minister’s Office has a working group, comprising key service delivery managers and stakeholders across the organisation. The group’s focus is on strategic issues and its remit includes facilities management, projects, sustainability, health and safety and the No.10 garden.

The BREEAM assessment was helpful in highlighting areas that require further attention and the group is currently developing a strategy to improve ecology and biodiversity in the building’s garden and surrounds.

A ‘Very Good’ BREEAM rating was an original target for the building’s modernisation programme, throughout which sustainability has been a key consideration. BREEAM In-Use was seen as an independent and impartial measure of progress, the building having previously been assessed as Part 1 (asset) ‘Good’ and Part 2 (building management) ‘Good’ in 2010. A detailed case study is to be published by BRE detailing how the improvements made had positively affected the BREEAM In-Use rating.


Under the modernisation, repair and renovation of the building and its infrastructure, initiatives introduced have included the following:

  • controlled lighting using motion detection and low energy lamps
  • voltage optimisation and power factor correction equipment
  • replacement condensing boilers and compact heat exchangers
  • waste heat recovery from IT equipment to heat hot water
  • thermal insulation
  • low water use fittings to replace existing fixtures
  • rainwater harvesting for garden irrigation
  • building management system with utility monitoring (real time use displayed on the No 10 website)
  • timber sourced from legal and sustainable sources
  • more than 90% of construction waste recycled.


The development’s top scoring categories included:

Part 1 – Waste (100%), Transport (100%), Materials (88.9%)

Part 2 – Water (100%), Management (89.3%).


  • Client: The Cabinet Office
  • Principal contractor and facilities management provider: ETDE
  • BREEAM In-Use auditor Kiruthiga Balson


‘It was important for Downing Street to have an independent and impartial assessment of the success of the environmental and sustainable initiatives undertaken, and their effectiveness in reducing energy consumption and cost. The assessment has mapped our progress so far and highlighted areas for future focus in our drive for continuous improvement.’