The refit at the UK-GBC's office in London's Building Centre provided an opportunity to implement practical, eco-friendly measures to create a greener working environment for their staff, as well as creating a more energy efficient building. The very large single glazed windows at the UK-GBC's offices were a major source of heat loss and, as the building is Listed, replacement windows or double glazing were not an available option. The organisation therefore consulted Selectaglaze with a brief to reduce heat flow through the glass and eliminate draughts at the windows. The 3m high windows were treated with a combination of Series 10 and Series 80 horizontal sliding secondary units set to match the window sightlines and glazed with single panes of toughened low emissivity glass. The U-value of the original windows was 6.5 and calculations show this has reduced significantly to 1.8. Following completion of the refit the building achieved a BREEAM score of 73.75% which translates into an interim design stage BREEAM rating of Excellent.