RETROFIT | 1 FINSBURY AVENUE The new tenant roof terraces The building has retained its distinctive faade Fortunately, the building had been pointcloud surveyed at the outset, making it easier to accurately coordinate the new with the existing services and structure. Having a point cloud scan was really important. It gave us a really good 3D model to work from to ensure we could maintain the clear height on the office floor, explains Beaven. Smart controls The services on the refurbished floors also include Internet of Things gateways on each BEFORE system to provide smart control. Beaven says that, as far as Arup is aware, it is the first existing building, as opposed to it being a new building built from scratch, that has been made smart. He says the control is there for current and future tenants to manage lighting and comfort conditions, if they want it. Fresh air to the offices is supplied predominantly from the two existing roof-mounted VAV AHUs above the buildings south core. These have been refurbished and heat recovery systems added. The units now run at a reduced capacity. The old VAV system [supplied fresh air and office cooling] on a recirculation basis, so it was pushing a lot of air around the space, says Pearce. Switching to FCUs and a fresh air-only system enabled us to reduce the volume of supply air. In addition to the two existing AHUs, fresh air is supplied from a new 19m3s-1 AHU located above the north core. This unit replaces the two giant VAV AHUs that have had to be removed to create access to the new tenant roof terraces. Moving to a FCU enabled the architects to provide lifts and stair access to the roof level for the two roof terraces, says Pearce. It was not easy: We spent an awful lot of blood, sweat and tears routing pipework to create the roof terraces, because there were an awful lot of services running between the two services cores, Beaven adds. Chilled water to the AHUs is supplied from the existing cooling towers and basement chillers. The cooling towers had new impellers, AFTER 28 July 2021 www.cibsejournal.com CIBSE July 21 pp26-30 1 Finsbury Avenue.indd 28 25/06/2021 16:24