Hopkins’ WWF-UK headquarters is not only an outstanding energy-efficient design, it achieved a remarkable 42 per cent cut in embodied carbon after Stage C, writes Hattie Hartman. Photography by Morley von Sternberg
The branding power of an environmental charity locating its BREEAM Outstanding headquarters over a brownfield car park is irresistible. I first encountered WWF-UK’s new headquarters when I glimpsed a model of it in Hopkins Architects’ office in 2010. So it was with long-abated curiosity that I set off to Woking recently to attend the press launch. A PV canopy over the front of Woking rail station reminded me that the town is known for its pioneering sustainable energy strategy. Its district heating system is one of the UK’s earliest.
Hopkins Architects was commissioned in 2007, before the environmental charity had located a site for for what was to become its new headquarters building. Woking Borough Council proffered the site, a surface car park surrounded by undistinguished 1980s housing estates separated by a main road and the Basingstoke Canal from the town centre. A planning condition stipulated that the car park be retained. Woking’s green credentials, along with the seven-minute walk from the station, which is just 27 minutes from Waterloo, were attractive to WWF-UK.
A short walk through Woking’s pedestrianised town centre leads to Jubilee Square and on past the library, where the wind cowls atop the roof of WWF-UK’s Living Planet Centre appear in the distance - BedZed come of age.
Navigating the road crossing and a purpose-built bridge over the canal built by the town, one reaches a landscaped plaza at the building’s entrance. A vaulted timber canopy, an extrusion of the 92m-long arched glulam diagrid structure, welcomes visitors. The dexterity of the design becomes apparent as soon as one steps inside the light-filled, arched interior of the 3600m2 building. It’s like stepping into a gigantic treehouse. The advantage of being one floor up - necessitated by building over the car park - is that the tree canopy is at eye-level. Hopkins senior partner Mike Taylor explains that windows were carefully located to capture the best views and screen out the less desirable ones. Landscape architect Grant Associates worked hard to plant the podium with an eclectic mix of bamboo, in keeping with WWF’s panda logo, and many native species.
The office space is organised in long bays on either side of a central atrium, a distant cousin of the Wellcome Trust’s Gibbs Building and Evelina Children’s Hospital. Double doors on either side open onto 5m-deep balconies, which at the far end near the kitchen and café include areas for allotments tended by the staff. Very green indeed.
The brief for the office space was developed with Alexi Marmot Associates (AMA), which assisted the client with the move of its staff of 300 from its previous premises, a cellular 1960s building in Godalming. Surveys revealed that only 40 per cent of desks were occupied daily, increasing to 60 per cent at peak times.
AMA developed three occupancy scenarios for the new building with varying degrees of hot desking. An underlying premise - and an important future-proofing strategy - was that the design should meet BCO guidelines. WWF-UK opted for maximum hot desking, which allows for 200 work stations, with an additional 30 spaces for sub-letting. Because people like to ‘belong’, team zones are retained, but staff are free to work anywhere in the building or remotely.
Extensive breakout spaces in the atrium and in peripheral areas which open onto the balconies are designed to handle occasional peak capacity. In his daylit, open-plan shed, everything is visible. Hopkins was also involved in furniture selection, with splendid results. The green booths in the atrium were popular on the day I visited.
The Living Planet Centre descends from a lineage of Hopkins buildings that includes Yale University’s Kroon Hall (AJ 27.05.10) and the London 2012 Olympic Velodrome (AJ monograph, September 2011).Taylor terms the assimilation of sustainability into an architectural aesthetic as ‘progressive modernism’. It implies both an honest expression of materials and an unflinching duty of care to do more with less. Here the materials are FSC-certified timber, galvanised steel and a zinc roof with high recycled content.
Environmental design consultant Atelier Ten has engineered a building with a daylit, fabric-first approach. The intention is to ventilate naturally for up to eight months of the year. The central atrium with its four bespoke roof cowls (closed in winter) of recycled aluminium facilitate a stack effect in the deep-plan (37m x 92m) building. Discreet red lights located above the balcony doors switch on when the building is mechanically ventilated, so that staff can easily determine when doors and windows can be left open.
A suite of proven technologies form part of the mostly invisible kit which comprises the building’s sustainability strategy. Six 100m-long earth ducts and a ground source heat pump made up of 20 100m-deep boreholes lie buried beneath the car park. PVs integrated into the rooflights are predicted to power about 20 per cent of the load from lighting, fans, and pumps.
The biggest win of all comes from connection to Woking’s district heating system. Thermal mass has been incorporated into the lightweight roof structure by bonding phase change material to the backside of the birch veneer plywood panels in the roof soffit to slow the building’s climatic response time.
So far, so good. WWF-UK’s Living Planet Centre is just what one would expect when an aspirational environmental charity meets an experienced and committed green design team. Yet what is most innovative in this building is completely invisible and didn’t cost a penny. Through a comprehensive carbon-tracking procedure led by Sturgis Carbon Profilng (SCP), the embodied carbon of more than 1,700 building components was measured. Brought in by the project manager at Stage C, SCP, together with contractor Willmott Dixon, delivered a remarkable 42 per cent reduction in the embodied carbon of the building at completion (from a Stage C baseline) with no additional cost. This target was a contractual obligation.
These dramatic savings challenge the received wisdom that the biggest sustainable design wins are made at concept stage. Although it is essential to get orientation, massing and glazing right through good passive design, the achievements at the Living Planet Centre demonstrate that, if sustainability is championed throughout design and construction, considerable further gains can be made. Every change order had a cost and a carbon metric against it. ‘Cost and carbon usually go together,’ observes SCP founder Simon Sturgis.
This rigorous approach had countless outcomes: substitution of double-glazed windows for triple-glazing in certain locations, use of natural polymer glue in place of synthetic glue in the glulam beams (to reduce CO₂e), 98 per cent recycled reinforcement in the concrete (market standard is 60 per cent).
Hopkins associate partner Steven Clarke smiles as he refers to SCP as ‘the carbon police’, but he is quick to note that ‘we would certainly work with them again. They bring an extra level of interrogation to the process aiding both costs and sustainability’.
WWF-UK’s Living Planet Centre is an exemplar building which treads lightly on the planet. The real test will be whether - with a flexible working culture which enables remote working - staff will make the journey to work there. My bet is they will.