[SUSTAINABILITY IN PRACTICE] An early and constant focus on sustainability was central to Hawkins\Brown’s green ambitions for the Wharves Deptford, says Hattie Hartman
More from: Nine of London's new housing zones announced
Masterplans are, by definition, prone to change. Long-time horizons and unforeseen circumstances make for complex staging, and later phases must adapt, chameleon-like, to new conditions. As energy and water use play an increasing role in planning applications, project teams are looking at new ways to ensure that what is specified at the outset will be delivered when the final plot is built out.
The Wharves Deptford project in Lewisham, south London, shows just how complex this process can be. In 2006, Hawkins\Brown was asked by City & Provincial Properties to transform a 4.5ha brownfield stretch of under-used warehouses in Deptford into a mixed-use community of 905 homes. ‘This is a commercially driven project but the developer is interested in doing what is right,’ explains Phil Armitage, partner at Max Fordham, services, sustainability and noise consultant on the scheme.
Convincing a client to take on a sustainability consultant from the outset of the project is often an obstacle
The sustainability agenda was boosted by the fact that City & Provincial was a repeat client working with same design team. Project architect Katie Tomkinson acknowledges that the approach to the project was a ‘significant departure’ from the practice’s normal working method. Convincing a client to take on a sustainability consultant from the outset of the project is often an obstacle. Armitage says: ‘The key is not to be presented with a scheme, which must then be serviced.’
Placemaking is the project’s main driver. A series of public spaces knit the site to the grain of the surrounding blocks, and a linear water feature has been reinstated at the centre of the scheme along the buried trace of the Grand Surrey canal. After placemaking, environmental factors have informed the orientation, height and spacing of the blocks. The performance specification of the building fabric combined with extensive use of renewables aims for Level 4 of the Code for Sustainable Homes and the 20 per cent on-site renewables target in mayor Boris Johnson’s London Plan. While these parameters may not seem pioneering today, they were first set in 2007.
Spacing and the height of blocks were constantly refined to ensure adequate daylight levels in ground-floor flats; there are no single-aspect, north-facing units. Likewise, roof orientation and pitch were carefully refined to maximise solar potential without sacrificing urban design objectives. Residential units have been designed to maximise natural ventilation and avoid cooling through careful use of shading. For commercial uses, where cooling is likely, absorption chillers are proposed – a more efficient but costly approach.
The water feature along the bed of the former canal doubles as a flood attenuation measure. The site uses a sustainable urban drainage strategy, combining the soft landscape and green roofs to slow water run-off.
As for renewables, the London Borough of Lewisham discourages biomass due to concerns about air quality, so ground source heat pumps and photovoltaics (PVs) combine to achieve just over 10 per cent of the mayor’s 20 per cent target. This is considered acceptable because of the carbon reduction achieved through passive measures and CCHP (combined cooling, heating and power). The bore holes for the geothermal will be shared with the structural pilings; a technique yet to take hold in the UK. Green roofs provide biodiversity on the lower buildings (meadow grass roofs 25 per cent, aggregate-based biodiverse roof 15 per cent), and PVs on the higher roofs (60 per cent of project roof area).
Connection to South East London Combined Heat and Power (SELCHP), a nearby waste-to-energy plant, is under discussion, and the energy centre was sited at the south-east corner of the site to facilitate an eventual link, which depends on coordination with nearby development sites since demand from the Wharves alone is not sufficient.
Urban and environmental design have been carefully balanced with social and economic factors
Urban and environmental design have been carefully balanced with social and economic factors. Extensive consultation with the local community included setting up a community development trust, which will include the headteacher of a local primary school and the owner of Ascott Cab, a local black cab dealership that will be relocated on to the site as part of phase one. Market research by Soundings, which worked on the Ebbsfleet redevelopment zone, compared the catchment area with Bermondsey and Camden in order to set the brief for the scheme’s non-residential uses, which include a health centre, offices and retail.
The planning application is in two parts. The more detailed part goes to RIBA Stage D and includes not only materials, and fenestration, but thermal performance and airtightness targets. To address energy use despite uncertainties in procurement, energy budgets have been specified for individual plots within the scheme and form part of the planning application for the entire site.
Sustainability-led masterplanning is a complex, iterative process. Once urban design parameters are established, a continuous process of refinement is essential to address environmental issues. One thing is certain: checklists alone cannot address complexity.
Based on a precedent in Malmö, Sweden, plot budgets provide an accountable approach for achieving a development’s sustainability goals, both as the design is developed and as individual buildings are brought into use.
While targets are established for the development as a whole by the planning process and project team aspirations, plot budgets define the end-user energy demand that each site within the development must meet in order to achieve the overall carbon emissions target for the project.
This ensures that as individual parcels are developed, sustainability objectives will be met. Targets are set for electrical use, water consumption and heat and cooling and water. Measurements for these targets are based on utility meter readings, rather than in terms of C02 emissions performance targets, which are difficult to measure in practice.
Total area 15,525m2
PVs 400m2 of roof
Rain collection 1,120m2 of roof
% of total area 87%
Heat 710 MWh
% of total area 13%
Hawkins\Brown’s green masterplan for the Wharves Deptford