The Ideas Architect: Strata SE1 / BFLS

Architects: BFLS
Location: London, England
Structural/M & E Engineer: WSP Group
Acoustic Consultant: Acoustic Logic Consultancy
Environmental Advisor: URS Corporation Ltd
Construction Advisor: Brookfield Construction UK
Client: Brookfield Europe
Landscape Architect: Townshend Landscape Architects
Wind Engineer: RWDI‐Anemos Ltd
Wind Turbines: Norwin AS
Project Area: 306,000 sqm
Budget: £113.5m
Project Year: 2007-2010
Photographs: Will Pryce, James Brittain, Edmund Sumner, BFLS

elevations

Strata SE1 is a 148 metre high 43‐storey residential tower that forms a dynamic new addition to the London skyline. The first building in the world with integral wind turbines, it also sets a new benchmark in terms of environmental strategy.

The client’s brief challenged the design team not only to develop a high‐rise residential concept that would kick start the Elephant & Castle regeneration but also to wholly embrace energy efficiency, targeting an EcoHomes assessment rating of “excellent”.

The site was already identified for a tall building by the local authority as part of the Elephant & Castle SPG. The design is very specific to the scheme, its location and addresses considerations at both local and at wider city scale and context.

With 408 apartments, Strata SE1 will be home to more than 1,000 residents. It offers a mix of market (310) and intermediate housing (98) in the form of shared‐equity affordable dwellings to satisfy direct local housing needs. 20 of the 98 affordable homes are reserved exclusively for residents relocated from the nearby Heygate Estate.

The project team worked closely with client Brookfield and engineers WSP to refine the original scheme in terms of the core in relation to common spaces, with the use of post‐tension slabs further reducing slab thickness, enabling greater floor‐to‐floor heights, and to eventually develop a high‐ performance, three‐layer, aluminium‐and‐glass façade. The façade’s sculpted effect and range of glazing shapes allow a wide variety of views from the light‐filled apartments and help break up Strata’s overall sense of mass.

typical floor plan

Environmentally, the adoption of 200mm thick post‐tensioned concrete floor slabs and high strength blade columns saved over 2000m3 of concrete and 1800 tonnes of CO2. This CO2 reduction is the equivalent of emissions from energy that the apartments will use over four years.

The language created by the façade adds a strong sense of hierarchy to the architectural order of this residential building. Hence, the overall form can enjoy a clearly articulated base, middle and top zone. At the base of the building, outer layers have been peeled back to reveal glazing and create transparency for the retail and entrance to the building. At the top of the building, a similar approach has been taken to reveal a crystalline apex; a top and side‐lit sky lobby provides access to the upper‐level apartments.

The main entrance looks towards the core regeneration area and the City and is signified by a 37‐ storey slot carved in the northern tip of the tower extending all the way down to ground level. This entrance is prominent and set back from the main pedestrian thoroughfare adjacent to Walworth Road, enhancing the sense of arrival. The double‐height lobby beyond allows for a gradual reduction in scale from outside to inside, further bridging the transition from public to private space.

The central bank of three lifts faces the entrance, providing a clear and unambiguous means of accessing the upper levels and on reaching the residential levels, the lift lobby is at the heart of the building. There are no dark corridors on the residential levels and each flat is accessed via short entrance halls off the main lobby to individual front doors.

structural diagram

The final configuration enlarged and defined a series of linked pedestrian friendly spaces at ground floor level, each with its own unique character, providing much‐needed permeability across the site. The orientation, scale, slenderness, articulation of its top and grain of its distinctive cladding are designed to both make their mark on the London skyline as well as create a strong sense of human scale that engages the public when viewed from close‐up.

The sustainability strategy created for Strata SE1 is to reduce the residential development’s total energy consumption through a combination of low energy design, integrated renewable energy generation and future allowances for connection to the planned E&C MUSCo (Multi Utility Services Company) district system, which will provide heat and electricity from Biomass CHP energy centres, grey water to all toilets for all affordable units within Strata SE1 and a connection to the site‐wide fibre network for high speed data access to all residents.

Various low energy features incorporated into the Strata SE1 include bespoke high performing facade with an air permeability leakage rate that is 50% better than current building regulations; vertical district heating system utilising high efficiency, low NOx boilers; low energy lighting in all landlord areas and 40% of the lighting in each apartment.

In addition, the three nine‐metre‐diameter wind turbines will provide effective on‐site renewable energy generation, which will feed directly into the landlords system and further reduce overall energy consumption to the building. The three turbines are rated at 19kW each and are anticipated to produce at least 50Mega Watt hours of electricity per annum or 8% of Strata SE1’s total estimated total energy consumption.

The concept of integrating technology was embraced throughout the design and construction stages. The use of sprinklers within all apartments, for example, enabled the omission of the standard fire‐ protected lobbies, creating more attractive, open living spaces. A further advantage was gained by the use of whole house ventilation systems with heat recovery, which reduced the size of radiators, allowing for more flexible space planning and improving the acoustic performance of the apartments, a challenge posed by the dense urban environment in which the building sits.

Finally, 96% of all waste material was also recycled during the construction stage.

Given that this was to be the first major scheme to come forward as part of the wider Elephant & Castle regeneration, the form and expression needed to be bold so that Strata SE1 could be a landmark in its own right, as well as be a catalyst for the ongoing regeneration of the area, which will in time feature a planned cluster of tall buildings.