Birchfield Estate

Location: London

Area: 3,900 sqm

Competition: NLA New Ideas for Housing 2015

Status: Shortlisted 

 

‘Better than New’ is the idea that the supply of housing in London can be increase by retrofitting and extending existing post-war social housing stock. Through an assessment of their functional obsolescence an economy of cost and resource can be made in delivering new housing that allows local communities to grow. The idea is illustrated using a case study of post-war masionette arranged social housing blocks in Tower Hamlets. 

 
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The major public investment, social optimism and increased living standards of the post-war estates were undermined by the faults in community cohesion they created. The transition from houses to temporary housing to social housing blocks following slum clearance broke up communities and was the root of the social entropy the estates experience through to the 1990’s.

The maisonette typology can be seen as in part obsolete from its inception as the units were a compromise of tenant ambition for houses. But obsolescence in buildings rarely occurs suddenly, it is normally an incrementally lose of value as a function of changes in standards, market effects, new technologies and a plethora of less tangible factors such as taste and fashion. Through the lens of social housing in London the appearance of obsolescence is distorted by the issue of demand, due to the established lack of supply. In this case the criteria of demand is replaced with the criteria of affordability. This highlights the need for economy of cost when delivering new housing to maintain social rents (as opposed to ‘affordable rents’). Other criteria that contribute toward obsolescence in the maisonette typology are outdated space standards, accessibility standards, energy efficiency and the performance of a number of building elements including the exposed reinforced concrete frames and the presence of asbestos. 

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Though not exclusive, physical deterioration plays a part in obsolescence. Deterioration of a number of the building elements of the masionette typology is occurring as a product of materials and techniques used in their construction, principally the failure of galvanized wall ties used in the construction of external walls and the deterioration of the concrete cover. 

When a building reaches a critical state of obsolesces it can either be replaced (demolition/reconstruction) with a more up-to-date version or a more critical assessment of the building elements state of functional obsolescence made for retrofitting. “Functional obsolescence is the inability of an improvement to perform the job for which it is designed” (Wofford, 1983)[3]. This assessment of the building elements in the maisonette typology reveals the latent capacity of the structural frame to be retrofit. This is the opportunity the idea exploits at a building scale. 

[3] Baum, A., (1991). Property Investment Depreciation and Obsolescence. London: Routledge.

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A socially sustainable community through development means the minimum of displacement, transformation of the public realm and composition of communities. By maintaining the urban arrangement we prevent the disconnection between communities and their surroundings, avoiding the problems faced in the original creation of the estates. The extensions to the buildings can occur predominately with residents in situ and will provide units to expand existing communities. The idea is delivered through Community Land Trusts (CLT) setup for each estate. The CLT vehicle is best positioned to deliver the idea that is essentially improvements to the current housing stock. The community involvement would give an opportunity to maintain engagement in the estate through the disruption of development.

 

The images provided show the idea scaled from a single building, to an estate, to a borough wide proposal. The case study delivers 900 Sq.m new floor area at Pennyfields, 3,000 Sq.m on the Birchfield Estate and an estimated 120,000 Sq.m across the borough. There is also scope to extend and adapt the strategic approach to different housing typologies including post-war high-rise pre-cast clad housing and point blocks.


 

 


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The idea’s case study application is on the Borough of Tower Hamlets. This location was chosen due to its extensive post-war social housing estates, with a particular focus on Poplar. Poplar is significant in the context of post-war social housing due to the landmark construction of Lansbury Estate as part of the Festival of Britain’s ‘Exhibition of Live Architecture’. Post-war 1950-60’s developments in the area are predominantly a mixture of flats and maisonettes. The maisonette typology in particular is prevalent, as it provided a compromise between tenant’s ambition for a house and the borough’s need to build flats. Four-storey and six-storey blocks of maisonettes one above another are the most characteristic feature of post-war social housing estates in the area[1]. This typology is used as a case study for the application of ‘Better than New’; the specific building chosen for illustration is Pennyfields on the Birchfield Estate. The maisonette typology is either constructed with a reinforced concrete frame or in combination with load bearing masonry and with brick outer leaf, blockwork inner leaf external walls. The units on upper floors are gallery accessed, arranged in a skip-stop fashion and served only by communal stairs.

[1] 'Public Housing in Poplar: The 1940s to the early 1990s', in Survey of London: Volumes 43 and 44, Poplar, Blackwall and Isle of Dogs, ed. Hermione Hobhouse (London, 1994)

 
“Building obsolescence can be interpreted as ‘a property in its existing form being unable to support the contemporary functional demands of occupation’ and may also occur ‘as the result of a decline in a demand for the building’s original use” Wurtzbach and Miles (1984)

“Building obsolescence can be interpreted as ‘a property in its existing form being unable to support the contemporary functional demands of occupation’ and may also occur ‘as the result of a decline in a demand for the building’s original use” Wurtzbach and Miles (1984)

The idea is to utilize the remaining building fabric not suffering from obsolesces to retrofit and extend the typology. By removing the heavy masonry cladding and replacing it with lightweight, thermally performing construction we can amplify the latent capacity of the existing structures and provide additional storeys to the buildings. Buildings of this typology would be identified, stripped of their masonry cladding then retrofit and extended to provide additional housing units. Prefabricated, lightweight materials with high thermal values are used to usurp the liberated structural capacity and create additional storeys. The existing and new storeys of the building are clad in structural insulated panels (SIPs) with an external face of lightweight rainscreen cladding. The new upper levels are formed structurally from cross-laminated timber panels working as load bearing walls and transfer beams. The external openings are enlarged to provide additional day lighting into the units and lift cores are added to provide disabled access to the upper floors. With the additional density there are new community spaces inserted into the cores and ground floor of each building.

 

The issue of sustainable development both socially and environmentally is fundamental in the delivery of new housing for London. Often this is only examined through the energy efficiency of new buildings. A boarder view should be taken then delivering new development with consideration of the embodied energy within the existing building stock. The economy of energy and cost from such a retrofitting approach is exemplified by the Bois le Pretre, Paris (2011) project by architects Frederic Druot and Lacaton de Vassell. The retrofitting and horizontal extension of the existing housing block met current environmental standards and provided a cost saving of £8.8 mil pounds versus proposals for demolition/reconstruction[4].

[4] (2011)Habitat Paris: Annual Report 2011. Paris: Habitat Paris. 45

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