sustainable urban regeneration- a case study in london

SUSTAINABLE URBAN REGENERATION- A CASE STUDY IN LONDON

Adam RITCHIE BSc CPhys MInstP 1 Randall THOMAS PhD EurIng CEng FCIBSE FconsE MASHRAE2

1 Max Fordham LLP, 42- 43 Gloucester Crescent, London, NW1 7PE, UK, [email protected] 2 Max Fordham LLP, 42- 43 Gloucester Crescent, London, NW1 7PE, UK, [email protected] Keywords: urban, regeneration, london, renewable, development, planning, density, energy

Summary The city of London is actively pursuing the reduction of energy consumption and the supply of energy from renewable sources through the development of sustainable planning frameworks and policies for both new development and urban regeneration. This paper outlines a methodology for environmental sustainability in the city. It draws principally on the planning context and the pre-planning design process for the redevelopment of a 1.2 hectare (ha) site with existing buildings, located in the London Borough of Lambeth. The outcome was a set of proposals that responded both to traditional urban design considerations and new ones resulting from energy considerations. Associated issues are that any initial target should be seen as simply one point in the evolution of a development. Lifetime goals for buildings should be introduced, potentially via an energy master plan, into the design and planning processes. Planning law needs to protect the ambient energy sources from being compromised by future development or a compensatory mechanism developed to maintain or improve overall sustainability. Finally, it should be possible to propose alternatives to a general policy; carbon emission trading for example. The paper concludes with an analysis of the key strategic and design decisions that informed the planning of the development and generated the sustainability strategy.

1. Context By the end of the twenty first century it is thought that 75% of the world’s population will live in urban areas. The same percentage of Europeans is expected to live in urban areas as early as 2020. We face the considerable challenge of developing and enlarging our cities in the light of a growing body of scientific evidence that climate change, caused predominantly by an ‘unsustainable’ rate of CO2 emissions, will significantly affect the way we live. Following the adoption and ratification of the Kyoto Protocol aimed at tackling climate change, the UK has committed to a reduction in CO2 emissions of 12.5 percent of 1990 levels by the year 2012. In 1995, the UK was responsible for 2.2% of global CO2 emissions which, per capita, is twice that of the world average (ODPM, 2004a). Despite its relatively small geographical size the UK has a responsibility to lead the way in demonstrating ways of de-coupling the relationship between industrialised, developed lifestyles and increasing CO2 emissions.

1.1 The London context Greater London is the largest and most populated city in the European Union (circa 7.4 million people, about 12% of the UK total) (ONS, 2001) and is classified as a ‘World City’. London, situated in South East England, is observed by Richard Rogers as ‘a commuter belt 200 miles wide’ (Rogers, 1997). Estimates put the population of this whole area at one third of the total UK population (Audley, 2005) and it is expected to grow further, with London the epicentre, through a massive sustainable development programme during the next ten years. Buildings in London account for approximately 73 % of delivered energy use (GLA, 2004). A significant proportion of the remainder, some 21%, is attributed to transport which could reasonably be considered as travel between buildings. Both the physical and spatial planning of the city therefore has a significant role to play in reducing energy use and the control of development through the planning system is seen as one of the key regulatory instruments to address climate change as a result.

The 2005 World Sustainable Building Conference,Tokyo, 27-29 September 2005 (SB05Tokyo)

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1.1.1 The regulatory context. Through the hierarchical structure of national planning statements, regional strategies and local frameworks the English government has set out sustainable development as the core principle underpinning the planning system (ODPM, 2004b) In London, the Greater London Authority is the strategic regional authority and, through the Mayor of London, sets out strategy aimed at improving London (GLA, 2005). The London boroughs who provide local planning services, take these strategies into account when developing their Local Development Framework which sets out the planning policies governing the way that development occurs in the borough.

1.2 The Regeneration Context As a result of neglect, poor management, inadequate public services, lack of investment and a culture of short-termism, parts of the country have been deprived of the opportunity to maximise their potential. Nowhere is this more true than parts of the major cities and towns in the UK. One such area is Stockwell in the London Borough of Lambeth where our site is located.

2. Regeneration in practice

2.1 The Site In 2004 City and Provincial, a London based development company, purchased 1.2 hectares (ha) of previously developed industrial land with buildings known as 15 Stockwell Green in the London Borough of Lambeth. Within the curtilage of the site lie buildings previously constructed as a bottling works for a brewery. Over the last two hundred years, the site has evolved from a rural village in the mid 18th Century to a local brewery in 1870 and finally an archival store today. In many ways the site is already a real example of evolution and regeneration in the city. As shown in Figure 1, the site is located within a five minute walk to the closest major underground transport node and several over ground bus routes. Figure 1 The wider context of the site in London (site at centre of shaded circle which represents a 12

minute walking distance). Courtesy of Hawkins\Brown Architects.


2.2 The Brief The client’s brief for the site calls for a sustainable, mixed use development consisting of private and affordable housing types (affordable housing encompasses both low cost market and subsidised housing available to people who cannot afford to rent or buy houses on the open market (DETR,1998)), home/office space, commercial and community premises. This mix of uses is an attempt to regenerate the area by providing residential, employment and social opportunities in one location and to stimulate the local economy by providing some balance to the residential typology of the local area, thus reinforcing the sense of community. The residential dwellings are predominantly flats with a low parking provision; less than 1 car park space per dwelling. In a central urban setting this suggests higher development densities between 650 – 1100 habitable rooms per hectare (Hr/ha) (or 240 – 400 dwelling units per hectare (U/ha)) are necessary in order to maximise the potential of this key site. Such densities which use land efficiently are now actively promoted and encouraged by the borough particularly where there is good public transport accessibility. (LB Lambeth, 2004)

2.3 The Design Process The design process typifies the modern approach which, greatly aided by an enlightened client, brings together at the very inception of the scheme, the collective skills of a professional team to consider and develop the brief in a coordinated and holistic manner. A successful project is no longer the sole preserve of the designers; the team comprises planning, sustainability, public relations, marketing and community liaison consultants all of whom provide a valuable contribution to the wide range of issues that need to be tackled. The first step in the briefing process is to understand the planning context of the site and its environs. The more novel and unusual aspect of this scheme is that, alongside the usual planning issues of urban grain and density, the team also explore the sustainability issues with respect to planning policy and how this will effect the brief.

2.4 Local Planning Policy The Local Development Framework for the area identifies 15 Stockwell Green as a preferred site for redevelopment and sets out certain developmental requirements, for example that some employment be retained on the site and a significant number of affordable dwellings be provided. Of particular relevance to the sustainability brief, the Framework also requires that ‘all major developments (above a threshold of 1000 m2 or 10 dwellings) are required to incorporate equipment for renewable power generation so as to provide at least 10% of the predicted energy requirements.’ and similarly that ‘All development proposals should show, by means of a Sustainability Assessment, how they incorporate sustainable design and construction principles.’ (LB Lambeth, 2004)

2.5 Site Constraints From historical records it is possible to see how the site boundary and the buildings within it have evolved over time to respond to the changing local conditions. This is an important lesson in looking within and without the site boundary when considering regeneration proposals and studying the impact of the development on people outside the site such a neighbours, employees and visitors.

2.5.1 Existing buildings The architectural history of the existing buildings reveals purpose designed structures for use as a bottling store (Industrial Architecture, 1964). Generous (3.5 m) floor-to-ceiling heights and a structural frame designed to withstand large static loads (0.5m thick concrete slabs) provide a satisfactory volume within which to adapt space for commercial uses. The retention of some of the existing buildings is also a significant move in terms of financial economy and reduced environmental impact on the local and wider community. This can be quantified by a reduction in demolition activities, less transport of waste through the city and less land fill volume in the region. Although now a physical constraint on the site layout (See Figure 2), the existing building is a clear link with the historical use of the site and this is considered a strong marketing tool for the developer.

2.5.2 Rights to light Building at higher densities and greater height can often reduce the daylight availability both within the confines of the site and to neighbouring buildings . In this latter case, UK common law confers a right to light to 'anyone who has had uninterrupted use of something over someone else's land for 20 years without consent, openly and without threat, and without interruption of more than a year.' (RICS, 2005) In this respect, neighbouring property has a right to object to, or seek compensation from, buildings that can be shown to reduce light levels beyond an accepted level. To address this issue a detailed survey is carried


out to assess the current situation and against which new proposals can be tested. The principle of extending the right to light to protect renewable energy sources is discussed later.

2.6 Design with Energy – An Energy Master Plan The process of large scale regeneration and development invariably happens over a number of years during which time some change is inevitable. We live in an uncertain climate and the history of the site is again a pertinent reminder of the impact of time on a place. In London there are many fine examples of places which have been adapted over time – function following form in some respects. Urban design is said to be a matter of working in three dimensions and time is often described at the ‘fourth dimension’ where any plan must be able to accommodate continuous change. From an energy perspective it is important to consider how energy supply and demand on the site will change over time. With few exceptions, there is a general consensus that currently it is both difficult and prohibitively expensive to make net zero energy developments but that this may change in the future. Within the limits of reasonable predictability, one can try to set this path of change out in an energy master plan that forms an agreed framework for the future. In the current carbon fuel economy, the energy used by the site can be directly related to CO2 emissions. There is a certain clarity in using CO2 emissions as a proxy for energy use as this allows the energy source and its associated carbon intensity to change without affecting the master plan. It also serves to keep the reduction in CO2, and not energy per se, as the principle initiative. Environmentally speaking, the site must move towards reducing its CO2 emissions and the first stage of the plan is to make those carbon reductions at the outset which it would be difficult to ‘retrofit’ later. The initial design must then attempt to easily accommodate subsequent stages of the plan such as the adoption of higher efficiency and lower carbon technologies as they emerge and become cost effective. A CO2 methodology is also consistent with governmental proposals that the overall energy performance of buildings should be related to CO2 emissions. The performance of a dwelling, for example, must be determined through a Standard Assessment Procedure which is an agreed national methodology for calculating target and actual CO2 emissions. The master plan therefore defines an approach to reducing carbon emissions through a series of ‘lifetime goals’ which defines a collaborative strategy between low-energy and renewable energy architecture. Importantly this also brings with it an ongoing management requirement that cannot be avoided and must be factored into the development proposal.

2.7 Low Energy Architecture The initial goal is to reduce energy demand as far as possible and up to a point, this can be done at very much lower cost than by providing energy from renewable sources. At the appropriate time, the smaller demand can then be easily and more cheaply met with renewable energy. Energy demand is usually a function of space use and occupant behaviour and a mixed use development requires individual targets for each type of use. In order to establish a preliminary sense of scale, initial targets are taken from good practice benchmarks and are illustrated in Table 1; the overall energy for residential and non/residential purposes being approximately equal in this particular case.

Table 1 Target Energy Benchmarks

Use Floor Area (m2)

Electrical Demand(kWh m-2 yr-1)

Heating & Hot Water Demand(kWh m-2 yr-1)

Benchmark Reference

Bar/Restaurant 424 650 1100 DOE, 1995a

Daycare Centre 334 20 126 BRECSU, 1998

Retail (supermarket) 467 915 200 Bond, 1999

Offices 6839 54 79 BRECSU, 2000

Private Residential 14692 10 90 Thomas, 2003

Affordable Residential 4949 10 90 Thomas, 2003

Affordable Work/Live 3581 10 90 Thomas, 2003

This case study goes on to analyse the planning implications of incorporating strategies to achieve the benchmark targets for the residential scheme.


Figure 2 Site plan and proposed massing (Existing retained building shown in bold). Courtesy of

Hawkins\Brown Architects.

2.7.1 Lighting Daylight is one of the most important factors in environmental design of buildings; it improves visual quality; reduces artificial lighting energy use during daylight hours and contributes to space heating. Typically, houses do not require much more than 50 Lux of general illumination and given reasonable room depths, this can easily be provided naturally during the day. At night, illumination can be provided artificially with 1 Wm-2 of electrical lighting. From an environmental viewpoint there are several issues to consider when looking at daylighting in high density development. Steemers (2001) points out that increasing relative building height, which translates into increased obstruction heights, can then increase the space heating demand by up to 22% by reducing solar gains. Conversely, of course, summer cooling loads are reduced. The adopted approach therefore is one where building heights are reasonably uniform with spaces between buildings maximised within the site constraints to increase solar access.

2.7.2 Space heating The heating load for a dwelling is easily reduced through increasing thermal insulation of the envelope and reducing ventilation heat loss through uncontrolled air infiltration and heat recovery mechanical ventilation neither of which significantly affects the planning of the site. Low energy residential architecture is most commonly associated with maximising the potential for passive solar heating through glazing. The glazing is generally the poorest thermal insulator but can be greatly improved with an insulating shutter or curtain. With shutters closed at night-time during the winter, a window or rooflight can be shown to save energy through a positive balance of light energy inward versus thermal energy outward.

2.8 Renewable Energy The energy flows for a site can be likened to a metabolic process. One approach is to analyse the natural, and, hence, renewable energy flows and find ways of harnessing them. The principle problem with most renewable energy sources is that they are less ‘energy dense’ than fossil fuels and for this reason they are much more expensive and less convenient to harness in the large quantities that we need, especially in the city. However renewable energy in the city presents the considerable advantages of reduced transmission losses across distribution networks and an associated security of supply.


2.8.1 Solar energy Over the course of one year, the site will have an annual irradiation of about 950 kWh (Thomas. R, 2001) per square metre of horizontal surface. Energy from the sun can be harnessed by means of photovoltaic (PV) cells which directly generate electricity (in London, at a rate of about 100 kWh m-2 yr-1 ). Urban areas present an excellent opportunity for PV since supply and demand are geographically adjacent and the periodicity between supply and demand is reasonably well matched except for artificial lighting at night. The grain and orientation of the buildings on the site can significantly affect the output of PV by unwanted overshadowing. Given a high density of development and necessarily reduced spacing between the buildings, the preferred solution is generally for roof mounted collectors. A relatively even overall building height will tend to improve the ‘solar access’ and generating capacity and this then needs to be translated into a form that is architecturally sensible for the site. To inform the ‘solar plan’ the approximate collector areas needed for this site can be calculated from the target energy requirements in Table 1. For photovoltaics, the planning requirement of 10% renewable energy generation would require a collector area of approximately 4500m2 to generate about 450 MWh per year. This area compares favourably with a total proposed roof area of about 5000m2. 2.8.2 Wind energy The energy in the wind is similar to that from the sun at approximately 830 kWh per square metre of vertical surface. (Rayment, R. 1976) . For noise and aesthetic reasons, urban wind has tended towards smaller diameter turbines. Using buildings as masts, turbines in cities must be suited to more turbulent winds. A 2.5kW (swept area 9.6m2) might provide 1200 kWh per year. Turbines are best suited to the roofs of taller buildings where the wind speeds are greater and the turbulence less. At the densities and likely building height proposed for this site their use is less attractive. However it is worth noting that the 10% renewable energy target could be met with about 375 such turbines which can be equated, very approximately, to one per dwelling. 2.8.3 Waste energy A less obvious energy flow through the site is in the waste stream from the residential and commercial activity on the site. This promising but as yet untested urban energy source exemplifies a synthesis of sustainable ideas by combining the simultaneous problems of urban waste and renewable energy. Human waste, kitchen waste and commercial (supermarket) biodegradables mixed together with biomass can be converted into biogas by the process of anaerobic digestion. Biogas can in turn be used to fuel a combined heat and power (CHP) engine producing renewable electricity and heat on site. The planning implications are somewhat different for this technological solution and require a space allowance for the treatment and storage tanks; the infrastructure to easily collect and sort the waste; and the infrastructure to distribute the final byproduct which is rich fertiliser. This is one example where a lifetime goal may be to move from natural gas powered CHP to biogas CHP with a corresponding reduction in carbon emissions.

Figure 3 North – South section showing existing and proposed building heights. Courtesy of

Hawkins\Brown Architects.


3.0 Conclusions This paper touches on an variety of broad issues from urbanism, planning and environmental design which need to be considered at the outset of a regeneration project. The case study demonstrates the application of a simple hierarchical approach to low energy design beginning with passive strategies to maximise natural daylighting and minimise heating in order to reduce the renewable energy burden. Several options for renewable energy generation in the city are shown to be easily incorporated provided the planning of the development facilitates its incorporation. This is encouraging given the regulatory requirement for a percentage of a new development’s energy to be met from renewable sources generated on site. One can envisage however that this general policy will not be appropriate to all developments and that in some cases it should be possible to propose alternative methods for achieving similar environmental benefits. One such mechanism could be a form of carbon emissions trading at the building or company level where, in simple terms, carbon emissions below an agreed threshold attract an financial incentive; emissions above the threshold attract a financial penalty. The development of an energy strategy should be done at the outset in order to inform the brief as it will have a fundamental impact on the planning of the site. It must be set out as a master plan to allow proposals to change with time and committed management over that period is required in order to champion the ‘lifetime goals’ for carbon reduction. The right to light study highlights a potential future issue that as urban areas become more dense so the accessibility to natural ambient energy flows such as sunlight and wind from a site could be hindered and reduced. With the significant financial investment over long periods required to harness renewable energy, a means not dissimilar to rights of light needs to be developed to ensure that the overall level of sustainability is maintained or, if possible, improved. Perhaps most importantly, the discussion highlights the need for a framework which is a synthesis of social, economic and environmental considerations. Success relies on the careful consideration of local context; a detailed review of the appropriate regulations and guidance; responsible use of resource; and finally, a strong vision for a place designed for people and which embodies the sustainable principles of welcome, delight and optimism.

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Rogers, R. 1997, Cities for a Small Planet, Faber, pp112 Steemers, K. 2001, Urban Form and Building Energy, Cities for the New Millennium, Spon, London p119 Thomas, R. 2001, Photovoltaics and Architecture. Spon, London. Thomas, R. 2003, Sustainable Urban Design, An Environmental Approach. Spon, London. pp 137-146


sustainable urban regeneration- a case study in london

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