DEGW is an international firm of consultants and designers, focussed on the workplace and the wider issues of urban change. The practice was established in 1973 and has, from its inception, advised both public sector and corporate clients. The practice is unique in its understanding of organisational demands and the urban and building design implications. We have a tradition of research that influences practice, beginning with the Orbit 1 study (1983) on the impact of information technology on office design. This led to a similar multi-client study in North America (1985), and was followed by a series of multi-client research programmes on the "Intelligent Building in Europe" (1991-92), Asia Pacific (1995-96), and Latin America (1998-99).

  DEGW is currently undertaking a research programme for the European Commission, SANE, with a network of partners. SANE (Sustainable Accommodation for the New Economy) is addressing many of the issues of the physical and virtual office environment and its impact on building typologies and urban form.

  DEGW was research, briefing and space planning adviser on both Stockley Park (Heathrow) and Broadgate (City of London), as well as Canary Wharf. Consultancy in Europe includes building assessment at La Defense, Paris, Babelsburg Film Studios, Berlin, and major developments in Barcelona, Milan, Copenhagen and Dublin. In the Netherlands, DEGW has advised the Dutch Ministry of Planning (VROM) on the impact of high-speed rail on urban regeneration and the redevelopment of Utrecht City Centre.

  DEGW is also involved in advising on high rise strategies for Rotterdam and Dublin, and is currently advising the GLA on the appropriateness and impact of high buildings in London. I chair a high-rise committee for Central Rotterdam on innovation and aesthetics, and an advisory panel to the City Manager on architecture and planning in Dublin.

  High rise and tall buildings are relative terms. In a city quarter of predominantly one or two storied buildings, those of three to five floors could be considered of significant height. From a construction and urban impact perspective, DEGW has identified four key heights:

—  Low-rise — up to five floors (15 metres)

—  Mid rise — up to 15 floors (50 metres) "groundscrapers"

—  High-rise — up to 40 floors (150 metres) "skyscrapers"

—  Super high-rise — above 150 metres high

  High-rise and super high-rise have a role to play in both intensifying and signposting the city. They can be effectively used in clusters to increase density dramatically and generate the sense of place. Used sparingly, they can become landmarks to navigate an increasingly complex urban landscape and provide spectacular views both for those who live in and visit the city, and whose who actually inhabit them. However, high buildings can equally be disruptive to build, inflexible to adapt, impossible to phase, inefficient in space utilisation, and costly to construct or replace; a closed system that separates inhabitants from the city below, and a source of congestion. The challenge is to find design solutions and appropriate locations that reflect the opportunities and respond to the shortcomings.

  Our research has shown that to gain significant increases in density, tall buildings should be used in clusters, the single tall building providing a significant landmark without a major impact on overall neighbourhood density.

  Evidence exists that European cities can achieve high densities within the mid-rise threshold of 50 metres (groundscrapers) by building to the perimeter of the city block with courtyards or atria within. Paris, Milan and Barcelona are highly dense cities built to this model. Broadgate in the City of London, the Grosshandelsgebouw in Rotterdam or Ake Brugge in Oslo, follow a similar pattern. However, to achieve such development requires large sites that can be planned comprehensively. Available in brown field areas (eg goods yards or port areas), but harder to achieve in existing city cores. In these cases, where there is a high level of market demand and multi-modal accessibility, but small plots, the need for greater intensification may be forced upwards (eg Heron Tower in the City of London).

  Four aspects impact on the need for urban intensification, and therefore the decision of whether to build high:

  1.  Market demand—"skyscrapers" and extreme densities tend to have been most successful and achievable in metropolitan areas with a 10 million plus hinterland and an excellent centralising public transportation network (Manhattan, Chicago, Tokyo, London)

  2.  Accessibility—multi-modal transport systems which are designed to absorb large numbers of people at peak periods of the day. Mainline stations and airports have addressed these attributes and shown themselves to be prime locations for high density, high-rise, nodes.

  3.  Site availability—to create a significant density increase the city will require large sites that can be comprehensively planned. This has tended to direct development to areas of change with large sites in single or partnership ownership.

  4.  Urban character— DEGW's study for Dublin Corporation identified a sequence of development opportunities depending on the character of an area. The spectrum of development ranged from "do nothing" and consolidate, in areas of conservation and high character value, to totally new development in brown field sites with few residents and low intrinsic value. High building developments inevitably have a significant impact on local townscape character, which needs to be considered in parallel to skyline aesthetic impact in cities.

  Approaches to comprehensive development in the past have invariably failed. The underlying conflict is that development to meet demand and use resources effectively needs to move fast, whilst local communities, to assimilate change, need time. The past was epitomised by comprehensive plans that were also comprehensively implemented (eg the inner road systems of the 1960s). Today, we are learning the need for a clear vision that can be delivered incrementally. A vision with humility.

  High rise developments are, by definition, large scale, high profile and need to be considered on their merits. Due to their special nature and impact on the urban landscape, it is probably unwise to handle them within the day-to-day planning process. Experience from abroad suggests the following factors that may contribute to the successful implementation of a high rise planning strategy.

—  A strategic framework for the city which locates high density (and potentially high rise) areas, the positioning of landmarks, and sets guidelines for how proposed developments that counteract the established development plan would be assessed. The strategic framework should recognise that conditions, site availability, and market demand are continuously under review, and that in order to grow and flourish cities will need to respond rapidly and change.

—  A clear planning control framework for approval and implementation within the public sector

—  The preparation of area plans to direct development, working closely with landowners, the community and key stakeholders

—  3D computer modelling to assess capacity massing and bulk. These models, which may be physical (eg L'Arsenal Architectural Centre, Paris) or electronic (ones exist for Bath and Glasgow), should be publicly available and centrally managed.

—  Iterative planning review process, where landowners, developers and the municipality agree the brief (ambitions and expectations), review development options, and establish an outline planning concept before giving permission for detailed plans.

—  Recognition that community interests for major sites is often national, regional or city wide as well as of local interest (eg Kings Cross lands)

—  Recognition that local communities need time to assimilate change, whilst developers are looking for speedy outcomes.

  We would advocate a planning policy that recognises the need for a clear long-term vision, a firm planning framework, tempered by appropriateness, humility, and a recognition that we are designing in a world of paradox.