How to build the 15-minute city

Of all arguments in defence of the 45-storey Waterfront South Central plan for Dublin’s North Wall Quay, the statement that the “meaningful height” of this proposal might be part of the solution to our housing crisis is perhaps the most contrived.

This is followed by those which claim the “hyper-density” of this and other high-rise schemes in the planning pipeline is necessary – whether in terms of combating sprawl, curtailing congestion, supporting architectural innovation or marketing Dublin as a modern and forward-looking capital.

The 2018 Urban Development and Building Height Guidelines are the latest attempt by the Government to increase the density of Ireland’s towns and cities. This ambition has been ingrained in national policy since at least the start of this century when the 1999 Residential Density Guidelines were incorporated into the 2002 National Spatial Strategy’s objective to “renew, consolidate and develop our cities, towns and villages, keeping them compact and minimising urban sprawl”.

It is not the historic core of Dublin that is particularly in need of increased densities

Yet in the decade from 2000 to 2009, at least 60 per cent of the 630,000 total completions were one-off, detached or semi-detached houses – by any standard an abysmal failure to achieve a key policy objective.

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While the height guidelines correctly require that arbitrary, and often politically motivated, height restrictions be removed from statutory development plans, they unfortunately perpetuate the myth that “our cities and towns must grow upwards, and not just outwards, if we are to meet the many challenges ahead”, as former minister for housing and planning Eoghan Murphy stated in his foreword.

In directing that increased heights be “actively pursued” in town and city cores, while the densities for greenfield and edge-of-centre development would remain at the levels in the 2009 guidelines, Murphy’s specific planning policy requirements open the floodgates for Dublin to continue down the path of the typical US metropolitan area: a high-density, high-rise and high-value downtown surrounded by low-density housing, shopping, schools, offices and suchlike. This is the most unsustainable form of urban development.

Intensity of suburbs

With a population projected to grow by over 400,000 in the decades ahead, Dublin needs to increase its 37pph density to at least 65pph, if not the European average of 78 people per hectare. This is if it is to achieve the compact urban form that is the goal of the National Planning Framework, as well as the city’s development plans and those of its satellite local authorities.

However, it is not the historic core that is particularly in need of increased densities. It is in the edge-of-centre suburbs that intensification is required; especially in light of Dublin’s inadequate public transport infrastructure and international evidence that the combination of higher densities and the concentration of facilities in city centres actually increases rather than reduces car use and congestion.

In Superdensity: The Sequel, four architectural practices at the forefront of UK housing design have come together to produce an update of their 2007 Superdensity report. This is in response to widespread concerns that London is “sleep-walking into hyper-dense development without proper regard for the long-term consequences”.

The Ireland 2040 National Planning Framework seeks to increase the nation's residential densities through a range of measures, including greater building heights

Questioning the need for the rash of tower proposals the city is subjected to, the report recommends mid-rise development as the preferred solution to London’s housing shortage. It includes case studies which illustrate that it is possible to create successful places – and densities of 150-300 dwellings per hectare (dph) – with street-based architecture and a diversity of housing types (including family homes) at heights that do not exceed five to eight storeys, save for some “carefully integrated” taller structures.

In a presentation to Dublin City Council’s Maximising the City’s Potential conference in 2008, I summarised research which indicated that the built form of Dublin’s Georgian streets and mews lanes could deliver densities in the order of 165 dwellings per hectare. Similarly, in Making Higher Densities Work, the UK’s Commission for Architecture and the Built Environment think tank pointed out that the average density of London’s Islington is 185dph – which is also no taller than the historic cores of Dublin, Cork and Limerick.

Compact city

The alternative to the 874dph (9:1 plot ratio) hyper-density of the Waterfront South Central plan, and other high-rise schemes in the planning system, would envisage Dublin being developed along the lines of the “compact city” that national and local policy aspires to: a conurbation of mixed-use neighbourhoods that are well-designed, walkable, affordable, well-connected, socially diverse and environmentally efficient, and which provide a high level of amenity for their residents.

Essentially, this is the “15-minute city” that is being promoted by Paris, Milan and other cities today. It is based on neighbourhoods with populations in excess of the 25,000 that is thought to be the threshold for the viability of local shopping, schools, leisure facilities and public transport – and all within a 15-minute, or 1,250m, walk from one’s home.

The Ireland 2040 National Planning Framework seeks to increase the nation’s residential densities through a range of measures, including greater building heights. Whereas buildings that exceed the “shoulder heights” of their receiving environments will be appropriate wherever densities are too low, or when it might be desirable to create an architectural “landmark”, the densities required for compact development – as has been indicated above – can generally be achieved with mid-rise development, and without unduly increased heights.

A Trojan horse in the cause of developer-led planning, the Waterfront South Central plan is of little relevance to resolving the key planning challenges of our time: how do we curtail the suburbanisation that has blighted Ireland’s cities, towns and rural places; and how do we combine compact development and higher densities in the development of neighbourhoods where people will want to live, work, attend school, play and visit ?

In the free-for-all created by the Building Height Guidelines directive that “increased building heights are to be actively pursued”, and that “numerical limitations on building heights” are prohibited, it falls to An Bord Pleanála to apply the most robust criteria in determining if applications such as Waterfront South Central will deliver the “highest standards of urban design, architectural quality and placemaking” referred to in the guidelines.

Paul Keogh is a former president of the Royal Institute of Architects of Ireland