Rethinking urban density

Let’s remove the stigma of density

When it comes to density in our cities, towns and neighbourhoods, understanding and expectation vary hugely among the stakeholders, that is, the community, the local authority, and the developer. Aiming at higher built densities has become a contested matter, where diverse sensitivities are touched, lines are drawn, and a negative image around density has evolved, unnecessarily.

How can the stigma of density be revised and lifted, for the greater good of vibrant, safe, and prospering urban centres in Ireland?

Why density matters?

The built density of our urban environment affects our social life and economic performance. The very reason why we built cities and towns and why these keep growing is: to participate in social and economic activities, in the safest and most convenient manner. Building dense is economic land use, in optimised built form while reducing unnecessary land cover, use of resources, and travel distance to a minimum.

Ireland is facing increasing demand for high quality living in dwellings that are affordable, central, suitable, and diverse, when household sizes are shrinking. Ireland is also facing increasing pressure to reduce resource consumption and GHG emissions. The logical response, backed by best practice examples and policy guidance is increasing urban density, in central locations, with quality public transport access, and appropriate to existing surrounding built form and scale.

This approach includes the critical review of existing development, where density does not meet the requirements of resource efficient land use, transport infrastructure and services. Densification here would secure the performance standards of these places into the future. Successful places (Jacobs 1961) are characterised by a healthy balance of the following four spatial qualities:

• Density
• Diversity
• Distinctiveness
• Connectivity

Qualitative density vs. quantitative density

The DPH dilemma

Density in Ireland is mainly measured in DPH (dwellings per hectare). While this measure might be suited for assessing suburban land capacity and general built form (detached / semi-D / terraced), it remains one-dimensional when it comes to floor space and occupancy. 40 DPH 2-bed houses generate a very different density to 40 DPH 4-bed houses.

Number of bedrooms appears an outdated measure when it comes to smart urban development, predominantly in apartment form, to comply with sustainable development targets.

Hence, plot cover and plot ratio appear to be a much more suited measure, to calculate demand, supply and certainly building and occupation and maintenance costs. The European continent has applied this approach successfully for decades and applies it across board for the mix of use a city or town would display.

In public discourse, density is often perceived synonymous with high-rise development, yet need not be, as recent residential developments in Dublin and Cork demonstrate. Very efficient density can be achieved with less than 10 storeys, while providing excellent quality (light, privacy, health) and a congruous response to scale and form – here, Paris and Milano are two leading example cities, among many others.

Developments of semi-detached and terraced houses achieve a density of 40 DPH max., an insufficient critical mass to support economically viable streets, public transport, green, services and facilities. Best practice illustrates how higher densities, in form of mixed town house, duplex and apartment arrangements work well, and pay for all required infrastructure.

Nonetheless, the economic paradox that building apartments is financially not viable for many private developers, while building houses at suburban scale is, has not yet been unfolded. Amply available, affordable greenfield sites being more attractive than expensive urban sites is only one part of the answer.

According to CSO figures, only 26% of units completed in 2024 were apartments, leaving 74% to the housing market (CSO, 2024). A market supplying a traditional demand drives this trend, against national and local policy guidance: People still want a house, no apartment – full stop!

It comes down to the preference of own door access, which is comprehensible and needs to be reflected in the supply. The solution lies in the creative design to provide such, either directly from the street, or via attractive, lobbied shared access that is perceived as a private address and entrance to a home. Compact own door houses, in duplex and triplex arrangement can generate densities of up to 100 DPH, achieving compact settlement targets.