Density and typology

In today’s blog post, I have looked in detail at two key aspects of urban design: density and typology.

Density and typology are interconnected concepts which have significant influence over each other.

Density is a measurement. Originally from physics, it simply means a quantity of mass per unit volume. Within the context of urban design, the mass is comprised of the built form and the volume – or in this case, area, is land.

The scale can range from one room, to entire cities. There are many different ways of measuring density: FAR (floor area ratio), residential density (dwellings per hectare, for example) and plot coverage (ratio of built area over the plot) are often the most popular. Other relevant density measurements include population density, perceived density, employment density – all of which can be harder to measure and can often show varied results.

The ability to compare quantitative measures such as dwellings per hectare on a like for like basis across different developments can be extremely useful for developers and planners. The current prevailing rhetoric is that higher densities are generally considered to be more sustainable as more people can use a concentrated number of services, which in term makes them more viable. Measuring densities has grown in political importance within development and is widely used as a guideline for major developments across the UK.

Typology is a means of classification of the built form, made up of three typical conditions: forms, functions and meaning. These characteristics encompass all elements of the built form: buildings, open spaces and streets and they can be analysed at every scale: building, street, block, city and region. Typologies of density also exist, for example, there are high density typologies such as towers or perimeter blocks; medium density typologies such as terraced housing; and low density typologies such as large detached dwellings. A case study for mixing typologies and densities could be mansion blocks. They typically have a high proportion of plot coverage due to a large floor-plate, medium rise and a shared communal garden. In comparison mews streets and associated dwellings have a very small floor-plate, little to no private garden and are low rise.

Controlling development through density is a long established practice, thus typologies are already set in a way for certain contexts and certain places. Within certain London boroughs for example, with high levels of connectivity, high land values and high demand, local authorities will demand over 250 dwellings per hectare. In order to achieve those high numbers, there are only certain typologies that can be employed. In a more suburban location, local authorities may only require 40 dwellings per hectare, which would be best achieved through a different typology, semi-detached and terraced housing for example. These two example shows the intrinsic link between these two concepts: there relationship is intertwined and co-dependent. You can’t think about density without typology, and vice versa.