Design: Putting Density in the right place
Density and sustainability
As worldwide population increases, more and more people are moving to urban areas, increasing the demand for high-quality housing in convenient locations. At the same time there is a pressing need to find effective ways to reduce carbon emissions and adapt to the effects of climate change.
Increasing housing density is often considered to be a key strategy to solve both problems, as recognised in the London Plan. Density has many benefits. In addition to providing more homes, higher densities also provide a critical mass for local services such as schools, jobs and shops. It also creates a sound business case for public transport provision, reduces the need for individuals to own an automobile, lowers driving distances, and thus helps reduce carbon emissions at the local level.
Since the 1960s, increased densities have often been associated with tall building developments. While tall buildings can provide the necessary densities, they also suffer from a variety of drawbacks. These include under used and inactive public spaces, increased segregation and separation from their environment, and reduced safety and security. They are also difficult to adapt to multiple uses, often age poorly and lose value over time, and can be very energy intensive if built with lots of glass and steel. Finally, many people find tall buildings unsympathetic to their surroundings, impersonal and dehumanising.
A "convenient solution" to an inconvenient truth
Click thumbnails to view larger imageDoes sustainability require tall buildings? We believe not. Our research has found that there is a better way to achieve sustainable densities, specifically through the use of mid-rise, high-density mansion blocks.
Just as the negative aspects of tower blocks have become increasingly obvious over time, so too have the positive aspects of mansion blocks. Mansion blocks are more efficient; they make best use of available land, provide more usable and attractive public spaces (such as interior courtyards and liveable street edges), and they are walkable and easy to maintain (they don't need lifts). They are also attractive, human scaled, and fit in well with their surrounding environments. Finally, mansion blocks are more energy efficient, safer and more secure (their lower scale provides more "eyes on the street", they offer direct and usable access to all public areas, and create a better sense of public / private space which encourages a sense of care and ownership).
At The Prince's Foundation for the Built Environment, we have found that mansion blocks are a "convenient solution" to the "inconvenient truth" of population growth and climate change. We suggest that they are a more effective, appropriate, and sustainable solution to the environmental and social challenges of the future, and provide the following tools to defend this point:
The Building Typology Explorer
We have created a bespoke educational tool to help planners, developers and architects explore the best scale and building type for any site in the Greater London area. This tool, called the "Building Typology Explorer", complements the Location Efficiency Calculator.
The Building Typology Explorer allows you to enter the postcode of a proposed or hypothetical development in your neighbourhood, then calculate the height and carbon consequences of different building designs. By entering a few simple facts associated with the building (commonly available through any planning or pre-planning application), the tool calculates the number of floors required to accommodate the proposed development, the carbon emitted and the number of kilometres travelled as a result of the urban development plan, and how the plan might work using different building styles.
The purpose of the Explorer is to show how high density can be achieved on most sites through the use of mid-rise mansion blocks, rather than tower blocks. Although the tool is mainly illustrative and educational (a variety of site conditions will influence the design, height and layout of real world projects) it demonstrates the point that tower blocks are not necessary in most cases and that mansion blocks can accommodate desired densities with many additional benefits.
The current version of the Explorer is limited to a single parcel and does not take into account larger, multi-building developments. It also does not incorporate energy efficiency gains produced by different building materials and technologies such as appropriate glazing, combined heat and power, or other such approaches. It is, however, a highly effective educational tool for visualising the height and massing impacts of different residential building types on a single parcel, as well as the level of carbon and the number of vehicle kilometres travelled resulting from the location efficiency of the site. It is therefore intended to produce evidence-based learning and discussion in the development process only, not provide final solutions or more advanced technical analysis.
Built to Last
This short film explores the connection between New Urbanism and environmental issues.
Winner of The Congress for New Urbanism CNU 17 video contest.
References
Urban Design Compendium 1 & 2, published by English Partnerships and The Housing Corporation, 2000 (second edition 2007)
Compendium 1: Building size and scale - page 93
Compendium 2: Density - Chapter 2.4, pg 84 - 91