2.2.2 Modifying climate
2.2.3 Energy
2.2.4 Water
2.2.5 Waste
Urban form has a major influence on climate change. Almost 30 per cent of carbon emissions come from buildings and a further 25 per cent from transport.1
We can design places to help minimise the use of energy and scarce resources, and to adapt to predicted climate change.
Coping with climate change calls for more than just token wind turbines or solar panels. It requires an understanding of how design decisions about matters such as location, movement, connections, orientation and biodiversity make a place more or less sustainable. Much can be achieved at the neighbourhood and building scale. Developments should be designed to influence the microclimate, minimise the use of energy, and maximise energy efficiency through local supply and the use of renewables. Consideration should also be given to factors such as water use and waste management.
Creative design can conserve resources and
improve habitats while also creating places that work successfully.
2.2.1 Movement
Pattern and locationMovement is perhaps the most significant aspect of urban form. Historic places have shown that patterns of movement that have been established over a long time to accommodate human behaviour are often capable of meeting changing needs. Cities are produced by the design of the built environment in response to social and economic pressures. New urban forms, developed to meet the challenge of sustainability, can be informed by an understanding of historic towns which often made efficient use of resources out of necessity.
Integrate local and wider movement networks
While there has been some success in creating permeable networks of connected streets within developments, too
often the local network remains an isolated development pod, with minimal linkages to the wider network. As a result, many developments are not an integrated part of a wider settlement. It is then difficult to achieve accessibility, security, vitality and effective mixed uses. The selection of growth areas or urban extensions need to take account of how well connected the settlement would be at the macro scale.
Opportunities should be provided for new connections to be made as a place develops. Growth should be seen as an opportunity to integrate improvements to the movement and public transport networks with an extension of the capacity and viability of the region or settlement as a whole.
Identifying areas for growth
In many cases, the location and circumstances of the sites selected will make it impossible to deliver regional growth, or to build town extensions that are integrated with settlements by connected streets. An important criterion for selection in any sequential or comparative test should be the ability to use or create routes through potential sites with direct connections on both ends to the wider movement network for all modes of transport. The selection of a site should also be based on an assessment of its relative accessibility from main routes, and the accessibility of important services from the site. Connections through routes to main routes in the wider network are the most effective way to achieve accessibility.
Creating through routes that are integral to development
Delivering growth with an integrated network of through routes requires looking not only outward to the wider network but also inward to the design of the through routes. Urban design is the context for highway design and engineering. To be successful, such routes must fulfil several different roles, accommodating transport, vehicular traffic, pedestrians and cyclists, and achieving the wider aims of urban design. It is essential to engage in early partnership working between the urban design, planning, highway engineering and transport providers to coordinate efforts, and achieve a balanced and effective solution.
The aim of the partnership working should be to find ways of accommodating appropriate volumes of traffic and public transport, orienting development with active fronts on to the main routes, giving access to development, reducing and mitigating traffic speed and noise, accommodating parking, accommodating pedestrian and cycle movement and crossing; and creating a safe and comfortable environment. Through routes are best when relatively straight. Use a street-place hierarchy rather than vehicle-flow hierarchy. Allow for frontage access as appropriate to the type of route type and position in that hierarchy.
2.2.2 Modifying climate
Creating microclimate 027Buildings and cities should be designed in response to local climate conditions. Considering topography, street layout, landscape, building massing and the choice of materials can help to avoid heat islands, modify summer peak temperatures and reduce energy loads on buildings. Urban design can significantly reduce the energy
consumption of buildings through shelter and by providing opportunities for passive solar architecture, while also helping create a comfortable public realm. The combined effects of solar radiation, convection, thermal capacity, albedo (the extent to which an object reflects light) and wind can cause microclimates to differ by as much as 15°C in different parts of a city.
Minimising traffic fumes and using appropriate building forms can make passive ventilation of buildings an option and avoid mechanical air conditioning.
Slope analysis
Slope is a major factor in determining the ground temperature of a site. The closer a site is to lying
perpendicular to the sun’s rays, the more solar radiation it receives. A site in Aberdeen sloping south with a one in 10 gradient receives the same direct radiant heat as a flat site in Southampton, for example. Each 10 per cent southerly gradient corresponds to a latitude six degrees further south. Frost pockets are caused as a layer of air immediately above the ground cools and becomes heavier. This layer of air slides down slopes until it is contained by mounding, vegetation or buildings which prevent it escaping. Such potential frost pockets can be identified by an experienced eye from a contour map, or more easily by an early morning walk over a site on a winter’s day. Frost pockets can be reduced by damming the channels along which the cold air flows by buildings or planting.
Humidity
Planting, lakes and ponds will increase humidity while evaporation will reduce temperatures. Vegetation will moderate and stabilise conditions more than large expanses of hard surfaces. Appropriate design decisions need to be taken according to location.
The Bo01 development in Malmö has delivered a distinctive, resource efficient and liveable place with 500 homes, commercial and community facilities. The high quality design was achieved through the ‘quality programme’, a steering instrument for planning and building.
“Prepared as a joint venture document in collaboration with developers and the city of Malmö prior to land transfers, the shared goals and vision of the Quality Programme was critical for Bo01’s success”, explains Eva Dalman, Architect with Malmö Stadsbyggnadskontor.
Its design outcomes include a street grid distorted to gain shelter from wind. Five-storey blocks front the sea, further protecting inner buildings while reinforcing the character of the sea-front promenade. Varied forms of on-plot vegetation such as green walls and roofs reduce surface water and create identifiable locations within the development. An advanced sustainable urban drainage system creates an ecological, recreational
and visual resource. Together these emphasise the varying hierarchical character of streets and public open spaces in Bo01.
A 100% local renewable energy approach adopted in the development has been successful. Orientation of building facades and roof forms maximise solar gain. In addition, solar thermal panels, wind turbines and photovoltaics help minimise energy use while maintaining the overall integrity of the architectural and urban form. Bo01 residents are encouraged to regularly monitor their energy consumption using information technology installed in their homes.
‘There were no sanctions or incentives for producing good technical solutions… the signing of the agreement was a moral commitment on the part of developers’ Tor Fossum, city of Malmö, environmental department, environmental strategy unit on the implementation of the Quality Programme.