Towards low-carbon housing developments
Reducing the carbon emissions of a large new housing development in north Bristol
Project duration: November 2004 to March 2005
The overall aim of this project was to achieve significant reductions in the total emissions of carbon dioxide for a large housing development (1,800 houses) planned at Emerson’s Green on the northern fringe of Bristol.
The project sought to test the feasibility of using a cumulative and hierarchical approach to carbon reduction, with a large-volume housing developer. The four specific objectives of the feasibility study were:
- to develop a hierarchy of carbon reduction measures for implementation on the Emerson’s Green housing development
- to work in partnership with the developer and establish how many of the measures identified in the hierarchy can be adopted in addition to those required under current building regulations
- to identify the barriers to the implementation of measures highlighted in the carbon reduction hierarchy
- to establish what additional support and steps can be taken by South Gloucestershire Council and other partners and third parties to overcome these barriers and in so doing enable the development to achieve further reductions in emissions of carbon dioxide.
The first task was to review examples of projects and best practice from across the UK, to ascertain what lessons could be learnt and applied in this instance. Following this an assessment was made of the projected baseline emissions of carbon dioxide from the development as proposed.
An energy hierarchy was then developed which defined the cumulative approach to reducing emissions, based on work carried out on a development in Kronsberg, Germany and for the London Energy Strategy. This was not restricted to thermal efficiency measures, but also considered spatial layout, built form, provision of heat and build quality.
The interim results of the study were presented to the project partners in February 2005, along with recommendations for measures which could be incorporated into the proposed development.
Discussions were then held with the developer to establish how many of the proposed measures could be adopted in this development and the barriers to further action.
Be lean, be green, be clean
One of the primary conclusions of this study is that additional measures should be applied on the basis of an energy hierarchy. This provides a consistent and rational framework for where to allocate resources. The hierarchy may be summarised as ‘Be Lean’ — reduce demand, ‘Be Green’ — offset fossil fuels with renewables, and ‘Be Clean’ — where fossil fuels are used, this needs to be as efficiently as possible, for example through the use of Combined Heat and Power.
Scope for inclusion of additional measures is determined by the residual land value for a given site. Where additional measures have not been taken into account at the outset, their implementation is unlikely. There is a need to raise awareness of the benefits of additional energy-saving measures so that they are regarded as a positive selling point by purchasers. Local authorities in partnership with other agencies have a role in this respect.
Setting targets for renewable energy in the Local Development Framework for new developments can lead directly to a lowering of energy demand. This is because it is cheaper to reduce the overall energy demand, so that smaller renewable energy capacity has to be provided than to have a higher overall demand and greater renewable energy capacity.
The Energy Saving Trust’s Innovation Programme part-funded the project. South Gloucestershire Council provided matched funding and in-kind support. The developer Gallagher Estates provided in-kind support.