Assessing the carbon impacts of development proposals and identifying the most cost effective methods of achieving higher performance standards.
At a glance
Housing Advisers Programme case study
2020/21 case study
- What went in
Priority area addressed: Developing a greater understanding of low carbon technologies and how they can be implemented at scale within a wide range of developments, as well as understanding their impact on the deliverability of schemes.
Other resources needed: Mid Devon District Council worked with the University of Exeter’s Centre for Energy and the Environment (CEE) to complete this project. The CEE comprises leading experts in sustainable buildings, energy and environmental policy and the impacts of climate change on the built environment.
Time taken to achieve outcomes: 18 months
- What came out
- A robust, easy to use tool that calculates carbon performance for new development and the cost uplift associated with achieving higher performance standards, from Part L to passivhaus.
Difference made / indication of success:
- The key success of this project is a model that is transferable and scalable to a wide range of developments and site contexts. This will help inform negotiations on a wide range of planning applications as well as informing the formulation of future planning policy.
- As an example, the tool identifies that for a development of 10 dwellings with a range of dwelling typologies, the average per dwelling cost uplift (over and above Part L) of achieving a passivhaus / zero carbon standard is £6,408.
Mid Devon District Council, like many other local authorities throughout the UK, has pledged to be carbon neutral by 2030. This requires the Council to take a lead in rapidly changing the way in which housing development comes forward in the District.
This project enables the Council to easily and robustly assess the carbon impacts of development proposals and identify the most cost effective methods of achieving higher performance standards. The tool is transferable and scalable to a wide range of developments, will assist with negotiations on planning applications and help inform the formulation of future planning policy.
Challenge and context
Mid Devon District Council declared a climate emergency in 2019 and has pledged for Mid Devon to be carbon neutral by 2030. Clearly, this is a challenging and ambitious target and one which requires the Council to take a lead in rapidly changing the way in which housing development comes forward in the District. The Climate Change Committee (CCC) 2019 Report ‘UK Housing: Fit for the Future?’ found that we cannot meet our climate objectives without a major improvement in UK housing and a near complete decarbonisation of the housing stock. At the local level, Mid Devon currently has the highest per capita emissions of anywhere in the Greater Exeter Housing Market Area and the highest proportion of households in fuel poverty. There is therefore an urgent need to build knowledge within the Council on a range of different low carbon technologies and how they can be implemented at scale in a wide range of challenging site contexts. There is also a need to develop a greater understanding of the practical applications of technologies, both in terms of carbon and cost impacts.
What we did
Mid Devon District Council, working with the Centre for Energy and the Environment at the University of Exeter, used Housing Advisers Programme Funding to develop a tangible evidence base and a transferable and scalable assessment tool that will be used to help inform the formulation of future planning policies, as well as helping to facilitate negotiations with developers to achieve affordable low carbon outcomes.
The tool calculates carbon performance (based on regulated emissions from Part L of the Building Regulations, and embodied carbon) of four dwelling typologies: detached, attached, 1 bed flats and 2 bed flats for a range of fabric and building services specifications. The tool then sizes the required PV array to meet Part L, and any further improvements that have been stipulated. It then establishes the cost uplift to achieve performance standards compared to the lowest cost means of meeting the minimum requirements of the Building Regulations.
The difference we made
The tool enables the local authority, developers and other relevant stakeholders to quantify the likely carbon performance of schemes and then justify potential low carbon interventions on the basis of carbon savings and likely cost impacts. Whilst not a substitute for detailed SAP calculations, it does provide a credible and evidenced basis on which to determine the carbon performance of development proposals. Through modelling a range of low carbon interventions, the tool then assists in identifying the cheapest way of meeting different performance standards (incremental improvements all the way to passivhaus standard) for different combinations of fabric, building services and roof mounted PV.
This allows the Council to engage constructively with developers to consider the potential for improving the carbon performance of a scheme whilst being sensitive to the impact of such interventions on build costs. The tool also complements and is responsive to the Government’s transition to a Future Homes Standard.
The tool will be used to help inform the formulation of future planning policies as well as helping to facilitate negotiations with developers on low carbon interventions. The Council is currently in the process of developing a new Local Plan for the area, “Plan Mid Devon’, and the tool will be invaluable in helping to evidence potential performance standards.
Over time, it is hoped that the tool will help build capacity and expertise within Mid Devon District Council on a range of low carbon interventions and their implementation in terms of energy performance and carbon savings, as well as their impact on build costs and development viability.
To aid implementation of the tool, the Council is currently exploring how best to incorporate the model into existing and emerging polices and strategies across the Council e.g. Interim Policy Guidance on climate change, Plan Mid Devon and potentially, as a planning application validation requirement.
Finally, the tool is highly transferable to other Councils. More than half of UK local authorities have declared a climate emergency meaning there is a significant need to create and share learning on what works, to help deliver on challenging and highly ambitious, but necessary carbon reduction targets.
Having tested the model against a range of development typologies, it is possible in many cases to significantly improve the carbon performance of a scheme with relatively low cost impacts.
This will be tested further over the coming months as the tool is used to assist in the determination of planning applications. The tool also highlights that there is an urgent need to develop more robust evidence of whole life cycle carbon impacts associated with developments and better understand the role of planning in reducing embodied carbon impacts associated with new developments.