2.7 Policy CP2: Sustainable Construction requires energy efficiency to be “maximised” and Policy SCR1: Onsite Renewable Energy requires major development to achieve a 10% reduction in carbon dioxide (CO2) emissions from renewable energy sources. The Sustainable Construction Checklist Supplementary Planning Document (2018) embeds this 10% requirement into a broader benchmark for all scales of new build development to achieve an overall 19% CO2 reduction for compliance with the Placemaking Plan. The SPD also establishes a 10% reduction target for medium and large scale development of existing buildings.
2.8 The preferred option is to set a net zero carbon policy with three elements reflecting the energy hierarchy below. This will replace policies SCR1 and CP2.
Residential development
2.9 The Future Homes Standard (FHS) was consulted on by the government in early 2020. The FHS would amend Building Regulations Part L1A and Part F to reduce energy demand and carbon emissions from new dwellings in two stages over the next few years.
2.10 Since Building Regulations are the baseline for the net zero carbon policies, if the Building Regulations change through the FHS, this changes the policy baseline. At present, the date for commencement of the FHS has not been announced by Government. Therefore, two options are considered to achieve net zero carbon development; one option for if the FHS has not been adopted and another for if it has.
Consultation Reference: DM1
Amending and updating/replacing Policy CP2 and SCR1 Residential Development - Net Zero Carbon Construction Policy
New Build
Option 1 – If the Future Homes Standard is not implemented
- A minimum operational CO2 emissions reduction of 10% through fabric performance from a baseline of Building Regulations Part L 2013
- A minimum operational CO2 reduction of 35% through on-site renewable energy
- Then offset remaining operational emissions that can’t be mitigated on site through a financial contribution.
Option 2 – If the Future Homes Standard is implemented as proposed If the Future Homes Standard is brought forward, then it is proposed that the new Part L requirements are used as a starting point delivering net zero carbon construction.
The policy would require the higher fabric standards set out in the Future Homes Standard 2025, with the remainder of the carbon emissions mitigated through renewable energy. Any remaining emissions that cannot be mitigated onsite could be offset through financial contributions, to achieve net zero carbon in operation.
For both options, the Passivhaus Plus standard will be considered as an alternative route to policy compliance.
Non-residential buildings
2.11 The proposals outlined in the Future Homes Standard only apply to new residential buildings and proposals for non-residential and existing buildings are yet to be consulted on.
The BREEAM Excellent standard is being considered for major developments in addition to the net zero carbon policy. BREEAM Excellent certification requires developers to address a holistic range of sustainable construction elements that would otherwise not be covered by local policy. BREEAM is an internationally recognised, widely used methodology that includes a robust certification process to validate the sustainability value of a development.
Consultation Reference: DM2 New Build Non -Residential Development
Amending and updating/replacing Policy CP2 and SCR1 Non-residential development
Proposed policy would use an energy hierarchy to achieve zero carbon as follows:
- A minimum reduction of 15% through fabric performance
- A minimum reduction of 35% through on-site renewable energy
- Then offset what can’t be mitigated on site through a financial contribution
A policy to require major development with 1,000m2 or more non-residential floorspace to achieve BREEAM Excellent Standard is being considered.
Heat and cooling hierarchy
For both residential and non-domestic buildings, a heat and cooling hierarchy policy will be considered, as follows:
- Development will be expected to minimise demand for heating, cooling, hot water, lighting and power through building and site-level measures.
- Residual heat and cooling demand is expected to be met using renewable heat sources whilst complying with District Heating Policy CP4.
2.12 The West of England Cost of Carbon Reduction study by Currie and Brown (the Study) provided evidence on the costs of a range of policy options for reducing operational emissions arising from use of the building. Other emissions e.g. those arising from the materials used in construction are considered in the Whole Life Carbon policy below. The study looked at residential and non-domestic buildings, up to net zero regulated and unregulated emissions which is the council’s preferred approach. These costs will be used to inform a viability assessment that will accompany the Draft Plan in Spring.
2.13 The Study also sets out options for reviewing the policy approach in response to the transition of the electricity grid to renewables. In recent years the mix of generation sources used to provide electricity through the national grid has changed significantly. The contribution of renewable energy has risen from under 5% in 2004 to over 30% in 2018. This trend of “grid decarbonisation” is set to continue in the coming decades. Electricity now produces less carbon per unit than gas. Government has stated that gas boilers will be banned in new buildings from 2025 or sooner which is already encouraging developers to switch away from gas heating and towards electric or renewable heat.
2.14 The best opportunity to improve building fabric is at the development stage. Post-occupation it is more costly and disruptive to improve the fabric. Many building fabric components will last the lifetime of the building providing long term carbon savings. Fabric improvements can deliver higher quality buildings which are healthier to live in and cost less to run. A 15% improvement is being considered for non-residential development since the evidence shows it is more cost effective for non-residential development to achieve energy efficiency savings through fabric improvements.
2.15 Generating renewable energy on-site helps meet the renewable energy target in Policy CP3 and can reduce energy bills for building users. Renewable energy can be stored (for example, with batteries) to support the transition of the electricity grid to renewable energy, by releasing energy at times when renewable energy production is low. The Heat Hierarchy policy will ensure that new development does not “lock in” the use of gas, which will need to be phased out as a heating fuel in order to meet local and national climate change targets.
2.16 Remaining operational emissions up to 100% regulated or unregulated CO2 can be offset by payments into a local fund for off-site carbon saving measures such as renewable energy or energy efficiency in existing buildings. The price of this offset is proposed to be £95 per tonne of CO2.
2.17 The measures outlined above will use the energy hierarchy to achieve net zero carbon construction in new buildings.