London Plan: Polices that Impact on Sustainable Building Design
London Plan 2021 is the strictest planning policy in the UK. The Plan sets out policies for housing, transport, and the economy. However, complex environmental policies often require our expertise.
Policy SI 2 – Minimising Greenhouse Gas Emissions, SI 3 Energy Infrastructure and SI 4 Managing Heat Risk are policies centred on sustainable development.
The supplementary planning guidance (SPG) document 'Energy Assessment Guidance' details how to meet the London Plan sustainability policy. It sets out the framework for energy modelling for new and refurbishment projects. The SPG works by using the 'Energy Hierarchy' (Be Lean, Be Clean, Be Green) to ensure that energy consumption that could be designed out of a project is done so before implementing low and zero carbon technologies.
For new commercial buildings, there is a target reduction of 15% from Part L 2021 Building Regulations for measures such as building fabric, lighting and heat recovery. For residential buildings, this figure is 10%. The architect and thermal modeller need to work collaboratively to maximise the reduction.
At the Be Clean stage, applicants must investigate the potential for connecting to a nearby heat network. The London Heat Mapping tool is used to do this analysis. If there are no nearby connections, designers must make an allowance within the plant room for a potential future connection.
The last stage is Be Green, where low and zero carbon technologies such as heat pumps and PV are added to the modelling. There is a requirement that the development is at least 35% better than the Part L 2021 Building Regulations at this stage.
The remaining carbon emissions from the energy modelling must then be offset into the local borough's carbon offset fund to achieve Net Zero Carbon. This payment is equivalent to 30 years' worth of carbon, with the rates generally set by the individual borough. The Greater London Authority has produced a carbon offsetting document that recommends £95 per tonne that should be used if the borough does not have their rate.
Refurbishments also need to achieve Net Zero Carbon. However, no reduction targets are to be met at the Be Lean and Be Green stages.
An essential aspect of the London Plan is the response to overheating. Applicants must complete dynamic energy modelling using CIBSE Guide TM52 for commercial buildings and CIBSE Guide TM59 for residential. This requirement is contained within the SPG Energy Assessment Guidance. The energy modelling must use the future weather file: DSY1 for 2020, high emissions, 50% percentile with a building needing to pass. Spaces must also be tested against DSY2 and DSY3, and measures must be implemented to reduce the risk of overheating under these weather files.
There is a requirement to complete a whole life carbon assessment using RICS Whole Life Carbon Assessment for the Built Environment 2nd Edition for those schemes that are referable to the Greater London Authority. Schemes that may be referable could include those built on green belt land, over a certain number of stories or a certain floor area. Some boroughs now ask that whole-life carbon assessments be carried out through their Local Plans for non-referable developments.
The assessment is usually completed using the RIBA Stage 2 cost plan to implement measures that a) use fewer materials and b) improve upon the carbon emittance of materials specified.
For Referable to the Greater London Authority developments, there is a requirement for a circular economy assessment to be completed. If an existing building is on site, this requirement could mean assessing whether there are materials within the building that could be reused.
The scope of these assessments is to ensure that the design team considers aspects such as ensuring buildings are being designed to be flexible in layout so that alternative uses can be sought for a building with minimal redesign. The ease of replacement of components should also be considered to reduce carbon emissions.
The Be Seen requirement of the London Plan is in place for Referable to the Greater London Authority developments. This requirement consists of two parts: firstly, during the design stages, modelling must be completed to understand what the building could consume in operation via a CIBSE Guide TM54 assessment. The modelling is needed at RIBA stages 2/3 and RIBA Stage 6.
Once the building is in operation, actual energy data from the building's operations must be uploaded to the GLA portal for at least five years.
The London Plan 2021 sets a high standard for sustainable development with comprehensive environmental policies, including stringent targets for greenhouse gas emissions, energy infrastructure, and managing heat risk. Key frameworks like the Energy Hierarchy and carbon offsetting ensure that new developments and refurbishments can achieve low energy outcomes.