The London Plan & Passivhaus

The Mayor of London's London Plan pushes projects built within the Greater London Authority (GLA) to go beyond building regulations, promoting higher levels of energy efficiency for newbuild homes & buildings.

Plashet Road, Newham Council. Image credit: Levitt Bernstein & Photographer Kimbo Fidelo Sito

GLA’s policies continue to push beyond national Building Regulations and demonstrate that these ambitious targets can be met by applicants...Energy efficiency measures help to keep London’s homes warmer in winter, cooler in summer, and residents’ bills down.This is why local authorities must retain powers to set standards above national regulations.

2023 Energy Monitoring Report

Energy requirements

The London Plan includes a requirement (Policy SI 2) for major developments to comply with the net zero-carbon target by following the energy hierarchy and maximising on-site carbon reductions.

A minimum on-site reduction of at least 35% beyond Building Regulations is required for major development. In 2022 this target was upgraded to a minimum of 35% improvement and ideal target of 50%.

Targets for energy efficiency measures

Within these overarching targets, there are specific energy efficiency targets:

Residential developments: minimum 10% improvement
Non-residential developments: minimum 15% improvement

Energy assessment

All major development proposals must be accompanied by a detailed energy assessment to demonstrate how the net zero-carbon target will be met.

Development applicants are required to demonstrate how their proposals apply the London Plan energy hierarchy:

Be lean: use less energy.
Be clean: supply energy efficiently.
Be green: use renewable energy.
Be seen: monitor, verify and report on energy performance.

Energy efficiency is the first stage of the energy hierarchy. Energy demand should be reduced as far as possible before the heating strategy and installation of low carbon and renewable technologies is considered.

Energy Assessment Guidance, June 2022

Energy Use Intensity & Space Heating Demand metrics

Since June 2022, applicants should also report the Energy Use Intensity (EUI) and the space heating demand of the development. These metrics will help applicants to demonstrate that they have maximised energy efficiency measures in line with the energy hierarchy, in addition to the percentage improvement target.

Offsetting

Any carbon shortfall is required to be paid as a cash-in-lieu contribution into the relevant local authority's carbon offset fund.

The London Plan & Passivhaus

‘Be lean’ – the first step in the energy hierachy

Passivhaus tends to help meet the London Plan as it takes a "fabric first" approach. The London Plan first stage of the energy hierarchy is a criterion called "Be Lean", which requires residential developments to achieve a 10% reduction in carbon emissions over building regulations through energy efficiency measures alone. This can be made through fabric and ventilation improvements. Passivhaus buildings are often easily able to achieve and exceed this requirement.

‘Be seen’ – eliminating the ‘performance gap’

Passivhaus buildings tend to help meet the London Plan energy requirements, especially because Passivhaus helps to avoid the 'performance gap' and achieve real savings in energy consumption for residents. This can help at the 'Be Seen' stage of energy use reporting within the London Plan.

EUI & space heating targets

Voluntary benchmark targets for EUI and space heating demand within the London Plan for residential, schools and offices align with the LETI climate emergency design guide.

The London Plan - EUI and space heating benchmarks

Although the targets are not mandatory, they need to be reported against and any shortfall justified. It is clear figures are only really achievable with Passivhaus levels of fabric performance and a heat pump.

NB Please note that the London plan uses GIA (Gross Internal Area) floor area rather than Passivhaus TFA (Treated Floor Area)

PHPP - acceptable modelling route

Although it’s not stated in the London Plan document or the Energy Assessment guidance, the pro-forma carbon reporting spreadsheet includes PHPP as an acceptable route for deriving the EUI estimates (which should include regulated and unregulated energy).

Challenges

Low U-values & good form factor

One note of caution when submitting Passivhaus projects with the London Plan is the fact that large Passivhaus buildings, with good form factor, can often deliver good overall energy performance without the need for low U-values, due to the savings made by their low form factor.

This can potentially offer the project cost savings, in not needing high levels of insulation, but can put such projects at odds with the limiting U-values set out in Part L building regulations (Table 4.1) which cannot be exceeded (something the London Plan would implicitly expect projects to adhere to). It is worth checking that good form factor does not make the project exceed Part L’s limiting U-values. It is advisable that this is checked before going too far down the road based on a Passivhaus-compliant design.

Passivhaus & district heat networks

The London Plan is currently enthusiastically promoting largescale heat networks as a low energy heating method. Passivhaus can integrate well with heat networks, which has been seen particularly in countries where these are more established. However, the extremely low heat demand of Passivhaus buildings means they can already meet zero-emission heating requirements, reducing the need to connect to a heat network, and therefore avoiding network energy distribution losses that become more significant when heat demand is very low e.g.with Passivhaus. Forcing projects to connect to district heat networks could also unintentionally push projects away from improved fabric efficiency (which runs counter to the GLA’s own energy hierarchy), because implementing both Passivhaus standards and linking projects to heat networks can create an undue financial burden on developers. It could be argued that heat networks should be prioritised for more challenging buildings with higher heat demand.

Fortunately, Passivhaus projects are managing to make the case for no heat network being needed but it would be helpful if the GLA and London Plan could reduce the uncertainty about whether district heat networks are necessary for Passivhaus projects. It could make sense to allow certified Passivhaus projects to meet their small heat load either through a heat network connection or another zero-emission heating solution. This would give projects more flexibility while ensuring that heat network capacity is available for higher-demand buildings.