Julie Godefroy
The draft London Plan is open for consultation until 15 October. Some of its proposals for sustainability policies (GHR1 to GHR11) are based on measurable outcomes, which is a very welcome shift and one for which CIBSE has long argued.
The approach to energy and operational carbon changes from a relative reduction beyond Building Regulations to absolute energy use intensity (EUI) and space-heating demand targets, complemented by onsite renewables and a minimum five years of post-occupancy reporting.
This is really positive: targets expressed as improvement on Building Regulations make it difficult to compare performance with targets and to track progress over time; an absolute metric (for example, kWh.m-2 per year) gives a stable and comparable benchmark.
The proposals include ‘baseline’ and ‘aspirational’ limits. The latter are aligned with the UK Net Zero Carbon Buildings Standard (NZCBS) limits for 2040 onwards, except for offices – where the London Plan is more ambitious – and industrial buildings. Here, the NZCBS differentiates between logistics and distribution sectors, and data centres.
However, the wording on refurbishments is ambiguous, seemingly without EUI limits. This must be addressed, as long argued by CIBSE, particularly now that the NZCBS offers an approach and possible EUI limits.
It is proposed to drop carbon offsetting, which has been used unevenly. The GLA Carbon Offset Funds monitoring report shows that around half of the £170m collected since 2016 has been spent, with some boroughs spending more than 80% of their funds and others less than 15%.
An absolute metric gives a stable and comparable benchmark
The largest category of funded projects is, however, a genuine positive – energy efficiency projects in council estates, schools and social housing, as well as projects such as heat networks decarbonisation. If offsetting goes, other funding streams will be needed.
GHR2 requires a low carbon heat appraisal on all major schemes, with heat-source selection based on upfront and whole life costs and carbon. This is a positive response to CIBSE’s repeated concern that heat networks are too often encouraged for their potential to deliver carbon savings, without actual delivery. However, the draft policy relies heavily on the national heat network zoning regime, under which connection can become mandatory in designated zones, with concerns about carbon content of heat limits and how they will be calculated (potentially continuing to favour gas-fed CHP). This is a real limitation to delivering low carbon heat, and ambition could be raised in the Plan.
GHR3 introduces upfront embodied carbon targets for new build. This is very welcome, building on how much industry has moved on in recent years, with whole life carbon assessments in the current London Plan, more widespread skills and data, and the NZCBS.
The limits for residential schemes below 11m and for Class E buildings are broadly aligned with the NZCBS. An important distinction is residential schemes above 11m, for which limits are much higher than in the NZCBS.
The policy also requires a pre-redevelopment audit, assessing retention before demolition. This is a step forward, but it only asks for assessing and reporting, not meeting a fixed test. A more robust approach could be taken – for example, following Westminster’s Retrofit First policy – and retrofit projects could be subject to limits; for example, following the NZCBS.
Other policies, and what’s missing
GHR4 strengthens the overheating mitigation hierarchy and expects shading on windows receiving direct sunlight. However, it sits oddly alongside a reduced 2.4m floor-to-ceiling standard and softened encouragement for dual-aspect dwellings (HN8).
Finally, for a number of years CIBSE has argued for more consistent and extensive monitoring of outcomes, both at scheme level and in aggregate, to track progress and inform future policy.
The GLA’s energy monitoring reports have improved significantly from past headline averages: recent ones publish EUI and space-heating demand by typology (though often based on Part L rather than performance assessments), and whole life carbon against benchmark by module.
What remains missing is the ‘be seen’ in-use layer: the most recent report shows only a handful of as-built submissions and in-use reporting yet to follow. This is largely to be expected, as a development approved now will not generate its first in-use data for some time. Looking forward to what the data will reveal when it does get published!
About the author
Julie Godefroy is CIBSE head of net zero