The draft London Plan is out for consultation – here’s what it means for the buildings we design…

The consultation on the next London Plan closes on 15 October. Look past the housing headlines and there’s a quietly radical idea at its heart: buildings should be judged on what they actually do, not what the model said they’d do.

Most of us don’t sit down with a 310-page planning document for fun. But every decade or so, London publishes one that sets the direction for every building we’ll design, engineer and occupy for the next twenty years, and this is one of those moments. The Mayor published the draft London Plan on 16 July, the consultation runs until 15 October 2026, and after examination in public it’s expected to be adopted in early 2028.

The headlines have gone to housing, understandably: 558,000 new homes by 2037, a 35 per cent affordable threshold from 2028, a cautious loosening of Green Belt review. All important. But for those of us who design the systems that make buildings work, the more interesting story is elsewhere, and it starts with a bit of history.

London asks first…

If you’ve worked on London projects for any length of time, you’ll know the pattern. The London Plan asks for something the rest of the country considers ambitious; a few years later, it’s simply how things are done. The cooling hierarchy that became law nationally as Part O in 2022? London Plan policy long before that. Carbon reductions well beyond Part L, and zero carbon homes? London asked while national policy was still deliberating; from next March, the Future Homes Standard makes low-carbon heating and tighter fabric the legal baseline everywhere. Five years of in-use energy reporting under “Be Seen”? That arrived in 2021, and national regulation still has nothing like it.

So when this draft strips out policies that now duplicate Building Regulations, that isn’t the Plan retreating. It’s the Plan doing what it has always done: handing its last set of asks over to national law, and setting the next one.

And the next ask is proof…

Here’s the uncomfortable truth the industry has lived with for years: buildings routinely use far more energy in operation than their design-stage calculations predicted. We’ve all seen it. A scheme sails through compliance, the certificates are framed in reception, and the meter tells a different story. The performance gap persists because we’ve been reporting against models, often SAP-based ones, which CIBSE has been politely pointing out for years were never designed to predict real energy use.

The draft plan goes at this directly. Policies GHR1, GHR2 and GHR4 set Energy Use Intensity and Space Heating Demand targets, baseline and aspirational, with performance reported for five years after occupation. The monitoring machinery already exists; “Be Seen” built it. What changes is the yardstick. An EUI target is set in kilowatt-hours per square metre and measured at the meter. There is nowhere for a performance gap to hide.

And where do those benchmarks come from? This is the part we’re quietly proud of. In 2017, a voluntary network of over 150 built environment professionals formed around a blunt observation: London’s energy policy wasn’t driving design decisions that cut carbon in the real world. It called itself the London Energy Transformation Initiative, LETI for short, and we joined in its first year; LETI is as old as our practice, and its thinking has shaped how we approach energy design ever since. Nine years on, benchmarks that began life in volunteer working groups are written into the draft development plan for the capital. Patient, evidence-led collaboration works. It just doesn’t hurry.

The £380 million question…

One thing the draft leaves deliberately open is carbon offsetting. The consultation says the role of offset payments “will be reviewed”, and the GLA’s own monitoring report explains why that review is overdue, just not for the reason you might assume. Since 2016, roughly £380 million has been secured through Section 106 agreements. Only £170 million of it has actually reached London’s boroughs; s106 money typically falls due at practical completion, and not every consented scheme gets built. Of the £170 million collected, £92.7 million has now been spent on carbon reduction projects, more than double the amount spent the year before, with £77.8 million allocated but not yet delivered.

Spending is accelerating, and that’s worth saying plainly rather than burying. But a mechanism where under half of what’s secured has even arrived, sometimes years after the agreement was signed, isn’t obviously a faster or simpler route to carbon reduction than requiring it on site in the first place. If measured performance is going to carry more of the weight offsetting was meant to bear, this consultation is the place to say so.

Keeping cool, honestly…

The draft’s emphasis on shading, orientation and natural ventilation ahead of mechanical cooling might read like a new demand. It isn’t, and the lineage runs the other way: this was London Plan thinking first, and it has been statutory for new homes since Part O came into force in 2022.

The real question, and it’s a live one, is whether the hierarchy works as well in practice as it reads on paper. Specialists giving evidence to the London Assembly this March argued that passive and active cooling do different jobs, and that treating mechanical cooling as a last resort can leave homes under-served on the hottest days, at which point residents solve the problem themselves with the cheapest portable unit they can find, which is usually the least efficient cooling money can buy. The government clearly heard something similar; a full technical review of Part O was announced in April, partly because noise, security and fire requirements elsewhere in the regulations routinely prevent the night-time window opening that passive strategies quietly assume.

Our view, formed on projects rather than in the abstract: the hierarchy is right, and the lazy reading of it is wrong. Passive measures should lead the design sequence; on our schemes they always have, long before it was mandatory. But leading the sequence isn’t the same as being the whole answer. Where noise, security or the urban heat island make night purge ventilation unrealistic, the honest engineering response is to design efficient, integrated cooling in as a considered fallback from day one, not to model an idealised occupant, collect the compliance certificate, and leave the real occupant to bolt a box through the window three summers later.

The buildings we already have…

Two more things worth your attention. Whole life-cycle carbon assessment carries on, with reporting expected to be streamlined rather than relaxed; embodied carbon stays in scope, as it should. And a new heritage policy formally recognises adaptive reuse and retrofit as contributors to housing delivery and carbon reduction, which gives policy weight to something we’ve long argued: in a city like London, the greenest building is very often the one already standing.

Before 15 October…

This is a draft, and drafts move. The version adopted in 2028 will be shaped by what comes back between now and 15 October, including the open questions on offsetting and the calibration of the new energy targets. If your projects are in London, this plan will shape them into the 2040s, so this is the window to influence it rather than inherit it.

And if it would help to talk through what the draft means for a scheme you’re working on, or you’d like a hand preparing a consultation response, that’s what we do every day. We’d love to hear from you.