Opt-in planning

The future of planning / part 8

Alastair Parvin
11 min readJul 20, 2024
An isometric illustration of a neighbourhood of semi detached houses. Two adjacent homes, and one adjacent property to the rear have ‘opted in’, indicated by a tick by those three houses

In this series of posts, I’ve made the case that by redesigning how we plan for the era of the web we can do more than just make it more efficient. We can also unravel some of the systemic barriers and misaligned incentives at the root of the planning system today.

Digital planning services can make planning simpler, faster and more accessible. Rules-based planning can make planning more transparent, more trusted, create better places, and de-risk development. Land value capture can make the system fairer, and fund community infrastructure and affordable tenure homes. Community-led planning can restore trust and unblock development. Performance-based planning will allow us to understand the impact of decisions.

But there is one more idea that combines all of these things. It goes right to the root of the incentives problem in planning today. It has the potential to unlock hundreds of thousands of homes, improvements to homes and community spaces, and with it inject billions into the economy, whilst still allowing us to meet our carbon goals.

Why are we so interested in greenfield development?

One of the features of planning debates in the UK today is how, when our minds turn to the question of how we can build large volumes of new homes, the conversation is almost always focused on new, large, undeveloped sites on the outskirts of towns and cities. Sometimes we talk about brownfield sites too, but again, much of the focus is on vacant land and commercial sites. We don’t talk as much about land that is already being used for homes.

Strictly from a land-use perspective, this seems strange. There is a huge need to improve existing neighbourhoods, and in suburbs especially there is a both a need — and the capacity — to organically increase the density of homes. Mid-density cities are good for the planet and food system because it means taking up less land, and it’s also good for places, the economy and public services, because it means creating gentle-density neighbourhoods that can sustain more shops, schools and public transport. It’s the concept of the ‘15-minute city’ — places where most of the essential things you need for life can be reached on foot, bike or public transport within 15 minutes.

So why don’t we talk as much about how to increase the density of homes on existing residential land?

In a sense, the answer is obvious. Politically it’s much easier to win support for new places than it is to mess with people’s existing homes. The process of land assembly (buying people’s homes off them) can take years or even decades.

And to be clear, there are plenty of reasons why we might also create entirely new towns (or extend existing towns) — for example around railway stations — providing we do it well.

But it seems strange to not first be improving and densifying existing neighbourhoods. Planning is the mechanism through which, as communities, we can give ourselves permission to develop more or less anything we want, within reasonable capacity limits.

So why don’t we want to?

Once again, it all comes down to incentives.

The winner / loser problem

Because of the UK’s consent-based model (asking for permission on a case-by-case basis), a planning decision today will almost always have winners and losers. In general, the ‘winner’ is the landowner, and the ‘losers’ are the surrounding neighbours.

So, let’s say an older couple wants to downsize but stay in their neighbourhood. They own a suburban semi-detached home with a huge garden. They’d like to build a small, warm home at the back of their property that they can downsize into, then either sell their home or pass it to their children, so they can be nearer to their grandchildren. Frankly, they might just like the idea of selling their home for a little bit more than it would otherwise be worth. But if they put in a planning application to do this, they would likely face a maelstrom of objections from their neighbours.

The strange thing is that their neighbours might want to do exactly the same thing too, but they can’t, for the same reason. So really, it’s a coordination problem.

Sometimes (especially with things like house extensions), neighbours work around this by forming an informal pact: ‘don’t object to mine and I won’t object to yours’. Even then, planners might refuse the application on the basis that the development is out of character of the existing neighbourhood. Taken case by case, each application has to be highly cautious – there’s no room for imagination. But wouldn’t it be good if there was a formal way to coordinate around a shared vision of the neighbourhood as it could be?

One of the ways that’s been proposed is ‘street votes’, which are more or less exactly what you think they are. A community can come together and vote to, for example, turn their street of semi-detached houses into mid-density flats or townhouses. One issue with the idea of voting however is that they are a one-time, all-or-nothing thing. You might get a ‘no’ one week, when the following week you might have got a ‘yes’. But you can’t be holding a referendum every week.

Another way to do it is for the community to come together to create a neighbourhood design code. One of my favourite examples anywhere of this is ‘We Can Make’ in Bristol. They brought their community together, understood their various housing wants and needs (which included things like overcrowded homes, and older people not able to downsize or live near their grandchildren) and developed a plan to unlock these small sites for affordable tenure homes, with the new land being transferred into a community trust, so the homes remain affordable forever. Not surprisingly, it was a hit.

But coordinating communities is a lot of work; a lot of organising. A lot of evenings and weekends have to be given up to make it happen, with no guarantee of success.

So is there another way to do it, that could make this kind of opt-in development easier? With the web, there is.

Opt-in planning

If we were to find a geeky technical term for it, it might be called something like an ‘asynchronous mutual opt-in protocol’. But most of us would just call it ‘swipe right’.

The way it would work is this:

An illustration of a laptop screen. A page title reads ‘Suggest a new planning pattern’. The page shows a menu of different development patterns to different types of property

1. The local planning authority would invite suggestions for development patterns: ‘bundles’ of development rights that allow you to do certain things to certain types of property, within certain rules and conditions.

The rules and conditions attached to a pattern might cover anything from design, use, tenure or performance (such as carbon emissions, water management and improving biodiversity). If the land values are high enough, they might also include preset development obligations like community infrastructure levy payments, to fund local schools, GPs and public transport. Patterns can also be locally-specific, to preserve and improve the character of an area.

Another screen. A hand cursor is selecting sites on a map

2. The planners select which patterns they would permit to be used and where, on the basis of their popularity and whether they comply with policy. They might modify them, or create their own localised patterns. These are published as part of national, local or neighbourhood codes, which are all published in one place.

A semi detached house illustration. Above it a hand is swiping right on a mobile device. The text reads ‘opt-in to development rights’

3. Property owners can search planning pattern codes online, and see what planning patterns are available for their property. They can ‘swipe right’ (opt-into) planning patterns that they want for themselves. In this case, let’s say its the example we’ve discussed: a pattern that allows owners of semi-detached houses with a large garden to add a small, affordable tenure infill home at the rear of the property.

However, here’s the key: by opting-in, they are also allowing their neighbours with similar properties to get the same development rights.

An isometric illustration of a neighbourhood of semi detached houses. Two adjacent homes, and one adjacent property to the rear have ‘opted in’, indicated by a tick by those three houses

4. You only get the planning rights for your property if a minimum number of your neighbours also opt-in. But this may not need to be the whole street. The minimum requirements for consent would depend on the pattern. Some patterns you might be able to opt-into unilaterally. Some patterns might only require opt-in from 2 out of 3 adjacent neighbours. Others might require the entire street, block or beyond. Importantly, there would be no way to see specifically which of your neighbours have or haven’t opted-in, but you would be able to see which patterns are popular nearby. People can be continuously exploring and improving new possible patterns, until something sticks and becomes popular.

An isometric illustration of a neighbourhood of semi detached houses. Several of the houses have built small additional dwellings at the rear of the property. Above, icons suggest a series of design and development rules they have to comply with.

5. If the minimum number of people opt-in, the planning code is amended, and you are then free to develop without applying for permission, provided you comply with the rules of that pattern. You only have one obligation, which is to tell the local planning authority what you’re doing.

If this were to work, the potential scale of development it could unlock is staggering. For example, around 800,000 homes in London are semi-detached houses. If half of those opted-in to double the density of their plot, that could create 400,000 affordable tenure homes within the M25 and an £80bn boost to the green construction sector, all without touching the greenbelt. Other development patterns might allow even greater densification, for example by creating townhouses or flats.

However, there’s a huge caveat here. The danger is that, using conventional construction methods, those new homes would also produce at least 12–20MtCO2e in embodied emissions and millions of tonnes of construction waste, vastly exceeding our carbon budget. That’s why it’s so important that the patterns must include performance conditions requiring net zero embodied carbon or less, and the reuse or recycling of waste materials. Where appropriate, it might only allow the repurposing (not demolition) of existing buildings. If those restrictions makes development financially unviable (for now) in some areas, that’s ok. That will drive creativity and innovation in the market (for example, companies who specialise in reusing materials), and open the field for other players.

Where land prices are high enough, the new homes could – and should – include affordable tenure homes too (such as social rent homes or affordable ownership homes), or emergency homes (homes for those escaping war, natural disaster or domestic abuse).

Opt-in planning for larger sites

Opt-in planning makes sense for existing neighbourhoods where there are rows of broadly similar properties. But could the same principle also be applied to one-off plots, and to new, undeveloped land?

I think potentially it could. In fact, here’s the twist: it could be how most rules-based planning works in future. One of the problems with the ‘zoning’ approach to planning is that determines a single, ‘one-size-fits-all’ development pattern. Similarly, in the UK today if you buy a plot that already has planning permission, it can be extremely restrictive because you’re stuck with just one design. Could opt-in planning be a way to offer alternative development options?

It might work something like this:

A laptop screen. At the top the header reads ‘Propose development rights’. A hand is pointing to a site on a map on the left. On the right, an isometric image of a rather basic development proposition showing a block of flats and some car parking spaces.

1. Anyone can suggest a proposal (a bundle of development rights) for a particular site. These don’t necessarily need to be exact, fully-designed schemes for those sites, and they don’t have to include models or layout drawings (although they could), but rather they would consist of multiple patterns, determining the types and number of buildings, public spaces, uses, tenures, design rules, density and any other planning obligations such as community infrastructure.

An animated series of screens, the proposal for the neighbourhood evolves through numbered versions, getting better and better. On the screen users can see the conditions / rules attached to development, the tenure mix and the viability. You can also see the increasing popularity of the schemes (more supports and likes, fewer dislikes and objections). At the bottom the user can like, dislike, comment or ‘fork’ the proposal (propose an alternative)

2. Planners and the public then have the chance to feedback on proposals or counter-propose alternatives, using the public deliberation methods I spoke about in this post. Feedback could be categorised based on distance from the site, so the voices of people who live close to the site can be weighed separately from those who live further away — allowing planners to balance the wishes of both groups.

3. If planners and councillors are satisfied that a proposed bundle of patterns would be policy-compliant, that reasonable strong objections have been accounted for, and the proposal meets a sufficient threshold for popularity, then it is made available for owners to opt-into.

Illustration of a site at the bottom of the page. There are two available development options. A finger on a mobile phone is opting-in to one of them.

4. There could, in principle, be many alternative development bundles permitted for a particular site, and it is entirely up to the landowner which, if any, they want to opt-into. They can take it or leave it. The landowner — or prospective developers — can see exactly what their development options are, and what planning requirements need to be priced-in when they bid for the land. Development is entirely de-risked and there is minimal bureaucracy.

5. As with planning permissions today, unused development rights for specific sites may expire, or require renewal.

Within a dotted framework of rules, buildings fade in.

6. Once they have been opted-into and used (even in part), those planning codes remain in place as a long-term enabling framework for continuous organic improvement and development. We no longer need to pretend that a neighbourhood is something that can be ‘finished’.

All this may seem a little strange and perhaps implausible to us now. We are so accustomed to the ordeal of applying for planning consent (or fighting against other people’s applications) that it is hard for us to imagine anything else.

But in many ways, what’s proposed here is not really that different from what we do today. It’s all the same pieces, just in a different order. It’s based on the same original principles of 1947 Act, applied in ways that weren’t possible then. In fact, I would argue that it is a process more true to the term planning.

I’ve called this series of posts ‘the future of planning’, but in truth, the six ideas I’ve explored are all technologically possible right now, or at least within reach.

But it won’t happen overnight. Changing systems is almost unimaginably hard. It will be the work of at least a decade, and it will cost millions. There will be false starts and frustrations. But if it works, it could yield billions or even trillions in benefits, and have a transformative impact on health, wellbeing, social equality, social resilience, the economy and the environment. It is too important not to try.

As daunting a project as it might seem, the good news is that there is nothing to stop us from beginning to prototype, build and deploy elements of those six ideas, right now. It doesn’t need to begin with everyone — all it takes is a few willing pioneers to get started. In fact a number of planning authorities already have.

This is the final Part of a series of 8 posts. The first part is here.

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