How many people live in the English green belt?

Over a decade ago I set out to understand exactly where England's green belt land was by getting my hands on the raw data. Eventually it became open data and there's an update every year, along with loads of stats. At the time of writing, the proportion of land in England designated as green belt* was 12.6% of the total. But nobody lives in the green belt, right? Or at least hardly anyone, right? Or at least not that many, right? If you search online you won't find an answer to this question so that's why I've been looking at it on and off for a few years and now I have what I think is a good approximation of the total number of people who live in green belt land in England - 1.2 million or, to put it another way, more than in any single English local authority area (Birmingham has about 1.1 million people). That's 2.1% of the population of England.

I believe this estimate is pretty accurate

Are you sure?

How can I be sure that this number is correct, after all we don't actually have population data that fits the boundaries of the green belt. For example, you can't just add up Census Output Area populations within the green belt because they do not nest neatly (at all) within the green belt and if you try this approach you will get a wildly wrong figure. That's why I used the OS Open UPRN dataset from Ordnance Survey because this allows you to identify individual properties. There's also AddressBase Plus but a) that costs a lot of money and b) we'll get to that later. So, because I used address-level data I am confident that my figure of 1.2 million people living in the green belt is pretty accurate but you will see some independent verification below too. Update: read on for more but my 1.2 million people in the green belt figure compares very favourably to the 1.15 million figure calculated using the 'ONS average occupancy count for "in use" properties (by OA)' stats in the spreadsheet from Drew.

The dots are UPRNs in buildings, green = green belt

York's green belt is very much like a big green donut

My methodology, for anyone who is interested

How did I go about this? Well it went a bit like this...

• Get the latest green belt boundary file from DLUHC
• Get Open UPRN data from Ordnance Survey
• Get building footprint data from OS Zoomstack
• Add all data to QGIS
• Extract only those UPRNs (UPRNs are the authoritative identifier used to uniquely identify addressable locations in Great Britain) that fall within a building footprint, so that you're not including non-buildings etc
• Identify how many of these UPRNs within buildings fall within the green belt (I got about 34 million UPRNs in buildings out of 40 million total, and 593,273 were in buildings in the green belt in England)
• Then we do a comparison between the population of each English local authority area and each of the following: number of building objects from the OS Zoomstack dataset, total area covered by buildings, total count of UPRNs in buildings
• Then we bust out Occam's Razor to do a few simple scatterplots - compare each of the above to the population - to cut a long story short, you multiply my UPRN number by about 2 to get a total population

Building area vs population: a bit messy

Building object count vs population: too messy

UPRNs in buildings vs population: quite neat

• So once I saw a fairly linear relationship between my 'UPRNs in buildings' count and the total population of each local authority district in England I decided to use this to estimate population
• Not all local authority areas have green belt though, only 180 of just under 300 do
• For those areas with green belt the relationship between 'UPRNs in buildings' and the population was even stronger so that's why I have a good degree of confidence that we can multiply by 2 here to get a decent population estimate

UPRNs in buildings in green belt vs total population

• This all leads me to a population estimate for the English green belt of: 1,186,546 - but this is too precise so I'm just saying 1.2 million. 

Verification?

I did all these calculations myself and got a figure that seems pretty reasonable based on the methodology described above. It also feels about right - 2.1% of the population of England on 12.6% of the land area. The 2x multiplier for UPRNs in buildings to get population holds pretty much all across England as we can see from the charts above, and the relationship is even stronger when we look only at those areas that contain some green belt land.

If you check out an earlier post of mine on Twitter you'll see some other numbers which back me up, calculated using the very expensive and not-open AddressBase Plus dataset. I will add these below for reference. 

Here are some screenshots of calculations that use AddressBase Plus, including some populations for the different bits of green belt in England. Thanks of course to Drew for these numbers derived from AddressBase Plus - here's more on his methodology.

ABP is AddressBase Plus - similar figure to what I got

Estimates for the different bits of English green belt

A spreadsheet you can explore and have fun with

If you look at the spreadsheet shown above you will see three different estimates for the population of the green belt in England, ranging from 1,073,863 to 1,236,452. My figure of 1,186,546 is very close to the middle figure in the spreadsheet of 1,168,301 which was calculated from the ONS population estimate of 2.4 people per dwelling. You will also notice a tab in the spreadsheet with green belt population by local planning authority.

The dots are UPRNs, the shapes are buildings

So there we go. Why am I writing about this again? It's a long-standing interest of mine, plus it has also been in the news recently so I thought I'd take another look at it. Oh, also, I discovered that I'm only 430 metres from the green belt even though I'm in a very densely populated area.

Want to look at a map that has current green belt boundaries on it? Check out the National Map of Planning Data for England and then just turn on the green belt layer.

Green belt near me, I didn't realise so close

*'green belt' is how I'm writing it here but the government tend to use 'Green Belt' but of course if you're being proper you might say 'green belts' but we also see 'greenbelt' and 'Green belt' - I'm not fussed, it's all talking about the same thing

English Green Belt Atlas, v5

Where is the green belt? Where are the green belts? How much of my area is green belt land? These are excellent questions, but it's not always super easy to find the answer, and that's why I originally began investigating this topic back in 2012. This then eventually led to me producing maps for each English local authority that had green belt land in it, thanks to an idea suggested to me by geo legend Prof Bob Barr. Since I last did this in 2018 the number of local authorities in England has changed and there is a more recent green belt dataset, so I'm returning now with version 5 of my English Green Belt Atlas. Currently, 12.4% of land in England is designated as green belt, across 180 local authorities, but it varies a lot between places, as you can see below. I have made one map for each of the 180 areas, listed alphabetically (they are really high resolution images). How big is 12.4% of England? It's 16,140 square kilometres or 6,232 square miles. This is just a little bigger than the South East region or Yorkshire and the Humber, and about 80% the size of Wales, just to give a sense of scale. From 2020 to 2021 there was a 0.1% decrease in the amount of green belt land.

I did my best with the labelling

I've tried to keep the maps fairly simple

An example of a very split local authority area (rail line)

This area has the highest % green belt land in England

Not an awful lot of green belt land here

Okay, so you get the idea with the maps - I've shown rail lines (dark), railways stations (little circle dots), places (square dots, different sizes), major roads (orange), buildings (dark), water, green space (light blue) and green belt land in a darker green. The little dot in the bottom right inset map shows you where a local authority is, just in case any are not familiar. I've automated the labelling but it's not 100% perfect, but I can't spend any more time on it. Want to use one of these maps, or all of them? Be my guest.

Here's a few more that I found interesting. You can find the full set, listed alphabetically, right here.

Green Belt Atlas, version 4

This is a short post about an updated version of my Green Belt Atlas, in which I've produced a map of every local authority in England that contains land designated as green belt. The original idea for this came from GIS guru Bob Barr a couple of years ago and there have been a few versions so far but this one uses the latest data and includes some new features and improvements. Here's a sample map, for York. I'm going to do a follow-up post about some of the technical stuff.

As you can see, York is 82% green belt

I have put all 186 local authority maps in a public folder, so you can check that out if you're interested. I'll post a selection here as well. If you want to find out more about green belts and their history, I'd recommend reading John Grindrod's Outskirts.

See the whole lot here

This version of the Atlas is, I think, an improvement on previous ones I've produced. I'll cover more of the technical details and design choices in the next blog post but for now I'm just posting the maps, and a bit of summary data.

The reason I've done this is because I'm interested in land use, land cover and suchlike, and I know others are too. This version of the Atlas uses the latest data (2016-17 green belt boundaries), which you can find on data.gov.uk, along with data for previous years.

Here are a few green belt maps from the full set, just click an image to enlarge, or go to the full set if you want a  high resolution download. Green areas are land designated as green belt, and I've also shown buildings, roads, railways and I've added some place names. A summary datasheet for all 186 areas can be found here as well as at the bottom of the page.

But wait! Why map this at a local authority level? Well, clearly the green belts were not designated at the individual local authority level, and that's fine. But if we're looking at the kinds of things local planning authorities have responsibility for (e.g. housing) then they do need to be aware of this kind of thing, in my opinion. The Plain English guide to the planning system (paragraph 32) is a good reference point for this:

"This means that the requirement to meet housing needs must be balanced against other important considerations, such as protecting the Green Belt or addressing climate change and flooding."

So, my view is that it's entirely logical and sensible to look at this from a local perspective. 

Full green belt spreadsheet