Green roofs, or "vegetated roofs" or "living roofs", are structures covered with living plants that enhance urban biodiversity. They provide habitats for various species, improving the overall ecological balance. By creating new green spaces in urban areas, green roofs support diverse plant and animal life, including birds and insects. These roofs offer numerous environmental benefits, such as reducing the urban heat island effect, mitigating stormwater runoff, improving air quality, and conserving energy. Green roofs contribute to preserving urban biodiversity while enhancing the sustainability and resilience of cities.
Thanks very much, Dusty, for your time on this podcast. I really appreciate it.
So, yeah, my name is Dusty Gedge, and I'm currently the president of the European Federation of Green Roof and Wall Associations, and are quite well known in the UK and around the world on my work on green roofs and specifically green roofs and biodiversity.
So let's go back to the beginning in how you first became interested in green roofs and urban biodiversity.
Well, I mean, I've got a rather interesting history, you know. When I was a teenager, I was a big bird watcher and naturalist. I was going to go off and, I don't know, do a degree in forestry or something.
And for whatever reason, sex, drugs and rock and roll, I ran away and did a degree in theater arts. And became a circus performer and an actor. That's why I moved to London, to Southeast London.
But twenty-three years ago, I set up a circus workshop for truants, who were smoking too much drugs, and these are young kids. I set up this workshop to try and use circus to get them to go back to school, really.
The guy paying for that was part of a project in Deptford, Southeast London. And they wanted a bird watcher, and they knew I was a bird watcher. They wanted a professional bird watcher, and I got employed all these bird surveys, and I found a bird called the Black Redstart, which is a protected species.
And it's an odd species because the kind of places that he likes to live are bomb sites, post-industrial landscapes, brownfield sites, you know, not pristine wilderness. And because he was protected, we had this idea we could put a heavy tower on the roof. And the rest is history.
And so it went from there?
Yeah. And there's nearly up until the 2008 plan, nearly all the green roofs that were going in in London were before the Black Redstar. So King's Cross has got green roofs. I wrote that report 2001 because it started working for us.
Okay. Got you. I know that you've contributed to many projects and publications and conferences, and you've worked with NGOs and private organizations in raising the awareness of the benefits of green roofs.
I suppose what I did was really, I was a birdwatcher. We found a rare bird, which we might talk about later. But I was really a bit of an environmental activist.
And my main role in twenty-three years ago was to try and get a policy in London. And so I basically went to Europe to find out everything. Well, I basically went so that I knew more than anybody else. And I ended up writing the technical document with a colleague of mine, Gary Grant, to support the London plan, and the policy was enacted in 2008. And we've got the green roofs in London.
Brilliant. I've done a podcast with Gary, and he mentioned you.
So yeah. Brilliant. And so I'm really glad to be recording this podcast with you, with yourself.
And also I see that in terms of why we need to do this, that there are some fifty-six percent of the world’s population are living in cities today.
Well, seventy-five percent in the European Union lives in cities that's even higher.
Right. Okay. And apparently, it's expected to increase up to seven out of ten people in 2050.
There you go. You know? I mean, what that's saying is majority, you know, UN, globally, the majority of people in the world will be living in cities. And cities have a lot of problems. And one of the problems they have is a lack of soil and vegetation, but they have a lot of buildings.
So if you saw vegetation on buildings, that should ameliorate many of the issues regarding the climate crisis and the biodiversity crisis. So green roofs help cities adapt to climate change.
But you can't believe how necessary this is today, with obviously global warming and all the problems we've got in society as well.
Well, I think a lot of us, even back twenty-three years ago, maybe even longer than that, Green Roofs isn’t on the agenda when I was in the ‘70s, ‘80s doing environment. But, you know because of the climate crisis and all the gaps we're recognizing, now governmental level, that seems important. I mean, I was just going to tell you 2004 was the first time UK government used the word climate change. I remember those things.
And in 2006, we had a heatwave in London, and I was getting millions of residents of council flats saying, you help us get on a green move car because we're overheating. Let's look at the six.
Right. Absolutely. So these things are moving things are starting to move a lot faster now. So there are many benefits to urban biodiversity in, you know, in green roofs. Can we just go through those benefits, what they are? But it's more than just having a pretty roof, isn't it? It's more than just having a green space.
Yeah. I mean, let's look at the headline issues. Obviously, my interest is biodiversity, which we can talk in more detail later. But the main reason we need green roofs is urban cooling. Roofs do something called the albedo effect. They basically reflect heat back at night, and it makes the city temperature hotter. And it's generally hotter than in the countryside because the countryside has got vegetation of sorts.
So what is known as the oven heat iron effect? Green roofs you know, you have to have a lot of them, will help cool cities down. So last year, we had the worst heat wave on record. The green rooms might not look as pretty as maybe some people may want, but they will help cool the city down.
And the other thing associated with that often after heatwave, we get these really intense summer storms. You know, these aren't the one in a hundred year storms. These are intense short five minute storms. And green roofs are sponges. And they suck the rain up. And they obliterate local flash flooding, some are flash storms.
Okay. Alright. So they helped to -- water management is a part of that then, stopping the water building up on top of those roofs, overwhelming the drainage as well.
Particularly in summer, intense summer storms because they're really, really intense. And then you've got all the other things. I mean, a big one for me now is well-being because of COVID, people being -- you know. And I was watching people in Italy locked away and I was going like, if they had a roof to go on and sit in nature.
So well-being is a very important thing, and it's slowly getting up the agenda in all cities and livability.
And then you've got air pollution, you've got noise pollution. Green roofs are really good at cutting out low frequency noise, which is airplanes. A lot of the noise pollution. And, you know, air pollution. And to a certain extent, there's some carbon sequestration.
If you got trees on it, the more [carbon sequestration], if they're marked on a green roof with your meadows, less carbon sequestration. The thing about green roofs, my friend Paul Collins always says, you're really good at saying this: Green roofs do a lot of things reasonably well. Most other things do only one thing very well. And that's a really important thing. Green roofs provide multiple benefits, not a single benefit. So a solar panel produces energy. That's what it does. But a solar panel on a green roof produces energy, and you got all those other environmental benefits.
I think it's just such an important subject urban biodiversity and urban greening, I think Gary called it. You know, just this idea of bringing the countryside into the cities and that has to be good for well-being, doesn't it? And families. So family is an important part of what we're trying to do in Awardaroo as well. So it's all about aligning the economy, the ecology with everyone. And family has to be a part of that, and green spaces can only help families too, can't it? I spoke with Jenny Bailey. And I'm going to be doing a podcast with her. What is it again? The Tales from the Countryside, a book.
I gave a lot of advice to it. It's a story about hairy-footed flower bee and the black redstart stars in it. And it’s a rather lovely book, actually. [It] Really is lovely.
Yes. So it's beautiful that that's bringing all of this together as well, you know. Businesses are interested in this as much as the public sector. Probably more so.
Well, I mean, I think it's starting to change. I mean, the main reason most people, most businesses have green roofs because there's an obligation in planning system, certainly in London. But what's very interesting this year, and I've noticed it already, most financial real asset companies have got to report on nature. It's a mandatory duty. And I go into a lot of banks and legal firms and, you know, a lot of people up in the city. And this year, I've noticed they're going, “Dusty, nature, it's really hit the business and our green roof.”
This is really interesting. So I think what's going to happen now is, I think, businesses are going to start recognizing that this is not just something they were obliged to do through the national government or the greater London authority. The edge is a mechanism for them to report on nature that they're actually doing something meaningful on their own building.
Right. Brilliant. Well, that's great news. And I mean, it's got to be good for employee well-being, hasn't it? You know, it's just nice to have a green roof to go to.
Yeah. Well, there's a little conflict there from my point, because what happened is, for whatever reasons, a lot of what happened in the United Kingdom has come from my laptop, or if it’s not from my laptop, it was Gary's laptop.
You two are the two main guys.
A lot of ecologists say, “Oh, you know, these green roofs, they're for biodiversity, so people shouldn't go on them.” And I go, well, why?
So there's a roof I go onto at 22 Bishopsgate. I can't remember which companies in here. I used to work at all there on open garden, open square weekend.
Once doing the tour, and several of the people worked in that building, and they didn't even know they had a green roof. And I said, would you like to come and sit out on this roof and have a cup of coffee. I said, we'd love to. I said, but you were happy. I mean, this roof looks like Dungeness.
If a roof is accessible, all of a sudden, it has to be private and lawn.
And there's a video I want to do soon, because I'm going to sort of tell viewers, I've got this YouTube channel. I've been doing all these videos. I went to a restaurant roof in Zurich last year when I was there. It's just a wild, what they call, alluvial gravel wildflower meadow.
It was just wild. And it's right in the center of Zurich. Now if that was in England, that would have been bamboo, lawn, and pivot hedge on.
And I think there's it'd be great if more people could, I think, anyway, you know, start promoting the idea of wild flowers and wild gardens, and getting everyone to not think that it has to be manicured to be livable.
Well, I hope you’d like to have lawn gnomes made, because I'm a massive fan of lawn gnomes, May, June, July…
So what about the challenges then? The challenges of implementing urban biodiversity.
[To be] specific, what we want in terms of urban biodiversity is, we want native wildflowers, native pollinators and native birds.
And certainly what I do, mainly what I do. I mean, I do other stuff at ground level. But, you know, in terms of roofs, what we need to do is get a lot of our lovely the oxeye daisies, the viper's buglosses, the bird’s-foot trefoils, all what we call calcareous wildflowers onto our roofs. And, you know, within that, if people are going to have access to it, you could add some non-native but good for wildlife.
You know, bamboo is non-native, but it It's got no use to wildlife. So what plants have got use to wildlife? And we started moving there, and there's one roof I should talk about, really.
So this is at the Museum of the Home, which is viewable as you go into the museum, all from above the DLR. And I was asked to design this roof, it’s not really what I normally do because it's what is known as a semi intensive green roof. And they wanted it to represent what Museum of the Home was about.
So I've got a friend of mine, David Matzdorf, who lives up in Islington, who's just (a) mad Yucca man, and he just plants all these mad plants from around the world. You know, not native. And, you know, I'm usually around wanting something like that. So I design this really amusing yuccas and alloys and curry plants.
And, you know, I'm quite pleased with it because actually when you go look at it, you go like, this is really quite interesting, but it's on the planter with the London wild flower mix, which we use on pretty much. And people said to me, you know, that's really great, Dusty, because we've got these mad yuccas sticking out. And then you go, the Echiums and the Salvias and whatever.
So, you know, there's a combination. There's a way of doing this that can give aesthetics. But for me, and I think Gary would agree because Gary is more like that, is it's the function first, not the form. Function - what is it functioning there to do? Deliver for porosity? So let's get that right.
And it sounds to me, you know, from what you were saying a little bit earlier that people can set these green roofs up and kind of leave them.
Well, that's what happens most of the time. But I think, you know, what's interesting you go to places like Berlin, you got a lot of social housing where the residents can come to these native meadows and look at them, and they will have sunbathe on them. There's a little rule. So sunbathe on them with differently, but in other examples, it says all it's like in Germany.
You find in Germany, it's really nice meadow roofs, which are my kind of roof, but they're maintained properly. They're installed properly, and they enjoy them.
Are unkept, green roofs still meet some requirements of whatever green roofs are meant to be doing there?
Only if it's done properly.
Still going to need to be maintained, though.
Only if it's doing minimal maintenance. Maintenance are a green roof, because it's not like a normal meadow ground level. It doesn't need mowing it. What it needs is a bit of an annual weeding for essentially woody plants. Do you want woody plants on the green roof?
Right. How often are these roofs just left like that then? How often is a project just to have a green roof up there as opposed to a nice living space?
Well, the majority of green roofs in most cities in Europe are what are known as extensive green roofs which really aren't roof gardens or parks. The issue in countries like the UK is because they're out of sight, out of mind, people aren't installing them as good as they should be, that's the issue.
And what's the consequence of them not installed as good as they should be?
They're not as diverse and they're not as florally rich. That's going to change because, essentially, from November, I think, this biodiversity net gain (BNG) comes in, which is a big extension. And in the city, about the only way you're going to get biodiversity net gain, and it will be in an inner city. And they're going to have to monitor those for five years. And I know that because I wrote the metric for BNG.
I'm already saying to some of these developers. I said, you know, you're going to have to be really, really careful about what you purchase. Because if you're going to have to monitor that, and it's not installed properly, you know, you can have some issues. So you're going to have to up your game, you know.
So issues being?
Well, if it doesn't deliver for biodiversity in terms of the metric, so it’s not in the scope.
And how is that going to be measured? This ten percent net gain.
Well, I have a process to measure biodiversity net gain on green roofs. But, yeah, that's a commercialism that I have. But, essentially, somebody's going to have to go up there and say whether it meets the metric. You know, all remotely like my company Gentian does?
What that means is, I specify a lot of those, and then for whatever reason, they asked me to come and basically inspect them and tick them off. I go back, I say that's not what I specified.
Okay. So how have they changed it? What would typically would they have done?
I don't want to go into that. I think it could be the assistance of my plan. I think this is going to be better, and he's convinced them. But if you do that with part of us in net gain, you use an inappropriate system. That's going to cost a lot.
We need those things done properly, don't we? Just tell us a little bit about your company then, please, Dusty.
I'll give you the background too. So, because we set up this policy in 2008, and when you go about 2010, there was about, 200,000 square meters of green roofs in London. Well, you know, I wanted to know how many green roofs were installed. So I'm not joking. I physically, every summer in 2015 until 2020, mapped all the roofs in London. Google maps.
I'm completely Sather. I'm a real Sather. So I have to meet a mate of mine, and he said to me, yeah, we could do that remotely using satellite. So we started the company, initially, to remotely map green roofs, and we're doing lots of work for local authorities across the United Kingdom. And in fact, that published a league table of the United Kingdom because I'm at thirty-four of the cities.
And that's now moved… well, it was always intended to move to be able to remotely assess a green roof in terms of part of us in that game. But we're also now doing that out in the wider country side, so we can map habitats. And we can put a plot life to map and verify whether our AI is really good at identifying you know, certain habitats characteristics. What we're very good at is identifying different grasslands, which, often, ecologists get wrong as well. So Gentian, it's a smart meter for nature, as we like to call it.
Smart meter for nature. How do you spell Gentian?
Gentian is a French well, it's an Alpine flower, G-E-N-T-I-A-N. And it's an Alpine flower. And we have a couple of French speakers in our company who I think they were the ones who decided.
Are birds returning to cities where there are green roofs? I mean, going back to your bird story, I guess?
There's a lot of black redstarts in London. I mean, I can’t be certain. But the story that I tell, I've got a video on my YouTube channel coming out in the next three months.
The linnet basically, the linnet is this small finch that was once really common. Victorians, it did have a bit of a collapse because Victorians got into caging it, and then that got banned.
But, you know, it's a very pretty, but it's not like a goldfinch. Everybody goes, all goldfinches. Linnets are kind of a little bit boring. But I've got a book of finches that I bought when I was a young teenager. It was written in 1953, but then it was common. Absolutely common. It's quite a famous book by Eric Simms for birdwatchers out there. In my lifetime, the linnets’ populations collapsed because of intensive agriculture. So in the early days when I was doing all this bird watching professionally, I was actually the official bird watcher for the Dome back in 1998-1999, 2000-2002.
So I did all the bird surveys around the Dome. And there were about six to ten pairs of linnets on the dome area, a whole peninsula, the whole peninsula.
Now, for whatever reason, there's a roof that I've been heavily involved with the last five years. And on that roof, that roof has been completely seeded by seeds that I've collected from around Kent in Southeast England, South East London. That roof in 2020 had twenty linnets feeding on it. There are now more linnets on the Greenwich peninsula than it was twenty-three years ago.
And that, because every single new development of the grand peninsula, which is a lot of developments all have green roofs, and the linnets are using the green roofs to feed on. When I stand up in front, I do a lot of public speaking, that really makes me cry.
That's brilliant. That goes to show then all and everything that follows from that, you know, kids looking out of their windows, seeing those birds.
You know, what do they need to do to go get themselves a green roof besides contacting yourself?
Well, the first thing is (to) be very careful when you go on to Google and don't buy the lightest system possible, which is what everybody does, and then in a heatwave it dies.
So I have said, I've got another little thing called greenrooftraining.com, which is a free guide to a DIY green roof, or garage and extension. And it explains all the structural implications, the waterproofing and inclinations.
And it tells you, right, you can go for that. But if you run a really good green roof and look out of your bathroom and clean your teeth, and enjoy it, do it like this.
Okay. Can you give us two or three things to think about, you know, in in terms of what they might learn on your course?
Well, it's an online guide. It's not a course.
Essentially, you want to have at least ten centimeters of soil. We call it substrate, which is a stony aggregate. You know that much. If somebody says to you, oh, we can give you the lightest green roof, you know that's not what you want. Light means not good in the green roof. You know, it's vegetation. Light means good from a structural engineering point of view, not from another point of view. That's a good point, I'd like to go ten centimeters.
And, you know, get it built by a contractor using our guide. So that it's coming out. And then what you want to do is you want a mix of sedums and wildflowers. But people say, oh, I want one of those sedum reaves, don't I?
You go, no. You've got a mix of sedum and wildflowers, and then you'll really get a lot of joy out there.
Let's get on to the other half of this, which is, you know, maintaining them, looking after them afterwards. Well, is it just like any garden then, I suppose?
I mean, the beauty of a green roof is they're so low maintenance if they're done well.
You don’t have to really worry about it. Now last summer, I'm not into irrigating because actually plants are quite good at bouncing back. So one of the problems with it last year was that it's the grass that goes yellow, and it's grass that sets on fire.
This is slightly relevant. So there was a wildfire near here. I went next day, and all over where the wildflower was, all the wildflowers were still alive. They were green because they're deep rooted.
So it was grass that was on fire. So, you know, the great thing about a green roof is you generally don't put grass on it. So it takes longer to die off, but it will. But the beautiful things about wildflowers are is they will bounce back.
When you water too much, once you stop irrigating, everything's going to die because they get used to the drug. So try to not put too much water on your roof.
Okay. That's a good tip. Really? I like that tip.
Lean and mean. The main thing is, you know, to keep things as native as possible, stop putting non-natives in, but do things which are good. And the other thing is what's important in a garden is to have you know, it's a bit technical this is have wildflowers which have different sizes of sepals.
Right? So long sepals, sepals which long tongued bees could go into, and then you have things like daisies, which have really tiny sepals. So the short tongued ones can, you want diversity is best. Diversity is best. Get rid of the lawn.
Get rid of the lawn. Absolutely. There's like a lawn near me. They just let it grow wild. Do you know? It looks great. And just so that they everybody knows that they've done it deliberately, they've sort of just mowed around the outside the circumference, the perimeter.
I get told off on social media for being -- Somebody told me, “You're the lawn Gestapo, Dusty.” I'm going like, I don’t like lawns.
Well, I think we have a problem with everything being too manicured, don't we? This is it, you know. So everything's too neat and tidy, which doesn't help nature.
You know, I walk around when we have an intense thunderstorm. I walk around and see all these downpipes coming from people's houses. And they just pour them onto the street, and all that rainwater was going into the sewage system. In parts of Germany and parts of actually United States of America, you're the polluter. You've got to do something about it.
So, you know, one of the things you can do is, like, when you got downpipe, you can run your rainwater through a rain garden and have, like, active storage.
So they're like, temporarily wetlands, they're not breaking the drainage route. They're just there. It's only rain gardens.
Gary and I wrote a guide on this a few years ago, but you just go rain gardens. There's hundreds of sites in America which tell you how to do it.
I've got forty videos I'm slowly making of different aspects of the work that I've done over the twenty-five years. And that's what I want to do is I want to communicate. I'm trying to move away from being, you know, mister policy guru, design consultant guru, because consultancies are a funny old game. And I used to be an entertainer, and I want to kind of bring my knowledge in my entertainment skills to the front because I feel I've got some stories to tell.
Absolutely, if you can bring your entertainment skills alongside your technical understanding and expertise, that's an absolute winner, isn't it?
Dusty, I really want to say thank you. I really appreciate your time and help to educate us and, you know, with the audience. Cool.
And, yeah, Thank you again.
Not at all, Paul. Thanks for inviting me.