 My name is Stefan Kampelmann. I'm an economist by training and I work at the Faculty of Architecture Lacombre Orta at the Université Libre de Bruxelles. No idea. I have to probably more or less around the same time that I got involved in circular economy. I don't think I could say which of these two concepts was the first. I think it was more or less the same time that I heard about urban metabolism and the circular economy. I think both of these terms were quite intuitive from the beginning. These things kind of you don't need a huge explanation of what is behind them because themselves, concepts are quite intuitive and accessible and I think that's also why I was I think really starting to use them by myself to illustrate certain things that before maybe didn't really have a name or like a catch-all thing that you could say okay you know this whole discussion about sustainability of cities or a new way of doing the economy. Well you have circular economy and urban metabolism and then I started to talk about circular metabolism so that's kind of a good way to have a shortcut to a whole bunch of different concepts and thinking in just this one term. As a way of explaining to people what I'm doing. What field are you working? I'm an economist that then moved into the exploration of environmental issues or environmental problems especially urban areas but that's a long line. So just to say like I'm working on how to turn the metabolism of cities more circular it's just a very straightforward thing to do. So it's more about like the tagline that was conveniently capturing the field that I'm working and not like one aspect of the field. It's the field that I'm working on circular economy and urban metabolism. I think it's mainly still I mean it's very different for circular economy and urban metabolism. Circular economy has made inroads in loads of discussions and policymaking consultants have been actually the first to pick it up and you know like putting it into their way of you know framing necessary transitions or new strategies of doing business and etc. So circular economy is everywhere or at least it's becoming like a mainstream thing whereas urban metabolism has stayed more like a more scientific term or more like a concept more than a policy also because it's more descriptive in its scope. It's like circular economy is already like we want to render the economy more circular. So there's a thrust, there's an objective, there's a normative thing to it as well because linear thing is bad and the circular thing is good. Urban metabolism is just like any city be circular or linear has a metabolism you know so it's just a descriptive rather than descriptive and analytical but less normative you know so it's more like a tool that you can use you know in academic discussions or in studies on how cities work and so it has been more limited to people who are studying and discussing cities in academic context or other I mean other people that in institutions have been trying to you know condense huge amounts of information and data on on cities into one you know one one approach but other than that I think many policymakers or I mean the general public would still find the term a bit exotic and and really just discovering the metaphor you know okay like his body has a metabolism and the city is also metabolism and okay you can talk about urban metabolism but but you know that's that's still you know that's still not into mainstream discussions it's hard to say because I'm obviously very biased in the kind of you know encounters and discussions that I that I have due to the fact that I'm you know I'm very interested in it and I meet people that are also interested in it so you might get the impression that that more and more people talk about it because you know that you meet all doing that this being said I think there's kind of a tendency and I mean in the large cities but also also maybe in smaller cities to try to find ways to to deal differently with you know big amounts of data that they have or gaining a more holistic understanding of what's going on in the city development and and this is kind of triggering maybe like a more interest also to to explore urban metabolism as a as a tool and as a like as a way to deal with that amount of information and and I think this is this increasing it's it's probably more has been picked up more on the on the other on the northern side of the the borders I think the Dutch policy makers or public administrations and you know consulting landscape has been a kind of more enthusiastic in embracing the term to to talk about complexities with loads of flows but also in Belgium it's you know it's it's maybe there's a tendency of saying okay you know this is maybe what we need to to understand the complexity of you know this this this this living thing of a city with loads of things moving all around and and different database that cover different things lots of lots of parameters that we want to understand it's too complex to do it right now but maybe this is something that we can use as a kind of yeah so as a framework or as a bunch of tools that we can they can deploy to me one of the the the challenges that I find very interesting and and to which like on which we I think should spend more energy on is to to find the representations of of this thing of metabolism I mean the metaphor is fine enough but but afterwards you end up with I mean these huge data sets and and and like a very well things that are hard to communicate in the end and they're difficult to use by non experts and the the risk is to to oversimplify things and have like very simple representations of the other metabolism so so I think if we had better tools to to to visualize and represent without oversimplifying the complexity of of metabolic flows I think that would really make a difference in terms of you know showing a minister in charge of I don't know like the development programs well you know this is what's going on this is how it could look like you know you know just to just to condense information in a more reasonable way and I don't think we have seen like the the perfect tool for that yet I mean there's there's people working on that that you know they create a very impressive graphics and then the you know flow diagram set up more sophisticated etc but but sometimes still ends up in spaghetti soup and then you don't really understand more you just see okay it's complex but you don't you know and you can't work with that to to formulate policy for example but this you know we need these kind of if you want policymakers to engage with it and use that in their decision-making it's it can't own not only it should not only represent complexity but also you know ways to deal with it lines of force opportunities etc so yeah like a better representations better way of condensing information without over simplifying or reducing to too much the the amount of information that is conveyed maybe to illustrate that this kind of kind of work with something that I'm working on right now so we we work on the different flows of organic matter here in Brussels and you could say okay there's this there's 400,000 tons of organic matter in terms of food imported into the city and out of that 200,000 tons end up in the incinerator and you discuss the the the overall metabolism in terms of you know these big flows and afterwards you can you can you can distinguish different types of organic flows if you know kitchen waste greenways in within greenways you can you know split it up into different fractions etc you can distinguish within different types of producers of organic waste you can look at different treatment options that you have for dealing with your organic waste you can look at different collection mechanisms so you can open the box of what is really going on in the city or how it could be improved and you end up with a with a with a matrix of a super complicated system okay with loads of them so I try to make a like a visualization of this based on like a you know big database of flows that we you know put together with with with the colleagues here at the the faculty and you end up in like a very sophisticated tool in which you see it all but in an incomprehensible way for anybody who's not you know used to looking at a big flow diagram so I did this with a like with a with a software for you know mapping material flow material flows so I was very happy with it so I say okay finally I see it all and I'm sure I don't forget anything and I like I follow the nuances and I make all the distinctions and everything and I showed it to the to the to the guy I'm working with at the regional environmental administration working on organic waste who is an expert on the topic and he told me like you know that's not useful that like I don't see anything nobody like I don't understand it nobody will understand it this is way too complicated the minister will throw it out like this is this is not helpful you know so and then he showed me a diagram that we produce like a synthesis diagram that we produce another study that that like an architect in the colleague of mine produced very nice very simple diagram nice colors like it kind of more appealing way and this you know that could be like it try to do something more like this you know and yeah and that like you know that proved to me like okay you know this simple diagram for me had a lot of lacuna because it missed certain things that we actually wanted to push you know so you know some of the things that we wanted to that the for example policymakers to to understand weren't really on that simplified diagram so I needed my complicated diagram and now I can you know I'm trying to explore something maybe in between or like maybe something that renders certain aspects of a more complicated diagram more appealing or more visual like you know adding I don't know you have in the flow diagram you have a picture of the the factory or the like a picture of like a treatment process or something to you know to create points of attention that this is the important stuff and all the other things maybe less important but if you want to look at them you can go into them so so and there's no like now there's no off-the-shelf tool that you can say okay you know this this is the exactly the right tool because I think in each case I mean the tension span is maybe different the knowledge of the people that are using the tools is different so you can expect maybe more from from a technical policy officer then from from somebody in a cabinet who has you know two minutes to discuss one thing before jumping into the next topic you know so so this is like a like an example of yeah like a like a like a concrete way that we you know try to invent new representations of urban metabolism that you know become used outside of academia maybe it's the tools you know so if you had the you know tools that everybody needs like all these different maybe there's a certain like there's different types of actors that that could use the same tool for their job like the academic can use it to deal with you know data complexity the policymaker can use it to show that their their policy you know reaches certain objectives you know the the the policy officer can use it to to monitor you know daily daily stuff so if you had the like tools that are used by different actors maybe that's that's a way to say okay we're always coming back to the same thing so that's why we like when tools evolve you need to you know talk to each other and and and collaborate so maybe it's maybe it's sharing similar tools which implies that you know certain things that are used in the academic world need to be maybe a bit less sophisticated a bit more more accessible or there's like different layers of things like you know that they can be a sophisticated version or complicated like in the spaghetti diagram that I just mentioned like you know I can have this at the back end but then the same thing feeds into maybe an interface that is much more accessible and much more yeah kind of condensing things and yeah so so so tools maybe but but I think like another avenue of further collaboration on urban metabolism I mean it's also I mean it would be nice to see worlds in which the policymakers see this really as a thing that they that they that they that they you know put a high up on the agenda and say like you know it's an actual thing that we try to improve like the urban metabolism of a city like I don't know Paris or London or Brussels it is something that we consider as a as a like as an object that we want to work with which they don't so far because so far like until now you have a guy that's in charge of energy if a guy in charge of water there's a guy in charge of whatever concrete or like a building building the building sector like urbanism and and nobody's in charge of the urban metabolism because it's the whole thing together you know so you know in order to you know to different people to work together like at some point you know it should be said that like you know like with climate change to say this whole abstract thing becomes a thing that we the climate change becomes something that we that we want to address and that we that we want to work on urban metabolism could be another like could transversal systemic thing that we say okay we we attach certain objectives to this to this way of seeing the world like let's say if there's a way to say the urban metabolism is so much linear so much circular it would be nice to to to then based on that measurement say okay our objective is to become so much more percent circular by by that by bite in ten years or something you know then everybody could work with it then policymakers could relate to it then researchers could say okay you want to reach their objective here's a couple of things that you that you might consider or we did some scenarios or tested things final things I think there's a risk in urban metabolism of being kind of non realistic it's a discussion I mean cities are gaining I mean cities have so much attraction to them I mean that they're gaining traction as we speak by the day big cities grow grow bigger and urban metabolism is I mean for me also include that is an attractive field because it feeds on that dynamism and and the attractiveness of cities it has the risk of of like of forgetting everything there is outside of cities you know so it's it's like urban urbanites that are interested in the environment look at what's going on in this parameter where it's maybe more important or is as important to look at things that bigger scales and look more as like at the scale of the territory on which the city depends and urban metabolism sometimes has the I mean has the risk of like you know just staying within these city boundaries and like okay let's improve the city etc like the way that the city works and and forgetting the relationship between the cities and and and the territories on which they depend and so so so like you know I this this notion of territorial metabolism or territorial ecology kind of circumvents that or like it overcomes a bit this this being confined to to the urban metabolism to the urban part of the urban metabolism because any urban metabolism is always a metabolism that that is an interaction between the the urban core and the peripheral territories or other cities with which they they they engage so I mean let's let's let's use urban metabolism but let's not forget that this there's a that the the the urban moment to it is only a part of the of the flows