Currently we are deeply concerned with the energy transition. However, our main problem is not energy, but material. There is enough energy without us having to exhaust it or without having nasty side effects such as global warming. Think of solar radiation, surface water, wind, geothermal energy, hydropower. However lost of materials are required to capture and convert it into a usable form. While materials in quantities decrease already, just as in quality. The ores are becoming scarcer and diluted. The forest area is also limited. And usable sand is already used up. We have a material problem. What we need is a material transition. Both in quantity and in type.
German scientists have since lang already shown the need for this material transition. Even though it started in the nineties with the ‘Energy Wende’, with Herman Scheer as the big driver behind it. Unfortunately he passed away too early, the day after he presented at our Int. sustainable building conference in Maastricht in 2010 . But even then, in the 1990s, it was already realized in Germany that a material problem was looming. There was Ernst Ulrich von Weiszacker, who put factor 4 on the agenda, and later Factor 10 for industrialized countries.  Germany is the guiding country here, with a long history. Also with Wackernagel, (ok from Basel, but that’s at the German border who put the eco-footprint on the map together with Rees.  And last but not least Schmidt-Bleek, who introduced the ruck sack: all sources that are directly or used to obtain a certain product.  Together with Brinzegu, this led to the MIPS concept: Material input per unit or service. 
Schmidt Bleek put all this on the agenda with his paper: “Wieviel Umwelt braucht der mensch?” (How many sources does man need?).  Later, during a World resource forum in Davos, he described this as the need for a ‘Ressourcen Wende’, a materials transition more important than the Energy Wende. After all, no energy without materials and vice versa, and there is enough energy… Braungart, together with McDonough, later published his Cradle to Cradle approach, a material strategy that put effectiveness on the agenda: If you do something, then do it right.  But the question is even before that : can we do it anyhow, , is there enough material?
Lettenmeier and co translated that last question , by combining factor 4, mips, rucksack etc. into the need to go from 30 tonnes per capita per year of raw materials to 8 tonnes. 
We must return in material quantity. Certainly with the energy transition at hand, which only drives material demand up, from wind turbines and solar panels for example. So the demand must go down. As the Swiss agreed in a referendum years ago to go to a 2000 Watt society in terms of energy, that must be accompanied by that “8-tonne society” (although that has not been formalized anywhere else, and it could well be even less so). Which requires even more radical changes: not the step-by-step introduction of renewable energy or a step-by-step introduction of sustainable housing, but the step-by-step introduction of consumption reduction, avoiding demand for alternative facilities, or the step-by-step introduction of a different lifestyle ! That is the real transition. And here again we can learn from Germany, which is already discussing this extensively: The ‘wohlstandswende’, or the welfare or prosperity transition. 
Scheer, Weiszacker, Wackernagel, Braungart, Schmidt Bleek, Brinzegu, Lettemeier, They showed us the way years ago.
The ‘8 tonne society’ alone is not enough as a indicator.. It generally shows the right direction, but if it is 8 tons of aluminum, it is still disastrous. Because it kills that energy transition, implying an even greater amount of wind turbines and solar panels, which in turn increases material demand. After all, energy and material are inextricably linked. And for energy we have an almost infinite source, the sun, but not for materials. The 8 tonnes of materials target, will also have to be materials that in turn have a low impact on secondary sources. Which soon leads towards organic or biobased sources, and then also those sources that can be used in bulk with little processing. The ‘low tech’ materials, with a low MIPS, and a small rucksack, so to speak.
Since the flows of materials must continue to run, the cycles closed, which depends on a combination of factors, per type of source, of the volume extracted, the speed of the resources through the system and the energy to drive that cycle. The energy being system energy (from natural cycles), or (driving) energy invested by people, in case they want to make products other than those that occur naturally within ecological processes.
It is comparable to what most of us can still remember from high school physics: the PxV / T = C formula: in a closed system, pressure times volume divided by temperature is a constant. In fact, with raw materials in a cycle, the same thing is going on: the volume times the driving energy divided by the time / speed determines the impact. Or, to keep the impact constant (within sustainable limits), then if 1 parameter changes, the others have to change to compensate for that, for equal impact. So if the volume of raw material use doubles, then the speed of use must halve (twice as long) in order not to increase the material impact over time. In other words: we can produce twice as much, but then everything has to last twice as long in order to remain on the same impact. Which in itself is already too high, we must even go for a strong reduction, at least to those 8 tonnes, to reduce the impact overall. Keeping the balance at current level, is already a passed station.
With more and more people, therefore, the available volume per person is also lower, or if every additional earth inhabitant would get the same, then everyone should spend much longer with the raw materials or products, so as not to increase exhaustion per unit of time.
That is why it will be less and less, as in less volume, less speed of use, less energy to drive the business.
But also translate as “less replacement of goods”, and “less material.” And not to forget: less meat, less fliyng, and even less (surface) heating, and so on and on . Not to cause the material volumes to explode via the energy transition, (see previous article, ).
That is not a nice message, but of course we saw it coming from miles away.
We need to change the way we live, renovate our way of life. Not just renovate our homes, we also have to live differently in them. Most obvious: on less m2 per person to start, and for certain on less heated m2 per person. But also re-invent how we move around, (if its unavoidable to move or travel), and re-think how we provide certain functions (think, for example, of drying laundry on lines), and , most important, how we organize things: not with profit driven consumption, but with cooperative solutions to our needs, within those planetary limits, to materials use in this case.
So a welfare transition. But its not all that bad: that also implies that you have to earn less money , and therefore have to work less …!
 Factor Four by Ernst U. von Weizsacker , Earthscan 1998.
factor 10 institute: http://www.factor10-institute.org/index.html
 ecofootprint: Wackernagel, Mathis & Rees, William (1996)”Our Ecological Footprint” (New Society Press) and: https://www.footprintnetwork.org/
 Der ökologische Rucksack: Wirtschaft für eine Zukunft mit Zukunft Broschiert – April 2004 , von Friedrich Schmidt-Bleek
en rucksack tabellen 2014
 calculating MIPS: https://wupperinst.org/en/a/wi/a/s/ad/584/
 boek ‘Wieviel Umwelt braucht der mensch”: https://wupperinst.org/a/wi/a/s/ad/343/
 C2C: https://epea-hamburg.com/
 Lettenmeier, M. et all, 2014, Eight tons of materials footprint, in Resources, 3(3), 488-515
 Lees “die Grosse Transition” , ( in Duits) , Uwe Schneidewind, Fisher Verlag, 2018, isbn 978-3-596-70259-6