Some time ago , I was in a meeting for writing a biobased building manifest. Very interesting discussions, which were hardly ever held at the policy level. Although I get signals that the discussion about the impact of materials, as a rebound effect of all energy measures, does penetrate mainstream discussions here and there, albeit without concrete results yet.
It has long been evident to insiders that it is impossible to escape from biobased building. As is evident from, among other things, work in the international IEA research group EBC Annex 57, on embodied energy. I quote from the final report:
Even without possibly including negative emissions (CO2 recorded in Wood), wood for load-bearing structures and finishing is proven to be the preferred alternative, compared to “heavy alternatives” such as concrete. Comparative case studies from Sweden, Norway, Korea, Denmark and the UK show this. . So let that be clear.
Just last week, at the SBE 19 conference in Graz, Dr. Urge Vorsatz, vice / chair Workgroup3 of IPCC, and co-author of the 1.5 degree report , stated “that in order to have any chance of staying within the 1.5 degree scenario, buildings must be zero energy, CO2 must be stored in building materials, and phasing out cement and steel. ” Let that also be clear. And she forgot to mention Aluminum. But: Don’t listen to me but to science, as Gretha Thunberg tweeted last week in the run-up to the UN meeting this week.
The problem, of course, is that the non-biobased industry is large and rich, and does everything it can to make itself indispensable, while the biobased industry, the bulk agricultural materials, is hardly organized, has no power and has no money.
How then do you get in the spotlight? The biobased movement is struggling with this. The interests are great. And as a discussion leader said: the word biobased does not give me a warm feeling, does not tell me much. That will apply to more people. Bioenergy, that’s what works.. But we don’t want that, that is to destroy valuable resources.  You better build with themt and possibly use them later for their energy value, since that is retained ! (but even then its better not to burn but reuse).
Then there is of course circularly, but circularly as is currently advocated is meant to keep non-renewable materials in the picture! Its promoted to get accepted that there is a ` technological cycle ` for so-called non-renewable raw materials? Nonsense, its just a depleting cycle (a non circular cycle) that is attempted to get accepted. But why would we accept that so-called non-renewable one receive that improper advantage compared to renewable ones, and are therefore treated equally? While they exhaust the worlds resources? 
The biobased or organic world joining the “Circular” world, as it is now taking shape, is in fact being encapsulated by the major financial interests of the non-renewable raw material world. In that sense, circular can even be seen as the enemy of renewable or biobased building!
Well, in the end , its now mainly about reducing CO2, right? In that case you must first focus at CO2. And circularity? Yes, but really, only with stock recovery. CO2 reduction, and non depleting of stocks will bring you to biobased materials. Maybe w eneed a new term for that, so from now on I personally propose to speak of “vegetarian building”. After all, what applies to food also applies to materials, a shift to a vegetable diet. In fact, metals can be seen as the ‘red meat’ of the building materials: with the highest impact that should be avoided. To prevent, as I wrote once, Carbon Bomb buildings. The benefits are countless. .
That brings me to a number of conditions for a “manifesto” on climate change and buildings:
1) CO2 impact must guide every decision
2) Naturally stored CO2 is of vital importance
3) it is only circular if the stock of raw materials recovers (or is restored).
4) For construction, this leads to biobased construction, or vegetarian buildings.
Some explanation with the issues:
ad 1: If we want to prevent or curb climate change, we need to focus on greenhouse gas emissions, and for construction that is mainly CO2. And that should not be packaged in all kinds of assessment tools as one of the many criteria, since it will be lost in effect. Absolute CO2 is the measure, the urgency is big enough for it. See the recent reports from IPCC on the 1.5-degree measures and the report following cop 23 in Katowice. [5,2]
ad 2 Every construction activity increases CO2 emissions, since It is impossible to change anything without using energy. Even using renewable energy, is via solar panels or wind turbines creating impacts. On the other hand, there are materials that, although requiring energy to produce, have already stored CO2 (carbon ) in themselves, and therefore drastically limit the impact. These are of course the vegetable or vegetarian materials. Applying these is the first step in CO2 emission reduction. (By the way, there is a limit to what nature can produce per year, without decreasing its stocked capacity: limiting construction in general is also globally a necessary strategy)
ad 3 In other words, if the stock of used materials does not recover, then it is not circular, but linear. It is only circular if the stock recovers or is restored. Or in other words: If it doesn’t grow, don’t use it. Not only locally, but also as a total global stock. So maintaining capacity within the time of use * (or give nature time to recover. )
ad 4 Construction is pre-eminently a sector that can use biobased or vegetable (and some renewable mineral) resources. Metals can be avoided for almost all parts, there are vegetarian alternatives. And here and there we could allow some small iron parts, for some door hinges for example. Aluminum, on the other hand, with a CO2 impact as high as 10 times as iron and up to 20 times as high as wood, must be eliminated.   Construction * can entirely do without.
Let’s get rid of the Carbon bomb buildings, long live vegetarian building!
* I am talking about main construction work here. A critical point however are installations mainly composed of metals. Here too, just like the car industry, we must look for alternatives, and where possible even avoid installations through good design solutions. Such as the Baumschleger Eberle office in Austria, ‘2226’, which functions without heating and ventilation system. 
 IEA EBC Annex 57 Embodied Energy: All reports can be found here: http://www.iea-ebc.org/projects/project?AnnexID=57 The described building is in the report of Subtask 4 pag 324 case studies.
 IPCC 1,5 degree report https://www.ipcc.ch/sr15/ IPCC, 2018: Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways
 UN The emissions gap report 2018 https://www.ipcc.ch/site/assets/uploads/2018/12/UNEP-1.pdf
 http://www.ronaldrovers.com/circular-in-circular-economy-is-missing-its-about-linear-slow-down/ and following blogs 2 and 3
[8 Sustainability analysis of window frames , M Asif et all, Building Serv. Eng. Res. Technol. 26,1 (2005) pp. 71 Á / 87