How to win a discussion on materials

Many colleagues in the field feel frustrated when trying to improve the materials performance of buildings: the lobbying and framing of materials is huge, blurring a real discussion on what materials with best performance and lowest impact should be applied. I have come across these discussions myself many times as well.

So, How to stay on top in such discussion with other people, clients, market parties? Which arguments to use?

It can make a big difference, regarding climate change as well as material scarcity or exhaustion, which materials are used for a building. The general principle should be that materials are selected that can fulfill the desired function with the lowest impact. Not always, but often they will be biobased materials, certainly in residential construction but not exclusively. (see the straw hotel here [1]). But the knowledge about that is not yet general, or people are not yet aware of it, or misleading framing and arguments are used. So you often end up in a discussion ….

Even with people who should know better, apparently framing and lobbying by the industry to position certain materials for certain functions is successful.

Let’s have a look at some of the arguments, in case you end up in such a discussion: for example want to build biobased and avoid metals as much as possible, for functions for which there is a good and less burdensome alternative. In terms of embodied energy, metals are the red meat of the construction world: we should use that as little as possible. To outline the perspective: in production energy ( embodied energy) wood requires around 5-10 MJ /kg, iron-steel 20-30, and aluminum far above 200 MJ / kg. Those kinds of differences remain if we do not look at kg but at functions, such as window frames [2]. There are more impacts than Embodied energy, such as the impact of ore processing processes, the rucksack, such as large amounts of water use, or ecosystem destruction by digging, and so on (see previous article). But overall, Embodied energy is a good indicator for that: The lower it is , the lower usually the other impacts as well. An intermediate case is cement / concrete. Concrete, the combination of cement gravel and sand scores very low in terms of EE per kg. The problem with concrete is that it is often used in bulk, and the quantity is much too large or too strong for the requested function, with the result that the total EE is again higher than that of alternatives. In addition: suitable sand is already very scarce in large parts of the world and is already being traded illegally. Therefor basically not an option…, since ‘not available’ (although the Netherlands still digs its own pits …).

But let’s take a general and common case, for example when you propose wooden window frames instead of aluminum. Then the discussion inevitably follows: (but works in other cases as well)

Yes, but with recycled aluminum the score is much better …

1 Firstly: all materials can be recycled, that is not a distinctive criterion and for virtually all materials in that case the impact of the process is considerably less. *

2 Even with recycling, the impact of aluminium is not lower than new steel, and still much higher than new wood. Let alone if we compare recycled aluminum with recycled steel or recycled wood. **

3 By recycling you condemn someone else to use new material, because at a certain point the amount to be recycled has run out.

Well yes, but aluminum lasts a long time …..

1 that applies to all materials. For example, go to Troyes in France (but there are many more such cities) and you will see wood constructed houses of 500 years old. And in Yemen even mud constructed apartments of 9 levels high (!), also hundreds of years old.

Its all a matter of design and maintenance. Apparently, If we need aluminum for a facade, we probably design bad facades and correct that with aluminum, what difference does it make …

2 If it lasts a long time, then why is it used for drinking cans, for example? If something has a short life, it is drinking cans. Yes, but again, ‘recycling’ follows. However as previously written here: the loop time is six weeks, and in the UK 50% is recycled: but then 50% has already disappeared !. And after 1 year, and 7 loops/ cycles, almost all aluminum has disappeared, so every year all aluminum has to be replaced with new. With again High Embodied Energy.

Yes, but if you produce the material (aluminum for example) in Iceland, with renewable energy …

1 even then it remains an enormous amount of energy. It is a misunderstanding that only fossil energy is a problem: renewable energy must also be limited, because it does not come without impact: huge amounts of materials must be used for this, for wind turbines or solar panels for example. Which again costs energy to produce …. Yes, we have to go towards renewable energy, but also towards less energy use!

2 Yes, Iceland has renewable energy, but we already need that renewable energy for our normal business, let alone that we would suddenly have to spill it to use high impact materials, especially if it is not necessary for certain functions.

3 all renewable energy that is put into an actually unnecessary production, as a consequence other real necessary production processes must therefore build new wind turbines or solar panels, instead of using the freely available renewable energy from Iceland.

4 The use of materials in general increases sharply and therefore the impact. Every alternative with a lower impact helps to reduce the impact, and to reduce the number of wind turbines and solar panels that are needed, which helps reducing the energy and material impact overall.

Another argument you may come across is:

yes, but in the future, when the building is ‘abandoned’, it is easy to recycle.

1 Perhaps, but as stated before: everything can be recycled, so also in the future. Moreover, what happens in the future cannot be counted as an advantage now. That is ruling far over your grave, who knows what happens in the meantime. (which, incidentally, science is sometimes also guilty of)

2 In addition, using new material now, with the argument that it can be recycled in the future, is in conflict with the Brundtland definition: it states that our children must have the same choices as we do: they are condemned recycling, they don’t have that choice. They should also have the opportunity to use new sources instead of living on our waste.

3 If someone uses this argument, just ask why he then did not use recycled materials now, today?

After the supposed advantages of the own material, follows the attack, to highlight the disadvantages of the alternative … in this case, for example, of wood:

Yes, but wood has a lot of maintenance and paint work, that is also an impact.

Yes and no: No, some types of wood can do without paint. It is only aesthetic that they are usually painted. Other types of wood indeed need to be painted, and yes the paint gives an impact, but that doesn’t come close to aluminum or even steel. And yes, someone has to paint. But what’s wrong with that? That is employment, and very sustainable. Yes, the painter could have done something else in stead of painting. But should we therefore opt for window frames with a very high impact? So that the painter might be free to work in the aluminum industry to sell even more aluminum?

And of course the inevitable final argument:

yes, but forests disappear if we all use wood.

That is the most misleading of all arguments: While everyone knows that wood is a renewable resource, and is being renewed, pretending it is also a non-renewable resource, while aluminum or steel ores, or other materials, are only being exhausted! The non-organic material adepts/ representatives never take responsibility for the recovery of the stock! [3] They just deplete….

Of course, wood is not infinite, which does not mean that we are not allowed to use it (then we would not be allowed to do so with other materials), but it simply means that we must also treat wood responsibly and thrifty, just like other materials. But the fact that wood has limitations does not mean that we have to use alternatives with a huge impact. Rather, we should limit our use, also of wood.

Incidentally, the above does not only apply to window frames, it generally applies to material choices, with biobased or renewable raw materials being preferred. Of course, there are applications that require iron or aluminum, or concrete. Great: if there is no alternative, then that may be the right choice. I have nothing against metals or minerals as materials: In general its good to realize there are no sustainable materials, or non sustainable materials: Its the use thats important: its sustainable use of materials that counts. (or use of buildings or products) .

Well, if you come across other arguments, I would love to hear them.



* WEBO in Rijssen, the Netherlands for example produces window frames from recycled wood.

** some figures ( estimations, ICE database) [4]

Alu virgin: 200-230 MJ/kg

Iron/steel virgin: 25-35 MJ/kg

Wood virgin: 5-10 MJ/kg

As a application, for instance window frames, the difference remain:

Recycled Aluminium , is still at the same level as virgin steel. And still much more as virgin wood. And if we make the fair comparison: with recycled steel and recycled wood, the differences remain:

EE-alu-recycled: 25-35 MJ/kg

EE steel-recycled: 8-10 MJ/kg

EE wood recycled: 0,3-3 MJ/kg




[2] Sustainability analysis of window frames , M Asif et all, Building Serv. Eng. Res. Technol. 26,1 (2005) pp. 71 Á / 87

[3] circular blog en

[4] Inventory of Carbon and energy (ICE) Version 2.0 , Prof. Geoff Hammond & Craig Jones Bath University, via: In juni verschijnt een nieuwe versie

Author: ronald rovers