research

On this pyramid, the most common materials used in the construction industry are ranked from bottom (most eco friendly) to top (most Co2 emmissions).

You can also click on each material to find out it's qualities and you can also make your own pramid for your project, which can exactly calculate how much Co2 your construction will use!

The environmental impacts of the building sector

Why are things not changing?

What can be done / what is being done ?

"In the time it takes you to read this sentence, the global building industry will have poured more than 19,000 bathtubs of concrete."

Very interesting extensive article on the environmental impacts of concrete

Almost 4 billion people live in cities today and an estimated 100 million will move to cities over the next 10 years, which means that a whole lot of new buildings will need to be constructed. But how can we do this responsibly if the most commonly used building materials are responsible for a whopping 38% of global Co2 Emissions?!

The dilemma of building high-density cities to respond to the growing housing crisis v.s. lower density neighborhoods which seem to be a better option for the environment :

"Plan voor nieuwe stad met 50.000 woningen"

Production:
10 billion tonnes worldwide (2019)

GWP:
229 kg CO2 /m3

*GWP = Global warming potential

"In the building sector,
for every $1 spent on energy efficiency, $37 is spent on conventional construction approaches."

Manufacturing +
Transportation +
Type of construction materials.

Most common construction materials and their footprint:

The energy use of all built buildings per year is responsible for 28% of Co2. Without the transport, the building sector is responsible for 11% of Co2 emissions and this is mostly due to the production process of concrete.

Production:
186 Million Tonnes (2020)

GWP:
structural steel:
8831.2 kg CO2 /m3

Roof panel:
26578 kg CO2 /m3

Production:
826 million tonnes (2020)

GWP:
Aluminium sheet:
28242 kg CO2 /m3

Frame window:
1172.7 kg CO2 /m3

Production:
No data on Mt. But with 36%, Rockwool/glasswool is the most used insulation material

GWP:
21.6 kg CO2eq/m3

Production:
I couldn't find exactly how much Mt. triple glass is used for the building sector per year, but with all modern skyscrapers we can assume it's a lot.

GWP:
415.6 kg CO2eq/m3

The GWP (global warming potential) data is based on northern Europe

40% of the worlds waste is coming from the construction industry, which is insane!
This is mostly due to excess production, packaging materials and coffrages (temporary kind of molds to hold the structure in place until it's finished)

Production:
1.820 million tonnes

GWP:
415.6 kg CO2eq/m3

As we can see from the data above, the most widely used building material is concrete, and even though it is not the most destructive in kg Co2/m3, it does achieve that status due to it's large quantity.

Wood and other biological materials are also being used and are certainly getting more popular, but the numbers don't come close to these six. Why not if it makes so much sense?

Chapter nine of this report answers this question for the Netherlands
specifically.

1. Cultural transition

In The Netherlands there is a "stone" mindset, we build a lot with clay from our rivers. It has turned into a tradition/habit over the decades, whereas The Netherlands is actually a very wood-based country with a lot of opportunities for wood-based constructuon. Developers find it difficult to step out of their comfort zone.

2. circular concrete

In 2018, the "concrete agreement"
has been signed by Dutch parties, stating that the goal is to reduce 30% of the Co2 reduction coming from concrete by 2030. This would be achieved by recycling used concrete. Even though some development is always better than none, the problem with this is that only a small percentage of all used concrete is suitable for recycling and compared to the growing demand for new concrete, it is not a good enough solution.

3. Lack of knowledge and specialists

In The Netherlands there is not a succesful and established bio-based building industry yet with all the specialist organizations that come with it.
So for Architects or builders who would want to transition, there are some places to look for knowledge and collaboration, but not enough.

4. The "reputation" problem

Wood and other biobased materials don't have a very good reputation in The Netherlands, because in the 80's they have been used in the wrong way and were not well-protected against the weather and other conditions. There are also success stories, but negative news resonates longer.

Wooden buildings are also thought of as more dangerous due to fire. But the opposite is true for the new way in which construction wood works. The way cross laminated timber burns is very predictable and it also does not burn more than 2cm of the outer side of the wood, which means that a construction will not collapse. Because the core of the wood does not get hot enough to burn.

Other biobased materials such as straw can also be made completely fire resistant with the right production process. Down below you can see that after hours of burning, only the outer layer of a wooden CLT beam has burned.

5. It is more expensive

Building with traditional materials has been in practice for so long that it has been optimised financially. Mostly due to the scale. But it is also estimated that building with traditional materials will increase in costs, simply because the needed natural resources are finite and due to increasing Co2 taxes. The Co2 absorbing qualities of timber constructed buildings is also not yet added to the environmental cost indicator, which makes this quality invisible in comparison with the environmental damages of existing materials.

6. Lack of local biobased production chains

For succesful and more affordable wood/biobased construction, it is important and very beneficial to have a local production chain, from the forest to the construction site. But in The Netherlands, there are currently no large Wood/ CLT manufacturers, which means the wood has to be imported from Germany or Scandinavia. This partially cancels out the environmental benefits of the wood, but for now, transport by train or ship could be better alternatives.

7. Lack of social concerns

The building sector does not yet think in terms of target groups, human needs and added values. The fact that people feel much more peaceful inside wooden buildings (which is measurable) is not yet a reason for builders to increase the costs and go fot it. The focus lays too much on new products, product specifications and building techniques. There is also a lack of knowledge of what bio-based exactly means. The past few years, multiple "sustainability"terms such as biobased, cicular, eco, sustainable, green, cradle to cradle, biologic, environmentally friendly etc. get constantly mixed up. This leads to a lack of awareness on what each term exactly means and this confusion also stands in the way of developments.

8. Don't we already cut enough trees?

People tend to think that building everything with wood will lead to more deforestation than there already is. People are misinformed on this subject. In the Netherlands, Staatsbosbeheer has been planting many more trees than there is cut for decades. It is also not true that cutting trees for the building sector will lead to less species diversity.
Forests can be managed so precisely and responsibly that more trees of several species can be planted than there are cut for one building. If you understand Dutch, hear architect Marco Vermeulen explain more about this!

There are a small number of architects in the Netherlands who already build all their buildings with wood and other biobased materials. In this way they are an example to the rest of the building sector. Daan Bruggink from Orga architecten is one of them.

Stimulating students to invent new materials!

I'm sorry this is also in Ducth...

Built a lot of wooden scyscrapers like these to show that it is possible.

1. Put it in curriculum

2. Architects setting examples

With clever systems like these, anybody with a plot of land and a group of strong friends can built their own wooden house in a couple of weeks!

Builder Bouw Novum built six affordable rental homes which are completely passive, deconstructable and can also increase and decrease in size. There is absolutely no concrete used, only wood. They talk about how a lot of builders are interested in working with them.