Material selection
Finding your way through a bio-based jungle
The number of different biobased materials is steadily increasing. Each new material claims to be better and have less of an impact on the environment. There seems to be a lot of hearsay in the architectural community about the right approach. Sometimes a lot of tools that are readily available are overlooked. For projects in the Netherlands we would recommend to first look at guidance that is available. Dutch building regulations has made big steps in the last 5 years to quantify the impact of materials and also offers the opportunity to not only comply with regulation but also excel and go beyond what is required. Before considering new materials to build with we should always consider what is already there. Where an existing building has to be torn down to make way for a new building, investigating ways to keep the existing structure as a part of the new project will have more benefits than simply specifying new bio based materials
So first retink a project from the very start and than follow the R -strategies as suggested by the Dutch government>>
Concerete recycling plant in Amsterdam photo: Paro
When a structure as a whole cannot be reused, maybe the materials can be harvested during demolition or dismantling the structure. Harvesting materials is often labour intensive and there more expensive than throwing everything in a skip. Luckily, even when construction waste is thrown into a skip it usually doesn't end up in Landfill. Waste disposal companies have also taken big steps in the right direction. The management of construction sites (which is all about logistics) usually work closely together with waste disposal / recycling companies (which are all about logistics). Of course, the role of an architectural office is limited. Nonetheless we can help with coming up with solutions to limit demolition waste and our drawings can be used to estimate the quantities of materials.
Only after exhausting all R-strategies we should be looking at what kind of new materials should be incorporated into the design. At the beginning of the design process it does not make sense to look at specific products. We can only look at estimated volumes of materials we consider using. A great tool that can help comparing the carbon footprint of volumes of materials is the Construction Material Pyramid. This is a great tool that is made available by CINARK of the Royal Danish Academy. It can help make broad strategic choices.
As the design gets more detailed we can start looking at the exact structural elements, roof, wall and floor build-ups and building products to select. Also here, tools are available to compare different elements and products with each other. Dutch building regulations demand a detailed estimate for the impact on the whole project on the environment in the form of the MPG. The available tools to make a MPG calculation can be found here: https://milieudatabase.nl/
Of course it is much more fun to experiment with Hemp Lime, rammed earth and wood construction than to fill in excel sheets, but just using a material because it is "in Vogue" will not get us to make the huge transition that is needed. Using the available tools we might come to conclusions that materials and products that may not seem very sustainable actually are and vica versa.
Rather than using the tools as a black box it is important to understand how classifications in the MPG are made. There is a lot of discussion about what parameters are included and what not. At the moment the potential re-use is an important factor which is favorable for steel. This is an estimation on how elements will be re-used after demolition. Of course you cannot be certain about the reuse until it actually happens. The CO2 that is absorbed by a tree growing is substantial. This is not included in the calculation. In other words: CO2 absorption absorption of wood is absolutely certain, a quantifiable parametre and is (for now) excluded. Reuse potental is an estimate, based on current practice (now there is a lot of steel in big structural elements and a lot of wood in smaller fitout elements that break during demolition) and is included. You can see that using these tools blindly will also not bring us forward very quickly. However, the tools can give us insights that, combined with our experience and knowledge can point us in the right direction. All it take is a little common sense and we can make huge steps forward.