If you have already checked out my background and general research page, you have read what my prototype will be. For convenience I will explain again what I will do.
I thought it would be nice to make something that's also related to my minor and my graduation, so I can learn something useful (for the future) from this practice. I will do Archineering at TU Delft as my minor. This is about material choice and making prototypes with those materials. I'll try to connect this with my graduation profile (still social) by working with earth-friendly materials. After my graduation I'd like to work at a progressive sustainability - based firm such as Waugh Thistleton Architects or Studio Marco Vermeulen.
On this page I show my research on the walls of passive and biobased buildings. Because the most important aspect of a sustainable building is what it's built with and how well it is insulated.
What goes into a wall?
1. Outer facade of wood
2. Slats for the wood
3. fiberboard
4. Wooden I-beams with insulation inbetween
5. wrapping foil / breathable membrane (let's humidity out but not in)
6. multiplex on the interior
Outer facade
Bamboo
This article (click) helped me understand different types of sustainable woods and which one to choose:
Gewoon hout, of toch bamboe, finti of accoya?
If I were to build a sustainable cabin, I would personally choose bamboo for the facade. Any type of wood is obviously already much more sustainable than a steel, brick or concrete facade. But bamboo seems to be the best of the best in terms of sustainability. Unlike tropical hardwood or other trees, bamboo grows extremely fast and has therefore no impact on any deforestation.
Dutch supplier MOSO also has their own facade slats that come with the bamboo, which is very convenient because you can built the entire facade in just a couple of hours if you are building something small like a cabin. The bamboo simply clicks in the slats and you don't have to do any hammering or drilling.
The structure: wooden I-beams
Finti I-Beams instead of traditional wooden beams
Finti is another very sustainable type of wood which is sourced from Finnish so called "production forests", which are managed specifically for using the wood and therefore other existing forests are not used. The I-beams can be used for the floor, walls as well as the ceiling and due to the double wood they are extremely stable. Insulation can also be tucked in nicely into the space in between and does not bulge out like often the case with single and smaller traditional beams. Despite the fact that Finti I-beams are larger in size, they are up to 40% lighter than traditional beams and you also need a lot less of them because of their high stability.
Insulation
Hemp as insulation
= no need for extra fireboard
I looked into multiple options for biobased insulation, but hempcrete seems to have the best qualities overall. It has all the qualities in one package; it is lightweight, has a very high insulation value (Hemp alone is R3.5 and together with the rest of the biobased wall, your total insulation value can easily go up to R5 which is when a building is completely passive), hemp is also fire resistant and completely reusable. But the best aspect to me is that an extra layer of 4cm fiberboard (extra insulation) is not necessary when you use hemp insulation.
Breathable membrane
Yes, it's plastic, but it's a necessity
Every building has to be wrapped with a membrane, to be able to regulate humidity. When there is wood in the construction, it has to be protected against rain. A breathable membrane in between the slats of the bamboo and the I-beams will make sure that any humidity that goes into the walls has a way to get out as well, without ever reaching the inside of the house. The brand of the membrane does not really matter, because they all do the same thing.