This part aims at presenting ecological structural materials.
An ecological material on the other side of the world will no longer be, if it is transported thousands of kilometers. We will consider a material as environmentally friendly if its environmental impact is low throughout its life cycle. Therefore it takes into account the energy required for its manufacture and also for its transport to the site. Above all, we must opt for materials produced locally. It will therefore be necessary to find out about their origin each time.
Among the ecological structural materials we can find wood. It is a natural, renewable and recyclable raw material. On the other hand, to avoid deforestation, in France and Europe, wood is subject to several labels. They certify that the wood comes from sustainably managed forests. The FSC label guarantees that the wood comes from forests managed according to ecological and social quality criteria. The PEFC on the other hand certifies that the wood used for construction and reforestation is of high quality.
Wood has the ability to fix carbon in its cells through photosynthesis. This allows it to have a neutral environmental impact. Moreover, its manufacturing requires little energy: 0,5 kWh/kg for solid wood and 2 kkW/kg for plywood.
Wood species that can be used as a structure:
- Deciduous: oak or chestnut
- Softwoods: Douglas fir, Spruce, Larch, Pine
- Suitable for seismic areas
- Appropriate for sloping land and for low-load-bearing land due to its light weight
- Able to absorb ans release moisture, which is conducive to a healthy indoor atmosphere (wood is a good hygrometric regulator)
- Healthy material when the adjuvants are non-toxic and that there is no dust during manufacturing (the fibers are carcinogenic)
- Speed of execution (4 to 5 months compared to 10 months for a masonry structure)
- Saving space due to thin walls
- Good thermal insulation (thermal conductivity of 0,12 W/mK on average)
- Little waste generated during its manufacturing
- Good fire resistance
- Carbon sinks
- Lightweight construction
- Possibility of pre-fabricating the elements in the factory
- Low acoustic comfort
- Does not resist moisture well
- Some wood treatments can be harmful to humans
- Lack of inertia
Building technology – building systems
Wooden constructions come in different forms, each with its own advantages and disadvantages. They need to be adapted according to the climate, the land and the desires of the occupant.
Buildings can be classified into four main categories:
- Log house: logs are in most cases stacked horizontally
- Solid wood houses: the structure consists of wooden beams and posts
- Lightweight frame constructions: the wall of a wooden frame construction consists of beams and are filled with insulating materials (straw, straw and soil, hemp…)
- Prefabricated or modular structures: separation into modules of several dimensions
Distributed insulation masonry construction
Distributed insulation consists of combining insulation and structural materials without the need for additional insulation. The walls are both lead-bearing and thermally efficient. There are different materials that fulfills this type of function:
- Clay honeycomb bricks
- Porous concrete blocks
- Pumice stone or lime pozzolana blocks
- Hemp bricks
If the filling consists of a single material, such as hemp concrete or straw bales wooden frame is a distributed insulation building system
Fore more details on the characteristics of the above-mentioned materials check out the following section on insulation materials.
This type of construction limits the risk of poor insulating.