Biobasecamp is a pavilion and an architectural expression of how “building with trees” can contribute to the reduction of CO2 and the reduction of nitrogen by replacing conventional building materials, such as concrete, with biobased materials. The deck is composed of large modular floorboards made of cross laminated timber.
The CLT used, was made in a German factory from German coniferous wood. But why is there no Dutch CLT yet? By creating more economic value for wood, more forests can also be planted. The building assignment can in this way contribute to combating climate change and the quality of the Dutch landscape. This may also apply to the Brabant poplar landscape that originated from the production of clogs and matches. That is why the deck was supported by branches of poplars that used to be on the A2 motorway near Boxtel, but had to be cleared due to their age and the risk of being uprooted.
With the pavilion at Dutch Design Week we wanted to introduce visitors to biobased building and in particular the use of cross-laminated timber. It generated a starting point of exploration for designers and clients towards the possibilities that this “concrete of the future” offers.
To compare this pavilion with the Crystal Palace built in 1851 in world exhibition in Hyde Park (London) and symbolized the industrial revolution is of course far too pretentious. But may this pavilion at the least mark this possible turning point for a new era!
Building against climate change
One of the main climate objectives is the reduction of our CO2 emissions. But can we also extract CO2 from the atmosphere at the same time? This is possible at high costs and in limited scale through machines currently being developed. However, there is still no machine as cheap and efficient as the tree. We learn early in school that trees convert CO2, under the influence of sunlight, into glucose to grow. When trees die and decay, this CO2 is released again. When we burn wood and use it to generate electricity and heat up our homes, the stored CO2 is also released. However, if we make building materials out of it, we can capture and store CO2 for dozens, perhaps hundreds of years!
In other words: by building with wood, CO2 is actually extracted from the atmosphere. In contrast to, for example, costly storage under the North Sea (CCS), this form of CO2 storage creates value in the form of buildings. The construction sector can thus play an active role in the fight against climate change. That is certainly true now that the Netherlands is on the eve of a huge housing challenge; one million houses have to be built in the Netherlands in the next 20 years. In addition, a large part of the existing homes must be made energy efficient. Both assignments act as a powerful driver for the transition to a biobased economy.
The emission of nitrogen over the entire construction chain is also many times lower in bio-based building than in the traditional building process. This is mainly due to the reduction of construction site handling when dealing with the prefabricated building components. In addition, biobased material is a lot lighter, which means that less energy, and with that, less nitrogen emissions, is required for transportation. In conjunction with actions such as shrinking the existing livestock and lowering the road speed limits, biobased building is a crucial piece of the puzzle in solving the current nitrogen crisis.
The construction sector is responsible for a large portion of global CO2 emissions. The global pressure on natural resources is also high: 40% is used in construction. In the Netherlands, that amounts to 250 million tonnes of raw materials per year needed for infrastructure, residential and non-residential construction. In addition, the construction sector is overheated and qualified personnel are scarce causing prices to rise. Change in the construction sector is therefore necessary in order to realize the vast amount of new housing required. Building with wood offers an alternative whereby the total production capacity can be increased. Prefabrication and simple assembly methods can also increase construction speed.
Solid timber construction
For almost all building parts there are bio-based alternatives such as wood wool and cellulose for insulation, and hemp fiber and flax as biocomposite elements. But especially the use of solid timber for the structural shell – the walls, floors and the roof -, is a highly potent material. Fast-growing wood can be sawn and glued in perpendicular layers, creating large sheets with different thicknesses, aptly named cross-laminated timber (CLT). These large structural elements can be industrially manufactured into the desired shape and provided with recesses for windows and pipes through CNC milling. These elements are then assembled “dry” at the construction site. This construction method is still in its infancy in the Netherlands, but its implementation in Austria and Germany, for example, shows the possibilities for faster construction speed, lower construction costs and better working conditions for construction workers. In addition, solid wood construction has a tactile quality and promotes a pleasant indoor climate. By making solid wooden elements modular, they can also be easily replaced or adjusted, which increases the flexibility of use. When a CLT building is no longer adequate, it can be dismantled relatively easily and its modular elements can be reused and reintegrated in a new building. If the wooden elements can no longer be re-implemented, they can be recycled into low-grade wood products such as veneer, chipboard and insulation material.
Where then do we get all that wood? The Netherlands has a total of 365,000 hectares of forest, more than half of which originated as production forest used for firewood and previously in timbering mine tunnels. 225,000 hectares of Dutch forests are now protected nature areas. The remaining 140,000 hectares of forest can be used for the sustainable production of wood, as is often the case in Scandinavia. This means that trees are harvested in a limited and selective way and replaced by young specimens of the same or different species. This yields an average wood harvest of 8m3 per hectare per year, with poplars even up to 15m3 per hectare per year. This amounts to an annual production of 1.12 million m3 of wood. By diversifying the size and type of forest plantations, we add ecological, landscape and recreational value the often monotonous forests. This also benefits soil life that suffers from nitrogen emissions from traffic, the bio-industry and (conventional) construction.
An average of 50 m3 of wood is required for the construction of a home. That means that we can make 22,400 homes from Dutch wood every year and will require 45 years for the realization of 1 million “home-grown” homes. In other words: 60 homes per day “grow” in the Dutch forests. If we want to speed up production, or use the available wood for other purposes, we can import wood or plant more forests. Higher demand for wood therefore does not lead to clearing, but to more and better forests! Adding value to forestry is also an incentive for parts of the Netherlands that suffer from poor soil quality, low spatial quality and/or a declining agricultural economy. Perhaps we may even live in these new forests. Building with wood could therefore make the Netherlands more beautiful!
If not now then when?
How do we kick start the transition to using biobased materials? After all, we are used to building with concrete, stone and steel in the Netherlands, with wood yet to prove itself here. A number of exemplary projects must therefore be realized quickly. Preferably entire neighborhoods should be built so to benefit from the economy of scale of prefabrication and to give the construction chain the chance to organize itself in the Netherlands. Governments can also play an important role in this by making building sites available under the condition that only biobased materials are used for construction.
The demand for biobased material use in construction will also increase if the price of traditional materials, such as cement, rises. The shortage of traditional raw materials will help, as well as the announced CO2 tax. And possibly storing CO2 in a building may even become a revenue model!