Pablo van der Lugt is an architect, author and speaker. His research focuses on the potential of materials such as bamboo and mass timber for the construction sector, and their positive impacts on the world. “Throughout my professional career both in university (including my PhD research on the carbon footprint of engineered bamboo and wood) and industry the past 15 years I have found there are many misconceptions about these materials which hamper their large scale adoption. For this reason I ‘translated’ my research findings into two contemporary books for designers and architects about the potential of bamboo: Booming Bamboo, and engineered timber: Tomorrow’s Timber. They aim to dispel these myths and show the incredible potential of the latest generation of biobased building materials in the required transition to a carbon neutral, healthy and circular built environment.” We recently had the opportunity to talk with him about these topics. Read more below.
Eduardo Souza (ArchDaily): Tell us a little about the untapped potential of bamboo. How do you see its contribution to a more sustainable future?
Pablo van der Lugt: Bamboo is an incredibly interesting resource; it grows faster than any other plant / tree (at almost 1 meter / day it holds the Guinness book of record of fastest growing plant) and has a multitude of uses (David Farrely in the Book of Bamboo reports over 1500 uses) including the recent development of bamboo paper, textile and most importantly for designers and architects, engineered bamboo building products suitable for many interior (flooring, walls, ceilings, furniture) and exterior (decking, cladding, outdoor furniture, joinery) applications.
There are over 1600 bamboo species of which the giant bamboo species (up to 30-40 meters tall, diameters 10-20 cm) such as Guadua (Latin America), Asper and Moso (South East Asia), which are most interesting for engineered bamboo products. Furthermore, several bamboos are very suitable for reforestation even on very degraded / marginal lands. In combination with its fast growth, this makes several giant bamboo a very suitable pioneering plant to stop erosion and restore water tables and biodiversity in degraded lands. Of course bamboo cultivation should never come at the expense of native forests (see the palm oil tragedy) but this is not the case for the 40 million of hectares of bamboo worldwide (with In China alone already over 7 million hectares, being extended through reforestation every year).
As bamboo is actually a giant grass species; the plant is interconnected through the roots and each year new stems shoot up. After 4-5 years the stems are ready for harvesting. As each year new stems grow up, this means that bamboo production forests are harvested like an agricultural crop; every year around 20-25% of the mature stems are harvested, actually accelerating growth of the mother plant. This means that bamboo by default is not susceptible for deforestation (clearcutting would mean the plant dies = no steady income for the farmer).
Because of the fast growth, bamboo is also a very good carbon sequestrator, not only in the forest itself, but certainly also in the many cubic meters of bamboo that engineered bamboo products that can be made from the high annual yield from bamboo production forest. In case these products are used instead of high CO2-intensive, often non-renewable materials such as metals, plastics or ceramics, there are also avoided CO2 emissions. Altogether, in case of reforestation of degraded grassland with giant bamboo, the total CO2 benefit can be over 1000 tons CO2 per hectare (1.5 soccer fields); see here for more information.
There are over 7 millions hectares of bamboo forest in China – growing every year by a couple of percentage points.
ES: What is needed for the adoption and acceptance of bamboo as a building material worldwide? Are there any limitations on its use?
PvdL: Zooming into architectural applications, there are basic two choices for bamboo.
First of all, the bamboo stem is a super environmentally friendly building material (no other building material can be harvested, dried and directly used as very effective structural building material). Although its shape and form – and for Western climates its susceptibility to cracking – definitively provides challenges, skilled architects can use the lightness and flexibility of the stem to design breathtaking fairytale-like designs, such as the structure of Ibuku in Indonesia.
Although clearly many high-end architectural constructions are possible with the bamboo stem, in certain regions (e.g. Latin America) bamboo is often still regarded as "poor man's timber", in particular when applied for low income housing.
Secondly, engineered bamboo boards, panels and beams hold a vast potential as a very hard, stable and aesthetic finishing material for both indoors and outdoors.
However, each bamboo stem is unique, making it more difficult to provide a strength classification for bamboo and making it meet Western building codes.
To a lesser extent this also applies to engineered bamboo; although far more consistent in performance, engineered bamboo as a building material and industry is relatively new (the first bamboo floors were invented about 25 years ago), meaning that there are also no clear classification systems adhering to building codes. This especially applies to structural use of engineered bamboo, although on a case by case basis some small exceptions are made; see for example the bamboo solar carport by BMW:
This limits engineered bamboo for now as hard, sustainable and beautiful finishing material in Western countries, which makes it a perfect fit with a bearing structure in mass timber.
ES: Switching now to mass timber, how could wood impact the civil construction sector in the coming years?
PvdL: The conclusion is exactly why I choose to specialize in mass timber (collective name for large engineered timber elements with consistent high-performance such as Cross Laminated Timber (CLT) panels, glulam beams and Laminated Veneer Lumber (LVL) beams and slabs). With this latest generation of timber products - which can be prefabricated based on file-to-factory practices – medium to high rise timber buildings up to 20 stories (highest timber building in the world is the 86 meter high Mjorstarnet building in Norway) can be constructed in very short time spans yielding reduction in construction times up to 50% compared to traditional building. Of course this also applies to detached housing based on industrial production.
As the source material is Spruce and Pine from abundantly available sustainably managed forests (e.g. in Europe there is a net annual increment of wood stock in the forests of 200-300 million m3 per year), which store carbon not only in the forests (European forests mitigate about 10% of annual EU GHG emissions, which could increase to about 23% by 2030 in case of increase Climate Smart Forestry practices), but also in the built environment; while substituting high CO2 intensive traditional building materials (see the carbon footprint of various building materials in this insightful CO2 pyramid), the CO2 benefit on the building level can lead to over 5000 tons for a mid-size building (equivalent of driving a mid size car 1000 rounds around the Equator).
ES: In addition to the climate crisis factor, there are others such as circularity and well-being that mass-timber buildings can provide. Can you elaborate on this?
PvdL: Circular building is a trendy word; every material producer nowadays claims to be circular, however in practice recycling rates worldwide are below 9% (Circularity Gap Report), with nowhere near enough secondary material to meet demand.
Building with biobased materials from sustainably managed sources is double circular; because of the light weight and easy workability, mass timber buildings can be built with demountable dry connections (instead of casting of concrete) that merit a second high-level life as the mass timber elements will keep its value and technical performance. Only in a third or fourth life, the elements may be chipped for production of panel materials, all the time retaining the stored carbon in the material (also referred to as Construction Stored Carbon – an interesting climate financing metric for which is developed by Climate Cleanup and ASN bank). There are many exciting projects that are designed for disassembly in this manner, both high end (see Triodos bank office) and low end (see Epos modular school in Rotterdam). That is single circular. Mass timber is double circular because of the fact that in the life time of the several wood lives (> 100 years, therefore defining it as permanent carbon storage following IPCC guidelines), the softwood trees have grown back at least 2 times in sustainably managed forests providing a surplus of material usable for many applications (besides construction also paper, textile, energy, bio-chemistry, etc); see also the graph below.
Besides this positive effect of mass timber building, the visible application of natural materials including bamboo and timber fits very well in biophilic design practices, showing higher productivity and well-being (lower stress levels) by users – this is a new research field (a good overview can be found in this publication by TRADA) which could have huge implications for the fit-out of office, educational, residential and even health care buildings. To win the war on talent, large multinational companies increasingly choose a biobased construction and fit-out.
ES: How can wood and organic materials tackle the climate crisis we are facing?
PvdL: There are 3 levers related to the climate crisis that the biobased value chain (wood, bamboo and other renewable fibers such as flax, hemp, reed, etc) combined could help mitigate: reforestation / afforestation (while halting tropical deforestation), Construction Stored Carbon, and substitution of fossil materials. If done on a large scale (e.g. 90% biobased buildings in 2050 instead of fossil materials in global cities), this can lead to a climate benefit of 100 Gt (still excluding carbon in new forests), almost 15% of the required reduction to meet the 1.5 degree cap.
Setting these conditions requires local leadership, such as shown by the French government (50% biobased use in public buildings by 2023) and the Metropole Region of Amsterdam committing to 20% of timber building in 2025.