Innovation in Wood: a conversation with Pablo Van Der Lugt, specialist in Biological Base Construction

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Pablo Van Der Lugt, wood and bio-based construction expert, TED Speaker and published author.

Pablo Van Der Lugt, specialist in bio-based construction from TU Delft | TEDx Speaker | “Built by Nature” Board Member | Owner Green Issues Consulting | Author of "The wood of tomorrow" and "The booming bamboo" | World Bamboo Ambassador

1. Innovation in wood:

In recent years, we have seen a resurgence in the use of wood in construction. What, in your opinion, are the greatest technological advances or what has happened in the world to make wood a competitive material in contemporary architecture again?

First of all, technological innovation in the timber sector. In particular through the development of large, prefabricated, strength graded mass timber products such as Laminated Veneer Lumber (LVL) and Cross Laminated Timber (CLT) the performance and efficiency of timber has significantly increased. With this latest generation of timber products – which can be prefabricated based on file-to-factory practices and parametric modelling – 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 https://www.archdaily.com/934374/mjostarnet-the-tower-of-lake-mjosa-voll-arkitekter  ) can be constructed in very short time spans yielding reduction in construction times up to 50% compared to traditional building.

Tallest timber building in Norway

Another significant difference is the increasing focus on sustainability and circularity in society. Also besides solely looking at operational energy consumption in a building, the embodied carbon i.e. the CO2 emissions related to the manufacturing of building materials has become increasingly important.

And the climate benefits of using sustainably sourced renewable materials, including timber, are enormous! There are 3 levers related to the climate crisis that the biobased value chain (wood, bamboo and other renewable fibres such as flax, hemp, reed, etc) combined could help mitigate: reforestation / afforestation (while halting tropical deforestation), storing carbon in the built environment (1 m3 of pine almost stores 1 ton of  CO2 for the lifetime), and substitution of carbon-intensive 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 25% of the required reduction to meet the 1.5 degree cap. https://www.pik-potsdam.de/en/news/latest-news/buildings-can-become-a-global-co2-sink-if-made-out-of-wood-instead-of-cement-and-steel?utm_medium=website&utm_source=archdaily.com

Edificio de madera. Timber Building

2. Sustainability and efficiency:

Wood is often seen as a sustainable material, but what challenges do we still face in terms of sustainability when it comes to the production, use and recycling of wood in large-scale architectural projects? Is it sustainable to build with Bamboo in Southern Europe?

I am still amazed by the many misconceptions and prejudices about timber building, many people still think tropical deforestation is linked to timber use (while this is caused by large scale agriculture, conversion to cattle land and mining), that timber houses are not durable and not fire safe, and it is predominantly bad to cut a tree. People have no idea that mass timber in Europe comes from sustainably managed production forests, mostly with FSC and PEFC certification, safeguarding the forest and biodiversity remains intact, which increase by 500.000 soccer fields each year, and still have a lot of additional capacity, but do not ask themselves where materials such as bricks, concrete and steel come from – these don’t grow back and their production is associated with high amounts of CO2 emissions.

In contrast, CO2 extensive mass timber products such as CLT and glulam store about 10 times more CO2 than is emitted during production (including the transport, manufacturing and the 1% glue content in the products).

I often ask people when they ask me about the availability of wood and if we don’t lose all our forests if we would build more in timber: “Where do you grow your concrete and steel”? Then people start thinking and understand that these materials are not renewable and can only be depleted and downcycled in End of Life, and construction based on renewable materials is the only way forward. I actually published a free online booklet funded by Built by Nature covering the most prominent timber and forestry myths, downloadable here: https://builtbn.org/news/discussing-timber-myths/318

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. There are many exciting projects that are designed for disassembly in this manner, such as the office of energy company Liander in Amsterdam https://www.dezeen.com/2023/07/14/liander-westpoort-office-complex-timber-buildings-de-zwarte-hond/

Liander Building, una oficina de la empresa energética Liander en Alemania. Liander Building, an office of the energy company Liander in Germany

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 several times in sustainably managed forests providing a surplus of material usable for many applications.

Besides timber, 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, see for example several engineered bamboo projects in Spain here: https://www.moso-bamboo.com/bamboo-inspiration/?_sft_countries=spain

Ejemplos de proyectos de Bamboo en España. Examples of Bamboo projects in Spain

Giant bamboo mostly grows in subtropical regions worldwide, with China being the largest producer of engineered bamboo product, however bamboo is recently also planted in the South of Europe including Portugal which would further lower the carbon footprint of bamboo products. This has a lot of potential as the combined carbon benefit when reforesting abandoned land with bamboo for the production of building materials can lead to a total carbon benefit of over 1000 tons CO2 per hectare, see for more information this report I wrote with INBAR: https://www.inbar.int/wp-content/uploads/2020/05/1541657603.pdf

Portada del artículo que Pablo escribió para INBAR. Cover of the article that Pablo wrote for INBAR.

I am a big fan of both timber and bamboo and instead of competing with each other they should complement each other, bamboo for the finishing inside and outside and timber for the main bearing structure. A beautiful example is Hotel Jakarta in Amsterdam: https://www.archdaily.com/899081/hotel-jakarta-search

Hotel Jakarta en Amsterdam

3. Structural challenges:

Despite its growing popularity, wood still faces certain challenges compared to other materials such as steel or concrete. What do you think are the main structural challenges that wood still needs to overcome, and what innovations are closest to solving them?

Regarding the structural challenges, as well as acoustic and fire safety, which will undoubtedly appear in this interview, I would like to formulate a combined response.

As mentioned previously, there are still so many misconceptions about timber building because of a lack of knowledge by building professionals. I therefore think knowledge dissemination is one of the largest key success factors in the transition to a more biobased built environment. This is also why together with timber minded organization like PEFC but bamboo related organizations such as INBAR and MOSO, we are spreading the knowledge from my books Tomorrow’s Timber www.tomorrows-timber.com and Booming Bamboo www.boomingbamboo.com in a succinct, accessible manner to key decision material decision makers in the built environment, such as architects, through CPD courses and online courses which can be requested, also in Spain through: https://pefc.nl/talks/

Portada Libro Tomorrow Timber. Cover of the book Tomorrow Timber

Portada Libro Booming Bamboo. Cover of the book: Booming Bamboo

On general level in terms of legislation and building codes we need a level playing field in each country for timber building – which often means that regulations which disadvantage light building methods such as mass timber building, need to be adapted.

This legislation related to several building physics dynamics such as acoustics, fire safety but also indoor air quality and temperature was developed over the last decades mostly with heavy building materials in mind. Building in timber is different and requires a fully different design attitude and approach from the start. And in several cases the current legislation and norms does not favour timber.

For example, throughout Europe the stored carbon in mass timber products the so-called Construction Stored Carbon is not accounted for in the required Environmental Product Declaration which determine the environmental impact, claiming the CO2 is emitted again during end-of-life. However, if constructed well, the lifespan of mass timber buildings is far longer than the IPCC horizon of 100 years, and mass timber can be easily reused — the elements will not be burnt as they simply constitute too much value–, storing the CO2 for even longer.

Having said that, when working with architects and builders experienced with timber and bamboo, it is easy to resolve these issues. To know the main design parameters and the starting point, I refer to my book Tomorrow’s Timber, www.tomorrows-timber.com, there I essentially develop all these concepts that we have been talking about.

4. Fire resilience and durability:

One of the most discussed critical points is the resilience of wood to fire and its durability in exposed environments. What innovative solutions are helping to mitigate these problems?

I refer to the previous point to answer the part that refers to fire safety.

Additionally, just comment that firesafety can be solved by encapsulation (adding fire rated gypsum board, although a pity as biophilic design principles of timber in sight are lost), adding a sacrifical layer to the mass timber elements (behind the charred layer the timber remains structurally intact) and/or adding sprinkler systems.

Durability is a non issue – look at our age old houses with timber structures in our medieval city centers; as long as wood is kept dry, or may become wet and is well ventilated to dry up again, it can last for ages. When using timber outside e.g. for window frames or cladding it is important to design it in the right way facilitating ventilation and also choosing a durable timber species. I am a big fan of thermally modified timber or bamboo (Bamboo Xtreme) as it is super durable, stable and also fireproof (in case of bamboo, euroclass B).

5. Acoustics in wooden structures:

Wood is a material that can present acoustic challenges in certain architectural projects. What advances or innovations are being developed to improve the acoustic performance of timber structures, especially in projects that require high sound control, such as offices or public spaces?

I refer to what was said previously: Acoustics in mass timber buildings are solved by first of all disconnecting large mass timber members such as the walls and floors through elastomers, acoustically decoupling them. As timber is 5 times lighter compared to concrete it is important to add mass in case of multi-story residential buildings to solve vibrations e.g. through footfall. This can be done adding a concrete screed foor on top of the CLT, see this example from Amsterdam https://www.archdaily.com/989552/haut-amsterdam-residential-building-team-v-architecture or better even in terms of circularity, using a layer of ‘dry’ mass such as gravel or tiles which can be demounted again in end of life, such as in this project in Rotterdam: https://archello.com/project/sawa

Edificio HAUT en Amsterdam. HAUT Building in Amsterdam

Proyecto SAWA en Rotterdam. SAWA Project in Rotterdam.

In addition: for offices the footfall / vibration requirements are less tough than for residential multi story buildings so the same measures can be taken as mentioned above.

For the inside of public places actually timber has more pleasant acoustics compared to mineral / synthetic materials. Did you ever wonder why all concerthall are almost all finished with timber? Beautiful example: https://www.archdaily.com/989552/haut-amsterdam-residential-building-team-v-architecture

6. Wood vs. other materials:

With the rise of other sustainable materials such as composites and bioplastics, what is the place of wood compared to these alternatives? Do you think there is an efficient coexistence between these materials or will one surpass the other?

Only use synthetic, non-renewable materials where there is no other biobased alternative. Synthetic materials have a far higher carbon footprint see the CO2 pyramid https://www.materialepyramiden.dk/ and are non-renewable. So only use concrete for foundations as here it is the best material alternative.

Gráfico de pirámide de materiales. Material pyramid graphic.

Bioplastics for the building industry may have biobased content but are usually not biodegradable, and sometimes take much energy (CO2 emissions) to produce. So although a step forward I would prefer to go for solid biobased materials such as timber and bamboo, and leave the use of bioplastics for packaging and (biobased) composites for e.g. the automotive industry.

7. Scalability in urban projects:

Regarding large-scale urban projects, such as skyscrapers or mixed-use buildings, what limitations or barriers does wood currently face, and what steps are you taking to increase its viability in these projects?

We can learn a lot from Scandinavian countries which have successfully developed a timber building culture, promoting its use, leading to high percentages of timber buildings up to 20-30% of the total volume, and even complete city neighbourhoods announced in timber: https://www.archdaily.com/1002823/stockholm-wood-city-construction-of-the-worlds-largest-urban-construction-project-in-wood-to-begin-in-2025

Ciudad de madera en Estocolmo. Wooden city in Stockholm

Although the percentage of mass timber buildings in various Western European countries is still relatively low, there are clear signs that this is rapidly changing with several countries and urban areas ramping up their timber building ambitions to meet their climate and circularity ambitions. For example, the Metropolitan Region of Amsterdam has committed to 20% timber use in new residential buildings by 2025, which is a major increase from the 2-3% the urban region is now at. The ambition is to grow further to about 50% in 2030. In these markets we also see specialized modular housing factories in timber popping up, which produce modular, circular homes in a very high quality and with very low construction times with far less nuisance (noise, but also CO2 and NOx emissions) for surroundings.

Still there is a lot of scepcis in the market, fed by the prejuices regarding timber construction (see above), so knowledge and information dissemination to all stakeholders involved, including authorities and the final consumer will remain key.

8. Future of Innovative Materials:

Your field of study in materials innovation seems to be constantly evolving. Where do you think the future of sustainable materials in architecture is headed, and how do you envision the integration of technology in this process?

I believe that besides all kinds of innovations and improvements in mass timber production, including higher efficiency from saw log to final products (e.g. LVL), new more efficient and demountable connection systems such as the spider from Rothoblaas https://www.rothoblaas.com/products/fastening/clt-floor-column-connections/spider, new hybrid components (e.g. I-joists combining various biobased materials), increasing reuse of timber for use in secondary timber products and increasing use of deciduous species (see for example the beech LVL used in the Black & White building in London https://waughthistleton.com/black-white-building/ ), we will increasingly use other biobased materials for the remainder for the building: for example, flax, hemp, bamboo, elephant grass, etc grow a lot faster compared to trees and are suitable to produce all kind of other materials to supplement a timber main bearing structures, such as for panelling, insulation and high end finishing indoors and outdoors (bamboo).

Sistema de conexión más eficiente y desmontable, como la araña de Rothoblaas. More efficient and removable connection system, like the Rothoblaas spider

Edificio Black & White de Londres. Black & White Building in London

In the future glulaminated bamboo might also be used more often in a structural manner in Europe, as it is already starting in e.g. China.

https://www.researchgate.net/publication/337990361_Mechanical_behavior_of_laminated_bamboo_lumber_for_structural_application_an_experimental_investigation/figures?lo=1&utm_source=google&utm_medium=organic

And this is super important – as the biobased route is the only way we can make sure that the built environment becomes regenerative, a net positive contributor to our planet instead of a burden as it is now.

Thank you very much Pablo for your time, it has been a pleasure to have you with us today and talk with you.

Many thanks to Ortiz Leon architects for inviting me.

*You can see examples of wooden architecture made by us, such as Ombú

 

Foto de Pablo Van Der Lugt, experto en construcción de base biológica
Pablo Van Der Lugt, Biological Base Construction Specialist
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