Wooden buildings against CO2
Wooden buildings will save the cities of the future
As with snowflakes, individuals and other products of Nature, it is not possible to find two pieces of wood that are perfectly identical. Perhaps it is also for this peculiarity that wooden buildings usually give us a greater sensation of warmth, make us feel more in tune with the environment, as if we recognized in them something alive and familiar that tells us of an intrinsic relationship between nature and the built environment.
The structure of the buildings of the future will be made of the same material as prehistoric pile dwellings: wood. New skyscrapers and large residential buildings made of wood will help reduce greenhouse gas emissions, responding to the housing demand of the metropolises of the next twenty years.
In Italy we are used to thinking about wooden houses in terms of cabins, cottages, bungalows or little more. Low buildings, usually in a bucolic setting or that in any case have nothing to do with the urban context. Or we use wood for roofs and laminated wood for sports halls, swimming pools and other large covered surfaces. Otherwise we can think of the residential neighborhoods of single-family homes in the United States, the ones we see in movies. But we are always outside the city and with a large consumption of land.
Italians are fond of brick and in big cities buildings have multiple floors, so they could not be built with a wooden structure.
The Canadian architect Michael Green he explained during a TED Talks 2013 which instead is possible, offering a vision that is as futuristic as it is simple and supported by data that leave little room for interpretation. Let's try to take up his speech again and apply it to the Italian reality.
Today, approximately half of the world's population lives in cities, and this share is expected to rise to 20% in the next 75 years..
It is estimated that 3 billions of people in the world in the next 20 years will need a new house, most likely in cities, or rather in those very metropolises that already today host 1 billion people in their poorest and most degraded neighborhoods, plus millions more homeless. Considering that urban space will be increasingly reduced, increasingly expensive and that it will be necessary to somehow find a home for so many people, it is unlikely that the buildings will be lowered, so they will not be wooden buildings.
No big deal, we have steel, cement and bricks, we can build as we have done up to now..
One of the problems is that the production of these materials involves ahigh carbon dioxide emission, partly due to the passage through a furnace at a higher or lower temperature. Today, steel and cement already contribute 8% to the production of greenhouse gases.
If we consider the necessary reduction of carbon dioxide and the increase in temperature due to greenhouse gases, the scenario of urban population growth described appears decidedly bleak. Already now the buildings and their normal functioning They are responsible for about half of the carbon dioxide produced, it is clear that being able to limit their impact has great environmental value.
Not that the situation is any better on the transport front, but when we think about pollution it is easier for us to associate it with cars than with houses and this is already a good guarantee to not let us forget that urban traffic is a problem. Perhaps for buildings this type of association is not so immediate.
We know that heating of civil buildings has a significant impact on pollution.
Even the famous 110% bonus aims to reduce consumption and emissions, especially in homes built during the years of the building boom and which today represent a significant part of our residential heritage. However, it is less common to hear about energy consumption that affects the cycle of production of buildings and building materials. Even if buildings are not disposed of as frequently as household appliances, we still need to think about their entire life cycle and their energy consumption that this entails. This is why it is important to start from Materials production, From 'energy, from sources used to obtain it and from emissions which this already entails.
Wood is the only building material that is produced using solar energy.
The tree uses the energy of the sun and the resources of the soil to grow, at the same time it releases oxygen and absorbs carbon dioxide. The natural epilogue of the life of the tree is that it dies, dries up, falls and rots, or in some cases burns, still returning carbon dioxide to the atmosphere and the soil. However, if the tree is cut when it reaches full growth and beams are made from it which are then used in a house, carbon dioxide is as if frozen inside them, does not disperse into the environment and, like the Palladian trusses, can remain there for several centuries.
One cubic meter of wood can trap one ton of CO2.
Wood may not be the magic wand, but it could rightly become part of the solution, because it can reduce emissions, lock up CO2 for years and also produce oxygen as it develops, especially during the growth phase of the tree, when the forest is still young.
- wooden buildings could represent a piece in alleviating the multifactorial and multidimensional problem ofair pollution. For this reason Michael Green and the engineer Erik Karsh thought of creating 30-story wooden buildings, using a technology they called Mass Timber Panels.
Who knows if any research has ever highlighted what meanings are attributed to wood in proverbs and popular culture, the fact that villages were set on fire and sword already makes one think that steel is worse off.
These are large panels of various thicknesses generated from young trees, not of large size, nor of particular value..
During TED, the construction system It is explained by referring to Lego, talking about the bricks that we all know and comparing the wooden panels to the larger Lego pieces. These panels of approximately 50 mXNUMX they form the system designed by the Canadian architect who takes the name of FFTT and it is a solution Creative Commons (therefore not covered by an exclusive patent, but freely usable) for assemble the structure of the buildings in a very flexible way and with great speed of execution, as shown in the animation presented during the conference.
The project is designed for a 100 meter high building in Vancouver, a city that also boasts a fair amount of seismic risk, but the designer declares it to be suitable for any context and stylistic solution.
Green's presentation continues by dispelling the most common doubts related to wooden constructions, such as the risk of fire and the cutting of the necessary trees. The most interesting thing is precisely linked to the need to have trees, which would lead to revaluing this crop, to investing in young forests and to cutting them consciously, placing a curb deforestation for agricultural purposes which affects the Amazon for example.
The carbon footprint of this type of construction technology is decidedly advantageous. compared to traditional ones, especially considering a future demographic and urban residence increase.
In the end, the biggest problem is, as often happens, the change of mentality, because it is a truly new technology for building skyscrapers that have always used steel and reinforced concrete..
The design, the technology, the availability of wood and the possible development of the supply chain compared to the mentality and common feeling, are simple things. Wood frame buildings are rising, just as a century ago there was a rush to the top with steel skyscrapers. There are already several wooden constructions 30-35 meters high scattered around the world, up to 85,4 meters of the Colossus of Mjøstårnet in Norway, passing through the 53 of the Tall Wood Residence in Vancouver, as Michael Green had promised.
Where are we in Italy with wooden buildings? How much can we make Michael Green's innovative drive our own?
It may be that a country with almost zero population growth like Italy will not be at the top of the list of countries with the high rate of urbanization predicted by Green in the next 20 years, and perhaps even the rate of urbanization will not be so disastrous. China, India, Brazil will probably take the lion's share.
Although the Vaia storm that hit the Dolomites in 2018 provided a certain surplus of material, Italy certainly does not boast the forests of Canada and is not even famous for its quantity of skyscrapers, which are rarely used for purely residential purposes. This does not mean that we will not be affected by these wide-ranging dynamics.
Although this is not the place to discuss technical and regulatory issues, it should be considered that the adoption of the wood for structural purposes in our country it is quite recent. About a decade has passed since the technical standards of 2008 that first placed this arrow in the quiver of the designer who wants to think of complex housing structures without using conventional solutions.
Such rules which allow for build complex wooden buildings, derive from various factors, among which an increasingly conscious push towards the bioarchitecture and the need for energy containment, but also by the practical needs linked to the earthquakes in L'Aquila and Molise which required the rapid construction seismic safe buildings.
It is in this context that in the last 10 years there has been a big push towards the use ofxlam (o CLT) for wooden residential buildings.
In this case too, it is a question of wooden panel structures, that is, full elements, which can “familiarize” with our construction tradition made of brick walls. Assimilating the adoption of the wooden frame construction systems typical of the Anglo-Saxon world would not be as easy.
We haven't gone as far up yet, certainly not as far as Michael Green suggested in 2017, but at least we're making progress in breaking down the equation "wooden house equals mountain cabin."
The reconstruction for L'Aquila required rapid completion times and this pushed towards the use of wooden structures with which they were made residential buildings up to four floors and a seven-storey hotel
Alexander Residence of Roccaraso, concluded in 2012.
The "Wooden Houses and Buildings Report” of 2019 reports a 2,3% increase in the sector and highlights the growth of this industrial sector especially in Lombardy, Veneto and Emilia Romagna, with a promising expansion towards Tuscany, Lazio and Marche.
One of the most comforting signals, also in terms of exports, comes from XLAM Dolomites of Castelnuovo (TN) which in recent years has also installed its panels in a 5-storey wooden building on the University of Melbourne Campus, in addition to the many creations in Italy. Browsing through his catalogue it is interesting to see how the short notes on each creation report the tons of CO2 saved and how this material lends itself, especially by virtue of its lightness, to elevations.
In our small way, even if we fly low, we are moving towards a greater use of wooden structural solutions for construction, without clear distinctions both in terms of typology and intended use. Considering all the advantages that wood can bring us and the technological-constructive level now reached, it is difficult not to want to encourage its development.
SOURCES
TED Ideas worth spreading – Michael Green | TED 2013 | Why we should build wooden skycrapers
Multi-storey wooden buildings with XLAM load-bearing panels | Agostino Presutti, Pierluigi Evangelista | 2014 Dario Flaccovio Publisher
Catalogue XLAM DOLOMITES construction 2019 | Building with Timber
The important performances of Xlam Dolomiti in Italy and in the world | impresadilinews.it
Cover image: IZM, Dornbirn from woodskyscrapers.org
