If we want to limit the effects of climate change, wood is the building material of choice as it can store carbon. As trees grow, they take carbon dioxide out of the atmosphere and, even when they are harvested, carbon remains stored in the wood for the lifespan of the product. Prof. Dederich from Rottenburg University of Applied Forest Sciences shows that even multi-storey buildings can be built from wood and be safe, durable and aesthetically pleasing.
“If we want to keep the effects of man-made climate change to within tolerable limits, all factors that favour decarbonisation need to be taken seriously and have to be implemented,” said Ludger Dederich from Rottenburg University of Applied Forest Sciences in his introductory lecture on resource efficiency opportunities in the building sector at the G7 conference “Innovative Biobased Products: Opportunities for substituting non-renewable resources” conference in Berlin on 24th November 2015. The conference, which was the first of several events that will be organised under the G7 Alliance on Resource Efficiency, was hosted by the German Federal Ministry for Food and Agriculture. The G7 Alliance was founded in Elmau Castle in June 2015 by the heads of state and government of the seven leading industrial nations in the West.
Speaking in Berlin on 24th November, Dederich pointed out that while the term decarbonisation has until recently only been known to experts, it now frequently appears in the media, notably following Chancellor Angela Merkel’s speech at the G7 summit in Elmau Castle where she said: “In addition to our efforts to decarbonise the world economy by the end of the century, greenhouse gas emission targets have to be considerably reduced to keep average global warming at less than 2°C above pre-industrial levels.” About two weeks after the G7 conference in Berlin, all nations of the world community adopted the first-ever legally binding global climate deal at the United Nations Climate Change Conference in Paris in December 2015.
Ludger Dederich is professor for timber construction at Rottenburg University of Applied Forest Sciences. Prior to his current position, Dederich worked in an engineering office in Uppsala, Sweden, a number of German architectural offices and as a consultant for Informationsdienst Holz, an information agency that specialises in the use of wood for buildings. He also co-authored the book “Die besten Einfamlienhäuser aus Holz” (The best single-family houses made of wood) published by Callwey publishing house in 2013.
Rottenburg University of Applied Forest Sciences (HFR) was created from a school of forestry in 1995 and is specifically focused on forestry and the wood industry, renewable energies, resource efficiency, nature conservation and environmental protection, rural development and water management. The campus is located on the premises of Schadenweilerhof, a picturesque, 17th century aristocratic estate close to the Baden-Württemberg city of Rottenburg am Necker. The University is proud to be the smallest excellence university in Germany; it has been awarded UNESCO's “Official Project of the Decade of Education for Sustainable Development” for its commitment to sustainable education five times in a row.
Large-scale projects aimed at removing C02 from the atmosphere and pumping it into empty oil reservoirs, deep layers of rock or the sea floor, where it can supposedly be stored safely, are currently attracting a lot of interest and funding as the world tries to limit global warming and its effects. “Now and no later is the time we need to leave the path of faith in progress in favour of simple, manageable and proven methods for long-term mitigation of climate-damaging CO2,” says Dederich, referring to the process of photosynthesis through which trees grow and take carbon dioxide out of the atmosphere, giving off ‘fresh air’ for us to breathe.
Dederich presented numerous examples to show that many different kinds of buildings, practical as well as whimsical, can be built with wood. Not just idyllic cabins or Alpine chalets, but also family houses and high-rise buildings. The administrative headquarters of Aalen-Waldhausen-based KAMPA Bauinnovationszentrum, a manufacturer of prefabricated houses, are in an eight-storey building called “K8”, built completely from wood, thereby storing 825 tons of CO2 for the life of the building. Multi-storey wooden constructions are becoming increasingly prevalent, in Baden-Württemberg In particular, but also in other German states. However, Germany still lags behind other European countries. The Scandinavian countries are decades ahead of us. A 14-storey timber apartment building has been erected in the Norwegian city of Bergen and tower blocks of 25 storeys or more have already been built or are in the planning stage in other European cities. In countries where wooden constructions are widely used, concerns raised about increased fire hazards are dispelled thanks to the inclusion of appropriate functional requirements into the building regulations. It is also worth noting that “modern timber load-bearing structures have been shown to withstand fire and high temperatures longer than those made of steel” (German Wood Industry Council press release, 20th May 2014).
Wood is a versatile and aesthetic building material that can store large quantities of atmospheric CO2 above the earth's surface easily and without risk. The beams in medieval timbered houses in many German cities or the roof of the church at Maulbronn Monastery, which was built with trees felled in the mid-12th century, bear witness to the resource efficiency of these “CO2 sinks”, as climate researchers call wood products or other natural carbon dioxide reservoirs. “As far as these buildings are concerned, the first phase of the material use of wood is far from complete,” Dederich points out. The utilisation cascade ends when the energy is utilised by burning the wood and carbon dioxide is released into the atmosphere, but this is still a long way off.
Of course, anyone who thinks that we can carry on exploiting fossil carbon deposits (coal, oil, gas) as we have done and that the only thing that needs to be done to compensate for CO2 emissions is planting trees, is on the wrong track, as the Canadian biogeochemist David Paré drily remarked at the G7 conference in Berlin. The Potsdam Institute for Climate Impact Research has calculated that you would need to replant all the agricultural land on Earth with energy trees in order to be able to suck half of the currently produced man-made carbon dioxide emissions out of the air. There is no alternative to the decarbonisation of the global economy.
Wolfgang Bachmann, Ludger Dederich: Die besten Einfamilienhäuser aus Holz. 176 pages. Callwey.de, 2013.