«You shall not concrete»
31.05.2022
The wind shifted. Overnight, architects went green. Wooden construction is becoming a megatrend, while concrete and steel are falling into disrepute because of the CO₂ problem. Architecture critic and columnist Benedikt Loderer sets out ten commandments for the new architecture and explains why concrete should be dispensed with today. Here you can find out why we share Mr. Loderer's opinion.
You can find Benedikt Loderer's entire architecture column in the Berner Zeitung and other newspapers. Here we show why we agree so much with Benedikt Loderer's 3rd commandment. Steel and concrete are the dominant building materials - and they are very CO₂-intensive. Cement plants in Switzerland alone are responsible for a good 6 percent of national CO₂ emissions. This makes the construction industry as a whole a climate polluter. The concrete industry has recognized the problem and is working to reduce the proportion of conventional clinker in cement. However, the possibilities for doing so are limited: There will always remain the process emissions that occur when limestone is burned. Only complex and expensive «carbon capture» methods, in which the CO₂ is to be separated directly at the high stack, can reduce CO₂ emissions from cement production in the future.
Over the past 20 years, CO₂ emissions from Swiss cement plants have been at a consistently high level of just over 2.5 million tons of CO₂ per year.
The situation is quite different with timber construction: Thanks to photosynthesis, a tree stores up to twenty tons of CO₂ in its branches, trunk and root system during growth. This is roughly equivalent to the CO₂ emissions of 150,000 car kilometers. The Swiss forest thus relieves our air by ten million tons of CO₂ every year. The only question is whether we can also use this CO₂. After all, when a tree burns or rots, the same amount is released again. The goal is to store the carbon beyond the life cycle of a tree. This is precisely what Timbatec has been working towards for over twenty years. Used in the supporting structures of buildings, the CO₂ remains bound in the wood used. As a CO₂ store, timber buildings thus make an important contribution to climate protection, as one cubic meter of timber stores around one ton of CO₂. This carbon store is recognized today.
New KBOB figures published
The updated and expanded KBOB lists ‹Life cycle assessment data in the construction sector› have been published since the end of April. Detailed information on the lists can be found on the KBOB or Lignum websites.
Like the previous version, the new KBOB data map environmental impact points, primary energy and greenhouse gas emissions. Corrections have taken place in various areas to bring the theoretical values closer to reality. Cross-laminated timber and other wood products are about 25% better off in the above criteria than in the previous data. On the other hand, concrete products are now classified as significantly more harmful to the environment. Structural concrete (without reinforcement) was given 94.3 environmental impact points in the old data, now it is 154.0 points. This is an increase of around 50%.
Significant changes Carbon storage
The political discourse has shifted from CO₂ emissions to CO₂ storage. As a result, the biogenic carbon (in kg C) contained in building materials and building elements is now also listed - i.e. the CO₂ that is absorbed by plants and remains stored in the building as a building material throughout its service life. This information was previously omitted from the KBOB calculation rules; now, according to KBOB, each kilogram of solid structural timber installed can be equated to a carbon store of 0.45 kg.
Indirect counter-proposal to the glacier initiative in the National Council
Last year, the electorate narrowly rejected the CO₂ law. Since then, solutions have been sought at all political levels to curb global warming. The Federal Council approved the revised CO₂ Ordinance at the beginning of the month. It prevents a regulatory gap until the totally revised CO₂ Act comes into force from 2025. Climate protection projects in which CO₂ is permanently bound in biological or geological storage facilities are now also permitted. This means that the sink capacity of the forest can now be put to good use. More on Wald Schweiz.
At the end of April, the National Council's Environment Committee came out clearly in favor of a strong indirect counter-proposal to the Glacier Initiative. The goal of net zero greenhouse gas emissions by 2050 is to become law, concretized by interim targets and sectoral benchmarks. With this indirect counter-proposal to the Glacier Initiative, the Commission wants to anchor a robust climate target in Swiss law as quickly as possible. The buildings and transport sectors are to emit no CO₂ at all by 2050, while industry is to reduce its greenhouse gas emissions by 90% by 2050. The only way to achieve this ambitious goal is to do without steel, concrete and brick in construction in the future.
