14. Jun 2022
Like the previous version, the updated and expanded KBOB list represents life cycle assessment data in the construction sector. Corrections have been made in various areas to bring the theoretical values closer to reality. Wood products perform significantly better than before.
The updated and expanded KBOB list 'Life Cycle Assessment Data in the Construction Sector' has been published since the end of April and, like the previous version, maps the environmental impact points, primary energy and greenhouse gas emissions.
Corrections have taken place in various areas to bring the theoretical values closer to reality. Glulam 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.
Key innovations: 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. As they grow, plants convert CO₂ into oxygen and sugar molecules thanks to photosynthesis. The oxygen goes back into the environment, and the sugar molecules are needed by the plants for their growth. Thus, CO₂ is stored long-term in biobased building products, such as wood. This information was previously hidden in KBOB's accounting rules. Now, according to KBOB, each kilogram of solid structural timber used can be equated to a carbon store of 0.45 kg. Wood used in buildings becomes a CO₂ sink.
Comparison of old and current KBOB data
A 200-millimeter-thick cross-laminated timber ceiling with 80-millimeter-thick split fill for sound insulation was calculated with 94,193 environmental impact points (UBP) according to the old KBOB data. The new figure is only 66,654 UBP. A significant improvement in the data is also evident in the area of primary energy for the production of building materials. The biggest difference, however, is in greenhouse gas emissions. According to the old data basis, a square meter of cross laminated timber ceiling including fill emits 40 kg CO₂ equivalent (CO₂-eq). The new figure is 24 kg CO₂-eq. This is a reduction of 40%. At the same time, the stored biogenic carbon may be counted today: In one square meter of the example ceiling, there are 153 kg CO₂-eq.
The situation is quite different for concrete
With the old data, a one-square-meter, 240-millimeter-thick concrete floor with a reinforcement content of 1%, i.e. a common and frequent design of concrete floor slabs, was quantified with 104,159 environmental impact points. The new figure is 137,308, an increase of 32%. The situation is similar for primary energy and greenhouse gas emissions - and concrete is not a CO₂ sink.