1. LVL AS A CONSTRUCTION MATERIAL Figure 1.19. Example global warming potential of different life cycle stages 3, 7, 8. 1.5.3 Global Warming impact of LVL In the manufacture of LVL, a large share of renewable energy is used (see Figure 1.18), resulting in lower fossil greenhouse gas emissions and global warming potential compared to other building materials. In addition, LVL stores biogenic carbon, which constitutes about one half of the dry weight of the wood. The biogenic carbon remains in the LVL throughout its lifetime until it is released back to the atmosphere to be absorbed by the next generation of growing trees. The global warming potential of LVL when used in a load-bearing structure of a building has been determined by LVL producers as follows: • Raw materials extraction and energy use are similar in different production units, but different energy mixes are used depending on the unit and country. Energy mix affects the greenhouse gas emissions of the production stage (modules A1–3). Biogenic carbon content is given separately. • Construction stage (A4–5) covers transportation to the Central European market and normal construction works. • Use stage (B1–7) is considered negligible. • End of life stage C1–4 scenarios consider utilization of LVL as a source of energy. • Module D, other benefits, originate mainly from the bio-energy substitution effect, compared to typical local energy mix, when LVL is used for bioenergy at end of life. Figure 1.18. Primary energy (renewable and non-renewable) use in the manufacturing stage (A1–A3) of LVL 3 ,7, 8. Biogenic Global Warming Potential is the sum of stored biogenic carbon in the production stage and release of biogenic carbon in the end of life stage. The sum is close to zero for the whole life cycle. Consolidated results for fossil global warming potential show that the production stage (A1–3) constitutes 90% of the result (Figure 1.19). The construction stage (A4–5) constitutes 10%, and end of life stage (C1–4) constitutes 2.5% of the fossil GWP. In module D the GWP benefits are shown as the amount of fossil fuels substituted by biomass energy. USE OF RENEWABLE AND NON-RENEWABLE PRIMARY ENERGY IN PRODUCTION STAGE Renewable energy, PERE Non-renewable energy, PENRE 0 1000 2000 3000 4000 5000 6000 Energy consumption [MJ/m³] LVL 01, Figure 1.16 • MUOKATTU 28.8. GLOBAL WARMING POTENTIAL (GWP) OF LVL (kg CO2 equiv./m3) GWP fossil GWP biogenic GWP benefits 1000 800 600 400 200 0 -200 -400 -600 -800 -1000 A1-A3 Product stage A4-A5 Construction stage B1-B7 Use stage C1-C4 End of life D Loads and benefits beyond system boundary Total (module D not included) 24 LVL Handbook Europe
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