The building and construction sectors represent a major source of greenhouse gas (GHG) emissions. Replacing concrete and steel with wood is one potential strategy to decrease emissions. On product level, the difference in fossil emissions per functional unit can be quantified with displacement factors (DFs), i.e., the amount of fossil emission reduction achieved per unit of wood use when replacing a functionally equivalent product. We developed DFs for substitution cases representative of typical wood-frame and non-wood frame multi-story buildings in the Nordic countries, considering the expected decarbonization of the energy sector and increased recycling of construction products. Most of the DFs were positive, implying lower fossil emissions, if wood construction is favored. However, variation in the DFs was substantial and negative DFs implying higher emissions were also detected. All DFs showed a decreasing trend, i.e., the GHG mitigation potential of wood construction significantly decreases under future decarbonization and increased recycling assumptions. If only the decarbonization of the energy sector was considered, the decrease was less dramatic compared to the isolated impact of the recycling of construction materials. The mitigation potential of wood construction appears to be the most sensitive to the GHG emissions of concrete, whereas the emissions of steel seem less influential, and the emissions of wood have only minor influence. The emission reduction due to the decarbonization of the energy sector and the recycling of construction materials is a favorable outcome but one that reduces the relative environmental benefit of wood construction, which ought to be considered in forest-based mitigation strategies. Broadening the system boundary is required to assess the overall substitution impacts of increased use of wood in construction, including biogenic carbon stock changes in forest ecosystems and in wood products over time, as well as price-mediated market responses.

中文翻译：

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北欧木质多层建筑类型的替代影响：能源部门脱碳和建筑材料回收增加的影响

建筑和施工部门是温室气体 (GHG) 排放的主要来源。用木材代替混凝土和钢材是减少排放的一种潜在策略。在产品层面，每个功能单位的化石排放差异可以用置换因子（DF）来量化，即更换功能等效的产品时，每单位木材使用所实现的化石排放减少量。考虑到能源部门的预期脱碳和建筑产品回收的增加，我们为北欧国家典型的木结构和非木结构多层建筑的替代案例开发了 DF。大多数 DF 为正值，这意味着如果木结构建筑受到青睐，则化石排放量会更低。然而，DF的变化很大，并且还检测到了意味着更高排放的负DF。所有 DF 均呈下降趋势，即在未来脱碳和增加回收假设的情况下，木结构建筑的温室气体减排潜力显着下降。如果只考虑能源部门的脱碳，与建筑材料回收的孤立影响相比，下降幅度较小。木结构的减排潜力似乎对混凝土的温室气体排放最敏感，而钢材的排放似乎影响较小，木材的排放影响很小。能源部门的脱碳和建筑材料的回收利用带来的减排是一个有利的结果，但会降低木结构建筑的相对环境效益，这应该在基于森林的减排战略中加以考虑。需要拓宽系统边界，以评估建筑中木材使用增加的整体替代影响，包括森林生态系统和木制品中生物源碳储量随时间的变化，以及价格介导的市场反应。