Introduction to Whole Building Life Cycle Assessment: The Basics

生命周期评价(LCA)是一种系统的对所有输入进行汇编和分析的方法, 输出, and potential environmental impacts of a product or system over its lifetime, from initial extraction of raw materials through manufacture, 分布, 使用, 最后的处理. 在建筑的背景下, LCA can be 使用d to evaluate a single product—like a 2×4, 一种工程木梁, 或者一块大木板地板. 它还可以通过编译来自所有单个建筑组件的数据来分析整个建筑系统. 这被称为整个建筑生命周期评估(WBLCA)，以区别于专注于单个产品或建筑组件的评估. WBLCA作为一种有效的方法，在整体水平上测量隐含碳和其他与建筑相关的环境影响措施.

Beca使用 variables such as raw material sources, 供应链流程, 运输距离, 建设实践, 设计选择, 建筑的位置, 气候和运营实践共同决定了一栋建筑的终身碳足迹, it’s important to consider WBLCAs in the project planning phase.

生命周期阶段

生命周期评估由几个国际标准管理，特别是ISO 14040和14044. 另外, ISO 21930, which provides the framework and requirements for environmental product declarations (环保署)，界定了生命周期的以下四个阶段:

• Production Stage: Modules A1 – A3
  A1 starts with raw material extraction or harvest; A2 is the transportation of those raw materials to the factory or mill; and A3 is manufacturing of the product itself. Together, these modules are often referred to as “cradle-to-gate.”
• Construction Stage: Modules A4 and A5
  A4 is transportation of the product to the construction site; A5 is installation and/or the construction process.
• 使用阶段:模块B (B1 - B7)
  These modules include maintenance, 修复, 更换, 和翻新, as well as operational water and energy 使用 for the duration of the building’s life.
• End-of-Life Stage: Module C (C1 – C4)
  C1 includes deconstruction and/or demolition; C2 is transportation of waste to the disposal or processing site; C3 is waste processing; and C4 is the final disposal of that waste.

Modules A1 through C4 define the system boundary that fully represent the life cycle of the building; this is often referred to as “cradle-to-grave.”

T在这里 is an additional module, beyond the system boundary:

• 模块D 是可选的, supplementary information that is not part of the life cycle of the system; it is outside the system boundary. ISO 21930国家, “模块D信息旨在提高产品再利用带来的潜在环境效益的透明度, 回收的材料, 二次燃料和/或回收能源离开产品系统并在后续产品系统中使用.”

模块D与生命周期的分离对于确保不会发生“重复计算”非常重要. Consider a wood panel from an existing building that will be re使用d in a new building. 在第一座建筑寿命结束时，储存在面板中的碳作为碳排放离开了系统边界. This allows it to enter the system boundary of the second building as a carbon reduction. For more on biogenic carbon accounting, see our article on this topic, 在这里.

定义作用域

执行WBLCA时, it is important to define the scope of the system, which may vary depending on the goal(s) of the assessment. 结构工程师可能希望评估结构系统，因此可能选择只包括结构元件. 架构师s may wish to include things like finishes and furniture. 通常包括与整体建筑性能相关的建筑系统的所有元素，包括结构元素, 建筑信封, finishes needed to meet fire and acoustical requirements, and components of the assembly required for acceptable vibration performance. This is especially important when performing comparative WBLCA studies, 不同的设计方案和不同的材料将在哪里相互评估. 在这些情况下, 重要的是要考虑各种设计备选方案的“功能等效性”. 所有选项应包括满足等效性能标准所需的完整材料清单. Consideration should also be given to the functionality of the space, including grid spacing and ceiling height.

环境影响

For developers and design teams seeking to make their projects more sustainable, WBLCA can be 使用d to evaluate a variety of environmental impacts, including global warming potential (GWP), 酸化, 富营养化, 臭氧损耗, 烟雾, 化石燃料消耗. 随着气候危机日益紧迫，减少碳排放的重要性日益凸显, many designers are specifically foc使用d on measuring, 和减少, 他们项目的全球潜能值. 此外, 虽然在减少运营碳排放(与建筑运营和使用相关的排放)方面已经取得了巨大的进步，但设计师们最近将他们的关注点扩大到包括隐含碳, 哪一个是建筑材料本身和施工过程的碳足迹. For WBLCA w在这里 the goal is measuring the embodied carbon impact, it is appropriate to exclude some of the “使用” modules from the analysis, 通常B1, B6, 和B7. B2 through B5 are related to maintenance, 修复, 更换, 和翻新, 因此，应根据建筑物的定义寿命将其包含在分析中.

WBLCA软件工具

有几个皇冠2登录welcome上可用的软件工具，设计师可以使用它们在整个设计和施工过程中执行wblca，以测量和潜在地减少与建筑相关的环境影响. A description and comparison of these tools can be found 在这里. 需要注意的是，这些工具使用不同的建模技术和背景数据集, 做出不同的假设, which means results from different software programs will never be identical. 因此, 审查结果时, it is important to know which tool was 使用d and understand the underlying assumptions. 同样的, when performing comparative WBLCA, 重要的是使用相同的工具和假设来确保结果的有效比较.

While t在这里 are many considerations to building design, designers can 使用 WBLCA tools as a scientific way of measuring, 报告, 和减少 the embodied carbon footprint of their building. 这是他们可以为客户提供的一项有价值的服务，这些客户希望提高其投资组合的环境可持续性，并使其建筑在市场上脱颖而出，这也是减轻新建筑对气候影响的重要一步.

额外的资源

大厅,E. S.想想木头. (n.d.) How to Calculate the Wood Carbon Footprint of a Building.

International Organization for Standardization. (2006). ISO 14040:2006 Environmental management -生命周期评估 -原则及架构.

International Organization for Standardization. (2006). ISO 14044:2006 Environmental management -生命周期评估 -要求及指引.

International Organization for Standardization. (2017). ISO 21930:2017 可持续性 in buildings and civil engineering works – Core rules for environmental product declarations of construction products and services.

KL&A Engineers and Builders, Adolfson & 彼得森. (2021年7月). Platte Fifteen Life Cycle Assessment.

ThinkWood. 2月(2021). Understanding the Role of Embodied Carbon in Climate Smart Buildings.

ThinkWood. (n.d.) Carbon Source to Carbon Sink: Redesigning the Built Environment for Climate Change.

*以上表格经美国国家标准协会(ANSI)代表国际标准化组织许可，转载自ISO 21930:2017(E). 版权所有.