Life Cycle Climate Performance (LCCP) is a widely accepted metric to evaluate the carbon footprint of air conditioning (AC) systems “from cradle to grave.” This paper: (1) reviews the invention and evolution of LCCP, including a comprehensive timeline and bibliography; (2) documents the successful application of LCCP in the replacement of HFC-410A with HFC-32 in room air conditioners; (3) compares the conceptual frameworks and the operational approaches; and 4) reflects on the drawbacks of current LCCP research and points out possible future work.

The major policy-relevant findings are: 1. The indirect emissions caused by energy consumption is 70 to 80 percent of the LCCP of AC systems in most countries but will decline in importance as electric power supply shifts rapidly from fossil fuel to renewable energy sources, which have near-zero carbon intensity; 2. The embodied greenhouse gas (GHG) emissions in refrigerant manufacture are, in most cases, negligible but the physical and chemical properties are crucial for system optimization for low carbon footprint; 3. The LCCP metric can be used for multiple purposes such as refrigerant selection and AC system architecture optimization; and 4. Data limitations in material manufacturing and the carbon intensity of electric power are the most significant challenges. Finally, this paper describes a variety of methods to fill in data gaps, including the correction factor method, the data-driven method, and the database searching method. The next-generation LCCP will be an enhanced evaluation process considering local climate, heat islands, and local power supply characteristics.

生命周期气候性能 (LCCP) 是一种广泛接受的指标，用于评估空调 (AC) 系统“从摇篮到坟墓”的碳足迹。本文：（1）回顾了 LCCP 的发明和演变，包括全面的时间线和参考书目；(2) 证明 LCCP 在室内空调中用 HFC-32 替代 HFC-410A 的成功应用；(3) 比较概念框架和操作方法；4) 反思当前 LCCP 研究的缺陷并指出未来可能的工作。

与政策相关的主要发现是： 1. 在大多数国家，能源消耗造成的间接排放占交流系统 LCCP 的 70% 至 80%，但随着电力供应从化石燃料迅速转向可再生能源，其重要性将下降，碳强度接近于零；2. 制冷剂制造中的隐含温室气体 (GHG) 排放在大多数情况下可以忽略不计，但物理和化学特性对于低碳足迹的系统优化至关重要；3、LCCP指标可用于制冷剂选择、空调系统架构优化等多种用途；4. 材料制造中的数据限制和电力的碳强度是最重大的挑战。最后，本文介绍了多种填补数据空白的方法，修正因子法、数据驱动法、数据库检索法。考虑到当地气候、热岛和当地供电特性，下一代 LCCP 将是一个增强的评估过程。