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Methodology

Room air conditioner stock and efficiency estimation

To estimate monthly room air conditioner (AC) ownership and average energy efficiency performance (measured in Seasonal Energy Efficiency Ratio, SEER, for RACs operating in cooling mode) in China from 2019 to 2024, we integrate data from multiple sources. We use average room AC ownership per 100 households from the National Bureau of Statistics (NBS), total households from NBS, and monthly room AC sales data and annual sales data by energy efficiency class (2018 – 2023) from ChinaIOL. We also use the Seasonal Energy Efficiency Ratio (SEER) metric from China’s RAC MEPS (GB 21455-2019) for the cooling functions of RACs. This methodology allows us to construct monthly estimates of both the size and energy efficiency profile of the installed room AC stock in China.

Modelling electricity consumption related to air conditioner efficiency improvement

To evaluate the potential impact of the consumer goods trade-in programme, we develop a monthly model of electricity consumption for the residential sector, where policy effects are likely to be the most pronounced. The model estimates electricity consumption as a linear function of:

• Consumer expenditure (from NBS, converted to monthly frequency using Denton’s method), as a proxy for baseload consumption
• Heating degree days (HDDs) with an 18°C threshold
• A temperature-based cooling indicator, taking humidity-adjusted cooling degree days (CDDs) with a 26°C threshold (following Chinese design codes) multiplied by air conditioner ownership and divided by average SEER

Energy saving and consumer bill reductions

Energy savings are calculated based on three temperature scenarios, assuming historical average temperature profiles scaled to 2024 26°C threshold CDDs. The scenarios assume respectively 10% less, the same, and 10% more CDDs than in 2024. This approach is consistent with expectations for a hot summer in 2025, confirmed by the State Grid of China. Maximum consumer bill savings are calculated based on the hot scenario, assuming prices of ¥0.54/kWh ($0.076/kWh). Savings calculations do not account for TOU pricing or geographical variation in price.

Acknowledgements

Contributors

Shiyao Zhang, Richard Black, Reynaldo Dizon, Aditya Lolla, Muyi Yang, Wilmar Suarez, Kavya Sharma, Ardhi Arsala Rahmani, Tito Das

External Reviewer

Jianlan Dou, Energy Consultant, International Energy Agency (IEA)

Photo credit:

Zoonar GmbH / Alamy Stock Photo