One in eight heating, ventilation, and air conditioning (HVAC) units in elementary, middle, and high schools, as well as special education schools, has exceeded its legal lifespan. In particular, regions like Daejeon and Incheon are leaving one in four units that have reached the end of their life cycle in operation, highlighting significant regional disparities. Despite a nearly 30% increase in average electricity costs per school over the past three years, the replacement of these units has been declining, prompting calls for urgent measures.
According to data submitted to the National Assembly by Rep. Han Byeong-do of the Democratic Party, as of the end of July 2026, there were 644,756 HVAC units in schools across the country, with 79,166 units, or 12.3%, exceeding the Ministry of Education's durability standard of 12 years.
Regionally, Daejeon reported the highest rate of outdated units, with 5,608 of its 23,216 HVAC units (24.2%) surpassing their lifespan. This means that one in four classroom HVAC units in Daejeon is outdated.
Incheon followed with 7,498 of its 36,590 units (20.5%) exceeding their durability, marking the second-highest rate. Both Daejeon and Incheon have outdated unit rates above 20%. Other regions with high rates include Seoul at 14.8% (13,549 units), Gwangju at 14.2% (2,651 units), Busan at 13.8% (5,117 units), and Gyeonggi at 13.7% (22,174 units), indicating a notable trend of aging equipment in major cities and the metropolitan area.
In contrast, Sejong, which has seen a rise in newly established schools, reported only 125 outdated units, resulting in the lowest rate at 1.6%. Following Sejong were Jeju (3.2%), Gangwon (5.8%), Ulsan (6.5%), and Chungnam (6.5%). The gap between the most outdated region, Daejeon (24.2%), and the best-performing region, Sejong (1.6%), is a staggering 14.8 times.
In terms of absolute numbers, Gyeonggi Province, with a large number of schools, has 22,174 outdated units, accounting for 28.0% of the national total. When combined with Seoul (13,549 units, 17.1%) and Incheon (7,498 units, 9.5%), these three metropolitan areas hold over half (54.6%) of the nation's outdated units.
As outdated units remain in use, the burden of electricity costs on schools has ballooned. The average electricity expenditure per school rose from 47.78 million won in 2022 to 61.83 million won in 2025, an increase of 14.05 million won (29.4%) over three years.
The surge in electricity costs was particularly pronounced in 2023, when the average cost per school increased by 9.4 million won (19.7%), accounting for 66.9% of the total increase over three years. By 2025, the regions with the highest electricity costs per school were Sejong (84 million won) and Seoul (83.04 million won), followed by Ulsan (70.2 million won), Daejeon (69.16 million won), and Gyeonggi (68.43 million won).
Despite the rising costs and the declining energy efficiency of outdated units, the replacement of these devices has been on the decline. The number of HVAC units installed annually peaked at 64,468 in 2023 but fell to 55,957 in 2024 (-13.2%) and 47,791 in 2025 (-14.6%), marking two consecutive years of decline. While electricity costs surged by 29.4%, the replacement of units decreased by 14.1%, creating a troubling mismatch.
Rep. Han Byeong-do stated, "In a situation where electricity costs have increased by over 14 million won per school in three years, leaving outdated units in operation is a clear detriment to both educational finances and students' learning environments. The Ministry of Education should not only tally the outdated units but also present a plan with annual replacement goals and a target for transitioning to high-efficiency devices."
* This article has been translated by AI.
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