Summer in the coastal city of Qingdao in east China's Shandong Province is often warm and sultry, with humidity heightened by the evaporation of seawater.

However, in Zhang Jie's apartment at Qingdao Sino-German Ecopark, there isn't an air conditioner in sight.

Featuring neither an air conditioner nor a heating radiator, Zhang's apartment is instead equipped with a fresh air system and fitted with extra insulation. Each room features a display board that shows the room temperature, humidity and PM 2.5 levels -- among other environmental indicators.

Zhang's apartment, certified as one of the country's first state-level ultra-low energy consumption buildings, is part of the ecopark's complex of passive houses, which spans 1.17 million square meters and includes residential, school and office buildings.

Passive house is a notion developed in Germany and refers to a rigorous standard applied to energy efficiency in buildings. It uses a combination of high-performance insulation, an airtight building envelope, a heat recovery system and photovoltaic power generation to reduce a home's reliance on artificial heating or cooling.

Energy conserved by passive houses in this ecopark cuts CO2 emissions by 26,800 tonnes annually. Offering outstanding performance in terms of facilitating climate goals, which is not limited to its passive houses, the ecopark in Qingdao serves as proof of deepening climate cooperation between China and the European Union (EU).

Such cooperation culminated in July when leaders of China and the EU issued a joint statement on climate change -- in which they recognized that strengthening China-EU cooperation on this issue would impact the well-being of people on both sides, while also being of great significance to upholding multilateralism and advancing global climate governance.

Qingdao Sino-German Ecopark, a project signed by China and Germany in 2010, broke ground in 2011 -- and has since expanded into a complex housing over 3,000 domestic and overseas businesses, along with educational and recreational facilities.

Notably, the ecopark launched research efforts on passive ultra-low energy-consuming building technology in 2013, while the following year, the park's first demonstration project agreement for such technology was signed by the two sides -- resulting in the Passive House Technology Center.

This center, a sleek building with a white facade, employs high-performance envelope structures, fresh air heat recovery systems, ground-source heat pumps and photovoltaic power generation facilities. It achieves annual savings of 1.3 million kWh in terms of primary energy consumption, reduces carbon emissions by 664 tonnes, and cuts annual operating costs by 700,000 yuan (around 98,554 U.S. dollars).

For Zhang, the novel experience of living in a passive house apartment is proving not only comfortable but also financially beneficial. "The entire fresh air system costs me about 3,500 yuan a year in electricity bills, which is roughly the same amount I used to spend in a single heating season," Zhang noted.

German passive house technology is well-suited to China, thanks to its adaptability and the presence of vast heating regions in north China, said Han Fei, deputy manager of Sino-German Ecopark Passive House Building Technology Co., Ltd.

Additionally, Han noted that China's vast real estate market, which includes a wide variety of public and residential buildings, presents significant opportunities for the application of this technology. Furthermore, many large Chinese manufacturers of insulation materials, doors, windows and fresh air systems are embracing such technologies, recognizing their business potential.

Thanks to its commitment to sustainability, the ecopark has become a hub for German enterprises. There are currently around 65 enterprises from German-speaking countries operating within the park.

Wang Yaowen, operations director of ElringKlinger Plastics Technology (Qingdao) Co., Ltd., has commended the energy-efficient plant facilities provided by the park -- explaining that these plants use a variety of cutting-edge low-carbon technologies.

"It offers solid support for our German-funded enterprises in achieving carbon reduction goals, perfectly aligning with our core commitment to sustainable development and further bolstering our confidence in deepening presence in the Chinese market," said Wang.

In 2024, Qingdao Sino-German Ecopark achieved a foreign trade volume of 15.8 billion yuan, utilized actual foreign investment of 71 million U.S. dollars and completed fixed asset investment of 23.42 billion yuan, a year-on-year increase of 17.4 percent. It is also worth noting that low-carbon industrial parks are attracting not only foreign businesses but also Chinese enterprises.

"In the past, inquiries from potential tenants mainly focused on land availability and tax policies. However, businesses are now increasingly concerned about the industrial park's carbon emissions and the share of green electricity used," Chai Qimin with the National Center for Climate Change Strategy and International Cooperation noted at a seminar held by the Beijing-based Institute for Global Decarbonization Progress.

Correspondingly, fostering zero-carbon industrial parks has been recognized as a key target for low-carbon development. China's Central Economic Work Conference last year called for intensified efforts to promote a green transition across all sectors -- including the establishment of a series of zero-carbon industrial parks.

Climate cooperation between China and Germany extends beyond Qingdao. In 2022, another passive house demonstration center was launched in north China's Tianjin Municipality, as part of their collaborative efforts. Additionally, in north China's Hebei Province, construction of passive ultra-low energy-consuming buildings, covering over 2.24 million square meters, began in 2024.

Boao in south China's Hainan Province, meanwhile, inaugurated a zero-carbon demonstration zone in March 2024 -- which is certified by the German Energy Agency.

"This demonstration zone was not meant to serve as a bonsai, but rather aims at promoting best practices that are sustainable, replicable and scalable," said Liang Kaijun, a manager at the Qionghai municipal investment and construction company, one of the firms involved in developing the demonstration zone in Boao.