Innovative river-water air conditioning system powers buildings in east China

NANJING, Dec. 5 (Xinhua) -- Though there are no conventional air conditioning facilities on the exterior of the civic center in Nanjing's Jiangbei New District, it remains warm inside in winter, thanks to an innovative air conditioning system powered by river water.

The "Jiangshui" or "river water" air conditioning system has been adopted by many public buildings in Nanjing, the capital of east China's Jiangsu Province.

It uses local river water, which is warm in the winter and cool in the summer, as its cold and heat source. The system provides heated water through pipes to local public buildings with a total area of nearly 12 million square meters, said Tan Jin, general manager of the district's State Grid branch. In summer, the system, with heat exchange equipment, delivers cooled water to achieve indoor cooling effect.

The system is capable of reducing carbon emissions by 140,000 tonnes annually, and of saving 140 million kilowatt-hours of air conditioning energy consumption, equivalent to the total annual electricity consumption of 56,000 urban households in Nanjing, Tan said.

The novel air conditioning system is a great example of the eco-friendly development transition of the city's architecture sector.

Data shows that since 2021, Nanjing has added more than 53 million square meters of green buildings and about 20 million square meters of renewable energy application area in buildings, taking the lead nationwide in advancing energy efficiency improvements to its public buildings.

The construction industry is one of the main contributors to carbon emissions in China. According to a research report, in 2020 alone, carbon emissions of buildings across the country topped 5.08 billion tonnes, accounting for more than half of China's total carbon emissions.

Wei Xu, chief engineer of the China Academy of Building Research, said that the development of green buildings is a powerful means to reducing carbon emissions in the construction industry and the only way to realize future carbon neutrality in urban and rural construction.

China has pledged to complete energy-saving renovations of existing buildings with a total area of more than 350 million square meters, and to construct more than 50 million square meters of buildings with ultra-low energy consumption and near-zero energy consumption by 2025.

On a busy street in Nanjing, a "breathing" building attracts attention. Its skeleton was constructed with wood and its roof consists of photovoltaic panels, and it is the largest prefabricated zero-carbon building in Jiangsu.

"Several hundreds of photovoltaic panels on the roof generate about 270,000 kilowatt-hours of electricity annually, and all the lighting, air conditioning and other electricity needs of the building can be met using clean energy. It can also store surplus photovoltaic energy for the surrounding communities," said Liang Long, a customer manager at State Grid's Nanjing branch.

To date, Jiangsu has a total green building area of more than 1.07 billion square meters, ranking first in the country. Economic powerhouses such as Beijing, Shanghai and Guangdong have also begun the green transformations of their urban architecture.

"With the rapid development of urban and rural construction, energy demand continues to increase, and effective action must be taken to promote energy conservation and carbon emissions reduction in the construction sector," said Ni Jiangbo, vice president of the China Association of Building Energy Efficiency.

Traditional concepts of Chinese architecture emphasize the harmony between people and nature, according to Zhou Lan, vice chairperson of the Jiangsu Provincial Committee of the Chinese People's Political Consultative Conference.

The development of green buildings should learn from the eco-friendly thinking of these traditional concepts, combining them with contemporary urban and rural construction and making full use of modern technologies and new materials, thus promoting the high-quality development of green urban and rural construction, Zhou said.