China has pushed hard to find a cleaner way of powering buildings, but much of its efforts end up wasted.

In a recently completed assessment study, researchers from China and the United States examined the performance of more than 40 Chinese buildings that deployed renewable energy solutions. By tracking real-time data during the past two years, researchers found that most projects failed to generate environmental and economic benefits as anticipated.

“Less than one-fifth of the buildings equipped with solar energy solutions met their targets. The performance of those with large-scale solar water heaters and geothermal heat pumps was even worse,” said Tan Hongwei. He is the team leader of the study and a professor at Shanghai’s Tongji University.

Since the examined buildings are scattered across China and ranged from public facilities like schools to commercial office buildings, Tan said that the group appears to represent the general situation in the field.

China has a strong interest in integrating renewable energy in buildings, as they now consume more energy than the nation’s three largest heavy industries — iron, steel and cement — combined.

Well-intentioned policies meet smog

To cut the building sector’s demand for coal, Chinese policymakers have financed technology innovations, subsidized pilot projects and issued supportive policies, including the mandatory use of solar water heaters in sun-rich areas starting next year.

The goal: By the end of the decade, solar, geothermal and other renewable energy will contribute to 15 percent of the total energy use in China’s new buildings. There are no statistics available on the current percentage, but Tan of Tongji University noted that hundreds of pilot projects are already established in the country.

“As more and more Chinese buildings are adopting renewable energy solutions, it is crucial to figure out how the pilot projects function and what problems exist,” Tan said, referring to the purpose of launching the study.

Through the assessment study, the first of its kind in China, researchers discovered that many Chinese pilot projects underperformed because of design flaws, poor construction and inefficient incentive mechanisms, among other causes.

One case in point is building integrated photovoltaic projects, which produce electricity from solar panels installed to replace conventional materials in parts of the building envelope like the roof or facades. According to the study, the electricity production of the solar panels was calculated on average sunshine in the region, but the projects are often located in downtown, where air pollution weakens sunlight and the resulting power output.