The following article is reposted with permission from the author from the SolarThermalWorld website.
The solar installations above the apartment blocks of the “Utopia Garden” Project in the Chinese city of Dezhou attract attention even from a distance. The 504 vacuum tube collectors have been placed horizontally in a massive metal casing that has the form of a wave and covers the entire roof of the building. The solar fields, with a gross collector area of around 1,400 square meters [15,070 square feet], consist of pressurized, heat pipe vacuum tubes, which harness the sun on the roof and feed it into a central heating and cooling system that runs through the entire building complex.
The design and construction of the eco-friendly houses, as well as the marketing of the apartment units is completely in the hands of Himin Solar Energy Realty, a subsidiary of the Himin Solar Group. The company has already sold out four blocks with a total of apartments at the waterfront of an artificial lake, and the new owners started to move in at the end of 2011. Two more blocks are now under construction.
“Seeing what modern living standards will be like in the future persuades people to buy the 300 to 600 square meter [3,229 to 6,458 square feet] big flats,” explains Chen Ping from the Brand Management Department of Himin Solar, one of the largest solar water heater manufacturers in China. “The price of the flats is around 12,000 Chinese Renminbis per square meter of living space ($180/square foot), which is around 50 percent more than for comparable flats. Advanced renewable energy technology and intelligent home technologies make the difference.” Still, apartment owners save up to 75 percent of annual energy costs in their new accommodations.
In summer, the solar field above the roof powers the absorption chillers for the apartments’ air conditioning. Any excess solar heat is stored in a seasonal storage area below the building complex. The size of the storage area - which includes 1,800 bore holes - has been constructed large enough to also supply the entire Utopia Garden Project, which is said to include, in all, 10 blocks of apartment units.
Electric compression chillers, as well as gas absorption chillers, have been installed to serve as backup systems when the solar heat does not reach a high enough temperature to run the solar chillers. The space heating demand in winter is primarily covered by the seasonal storage’s ground source heat pumps. If they do not prove sufficient, the buildings will get the rest of their energy from the district heating system.
Each apartment also includes a vacuum tube collector, which has been integrated into the façade, and a 300-liter [79-gallon] tank, which has been mounted to the balcony and supplies a family with hot water. These solar systems represent a totally new way of using residential solar hot water in China. They are pressurized, indirect systems that include U-pipe collectors and a closed loop solar circuit filled with glycol. Whenever the façade collector does not reach the required 60 degrees Celsius, an electrical element will take over the heating process. In these buildings, the apartments’ solar hot water is kept separate from the central heating and cooling system.
Bärbel Epp is the founder of Solrico, a market research agency focusing on solar thermal technology.