Operating performance in cooling mode of a ground source heat pump of a nearly-zero energy building in the cold region of China

• The first building that was built with nearly zero energy target as 25 kWh/m2 yr.
• Ground source heat pump system is utilized to cover the cooling demands in 2014 summer.
• Heat exchange result of single U-tube and double U-tube are compared in summer.
• Test result on a typical day show the COP of heat pump unit could reach to 5.

A hybrid ground source heat pump system is utilized to meet the energy demands of the first nearly-zero energy office building located in the cold region of China. The simulation result shows that the heating, cooling and lighting demands of the building could be reduced to 25 kWh/m2 yr with the utilization of high-performance envelopes and the hybrid renewable energy system. A ground loop consisting of two rectangular fields of 70 borehole heat exchangers is utilized together with the solar energy system to meet the building's energy demand. During the system commissioning phase, from 1 July to 15 August 2014, the inlet and outlet water temperatures of the heat pump unit and boreholes were collected and analysed. The coefficient of performance (COP) of the heat pump unit could reach 5.0 in cooling operation strategy, which satisfies the energy reduction requirement and meets the room temperature standard.