At present, the development and utilization of renewable and clean energy as a priority to the development of the national energy strategy, the goal is the 2020 renewable energy in new buildings 50%;
????Air conditioning energy consumption in China accounted for 65% of the energy consumption of the building, the development of energy-efficient environmentally friendly renewable energy heat pump technology has become the key to green building and national energy strategy goals.
????Single air source heat pump: Winter outdoor temperature is too low, the heat pump system frost serious heat supply is obviously insufficient, a sharp decline in energy efficiency, and even does not start properly, can not meet the heating requirements.
????Single ground source heat pump: use by domestic solar hot water  sources and geological conditions conditions strictly chinese solar water heater consumption, all recharge difficulty, a large one-time investment, high energy consumption of pumps.