In simulation, storage cuts heat-pump upfront investment by 29.7%

At 23:00, the system designed by researchers at China’s Hebei University of Technology would switch on six air-source heat pumps and begin filling a thermal store. In their simulation of a six-story, 10,030 m² office building in Tianjin, the stored heat or cold then supplied most of the building’s needs during the working day.

The mechanism is simple: the pumps run at full capacity during the eight-hour low-tariff period, from 23:00 to 07:00, storing hot water in winter and chilled water in summer. A stratified 1,010 m³ tank, divided in the model into four vertical thermal layers, releases that energy from 08:00 to 18:00; the pumps run during intermediate-tariff periods only when the stored supply is insufficient.

That shift also changes the size of the equipment. The storage-assisted design was sized for cumulative daily demand and used six units, each rated at 146 kW for heating and 130 kW for cooling. The conventional air-source heat-pump system had to cover the maximum instantaneous load and therefore used 11 units. The researchers calculated a 29.7% cut in upfront investment, from CNY 3.43 million to CNY 2.41 million, and a 51.4% reduction in annual operating cost.

So what changes in practice? For a building owner in a region with peak-valley electricity pricing, the modeled design could mean a smaller heat-pump installation, lower electricity use and less exposure to daytime tariffs. The simulation reported 21.9 MWh less annual electricity consumption and about 17.6 metric tons of CO₂ fewer emissions each year. But this is still a proposed, simulated system: the reported performance has not been presented as a deployed installation or a field result.