A case study of ground source direct cooling system integrated with water storage tank system

Energy consumption for the commercial buildings has increasingly gained attentions, due to the significant electricity consumption and peak power demand. To solve this problem, this paper focuses on performance on the Ground Source Direct Cooling (GSDC) system integrated with a Water Storage Tank System (WSTS) in the summer, which directly utilizes the low-grade energy to supply high temperature water for the radiant floor cooling system and make full use of the electric rate difference between on-peak and off-peak periods. In summer, the indoor air temperature is controlled between 23 and 26 °C, resulting in a comfortable thermal environment. The total cooling capacities in 2014 and 2015 were 32.6 kWh/m2 and 30.7 kWh/m2, respectively. The annual energy consumptions for Electricity Unit Intensity (EUI) in 2014 and 2015 were 33.0 kWh/(m2·yr) and 32.1 kWh/(m2·yr), and the cooling energy consumptions only consumed 4.19 kWh/(m2·yr) and 4.55 kWh /(m2·yr), respectively. The annual operating cost of this cooling system only reaches 9 yuan/(m2·yr) through the analysis of 5 years’ operation. Compared to a conventional air cooled heat pump system, this cooling system has a larger initial cost, but its recovery period is less than 4.3 years, due to the extremely low operating cost. Overall, this GSDC system integrated with WSTS in the summer has remarkable advantages in thermal comfort and energy efficiency.

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