No. 17: Using earth thermal for the air-conditioning of convenience stores (November 10, 2011)

Japan’s largest convenience store chain Seven-Eleven will start an experiment to use earth thermal for the air-conditioning of its stores. Using the piles to be driven into the store underground, the system will circulate water that is warmer than outside air in winter and cool in summer, thereby reduce the power used for air-conditioning by about 30%. In the initial stage, the company will install the system in three stores. The experiment will start early next year. The system was developed by JFE Engineering.

According to JFE Engineering, earth thermal is constant at 17 degrees centigrade all the year round in Tokyo. Using the circulating water, the system lets heat go in the ground in summer and collects heat in the ground in winter. To build a convenience store on soft ground, it is necessary to drive 20-30 piles, each of which is 10-20 m long, into the ground. The system fills the piles with water and inserts pipes for circulating water connected to the outdoor equipment for air-conditioning in the piles. As Seven Eleven will build about 400 stores on the soft ground, it will introduce the system to them depending on the results of the experiment. Since the system requires an initial investment of 7-8 million yen per store, reducing the price through mass production is vital for its spread. New Energy and Industrial Technology Development Organization will bear two thirds of the cost necessary to introduce the system into the three stores.