On the streets of Japan, there are convenience stores everywhere stocked with various foods, magazines and daily necessities. Many of them are open 24 hours a day, seven days a week, supporting convenient lifestyles with locations where you can even shop in the middle of the night. On the other hand, these stores lit brightly at night and the refrigerator cases that keep beverages cold at all times use up a lot of electricity. As a result, electricity costs account for a large portion of the stores’ operating expenses. Convenience store companies are now working to make low-cost stores while reducing their impact on the environment by utilizing natural energy.

Cooling the Summer with 100 Tons of Snow

In Akita Prefecture where it is covered in deep snow during the winter, a store was opened in November 2013 that saves snow until summer to be used for air conditioning. One hundred tons of snow can be put into a storage unit on the premises. The outer walls of the unit contain insulation so that there are no electricity costs to keep the snow. In the summer, cold water from the melted snow is circulated through a heat exchanger and then the cooled air is used to air-condition the store. Water from the melted snow that could not be used up is then sprayed onto outdoor equipment for the refrigeration cases inside the store. By cooling the outdoor equipment that is out in the summer heat, it can also reduce electricity costs for the refrigeration equipment.

The double-paned windows that increase the efficiency of heating and cooling also have “heat pipes” installed in them that make hot water by using the solar heat between the two panes. This hot water is used for floor heating at the counters used by the store clerks, saving electricity costs in the winter. There are solar panels on the roof and a system has been installed that automatically regulates heating and cooling by working in conjunction with outdoor temperature sensors.

This store was built by a major convenience store chain in order to study the effect of the latest energy saving equipment. It is expected that the amount of electricity used each year will become about half when compared to the stores up until now. Once the effectiveness of summer cooling has been verified, it will be considered whether or not to put the same equipment in other stores as well.

Reusable Paper Display Shelves

At another store just outside of Tokyo, a hole 100 meters deep has been dug on the premises, and a heat exchanger for air-conditioning has been embedded into the ground. Groundwater temperatures remain stable throughout the year at around 17 degrees Celsius making it usable for cooling in the summer and heating in the winter. This could reduce the amount of energy used for air conditioning by about 30 percent. Standard air conditioners are said to contribute to the “heat island effect,” which raises temperatures in urban areas due to the exhaustion of heat as it passes through the outdoor units during cooling. The new equipment can minimize its effect on the surrounding environment by sending the heat generated during summer cooling, into the ground.

In order to reduce electricity used for lighting during the daytime, the major chain operating this store has also adopted the use of “light ducts,” which deliver sunlight using a special tube to light certain areas in the store, such as restrooms where it is often difficult for outdoor light to reach. In addition to that, they have also developed display shelves using 100 percent reusable hard paper. Up to 15 kilograms of merchandise can be displayed on each shelf. While they maintain the same strength as the conventional steel types, carbon dioxide emissions during the manufacturing and transportation of them can be reduced by 70 percent.

As a Lifeline During Disasters

The advancements of convenience store companies toward using natural energy are also meant to serve as a lifeline to supply food and daily necessities to surrounding residents after the large-scale disaster occurred.

The largest chain, with 16,000 stores open throughout Japan, began demonstration tests by storing electricity into storage batteries during the night when power consumption is low and the price is comparatively cheap, and using it during the daytime when power usage is at its peak. Use of these storage batteries can cover enough power necessary for operations not only to avoid power shortages during the summer when power demands increase all over Japan, but also during power outages for a certain amount of time. Even when there are power outages during the night, as long as part of the store is lit up, residents will have some peace of mind.

This chain is also actively introducing solar panels for power and has already installed them at 6,600 locations. Equipment that reduces daytime lighting is also being introduced, capturing sunlight directly into the store through skylights on the roof.

Convenience stores have become an essential part of Japanese society. Future initiatives will continue to expand in order to accommodate convenient lifestyles and respond to global warming.

(April 2014)