Study on Cost Performance of Gain and Payback Period in a Plant Factory of Spinach in a Cold District

—Energy supply and demand of a plant factory facility on our campus were investigated for the purpose of energy saving in a cold region plant factory with renewable energy. The average value of the highest temperatures in November to March is 20 degree Celsius or less in Kitami. Therefore, the environment temperature of the plant factory was adjusted to 20 degree Celsius by air cooling with a ventilation fan. In addition, by supplying surplus heat of cogeneration to an external greenhouse, an increase in the harvest volume of spinach was expected. Moreover, a facility consisting of a cold region plant factory and a greenhouse is defined as a "plant cultivation system". When spinach is cultivated in this system, cost performance of gain is 2.57 (price of farm products to production costs) and the payback period is 9.70 years, so a general introduction can be expected.