HOSHINOYA Karuizawa is powered by the Energy In My Yard (EIMY) system, which runs on hydroelectricity－provided by the river flowing through the premises－and geothermal energy. It was developed from a simple idea: Using energy without damaging the resort's rich natural environment.
Development of EIMY initially focused on the use of hydro power, but soon incorporated the abundant geothermal energy that makes Karuizawa a hot spring hotspot. The three wells built to draw up this power achieve ten times the heat exchange efficiency standard in Europe and the U.S.
Combining this system with architectural ventilation elements has allowed the resort to become 70% self-sufficient and to use absolutely no fossil fuels. Thanks to EIMY, guests can enjoy natural cooling from the winds of the highlands and floor heating that produces no carbon dioxide.