An eco-house is an ecologically adapted house that dramatically reduces the use of oil, gas, and electricity to minimize CO2 emissions. Sekisui House introduced eco-houses onto the market in the summer of 2008. These houses are equipped with fuel cells that produce energy through a reaction of oxygen and hydrogen taken from natural gas, as well as with photovoltaic panels. They also reduce energy consumption with the use of highly airtight insulation material and light-emitting diode (LED) lighting. Households account for about 12% of Japan’s total CO2 emissions, and so environmentally friendly houses should have a positive effect on the environment.