Energy conservation or energy saving is one of the most important methods for reducing CO2 emissions, which is known to be associated with global warming. Although development of renewable energy sources such as solar or wind energy is necessary, we must first pay attention to the fact that enormous amounts of energy are consumed uselessly at present. Energy saving should therefore be one of the first problems to be tackled. It may not only bring reductions in CO2 emission, but also may lead to savings in expenditure on energy. This paper introduces some of the initiatives taking place in Japan aimed at energy conservation.