Going Green... Cold water washes are greener, but will they get my clothes clean? For a hot-water load, about 90% of the energy used to wash clothes goes to heat the water, not agitate your clothes. The good news is washing your clothes in warm water or even cold water will get rid of almost anything, except for the worst dirt or oily stains. Reader Digest Version: Switch from hot to warm water to cut energy use in half; cold, to cut even more.