Water Heating: A Look at the Options

Rarely the focus of much attention, water heating accounts for surprisingly large energy loads and environmental impacts. Water heating is typically the second largest energy expenditure in homes (behind space heating) and the fourth largest in commercial buildings (behind lighting, heating, and cooling). In terms of greenhouse gas emissions, a standard residential electric water heater is responsible for nearly half the carbon dioxide emissions of an average passenger car!

system efficiencies, and a wide range of options for heating water. Some strategies discussed in the article apply primarily to residential applications and a few only to commercial, but most can be relevant to both residential and commercial buildings.