You can cut your water heating energy use by 30% with a new ENERGY STAR qualified gas condensing model. By shaving about 75 therms from your natural gas bill every year, you are also reducing your greenhouse gas emissions. If just five percent of the gas water heaters sold each year were ENERGY STAR qualified gas condensing models, the U.S. would avoid wasting $25 million — and 17.2 million therms of energy — each year. In terms of greenhouse gas emissions, that's equivalent to taking almost 17,000 cars off the road.