HEATING WATER ACCOUNTS for 15 percent of a home’s energy budget, and half of that is used in bathrooms. You can maximize water and energy savings in the bath by choosing the most efficient way to heat water. Tankless water heaters heat water on demand (via a heat exchanger heated by gas, propane or electricity) rather than maintaining the temperature of a given volume of water. These units offer several advantages over conventional storage water heaters. Because energy is only used to heat water when it’s needed, tankless units are more energy efficient and can produce “endless” amounts of hot water. According to Energy Star, high-efficiency tankless water heaters can save between 45 and 60 percent more energy. They also last up to twice as long as conventional tank heaters and take up less space. Parts are modular and can be replaced easily, and many tankless units are made of recycled components that are themselves recyclable. And you don’t have to worry about the unit rupturing and releasing 50-plus gallons of water into the mechanical room—and beyond. On the downside, tankless units cost more up-front, and do require more mindfulness when using several fixtures or appliances that require hot water at the same time. However, most manufacturers offer models tailored for various household sizes and hot water demand.
All tankless units are not created equal, either. While non-condensing tankless units are highly efficient and most are Energy Star rated, some companies, including Noritz, Rinnai, Rheem and Bosch, make condensing-type units, which extract the heat from exhaust gases. These units achieve ultra-high efficiencies of 90 percent or more.