Tankless water heater
Source: https://www.bankrate.com/real-estate/eco-friendly-home-improvements/
Tankless water heaters have the ability to heat only the water you need - and they do so as you need it. They’re generally powered by gas or electricity, but these systems are not commonly pre-installed in homes in the United States, as tankless water heating has only been readily available in the past decade or two. Still, their on-demand design is 8% to 34% more efficient than storage water heaters, according to the Department of Energy. And that efficiency translates into savings in your pocket. A gas-fired tankless water heater can cut your annual energy costs by as much as $108, according to the contractor search site Angi. The savings associated with electric tankless heaters amounts to about $44 per year.