On average, a house fueled by natural gas is responsible for about one-third fewer greenhouse gas (GHG) emissions than a comparable all-electric home. Why? Let's take a look at what's called the full fuel cycle, which accounts for how much energy is retained – or lost – from an energy source until its final use in your water heater, oven, or home heating system. With the full fuel cycle in mind, natural gas's direct use comes out as a winner in the energy efficiency race.