Product Guide Water Heaters – Fuel-Fired Commercial In terms of greenhouse gas emissions, a standard electric water heater is equivalent to nearly half the carbon dioxide emissions of an average passenger car. Photo: A.O. Smith Behind the recommendations Related articles Behind the recommendations Related articles Water Heaters – Fuel-Fired Commercial Systems with thermal efficiency ratings of at least 96% for gas and 87% for oil, plus other environmental features More about Water Heaters – Fuel-Fired Commercial Water Heating: A Look at the Options A Look at Heat Pump Water Heaters A New Generation of Demand Water Heaters