Question

Suppose you are deciding whether to buy an electric or a natural gas hot water heater. Assume you live in California.

Note: 1 therm of natural gas equals ~30 kWh of electricity

Natural Gas Price in CA = $13.35 per Thousand Cubic Feet

Electric price in CA = .16 cents per kilowatt-hour (kWh)

Gas Water Heater Uses 258 therms per year

Water heater numbers are based on 40-gallon models with a 0.63 EF rating using 40,000 Btu/hr and based on the U.S. Department of Energy’s (DOE) national average of 64 gallons of hot water use daily.

Electric water heater Uses 4,881.25 kWh per year

An average water heater runs three hours daily. A 50-gallon, 5,500-watt water heater with a .90 EF and an electricity rate of $.16 per kilowatt hour.

For each sub question, show your assumptions and calculations.

1a) Which would you pick to minimize your operating costs?

1b) If the electric water heater cost $1250 and the natural gas water heater cost $1600, how much would this change your calculation for 1a?

1c) Which would you pick to minimize your total energy footprint, and why?

1d) Which would you pick to minimize your environmental footprint, and why?

Answer 1