Some people say, "I don't want to heat the whole house, the furnace is wasting energy, space heaters are just fine." The electric space heater on the left is very safe. No hot glowing coil to start a fire. Maximum output is 1500 watts or about 5100 BTU/hr. The natural gas space heater on the right has a maximum input of 40,000 BTU/hr with an efficiency of about 75%.The output level is fully adjustable depending on ones needs or wishes. As an example, turn down the output to half-level (20,000 BTU/hr input and 15,000 BTU/hr output. In one hour it consumes 20,000 BTUs or 1/5 of a Therm for about $0.18. Three hours with the electric space heater on the left puts out about the same energy or heat and uses 4,500 KWh for $0.78 or around 4.3 times more. Which one would you like to see in the morning after a cold night or coming home from work on a chilly night. The gas space heater can heat a home in Palo Alto's winters on all except the very coldest days (less than 30°F). It can be easily connected to the thermostat on the wall for trouble-free convenience.