Buying gas is way cheaper than buying electricity; however, if your electric grid contains any significant portion of carbon-zero producers (hydro, nuclear, solar, wind), using electric space heater will emit less CO2 than gas furnace, for the same amount of heating. If you care at all about CO2 that is. This is the main reason why burner heaters have been so difficult to replace - we thought we could price our way out, let market forces pull us gently into a renewable future without having to make personal sacrifices, but gas is just so much cheaper it's tough to give up.

An electric heat pump will just about break even on cost with gas, while giving even greater CO2 savings. Annoyingly, a gas-powered heat pump will still be cheaper.