The calculated payback times for GHG emissions are 23.4% (3.5 years), 21.9% (2.9 years), and 18.7% (1.9 years) for electrical heating and 53.7% (8.1 years), 50.3% (7.2 years) and 42.8% (4.3 years) for gas heating for the SC-A, SC-C, and SC-P, respectively.