I copied and pasted my previous response from your other post Robert in case this can help anyone else.
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Gas heat = About $8.50 per 1,000,000 BTUs of Heat
Electric Resistance heat = About $31.00 per 1,000,000 BTUs of heat
Heat Pumps are a great option when gas is not available, but in philly gas is available.
Heat pumps = About $9.50 per 1,000,000 BTUs, but the catch is it will only heat down to about 30 degrees outside then you need a electric furnace or gas furnace as a backup/ auxiliary heat. Heat pumps also act as central air in the summer months.
The Mitsubishi H2i ductless mini split heat pumps heat down to -15 and no backup source of heat is needed and is more efficient then even a high efficiency gas furnace, which is ridiculous.... but they are very expensive.
IMHO,
Gas heat is the cheapest when balancing up front installation cost and long term utility cost
We are talking a $22.50 difference between gas or electric per 1,000,000 BTUs burned. Over time that is a huge savings or added expense.
Free Department of Energy Comparison Chart
Punch in your local rates for the numbers to be dead on.
http://www.eia.gov/tools/faqs/heatcalc.xls
*I have been using the Emerson Sensi Wifi Stat because it is only $120 and you can lock it so it can only be controlled by YOUR smartphone. The tenant can push buttons all day and it will do nothing if you choose to disable the keypad.
https://sensicomfort.com/
I hope that helped :)