Here’s an article on the topic from the Energy Star website.
They call it site/secondary energy (“consumed energy”) vs source/primary energy (“raw fuel”)
There is a PDF linked there discussing the “site/source ratios” that Energy Star uses.
The national average (2001-05) they use for electricity is 3.34 which is based on 70% fossil fuel, 20% nuclear, 10% renewables.
(I believe the mix I came up for MA as reported by National Grid each month in my bill in Shutesbury, MA in 2008 was ~40% coal/oil, ~30% nukes, ~30% nat gas.)
Anyway, point being… only 30% (=1/3.34) of the energy in the fuel actually gets to the houses.
But one gets 100% of the particulate pollution and greenhouse gases. So unless you are generating your electricity renewably (as with PVs or a “green up” option on your electricity bill) you are polluting 3 times as much when you are heating your house (or heating water or cooking) with electricity (vs using propane/natural gas).
PVs are especially nice because one is directly helping out with peak load times (during the day when people are at work and using heat or AC) — the difficult times for power-plants.
HERE’s the LINK