As promised, there is now a tool on this blog for estimating how much you'll save or lose annually in heating fuel costs if you switch completely from oil, propane, or natural gas to either electric radiant heat or electric geothermal heat. In order to use the estimator, you'll need to know what you expect to pay for electricity next winter, make a guess of how much whichever fossil fuel you now use will cost, and look up or guess how much of that fossil fuel you used last winter.
$5.00/gallon oil, for example, costs roughly the same to use for heating as $.15/kwh electricity when the electricity is used to produce radiant heat. Geothermal electric heat is, however, much more efficient but also has a higher capital cost. The estimator does NOT take capital expense into account but is useful in seeing how much savings you'll have to amortize any capital expense you may be considering.
The model also does not take into account the fact that using electric heat may throw you into a penalty electric rate in some places (Stowe, VT, for example).
The estimator is here.
All calculations are based on the data in this spreadsheet from the US Energy Agency.
A primer on geothermal heat is here.
A post about a cheap and partial conversion to electric radiant heat is here.
You are welcome to put the code on any site you want but please don't change it in any way. The code is here.