Oil and propane do not make as much CO2 per unit of heat as coal does, wood is closer to coal as far as CO2 emission, as quoted:
"Producing the necessary electricity would require 876 lbs. of coal, 377-324 lbs. of natural gas, 508 lbs. of oil".
Natural gas and oil have more energy per weight because Hydrogen is a source of the energy. Methane is CH4.
"The chemical formula for propane is C3H8"
http://www.c-f-c.com/specgas_products/propane.htm
Coal of course comes mostly from wood, so they are similar.
Here's chart of vermont: Residential Sector Energy Consumption Estimates, 1960-2002, Vermont.
http://www.eia.doe.gov/emeu/states/sep_use/res/use_res_vt.html
This comes from:
http://www.eia.doe.gov/emeu/states/_states.html
In 1960 in Vermont:
Coal:45 Wood: 173 Propane: 258 Electricity: 451
In 2002 in Vermont:
Coal:0 Wood: 66 Propane: 1,804 Electricity: 2,047

So there has been decrease in coal and wood, but propane is commonly used in vermont [very little natural gas- & heating oil is flat or declining].
If electrical power is cheap, then it's generally the preferred way of heating houses and cooking. For example using one of those small electrical space heaters will cost you a lot money if your electricity cost are over say 10 cent Kwh and you using as a main source heating a house- same applies if your central heating uses electrical heating elements.
Generally speaking it's takes more energy to cool than heat, and as I quoted:
"The most significant end uses were central air-conditioning and refrigerators, each of which accounted for about 14 percent of the U.S. total."
Refrigerators used to be hideously inefficent, and they are still are inefficent.
Though if there are lot homes in vermont which older and if they haven't been properly insulated, then heating costs could be very high, but generally people are smart enough to spend the relatively small amount of money to properly insulate a house, esp if the cost of heating rises.