Propane - 92k btu gallon. Typical rate is $2.50. So 100k btus costs $2.70 or so. Assuming a 95% efficient furnace and you are just under $3. Electricity - 3.3k btu/kwh. Typical rate $.10. So 100k btu costs $3.30 or so. All electric heating strips are 100% efficient. So at average rates, they are pretty close - maybe electric is 15% higher. With electric you can add a heat pump - but that costs $$ since you probably don't need a/c. If you need a/c, then the extra cost for a heat pump is minimal. If you can get propane for much less than $2.50 or your electric rate is much less than $.10, it can really change the situation. Either way, I am going to do the impossible and guess - $500 a month. It is an insanely wild guess. Build you house tight and with good solar gain and it might be $200. There are other options. Geothermal has a 30% tax credit and uses electricity. It would probably be $50 a month with a tight house. There is oil, wood, pellets etc. - none of which are recommended (oil) or maintenance free - other options. Jfelen - 39 degree is way high. I believe MD has higher than average electric rates but you would definitely save money going lower. With propane, 25 is common. Your electric rates may change that to 30 but no way is 39 the best economic answer. Now - you might like the warm air and that is a different issue. I would try inching down a few degrees and see if you don't mind it. I'm at 35 (with NG) and I've never noticed unacceptably cool air (but that's me and my wife).

Thanks for the replies. Had two highly rated (Angies List) HVAC installers come out today, one specializing in Trane and the other Carrier. Both were very nice, took measurements all over the house and calculated required heat load. Both identified that my electrical panel had insufficient breakers available, so they would have to add a sub-panel. Both noticed that an upstairs return setup was poorly designed (and it is in an area of the house that is very tough to keep cool when it gets warm). Carrier guy seemed more knowledgeable about this issue, though maybe he just explained it more to me. Trane guy calculated the need for a 3 ton system, and said it would take a day or two to put together a good-better-best bid on the standard heat pump, and several more for a bid on Geothermal. I don't have high hopes for geo making $-sence, but I'd just like to get an actual quote as opposed to going off of internet rules of thumb, to be sure as to whether it's even worth considering. The Carrier guy calculated ~40kBTU/h need, so a little over 3 ton. He sat down with us and talked in detail about what feature and equipment would be best for us. He used Carrier's 'Right-$' operating cost calculator to estimate the relative operating cost difference between the units he quoted. He did this all during the initial visit, which was nice. Below are the options they quoted. Baseline: Outside unit: 25HBC342A0030 Air handler: FB4CNF042 SEER: 13 HSPF: 7.8 Cost: $7200 Midrange: Outside unit: 25HNB636A0030 Air handler: FV4CNB006 SEER: 17 HSPF: 9.5 Cost: $10000 Estimated annual cost savings over 'Baseline': $202 Top of the line: Outside unit: 25VNA048A0030 Air handler: FE4ANB005++UI (not sure if the ++UI is part of the #) SEER: 17.9 HSPF: 11.45 Cost: $12700 Estimated annual cost savings over 'Baseline': $522 *The Greenspeed option did not come in half-ton increments, so he spec'ed a 4 ton unit, but said with the variable speed features it could essentially run like a 3.5 ton unit. Made sense to me. All options included installation and removal of old equipment, new line set, whole house humidifier, small necessary ductwork mods to connect new system, staged resistance back-up heat strips (unsure what wattage) wi-fi capable (we don't care about the wi-fi bit) programmable thermostat and 10 year parts/labor warranty OR with the top level Greenspeed option, the Carrier Infinity controller and 15 year parts/labor warranty. We really appreciated the time the Carrier guy spent with us. We liked the two higher-end options due to being quieter and having the ability to dehumidify on demand, but they are a lot more up-front cost than the basic unit. The basic unit will no doubt be a little quieter than our current 16 year old A/C and furnace blower. The biggest cost savings for us is moving off of propane. I'm estimating ~$1500 per winter savings due to switching to the 'Baseline' heat pump, with perhaps another $300 in winter savings going from the 'Baseline' to the Greenspeed model (which is roughly in line with their $522 annual savings estimate for the whole year). Economically it's tough to justify another ~$3k or ~$5.5k when ~80% of my potential total savings are realized with the cheapest setup. Perhaps I will see if I can get the higher end variable speed air handle with the cheapest outside unit. Lastly, on the water heater, we are planning on switching it over to a high performance electric model. The Carrier installer will also apparently replace water heaters, though I need to wait to hear from them what their install cost is for a unit I buy myself ... which matters b/c I work for GE and get a pretty hefty discounts on their appliances, and they make high efficiency water heaters (http://www.geappliances.com/heat-pump-hot-water-heater/). I don't really care that it is from GE, aside from the discount, but unless I suddenly hear that their high performance electric water heaters are total junk there's a strong financial incentive for me to buy the unit myself. I'll update when I hear the bids from the Trane dealer. Thanks for any input folks feel like providing.

Alright I'm going to try and reply to everyone. sktn77a: I do not have the breakdown of the prices in front of me, but the total cost including installation is approximately $16,000 vs $18,200 vs $19,000. I did not mention that with the first option we are still getting an air conditioner, just not with the heat pump option. jn3344: Thank you for your feedback, this is the exact information I was looking for with this post. What was the temperature like for the $650 month? tigerdunes: Thank you for your opinion. We have had a heat load calculation done. David Cary: Thank you for your feedback. We have not considered solar, as we could only put them on the east side of our roof, our house is in the middle of the woods so a lot of shade, and we have no room to mount them anywhere besides the roof. And yes, the ducts will all be in a conditioned space. armoured: We are doing a tankless hot water system, and as explained above, solar will not work with where we are located. Thanks for your feedback. Springtime Builders: We are going to have propane on site whether we choose a heat pump system or not. Gas stove is a must, as well as a propane generator. "You could have a safer, healthier and more affordable home by replacing those combustion appliances with electric." I do not agree with this at all, but that is for a different conversation on a different day. There's also no hidden costs with gas, I have them all accounted for. We are purchasing our own propane tank and are having it buried. All supply piping is accounted for as well as any ventilation requirements. Thanks for your comments Elmer J Fudd and mike_home.

Some thoughts that go through my head when I read the OP concerns. I am a rookie who only built once, but it was plenty to know how challenging the process is. I really cringe when I read post posts about costs and "unforeseen out of pocket" costs. There are so many. I could not imaging building without full well knowing in advance you are going to blow through the budget. The nonsense about going over 10 or 20% are not true, even if you are disciplined and don't deviate from the plans, which is nearly impossible. Thats half the fun in building is changing your mind midstream because you wanted something a bit different, who cares the headaches and extra cost. There is a moment in time when you can adjust the sails and you do. I know this goes against the advice of the pros like Virgil who like to see every single thing spec'd out and written with no change orders required and thus no surprise bills, but that seems a fantasy to me. Not that it's impossible, but that seems to me that if one were to do that, you would have all the plans and specs done, and then just walk away and have someone call you when its done a year later, because everything should be all on the plans spelled out. What could go wrong with that? I had so many surprise costs, its comical looking back and thinking of them all. Plus changing my mind all the time..plus its impossible to stop searching and exploring for better things once construction starts...plus its a usually once in a lifetime thing..plus its a great time to splurge so you don'y have regrets about skimping out along the way. I understand that some folks want to build a utilitarian structure at bare bones pricing, but for all the others who are trying to get a nice quality home without surprise costs along the way, I would recommend not building. In fact, I can't believe there is not a sticky thread right at the top of this forum about what one should seriously know going into a new build. It should be written clearly and colorfully for maximum effect. All the pitfalls, dangers and concerns all rolled up into one. The first line of danger should be a warning that the budget will go over by at least 35% under the best of scenarios! I will start working on a thread for other rookie builders. Seems like a worthy cause.