Don't forget to check out the 'heating and a/c' forum and have you had a J-load calculation done yet? I think that is what it is called; heating and a/c should be able to help you!
Good Luck!

if you didn't have ng I would advise you to go heat pump.
however ng is more efficient.
equipment cost is more upfront that hp, but savings make it worth the upgrade.
I always recommend ng over hp when available.
a lot of folks don't upgrade from 80% to 90%+
but most of my clients go 96% the argument here is that we don't have long winters..but it does get cold.
from the viewpoint of getting 96% of the heat into the house vs 80%..its a no brainer.

I do like hp's.
the 'sweet spot' is 15 to 17 seer above 17 seer the temp
drop across the coil isnot always achieved, and efficiency suffers. below 15 seer you are limited to single stage
variable speed starts at 15 seer and vs is a great thing.
better humidity control in low fan speed settings and the capcity to handle the few days when you have company and
more cooling is needed.

heat pump will cost approx 700 more than electric strip
(the most expensive way to heat)
96% will cost approx 1500 more.
cost varies in different locations, just base prices to give you an idea.

have your hvac companies give you a good better best bid
14 seer (good) 15 seer (better)and 16 to 17 seer (best)
request this from each company to get an apples to apples
comparism.

load calcs are good things, make sure that the company understands that you are doing air sealing and a better insulation package than the minimun code. also include
u-factors and solar heat gain coefficints of windows to
the company.
otherwise you will get that old 500 sq ft per ton and have an oversized short cycling unit.
expect to pay for the load calc. unless you get it from an independent the hvac company will not do the load calc until you sign a contract with them.

best of luck.

HP and furnace is the best. But I'm not sure it is worth it for you. This winter we had $100 in NG bill and about $400 for electric to run the heat pumps(2000 sq ft x 2 floors plus 1400 walk out basement). I have a 90% furnace downstairs and basement with heatpump and upstairs just has a heatpump. The heatpump is used above 35 degrees downstairs and all the time upstairs.

You will absolutely save money with a heatpump when the temp is relatively high. Whether it is enough money to justify the cost is another story.

Around here, the absolute lowest cost is achieved by not using NG. That is really surprising but for me it would be true. Now we have solar hot water which changes the equation. This year I spent $120 in connection fees for NG and about $120 in usage. Doesn't really matter since we wanted NG for cooking.

Since you are going to have NG already, you might as well use it to heat. The only question is do you add a heat pump. It generally costs less than $1000 to do so (or maybe $1500 for 2 units). But it probably would save $200 a year or so. Really hard to say but it would definitely save you money.

Seer 15 is considered the sweet spot. I have 15/16 which I take to mean 15.5.

By HP and furnace, do you mean the heat pump that kicks on the furnace when it gets below a certain level? Not super familiar with the options!

HP and furnace - heat pump runs at higher outside temps. When it drops below a set temp or it can't heat the house fast enough, then the furnace kicks in. Heat pumps tend to be very efficient at warmer outside temps but less so when it gets colder. So you run them when they are most efficient. If you are going to have a/c, the heatpump is not much to add. This also protects you if NG gets expensive since you can run the heat pump more (ie down to lower temps). Right now, NG is so cheap that it is hard to justify spending much on a heat pump but 5 years from now who knows.

Even now I still probably save $200 or so a year by having a dual fuel system. If NG were to double in price, the savings would be $500 or more (since I would run the heat pump down to a lower outside temp).

I think If I remember correctly this is your last house? If so, you might want to look into geo.

Geo in Georgia is truly overkill. I'd guess that tax credits take the payback from 150 years to 50 years. Easily a $10k premium for saving $200 a year. My energy audit suggested $300 a year in a colder climate and my actual costs are about 1/2 my audit. The audit was based on 80% NG and seer 13 so only saving $300 from that is pretty bad. I saved more than geo by going to seer 15 and 90%NG.

Geo shines in the North and where NG is unavailable. While it does help with a/c, the savings are minimal.

We looked into geothermal - really really expensive and I bet our payback is at least 150 years. One quote was 75k more (from the experts who install geo all over Atlanta and north GA), and one was 35 k more than using dual fuel 15 seer heatpumps with variable speed. The lower bid was from someone who had never done it and I understand this is something you want put in by someone who does it all the time . . . If it had been 10k more we would have considered it :)

athens, you might want to ck out a thread over a greenbuildingtalk.com There is a thread there on 'why does geo cost so much'.
David, don't forget you also get free hot water with geo and with the tax rebates it makes it very comparable. NG can go up and down just like oil and you know where oil is now.

Well - the hot water isn't free. Even with solar, it isn't free.

NG certainly can go up. The main reason it isn't up right now is that it is an American product. That changes everything. It is also hard to store large quantities. Fracking makes the US the Saudi Arabia of NG. Now - a fracking disaster might change things but barring that, NG will not behave anything like oil.

And besides - I was recommending a dual fuel system anyway. But geothermal in the south is such a marginal proposition that if you throw in the availability of NG, it makes it a no brainer. Add in that experienced contractors charge a ridiculous premium in the south and it looks like Athens payback is actually around 350 years.

Geo using coal as a generating source most likely creates more greenhouse gases than NG. NG is that good (well really coal is that bad).

My energy audit gave more points (ie more $ saved) with solar hot water than geo. My cost was about $2000 after credits. Compare that to geo in the South where $10k after credits is minimum.

This subject is my passion and I apologize if my responses get a little over aggressive. We need to reduce energy consumption but we need to do it right.

Thanks for the input, guys. You bring up a great point, David, that folks forget. In Georgia, most electricity is generated by coal. Natural gas is a much more environmentally responsible choice. Put that together with the fact that our geo bid from the market leader was 100,000 (yes you read that right!) and it was a no brainer. Rebates don't bring it anywhere close to making sense here either. Add that to the fact that it is no better for the environment and it just didn't make sense for us.

Solar hot water is out for us I think. We are building on a heavily wooded lot and the only direct sun we have is in the front yard :)

David, I agree with everything you said but I still feel geo is the way to go even in the south. The hot water is free when the geo is running...you won't get 100% of needs but alot of what you need. Don't forget that NG is also priced by the NG traders....just like oil. Even thou oil is actually plentiful now....the Oil traders are pushing up prices using excuses.....to make MULLA money for themselves!!!!
Athens....that price for geo is nothing but a complete rip off!!!!!!! From what I've learned over the years they seem to price it on how much money the people have that is getting quotes....which means veryyyy little competition!!! How big is your house? How much is your elect by kw? The main cost difference is either well drilling or trenching. If I were you I would go to that web site and see if you can find someone from there in your area. You might want to ck out some of these.

http://www.bing.com/search?q=geothermal+companies+in+georgia&go=&form=QBLH&qs=n&sk=

We found geothermal to be extremely expensive as well. Here in Birmingham we don't have a lot of options and ended up getting our estimate from a company in Georgia. For 3200 square feet plus basement the bid came to just under $70,000, which we just couldn't do.

If well drilling is not common in your area then GEO can get expensive (unless you go for the shallow trench GEO that is not as efficient, deeper ground sources are always more efficient sine the earth temperature is more stable).

Many of the high SEER systems are not economically worth the cost. The energy savings will be swamped by the required repairs.