thanks for the replies. I will try to touch on some of the questions: I am getting about 4 different load calcs, along with my own which include loading my Revit model into Autodeck Green Studio which analyzes everything and produces costs and loads. So once those start to get in, we can compare everything for similarities. For wells, we are building on about 1 acre. However we also need a septic in that space, so that eats up some. The house is modest size, with a footprint of around 58'x36'. There should be space for 2-3 tons worth of horizontal. THe guy digging my basement and septic can also dig trenches for the ground loops. However vertical wells cost around $2k in my area, depending on the depth of course. Most like to size up .5-1 tons worth of well around here. all windows will have coverings on them. I am toying with making the north glass triple pane. it would be roughly 800 for that upgrade for the north windows. According to the cost vs savings, that is a pay off of around 11 years....over high performance duel pane. not sure its worth it at all. I am way ahead to put in some nicer insulated shades instead of the glass. Looks nicer and is more efficient. Any thoughts on the more "DIY" approach? Meaning supply the products and just hire out the install? I have subs that can do vertical wells, grouting and hooking them up to the system for about $2k per well. I am not sure how many I need just yet, depending on the depth obviously. It looks like I can buy everything I need for 8k or less. Plus wells and install costs, I am probably around 15k or less, maybe.

Mike_home, 12 inches of blown insulation. The builder doesn't recommend increasing the attic insulation amount, but we are willing too if it is cost effective and will additionally cover more of the ducts. They do have the shiny insulation on the outside that I think is R6 according to our code in Florida. For the walls, there will be the rigid foam panels on the inside of the exterior walls, and in addition they will spray the closed cell foam. The masonry blocks are hollow--so the spray foam is sprayed inside the hollow blocks, filling them completely. This is my understanding, anyway. I imagine 2-3 inches might be about right, but I don't know for sure. I can ask. We are on a pretty tight budget but also want to do what we can to have a relatively efficient, comfortable home. Thank you for your help!

Hi, Thanks very much for your responses. - Everyone I've spoken with, and you've confirmed, that one zone per floor makes sense. If I'm missing anything else about "zones", please let me know! - How much should it cost to go from 2 zones to 4? - We are definitely going to put in all new ductwork. Is there anything here that I should be aware about or ask for? Any sites (besides GW) to get more knowledge on this area so I can ensure we get the ducts sized properly? - Good comments on getting more info on the geo wells, piping, etc. Will do. - Can I get a Manual J done even if the house is under construction? Framing is almost done, but the exterior work is not complete, and so it's open to the elements right now. - Yes, we have a natural gas furnace and electric AC in the house. It appears that a NG furnace was installed in 2007. The unit is a Lennox Signature Collection, model CX34-62D-6F. We also have an electric hot water heater, AO Smith ProMax Plus, model FCG 75 300. Does it make sense to re-use these or upgrade? Obviously, the furnace will be out if we go with geo. - Here's a summary of our NG and electricity rates. I hope I'm doing this correctly -- taking the bill amount and dividing by the energy used. Some months may need to be taken out because the numbers are too high/low. Please note that we have not lived in the house, so this is what we were paying for several months before construction commenced. So I would expect actual usage, and thus our bills, to be higher, but I guess that the cost per unit would be somewhat proportional. Natural Gas Monthly Charge / Therms Used / All-In Cost Per Therm $18.06 / 5.1 / $3.54 $16.76 / 5.1 / $3.29 $51.90 / 32.5 / $1.60 $78.53 / 57.7 / $1.36 $339.62 / 314.7 / $1.08 $362.71 / 321.1 / $1.13 $184.41 / 154.8 / $1.19 $81.98 / 60.4 / $1.36 $66.62 / 47.4 / $1.41 $18.45 / 7.1 / $2.60 $16.18 / 5.1 / $3.17 $1.97 average Electricity Monthly Charge / KWH Used / All-In Cost Per KWH $285.18 / 1757 / $0.16 $137.36 / 786 / $0.17 $77.44 / 416 / $0.19 $57.91 / 316 / $0.18 $66.29 / 382 / $0.17 $86.87 / 524 / $0.17 $61.02 / 341 / $0.18 $24.50 / 76 / $0.32 $25.22 / 80 / $0.32 $38.34 / 73 / $0.53 $21.23 / 53 / $0.40 $32.62 / 140 / $0.23 $0.25 average - It must not be code on my state (MD) to have each floor zoned. Our bids have been for two zones (on per system, one system covering basement and first floor, second system covering second and third floors), or for four zones (running off two systems). - Thanks for the heads up on the tax credits. My husband is tracking these, so I'll make sure he knows this. - The addition is on a loggia, not crawl space. So the basement is a walk-out basement, and the loggia will in effect extend the basement, and then the kitchen/family room addition will be above this, and our master bedroom addition above that. It's at the back of the house. Here's an early photo so you get the idea. The house is brick, and the addition will be part brick, part clapboard. - I am trying to learn what an HRV is, so am looking into this. - If it's not a good idea to go with spray foam insulation, let me know! Thanks for the info on what type would be good. - More thoughts on what system to go with, pricing, etc.?? THANKS AGAIN!!

Now that you have discovered you have natural gas, are you going to investigate who much it will cost to bring a pipe into your house? I don't see in the load calculation the R values for the walls and attic? Do you know what values were used for spray foam and batt insulation? Do you know how the spray insulation will be installed in the attic? Will it be open or closed cell? The firs quote is for a 4 ton single stage heat pump (XR15) while the second is for a 5 ton variable speed heat pump (XV20i) which is Trane's top of the line product. It is not a fair apples to apples comparison, but the price gap is big. You need to ask about the size for the second quote.