We are planning on building our retirement home on a 30 acre lake in NE Mississippi this spring. We want to build as energy efficent as possible and keep the cost as low as possible. We’ll have 2072 sq ft on main floor and the same in a walkout basement that includes a storm room.
Using Geothermal will be upmost important to us in order to keep the cost of utilities to a minimum. Any advice and suggestions anyone can give would be appreciated. Items such as: What to be concerned about? What are some good systems on the market? Things to avoid?
Dean
Replies
Backwards thinking
Spend your money to eliminated heat gain / loss instead.
Insulation is cheaper, and usually lasts as long as the house.
Put your duct work in conditioned space. Design the house to shade all your windows in the summer. Air seal the house to the point where you have to add fresh air - but in a contolled manner.
you need to talk to pony since hes in memphis, and also use the lake at the heat pump source
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two ways to screw up concrete 1) concrete driver 2) concrete finisher
Thanks, I see if I can locate Pony.
Dean
if you plan to put a loop in the lake make sure that you talk to your fish cops first to see if it is okay. you could also consider drilling a well close to the lake and putting the tubing in the well.
If this is a retirement home, and you are of the age to retire, I have serious doubts as to whether you will ever recover the capital cost of a geothermal system in your lifetime. Nice of you to put it in for the next owner though......
Scott.
Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.”
With the cost of energy going up every year and sometimes more then once a year Geothermal is a good consideration. Even if the cost of electricity doesn't go up the pay back for Geothermal should be 5-8 years and I hope to live in this house much longer then that. With the bids I'm receiving the cost between the two are that much different.
Also, I will insulate my new build for energy efficiency regardless of the type of HVAC I use. It's makes good sense, plus again the cost of lets say fiberglass and Celulose isn't that much different. I believe that it is due to more and more home owners using Celulose over fiberglass in our area.
Thank you all for your comments. Keep them coming.
Dean
we're seeing geothermal systems really pick up in interest in the chicago area. i just wanted to chime in on the insulation... it's very important no matter if you're using geothermal or conventional HVAC! no matter what energy you're using, it's imperative to insulate well to make it as efficient as possible.the best way to insulate your house is to install blown-in CLOSED-cell foam. it is considerably more expensive then your typical installation, but your insulation contract will still be a much smaller fraction of the cost of the overall construction.the closed cell foam seals the house to air infiltration, as well as providing good R-value. you will also need an ERV, or fresh air fan as mentioned by someone above because your house will be so tightly sealed.i believe one of the top responses also mentioned several other passive solar design techniques, which are great to consider in the design. lastly, get double-pane, aargon filled, low-E windows. windows are the greatest source of heat loss in the house.
the best way to insulate your house is to install blown-in CLOSED-cell foam. it is considerably more expensive then your typical installation, but your insulation contract will still be a much smaller fraction of the cost of the overall construction.
That is true of a renovation, but it sounds like he is building from scratch, in which case something like SIPS could provide superior efficiency to foamed stud bays.
jt8
"It is difficult to get a man to understand something when his salary depends on his not understanding it." --Upton Sinclair
I have a 2,230 sq. ft. house with a full walk out basement in north central Texas. Manual J says I need 1.5 ton of A/C. If you build the house "right", the A/C requirements are much lower.
I recommend something simple, and relatively easy to fix. GSHP look great on paper, but finding somebody that knows how to work on one is the issue.
Go with a simple heat pump, add a variable speed blower and a good media air filter. Finding somebody to install or work on that is much easier.
Get plenty of references on your installer and follow up on them, there have been lots of maintenance nightmares with geothermal down here in NC. Great when it's working though. I agree that your money is best spent on energy conservation through envelope tightening and insulation before investing in geothermal.
But if you do enough insulation you will need so little heat and AC that you won't get the value out of the geothermal. Some kind of paradox there.
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"You cannot work hard enough to make up for a sloppy estimate."
But if you do enough insulation you will need so little heat and AC that you won't get the value out of the geothermal. Some kind of paradox there
All things being equal as far as an energy efficient home is concerned, what is the "pay back" for a standard vs. GSHP system?
He is talking about 4K sq.ft. of conditioned space. Using a high efficiency gas furnace and a 16 SEER a/c unit installed with duct work, what is your best guess at system cost?
What then is your best guess at the same installed cost of a GSHP?
Now which cost are you trying to recover? The total cost of either system, or the difference between the two?
The "pay back " on investment should be calculated on the difference between the two, IMO.
A properly installed GSHP will operate at roughly 60 to 70% of the cost of a conventional system, depending on occupant life style, from my experience. In some cases I have seen that as low as 50%.
To me, a retirement home means they are going to be living on a fixed income. So the question then becomes do they want lower monthly bills after they retire, or do they just want to save money on the front end of construction cost ?
I'm not trying to be argumentive here. I just think that we sometimes are to quick to offer comments without any explanation of our reasoning for them.
There is no paradox as you put it. Building a loose house and putting a GSHP system in won't save anyone money, just because it is more efficient than other systems.
BTW I agree about getting plenty of references for HVAC contractors.
Edited 1/24/2008 4:13 am ET by DaveRicheson
Will hit on a pet peeve first. Geothermal is the correct term used for ground water or ground temperatures above about 90F (AKA 'hot rocks"), relatively useless for cooling.
As in previous posts, GSHP is the correct term for what you are describing.
That said, NE Mississippi likely uses cooling much more than heating. If you can get seasonal data on lake water temperature you may be better off for AC of simply circulating lake water thru some heat exchangers in your house, no compressor. A small air to air HP may suffice for NE Mississippi. (I've not gone to the trouble to download climate data)
Since you are retiring, once you move into the house (with whatever system is cheapest to install as first cost) you have lots of time to DIY a full up lake water system with surplus equipment, then the repayment time is less than a year!!!! You can install your add-on lake water system into the existing HVAC system. example: I've all the parts for a 4T GSHP in the garage, but still working 60 hr weeks often and have not gotten around tuit. Cost of all parts was <$500, less than $50 to installl DIY, that mostly for brazing rod, fuel for the backhoe, etc <G>.
A lot of nice advice here but I am not sure we all understand your definition of geothermal. If you are thinking of drilling down and sucking heat out of the earth, that will get different answers than if you are talking about a heat pump, using air or a water source for the heat.
It sounds like you're heading in the right direction. A well insulated (or a super insulated) house combined with a geothermal is a great combination.
As a couple other people have mentioned already, make sure you get a good installer. Most of the complaints I've heard about geothermal stem from bad installations.
jt8
"It is difficult to get a man to understand something when his salary depends on his not understanding it." --Upton Sinclair
At present I'm considering Hydro-Temp Water Source Closed Loop system (http://www.hydro-temp.com/). The are manufactured in Pocahontas, AR. They will do the installing. Hydro-Temp sells and installs many systems in AR & MS and other areas as well. Both residential and Commercial/Business. Thus far they have a good track record.
Dean
I've never seen a closed loop water source.
Hope you can post some pictures of the install when you get started on your home.
Have they done a load calculation (based on your prints) yet? My guess would have been a 4 1/2 ton, two stage, two zone systen for GSHP, Will a water source be smaller?
Dave