VT has yet to adopt IECC 2012, and code is currently set at IECC 2009 levels, except in some towns who have upgraded.

http://www.iccsafe.org/gr/Documents/stateadoptions.pdf

IRC 2009 code minimums for walls in climate zone 6 is R20 or R13 + R5 c.i.

http://publicecodes.cyberregs.com/icod/irc/2009/icod_irc_2009_11_sec002.htm

R20 + 5 is legal from a thermal point of view, but does not meet code without an interior side vapor retarder per chapter 7:

http://publicecodes.cyberregs.com/icod/irc/2012/icod_irc_2012_7_sec002_par025.htm

Zone 6 demands R11.25 on 2x6 framing for dew point control to be able to skip the framing.

You can't safely use polyethylene sheeting for the interior side vapor retarder on an R20+5 assembly unless that R5 is something fairly vapor permeable, such as 1.5" of Type-I EPS or rigid rock wool. But you can use smart vapor retarders such as MemBrain or Intello Plus. R13 + R10 c.i. is about the same cost but more resilient than R20 + R5 c.i. when all is said & done (and quite a bit cheaper than R20 + R11.25 c.i.)

Code minimums are just that- minimums- bottom of the line tract houses must meet that. If you plan to live there for a decade or more, it's worth taking it to a higher performance level, even if you're not taking it anywhere near the PassiveHouse extreme.

The thermal output of sleeping caribou or bison aren't relevant to a VT location, since they are neither native species nor commonly kept either as pets or livestock. In Quebec or Minnesota that might have to be revisited. ;-)

The very best way to heat/cool your home would be to install a DX Geothermal heat pump.  A desuperheater on this unit can provide the majority of your DHW as well as heat the home in the winter and cool it in the summer.  It is more efficient than a typical GSWHP, cheaper to install, requires less space, less ground loops, fewer parts and costs less.  It will be slightly more expensive than an air-source mini-split to install but the energy savings will pay the difference. At .17 Kwh it is a great investment.

New directional boring equipment makes installing the ground loops quick, un-obtrusive and less costly requiring virtually no excavation or costly well drilling. Can be done on virtually any size lot. Efficiency in winter will be the same as in summer and many times more efficient than an air source HP.

You would do well to check it out.

Posted By 1blueheron on 13 Aug 2014 10:57 AM
The very best way to heat/cool your home would be to install a DX Geothermal heat pump.  A desuperheater on this unit can provide the majority of your DHW as well as heat the home in the winter and cool it in the summer.  It is more efficient than a typical GSWHP, cheaper to install, requires less space, less ground loops, fewer parts and costs less.  It will be slightly more expensive than an air-source mini-split to install but the energy savings will pay the difference. At .17 Kwh it is a great investment.

New directional boring equipment makes installing the ground loops quick, un-obtrusive and less costly requiring virtually no excavation or costly well drilling. Can be done on virtually any size lot. Efficiency in winter will be the same as in summer and many times more efficient than an air source HP.

You would do well to check it out.

At northern Vermont type subsoil temps (and strata) that is not a no-brainer. In N.VT you're looking at subsoil temps in the low 40s F, and the subsoil is most often granite (for hundreds of feet.)  By the time you've drilled through enough granite to heat the house adequately through the 8000+ HDD season it's usually more expensive than just superinsulating the place enough to heat/cool with a couple of cheap mini-splits and throwing enough PV on the roof to cover the heating bill.

Given the miniscule cooling season desuperheaters would be a dubious investment at best.

Even in places where you don't have to drill through granite DX systems,. industry scuttle butt has it that DX in New England always seems to develop pin-hole leaks in the copper over time (probably due to the local soil chemistry).

The efficiency of any type of ground source heat pumps is highly dependent upon the competence of the system designers & installers. Given the how few GSHP installers there are in N.VT it would be tough to figure out if ANY of them are good enough to beat a right sized ductless solution on efficiency (or whole lifecycle cost of owning/operating.)

Just as I'm sure there are many places where DX geo makes sense, I'm pretty sure N.VT isn't one of them.

The market seems to be deciding that DX geo typically isn't the best way to go.

Regarding using space heating ASHPs for water heating, my guess is that the temperatures/pressures needed for domestic hot water are enough higher than what is needed for space heating that it would make sense for the water heater to be a separate "head" (ie, a multi-split) that only ran when the normal heads weren't running. Otherwise you take an efficiency hit from the higher pressure.

"The very best way...."
Not sure......http://www.greenbuildingtalk.com/Forums/tabid/53/aff/13/aft/79941/afv/topic/afpg/3/Default.aspx
http://www.greenbuildingtalk.com/Forums/tabid/53/aff/13/aft/82456/afv/topic/afpgj/4/Default.aspx

It will be slightly more expensive than an air-source mini-split to install

Maybe you could define "slightly" for us. Air source mini-splits can cost as little as a few hundred dollars to install. It was my impression that the drilling and whatnot associated with DX systems ran into the thousands, if not tens of thousands.

Certainly not all sites are suited to DXGHP. Respectively, I think howeve,r the assumptions being made about it are a little less than forward thinking. Granite is actually a great thermal conductor 1.7- 4.0. Typically granite ground structures have few voids. Drilling in granite has become less trouble than one might expect if the proper equipment is used, in fact, it is much easier to do boring in a solid, stable substrate than in mixed, unstable strata or cobbles. A granite borehole is very stable and predictible. in performance so the depth and number of bores is more accurately estimated and less are needed. Mid 40F certainly beats ambient air temps in the winter. Once a borehole is completed proper attention to installation of the copper pipe ground loop is necessary as is proper grouting mixtures to prevent copper degradation. In extreme cases current can be used to counteract and electrolytic action on the pipe. The biggest concern with DX GHP in the northeast should be thermal saturation of the loop. Using gas and no ground water this is less likely than with other GSHP systems. The technology is maturing and has come a long ways just like air source heat pumps. We need more people to think outside the plug and play box. What is cheapest and quickest is not always "the best" and the OP asked for the best.

There are a few tricks to designing a DX GHP for use in the northeast, first you must design for low water temps. This lends itself to radiant floor heat. Stay away from ducted air exchange systems or hydronic radiator heat in design and layout if at all possible. Use thermal mass in the home to retain and limit cycling of the system. Insulate well and pay close attention to thermal bridging in the radiant slab.

There are certain elements of heating and cooling that cannot be quantified by COP or KWH measurements. With mini-splits, your head will always be hot and your feet will always be cold. This is never "the Best". With a radiant system, your feet will be warm and your head will be comfortable allowing a lower t-stat set point. Water and concrete area a much better material for conducting, transporting and maintaining a temperature than air.

Powering a Minisplit system in the NE with PV is no better a proposition than drilling in granite. The days are short and snow is an issue. At the times and days you need power most, you will be relying on the grid or having to install a huge storage system. Units need to be oversized to handle low temp extremes or backup resistance heat employed creating even larger loads. I suppose you could argue for grid tie banking and orient all your panels to maximize summer yield but this does little for reducing grid load or peaks and leaves you in the cold should grid outage occur during the heating season. Power draw on a right sized DXDHP would be modest in comparison and would be relatively agnostic toward nightime low temps.

By using radiant heat you are less likely to have low humiidty issues that are often experienced during the winter in the NE with air based systems that run continuously.

I have lived near Vermont (Schroon Lake, Ticonderoga, New York Area) and am not totallly unfamiliar with the climate.

Certainly all factors including time and budget must be weighed. Everyone has a different veiw of "best" maybe OP can give further guidance of how he weighs Cost of install vs. operational costs ROI and TCO as well as potential resale. All are important in making a decision.

What is cheapest and quickest is not always "the best" and the OP asked for the best.

Are you talking about the OP who titled the thread "How To Heat...Cheaply"?
Maybe you could show us how the upfront costs of drilling for DX are justified over the long term.

I certainly hope anyone with a DX system has good luck with it. I hope anyone shopping for geo takes a hard look at the "cons" of DX before making their purchase.
1 Blue, you seemed not to have noticed the thread I put a link to where the homeowner spent an inheritence on a DX system that had to be replaced in just a few years.

Joe, Looked briefly at the thread Joe and it appeared most of the problems discussed were a result of poor QC on the part of manufacturer(s). Has nothing to do with the technology everything to do with manufacturer and quality of install. Although DXGeo is not new, it is a very small portion of the market and does not enjoy the economy of scale some other systems do. I remember in the 80's "pro's" said anyone north of the Mason Dixon was a fool to install a heat pump of any sort as all they do is blow cold air in the winter. The technology has improved as has efficiency for both.

I don't have a dog in the fight. I don't sell, purchase or install heating equipment. If its not for you or your business model, then that's OK no hard feelings. They are definitely more of a headache to replace if you get a lemon. I just think the public needs to be aware of the options and benefits rather than herded down the same air source path time and again without options and told that geothermal requires massive amounts of land, excavation or expensive wells as most WTW systems require.

ICFhybrid,

If all you are doing is installing a heat source then no they probably will never show an ROI. However for someone who approaches heating and cooling from a holistic veiwpoint and is looking to be energy self sufficient and eliminate demand peakes so that they can use a smaller PV array etc, the paybacks come in the form of being able to downsize everything and still have a great degree of comfort without compromise. It is difficult to say what the upfront costs are as each situation is going to be slightly different. I would say DXgeo is like custom wood kitchen cabinets and mini-splits or package units are like factory production cabinets from the big box store. If you find the right cabinet maker you can get a better quality cabinet built to fit your specific needs for a similar price or perhaps a slight premium.

Just my opinion. I may have mixed up posts on "the best" part. My apologies.

I'm new here so I haven't had a chance to read all the horror stories and find out who hates what.

In a location such his part of northern VT that experiences more than 8000 heating degree days in a typical heating season, and fewer than 300 cooling degree days in a year it's all about heating, not at all about cooling. At what the (fewer than 5) GSHP contractors operating in that area charge for drilling it's hard to make a case for any type of GSHP system for new construction. Spending the money on the building efficiency will deliver greater (and more reliable) reduction in power use than the efficiency difference between a bigger GSHP to manage the loads of a code-min house and ductless heat pump heating the high performance house.

The great thing about N-VT is that nobody lives there. :-)

The bad thing is there is no great depth of local expertise on GSHP systems, which is even worse when you consider that the 99% outside design temp in his location is in negative double-digits F. There are lots of mini-splits being installed there (I've even seen them used for heating ski-condos in locations that regularly see -20F), which makes them workable if you can get the heat loads within range. There are quite a few builders of high-performance homes in N-VT, easier to find than competent geo contractors.

Even in southern New England where the design temps are warmer and the contractors actually exist, GSHP systems average about $35-36K for 4-ton systems, and even 2-ton systems are over $20K, and they don't always beat mini-splits on heating efficiency. Even if you peeled 25% off going with a DX (if anybody is still installing them here- word is they aren't), it will be at higher risk. High performance houses are low-risk, lower maintenance, longer lifecycle, with predictable well-modeled performance.

I don't hate GSHP systems (though some folks here may have that impression :-) ), but in my area from a cost perspective GSHP rarely pencils out favorably against improved building performance for new construction. In some other situations GSHP often make sense though- deep energy retrofits + ductless can be double or triple the cost of more modest envelope performance improvements + GSHP, even when the GSHP is north of $50K (which it often is.) But even there one has to balance the costs of PV (which is getting cheaper by the minute- I've seen quotes for under $3.75/watt in Q2 2014, and expect it to be under $3.50 by Q2 2015) + air source heat pumps vs. the potentially higher efficiency of GSHP (which doesn't seem to be getting cheaper at all.)

looking to be energy self sufficient and eliminate demand peakes so that they can use a smaller PV array

I'm not at all sure how that applies. Won't "demand peaks" with either DX or air source occur at night when PV output is, well...zero?

you can get a better quality cabinet built to fit your specific needs for a similar price or perhaps a slight premium

There's that word "slight" again. I'm having a hard time seeing how there is a
"slight" difference between a mini-split at a few thousand and a ground source system at $20K and up.

I'll try not to beat a dead horse but would point out 2 things. The cost of a DXGSP should not be 20K and up. If GSHP installers are charging exorbitant amounts to drill, perhaps folks need to be talking to directional boring contractors who know how to do this stuff cheap and do it everyday, all day through all kinds of structure. We need more price competition and more knowledgeable/skilled installers, not more air source heat pumps

Demand peaks will occour with either system but they will be much smaller with a HP that uses a higher steady state source temp and much higher with one that uses lower ambient air temps that swing more radically.

I can go with the logic presented for areas which have lower ground temps and longer heating seasons with difficult bore conditions.

"it appeared most of the problems discussed were a result of poor QC on the part of manufacturer(s). Has nothing to do with the technology everything to do with manufacturer and quality of install."

Unfortunately that is the biggest DX manufacturer in the states. The reason so few companies are around when things go wrong is they are already out of business.

"I don't have a dog in the fight. I don't sell, purchase or install heating equipment. If its not for you or your business model, then that's OK no hard feelings."

That explains quite a bit. DX actually costs more for me to install than water source. Few systems would be sold or installed for less than 20K.

"They are definitely more of a headache to replace if you get a lemon. I just think the public needs to be aware of the options and benefits rather than herded down the same air source path time and again without options and told that geothermal requires massive amounts of land, excavation or expensive wells as most WTW systems require."

A one ton DX loop trench is 125' long. My average WTW trench is 110' long.

You are raising awareness for how you percieve DX to be not reality. The technology has merits which is why I (not you) trained in installation of 2 different brands. Ultimately I decided they were not reliably superior to water source and in fact higher risk for myself and my clients.

I wonder if someone can comment on how much I should expect to pay to upgrade from:

-2x6 R21 to double stud R43 (dense cellulose)
-R15 to R30 basement walls (Thermax)
-R50 to R80 roof (loose cellulose)
-No insulation to R30 under slab
-Add ASHRAE 62.2 HRV
-Anderson 400 U0.29 to U0.19 windows (unsure of brand)

Building suggests around +$25k on 1800 sq ft. which is about 15% higher than code/stock build.

The complexity of the footprint can make a huge difference in the cost of framing the double-studwall. Don't know what they were charging for the R21 insulation package, but R43 dense packed cellulose would likely come in somewhere between $2-4 per square foot, depending on just how big a PITA it is due to framing complexity, and the hunger level of cellulose dense-packers in your area. (Sometimes open cell foam is cheaper.) Assuming the R21 2x6 was a buck a square foot, figure it's something like a $2-3 per square foot cost adder.

R30 under the slab is about $3/square foot using EPS. Mind you, that's a lot of sub-slab insulation for something with R40-ish walls, even if you were heating the place with a radiant slab. Half that or even R20 might have some rationale.

R30 basement walls are probably going to be cheaper (and would have lower thermal bridging at the top of the foundation) using a standard R20 ICF with a 2x4 batt-insulated studwall on the interior. An R23-ish assymetric ICF (Say, 3" exterior foam, 2.5" interior foam) without the interior side studwall might make more sense. Unless you have exterior foam you'd have to de-rate Thermax to reflect it's mid-winter performance of about R5/inch in a VT climate. (R30 would really more like R25, which is fine). but the thermal bridge where the foundation meets the top of the foundation is pretty severe if the foundation insulation is only 5" of interior-side Thermax.

R50 cellulose open-blown would come in around $1.25-$1.50 per square foot. Bumping that to R80 would be between $2.25-2.50 /square foot. It may require tighter truss spacing or reinforcement of the ceiling to handle the higher load, which would add something to the framing package too.

Harvey makes some pretty-good triple panes in the U0.20 range for not a gia-normous uptick over U0.30-ish windows, as does Paradigm. You'd really have to get it quoted, but figure it's ~40-50% more expensive, not 2x more. There is additional cost to a large volume housebuilder type general contractor for special ordering something other than their standard fare, which will add something to the cost quote to you as well. For custom-builders it's not much different overhead than ordering any other window- just their standard mark-up.

An HRV system on an 1800' house in new construction would be on the order of $3K-$5K (maybe even under $3K if the floor plan makes it a dead-simple installation with minimal duct work.)

If the whole shebang on the building envelope upgrades costs you only $25-30K more to build, but saves you 60-80% on the heating bills, the bump in the annual mortgage outlay may less than the energy cost savings- a net cash-flow win. Since home financing costs are tax deductible but utility costs are not, be sure to factor that into your financial model as well.

Ok - here are the latest insulation specs.

Integrity Tripane @ U0.20
Under slab (not sure of type) = R15
Basement wall (2.5" Thermax)= R15
Walls R43 2x12 dense pack
Ceiling R60 loose fill

I've always heard about the "5/10/20/40/60" "windows/slab/basement/walls/ceiling" mantra. Assuming I want to keep budget where it's at, should I be decreasing sub-slab insulation to R10 and increasing basement wall to R20?  

Posted By patonbike on 07 Oct 2014 05:24 PM
Ok - here are the latest insulation specs.

Integrity Tripane @ U0.20
Under slab (not sure of type) = R15
Basement wall (2.5" Thermax)= R15
Walls R43 2x12 dense pack
Ceiling R60 loose fill

I've always heard about the "5/10/20/40/60" "windows/slab/basement/walls/ceiling" mantra. Assuming I want to keep budget where it's at, should I be decreasing sub-slab insulation to R10 and increasing basement wall to R20?  

Maybe, but probably not if you're using the slab as a heating radiator.  It also matters how much of the basement wall is above grade.

Have you considered downloading a copy of BeOpt and learning how to use it?  The tool is designed specifically for answering these types of questions.

I'll check it out, I had not heard of it before.