I still don't get how anybody could quote a GSHP system without calculating the loads.

The estimated 70,900 Btu/hr @ +10F for a 4270' house that meets IRC 2012 code min is simply fug-nutz, let alone a high-R upgrade from code-min. That's 17 BTU/hr-ft^2, about than twice what a high-R house would normally deliver, and more than many sub-code antique houses (such as mine.)

Many (or even most) 2x4 /R13 houses with wood-sashed single-pane double-hungs + clear glass storm windows and R19 attic with some amount of foundation insulation will come in at ~15 BTU/hr-ft^2 @ 0F, if tightened to 3 ACH/50 (code max for new construction). Code min new construction is typically 12-13 BTU/hr-ft^2 @ 0F. It might come in as high as 12 BTU/hr-ft^2 @+10F if it has a lot of corners due to bump-outs ells & dormers, &/or a max-legal window to floor ratio.

The only way to know how YOUR house is going to perform is to run an aggressive (not conservative) load calculation based on construction & insulation type, window & door U-factors, site factors & orientation etc, but you'd have to work pretty hard at UN-optimizing it to get it up to 71K @ +10F.

The cooling load of 30.4K might be close to reality, but again that depends a lot of window size / orientation / placement, and shading factors.

The U-factor of an R30 whole-wall stackup s is about 0.033 BTU/hr per square foot per degree F. Assuming an interior temp of 70F and a 99% outside design temp of +10F, that's a difference of 60F. Every square foot of wall then contributes:

U0.033 x 60F= ~2 BTU/hr per square foot to the heat load.

A U0.25 window or door contributes:

U0.25 x 60F= 15 BTU/hr per square foot.

A code-min R49 roof has a "whole assembly R) of about R38, a U-factor of about U0.026. So for yuks, assume you only go with that, not higher, and the roof area contributes:

U0.026 x 60F = 1.6 BTU/hr per square foot.

An IRC code-min foundation wall has a U-factor of about U0.050. For simplicity's sake only count the above-grade exposed foundation, and about a foot of the below grade portion. The foundation contribution is about:

U0.05 x 60F= 3 BTU/hr per square foot.

So, looking over your plans/sketches, estimate all of those areas first on on a room by room, then floor by floor basis, then add it all up. If it's a tight house the plug loads and warm bodies might balance any infiltration losses, but if this li'l shack is a low occupancy vacation spot for two with only one refrigerator, no DVRS etc. give it a 15% fudge factor, see where it is, and use that spreadsheet calc to sanity check any contractor's heat load numbers.

A crummy none-too-accurate sketch of this 3400' + 1000' house is a 1700' foot print x 2 floors 10' high with 1000' of conditioned basement, and 700' of drive-under garage.

The upper floor has 1700' of ceiling, so at code min the ceiling losses are 1700' x 1.6 BTU/ft= 2720 BTU/hr

Assuming its an L or T shape, not a perfect rectangle, it might have as much as 200' of wall perimeter, so at 10' per story is 2000' of gross wall area. Assuming a 15% window/floor ratio that's 1700' of wall area. At 2 BTU per square foot for the R-30 better than code wall that's a wall loss of 2 x 1700 = 3400 BTU/hr (double that for a code-min wall.)

The 15% window area on that floor is 0.15 x 1700' =255 square feet, and at 15 BTU/square foot that comes to 3825 BTU/hr for window losses.

Add it all up and the top floor losses are 2720 (ceiling) + 3400 (wall) + 3825 (window) = 9945 BTU/hr.

And that's the lossiest floor of the house (the basement is at least half below grade for a lower temperature difference, and neither the basement nor first floor have ceiling losses.)

Multiply x 3 and you're still at only 30,000 BTU/hr. With a generous 15% fudge factor for infiltration & ventilation etc. you're under 35K, less than half the heat load specified in the GSHP quote. (Think that might affect the GSPH cost?) That's a load/sq.ft ratio of about 7 BTU/hr-ft^2, very realistic target that you'd probably beat using the real numbers, and a load that's low enough that the extra comfort-cush of radiant floors begins to fade, since your average wintertime load is about half that.

If you went with a code-min wall it adds ~3400BTU/hr per above-grade floor to the wall losses, and if you went with code-max U0.32 windows it adds about 1100 BTU/hr to the window losses. That would make your lossiest top floor something like 14,500 BTU/hr. Times 3 that only comes to 43,500 BTU/hr. Add a fudge factor of 15% for air infiltration and don't subtract any plug loads and body heat and you're still at only 50K. (Fudge factor not necessary, since other floors are lower loss, and we've multiplied the lossiest floor x 3.) That's a heat load ratio of about 11 BTU/hr-ft^2, which would be slightly to the high side of a typical code min house @ +10F.

So, just how the F- did they come up with a whopping 70,900 BTU/hr, even for the code min version? Maybe they made a typo, and inserted an outside design temp of -10F? (It's gotten that cold at least once in the last century, right? :-) ) Assumed that you sleep with the windows open on the coldest night of the year, mayhaps?

It just doesn't add up. If the contractor can't do even THIS level of lipstick-on-mirror ( crayon-on-napkin ?) heat load math, it's not a contractor you want to use for a GSHP system.

Say you find a contractor who will right-size the GSHP for you- it's still going to run you about $40-50K in this part of the world. If they do a really great job it'll have a seasonal COP of about 4-4.5, maybe even 5 with low-temp radiant floors and absolute best practices (which will cost more than 50K, even for the high-R version of the house).

If they do a "typical" job it'll perform at about 3.5, which is about what you'd get out of a Fujitsu -12RLFCD mini-ducted min-split in this climate. With duct-work included it might run as much as $5500-6000 per mini-split, one per floor in the above-grade floors, maybe $5K for a 3/4 ton -9RLFCD in the basement zone. That's still well under $20K. If the floor plan on any floor is sufficiently open to use a ductless wall-coil version it would be about $3.5-4K for that floor and it would deliver even higher efficiency. (Any of the cold-temp 3/4 ton minisplits out there can deliver more than 10,000 BTU/hr @ +10, and would run no more than $3.5-4K, installed, and would average a COP of ~3.7-4 in this climate.)

With the ~$25K difference in up-front cost for a middle of the road smaller GSHP system for the high-R version of the house you can buy right now, today before subsidy about 7000-8000 watts of rooftop PV, which would bring your marginal heating and cooling costs down to near zero. You can play the competing subsidies of GSHP vs. PV off against one another, but it's still tough case to make for GSHP, which also comes with a level of system design risk that mini-splits don't have.

I agree, everything above 50 KBTU should trigger an insanity check for a new built house the way you describe it.

BTW: I was recently introduced to this bit of datalogging results  over the winter of 2012-2013 for the all-in seasonal GSHP efficiency of a few recent systems in New England, performed by some folks written up in the heatspring mag blog (a green building industry site.)

Take a gander at Table 1, p4.

The only GSHP system with an all-in COP that would beat the current better-class mini-duct cassette type mini-splits on operating efficiency (HSPFs in the mid-11s for the 1 &1.5 tonners, 12+ for the 3/4 ton) in an RI climate was the variable speed compressor units on the horizontal closed loop at a seasonal COP of 4.2 (as-used HSPF of 14.3).

Even the variable speed system would be challenged to beat the 1-ton Fujitsu 12RLS3H (HSPF= 14.0) if optimally oversized for the 99% load, with at least some (but not too much) modulation range overhead even on design day.

The financial justification for taking the design risk at a substantially higher upfront cost is a lot tougher now than it was when typical ASHP systems were struggling to break a seasonal COP of 2 in a US climate zone 5 climate.  You can easily end up paying an order of magnitude more for the system that even has marginally higher operating costs, even when installed by a non-hack.  It seems like the financially rational latitude for GSHP moves north a few degrees with every new cold-climate mini-split product release, even at national average pricing for GSHP (let alone the high pricing seen in southern New England)

Excellent information.. and yes.. I thought they were insane as well.. your reply make me laugh.. since you articulated what I was thinking... IE.. no way in hell I will pay for a system that expensive.. I CAN'T be correct given the R factors we are aiming for.  I was pitching an UNDER designed system (by their standards) that I could add to if I needed it.. IE.. let me buy half of what you think I need and grow if needed.

I will take your formula and apply it to my plans and see what I come up with.  That may take some time... I would be nice if I could build a spreadsheet to share with others so they can use it for their homes... may be we can work on one together.. I have excellent excel skills..
I would be happy to upload the plans somewhere if anyone wants to see what I am working with.

I have a question on ASHP.  If I install one for the basement, or even per floor:
1. Would I need the standard duct work?  So it would be similar to forced hot air classic model from a logistics perspective?  
2. They are only use electricity correct? or can you use other sources of fuel? 
3. They are ugly, do you have suggestions on making the installs cosmetically better.  One benefit of GSHP is .. you don't see it..
4. What of cooling? on a 110F day? 

In general it seems more logical to exchange heat/cooling with a constant source (the ground) than a variable source like the air... since everything you want to do it is the opposite of the air.  IE.  heat when it is cold and cool when it is hot outside.

This discussion might be worth pinning..
-Ken

You were not THAT far off on your guesses..

Here is what I worked on..PLEASE check my math..
I looked at the Anderson window quote.. took each window height x width in feet and got sq/feet of windows. That all came to 668.27 sq/ft  
The windows came in at an average U factor of .306 with a 60F gap that puts the windows at 18.3BTU/hr per sq/foot (400 series)
That would be 12,275 BTU/hr loss from windows alone.

The basement perimeter is 233 feet.
The 1st floor perimeter including garage is 288' feet.
The wall height on the 1st floor is 10ft
The 2nd floor is 9ft.
The basement is not completely finished (1000' sq/ft livable) and is also 9' finished (10' cement)
The roof area would be roughly the sq/feet of the 1st floor 3131 sq/ft.
The 2nd floor has unfinished space.. no sure how to count that.. if I use spray foam on the rafters then I think I would have to include it.
which would be roughly the same as the basement (since there is no garage to account for) which us 2397 sq/ft

The walls at 1.98 BTU/hr per sq ft worked out to be 12,932 BTU/hr  (the basement BTU/hr was at 3 in your example I used the standard wall number since mostly walkout)

so far we have walls @ 12,932 + windows @ 12,275 (interesting that they are about the same... ) = ~25.5k BTU/hr

We still have the roof.. and doors..
The roof is about 2397 sq/ft x 1.6 = ~3835 BTU/hr
There are about 39 feet of doors (3x 9ft garage doors + 4 x 3ft entry doors  I rounded and got about 273 sq/feet of door.
Figuring 3BTU/hr (based on R20 doors) That adds another 819 BTU/hr

For a grand total of 25,500 + 3835 + 819 = 30,154 * 1.15 fudge factor = 34,677 BTU/hr

Does my math make sense?
As you stated still less than half.. and that is figuring we heat/cool unfinished spaces.
I will be sending my plans to other companies, see where they land.

What did I screw up?

-Ken

This methodology is the I=B=R methods, which will overshoot reality by a bit, since it doesn't subtract out the hot-mammalian occupants or the 24/7 plug loads like refrigerators & DVRs, etc. But it's good enough for sizing the equipment, unless you're going for something like GSHP where every 1/4 ton has a significant cost adder. Manual-J methods are pretty similar, but account for all of that other stuff. I=B=R numbers are typically 15-25% higher than Manual-J (and never lower), so if you just back out the infiltration fudge factor for infiltration it may end up pretty close to a Manual-J.

When sending the plans to other companies it's important to highlight that you're going with a much higher than code-min wall R which will have a much lower U-factor for walls. If they don't correct for that and assume code-min in they'll come up with something around 45-50KBTU/hr if they do the analysis, or they'll do some dumb xx BTU/hr x YYYY square feet calculation with some padding and come up with something even higher. None are likely to do a full Manual-J at the bidding phase without charging you something for it, since it takes some amount of time to do that. A good HVAC contractor will do the load calculations more carefully if/when they win the bid, but many don't bother unless you or the code officials hold their feet to the fire.

Unless you're actively heating garage, don't count that load, and just assume the partition wall with the rest of the house is insulated to the same as the rest of the house, and that the garage is really outside (which it might be, if you happen to leave the garage door open.)

An "R20" garage door is a marketing myth- I'll believe it the day I see the tooth fairy riding by on a unicorn. Most door manufacturers have published U-factors. The R20 is some exaggerated center-panel number based on a fantastic R7.5/inch or something for the polyurethane, and does not include thermal bridging of internal structural elements, the frame, or air leakage. Figure at-best it'll be doing about U0.13 (R8) - U0.17 (R6) with all aspects factored in. But even R6 is better than R2, which is about the best you'll do with an uninsulated garage door.

If you're going for a mini-duct mini-split solution the total heat load is a bit out of range (and the duct lengths a bit long) for it to work, but the single cassette per floor can work.

Build yourself a spreadsheet with the room-by-room loads calculated, and summed by floor. You need to know each individual room load to adequately design the ducts. And knowing the load of the individual floor is necessary to spec the head/cassette.

You'll probably only need one supply register per doored-off room, and only a single register for any larger open spaces, but it depends a bit on the floor plans. You'll have think a bit about where the mini-duct cassette/air handler will live relative to the rest of it to minimize duct run lengths (which affects efficiency & capacity) , and where the outdoor units would live so that it stays within the specified limits of the refrigerant lines (which mostly affects capacity.) The duct design still needs to follow ACCA Manual-D, but when you home-run them to somewhere close to the cassette the diameters of the ducts to individual low-load rooms are small. It should be fairly straightforward to set it up home-run style if it's only 2-4 supply registers per floor- but beyond that some amount of trunk plenum & branch approach would likely be called for. Returns can use door cuts of sufficient cross section, but there may be rooms which require ducts or jump-ducts to get there.

If any floor has a mostly open floor plan with few or no doored off spaces it may be better to use a wall-coil type mini-split on that floor, and use small resistance heaters to manage the loads in the doored off rooms. The Fujitsu RLS3H series wall coil mini-slits deliver about 20% more heat per kwh than their pretty-good mini-duct cassettes (and the installed price would be cheaper). Some people object to them on visual aesthetics grounds, but that's really more a matter of what you're used to. (How many people love the look of radiators or baseboards, or even ducted register grilles?).

Unless your roof is really steep, with substantially more area than the attic floor the error will be kind of in the noise. But you can put your high-school geometry to work and calculate the insulated roof area more precisely if you're close to an equipment model sizing boundary.

For the basement load, use only the above grade wall area down to 1-2' below grade and you'll be close enough to ignore the floor losses. As long as you know the magnitude of the load you can avoid oversizing it. To meet code every fully conditioned room has to be able to hit 68F at the 99% outside design temp with the heating equipment used. If the inspectors allow you to defer the heating equipment for the zone until you finish it, great, but if they insist on seeing something in there right now, divide your calculated BTU/hr number by 3.412, which converts it to watts. You can then install electric baseboards of sufficient wattage to cover it, and be done with it, saving the cost of a third mini-split head/cassette.

If you want to find competent mini-split installers, start with their contractor search pages:

http://www.fujitsugeneral.com/distributor_locator.htm

http://www.mitsubishicomfort.com/contractors

http://daikincomfort.com/find-a-dealer

Any of the units listed on the Efficiency Vermont's rebate-approved list would work at high efficiency in RI:

https://www.efficiencyvermont.com/docs/for_partners/contractors/evt-cchp-qpl-bymanufacturer.pdf?v=9

Note, the only mini-ducted versions they have listed are the Fujistu -xxRLFC units, but they also have the -xxRLFFH floor units, which may be less visually objectionable than the wall-coil type mini-splits. The Mitsubishi SUZ/SEZ mini-duct units are somewhat lower efficiency (HSPF=10) and crap out on capacity by +5F, but might work for you as well.

Don't be shy about telling them YOUR estimated load numbers (have the room by room and floor by floor stuff already in your back pocket), and how you want it done, particularly the wall-mounting of the outdoor unit(s) above the snow line and protected by roof overhangs, since it affects their installation costs a bit (sometimes it's cheaper to wall-mount them, other times not.)

Posted By Dana1 on 28 Apr 2015 03:43 PM
BTW: I was recently introduced to this bit of datalogging results  over the winter of 2012-2013 for the all-in seasonal GSHP efficiency of a few recent systems in New England, performed by some folks written up in the heatspring mag blog (a green building industry site.)

Take a gander at Table 1, p4.

The only GSHP system with an all-in COP that would beat the current better-class mini-duct cassette type mini-splits on operating efficiency (HSPFs in the mid-11s for the 1 &1.5 tonners, 12+ for the 3/4 ton) in an RI climate was the variable speed compressor units on the horizontal closed loop at a seasonal COP of 4.2 (as-used HSPF of 14.3).

Even the variable speed system would be challenged to beat the 1-ton Fujitsu 12RLS3H (HSPF= 14.0) if optimally oversized for the 99% load, with at least some (but not too much) modulation range overhead even on design day.

The financial justification for taking the design risk at a substantially higher upfront cost is a lot tougher now than it was when typical ASHP systems were struggling to break a seasonal COP of 2 in a US climate zone 5 climate.  You can easily end up paying an order of magnitude more for the system that even has marginally higher operating costs, even when installed by a non-hack.  It seems like the financially rational latitude for GSHP moves north a few degrees with every new cold-climate mini-split product release, even at national average pricing for GSHP (let alone the high pricing seen in southern New England)

1) The data logging was done by the same folks who designed the data logger themselves. They seem to have logged systems which are not really comparable in terms of installation standards.
2) Two of the 5 systems were not even monitored for energy consumption, but they are simply took the power consumption from the HP specs
3) One site has single stage units, 3 sites are open loop without knowing the pumping consumption.
4) The nameplate COP they elude to suggest not very highly efficient HP equipment, but you compare it to the highest efficient air source equipment? Why?
5) Why they computed with (a guessed) 500 W pumping power, wether it is a open or a closed installation, is unknown. Usually our 3-5 ton application run with a single 26-99 consuming 230 watts.
6) They own data logging shows a significant variation in COP of the same HP under the same operation conditions.
7) Was the equipment malfunctions of faulty expansion valve, low refrigerant or circulation pumps running permanently included in the analysis?
I find that kind of study pretty much useless where substandard equipment and installation is used, and energy usage is not really monitored in some cases, but assumed. Then to come in and compare the COPs under those conditions to higher end air sourced heat pumps without whole house distribution (mini split) to continue to build your case for ASHPs? Again, I find it kind of useless.

Posted By Dana1 on 28 Apr 2015 03:43 PM
BTW: I was recently introduced to this bit of datalogging results  over the winter of 2012-2013 for the all-in seasonal GSHP efficiency of a few recent systems in New England, performed by some folks written up in the heatspring mag blog (a green building industry site.)

I don't disagree with the conclusion that on a 1 or 2 or 3 some odd ton basis, mini-splits are more cost effective than GSHP systems.

What surprises me, though, Dana, especially with your amount of expertise, that you don't see the 'this bit of datalogging results' as simply an elegant marketing and sales piece for the limited instrumentation, and not much more.

No measurement of flow, no measurement of power, and some would argue no measurement of pump motor power (but not me) severely limits the conclusiveness of the 'results.'

Measurement of kWh/CDD using a histogram approach, or measurement of kW/ton instantaneous basis, done well, takes more rigor that what was published.

I speak with some amount of experience on this.  We (my company) are asked to do the economic analysis for actions being sold as actions that can extend the lifetime of commercial roof top chillers, including nano-technology coatings applied to condenser coils, 'secret sauce' additives to refrigerant, refrigerant oil change-outs, adding cooling towers to refrigeration lines, and now adding thermo solar energy to refrigerant lines.

Best regards,

Bill

I totally get that it was a marketing fluff for his data logging tools. But assuming there is any competence to the methods (TBD- I wasn't bowled over by their awesomeness either) the low COP numbers as-presented aren't very encouraging.

Is THAT what people are really installing? It SEEMS like it is, even if better GSHP designers are doing better. Whether the average GSHP system being installed in 2015 is any better than those presented is still an open question.

Can the paying clients paying tell the difference between a best-practices GSHP system and the mediocre stuff shown? Can the installers themselves even tell the difference? The purveyor of the monitoring system seems to think maybe they don't get it- is he wrong on that aspect? (That is, independent of the flaws in their own measurement methods.)

The comparison to highest efficiency ASHP equipment to lesser quality GSHP systems is still apt, given the huge divergence in after-subsidy system price between a so-so (or mediocre) GSHP system and a better class mini-split of equal or better efficiency. It all leads back to how much design risk is being taken, by whom, and at what cost, and compared to a cheap pre-engineered system-in-a-can approach, where the biggest issue is just getting the sizing down for the climate & loads.

A decade ago I had great hopes for GSHP eventually hitting better price points and continuing year-on-year improvement in real-world efficiency, boosted along by 30% tax credits driving higher volumes and lower cost. Even though the heat pumps themselves have shown the incremental improvement, the designer competence still seems to be all over the place, and the installed prices seem to be incrementally higher, not lower. Published performance data on real in-situ systems is still pretty sparse, but apparently not growing anywhere near as fast as the name-plate efficiencies of the heat pumps. If the real system averages are really better than web-available third party data would indicate, the industry is in serious trouble. No matter how well engineered the heat pump is, the quality of average the system design really has to step up to see that improvement. But independent evidence that the installer base has kept pace is lacking- it seems to point the other direction.

A decade ago I also didn't think much of the prospects of the heating efficiency of any ASHP breaking out of seasonal COPs in the high 1s / low 2 in cold climates, with at best minor incremental improvements in cold weather efficiency. But as of a handful of years ago the growing body of available data proved me wrong. Whenever the technology seems close to stalling out, some vendor releases another line-up that beats the prior versions on cold weather efficiency by double digits. The year on year improvements in mini-splits do not seem to have slowed a bit, while the inflation adjusted installed cost has been flat to falling. This is not a great trend to be competing against.

My disillusion on the prospects of GSHP becoming ubiquitous is now nearly complete, with the possible exception of larger, better engineered systems, at much bigger loads than most code-min homes. For awhile there was a financial case to be made for GSHP on older stock middle-of-the road housing measured against the high cost of deep energy retrofit on the building envelope (to where the loads could be managed by point-source heating/cooling with mini-splits.) But now that best in class mini-ducted mini splits are ahead of where the wall-coil heads were five years ago that case is evaporating too. It doesn't take a super-insulated house to bring it within load range of the 1.5 ton Fujitsu mini-duct unit at US climate zone 5 outside design temps, and despite it's lower nameplate HSPF, it has comparable capacity at sub-zero temps as the more expensive & bigger 2-ton Carrier Greenspeed ASHP. Even if it takes multiples to manage the loads of a code-min house bigger than 2000', it's still a lot cheaper and less risky than many of the alternatives. And on new construction it's more cost-effective on a lifecycle basis to bring the loads down to that range before resorting to a GSHP option.

So, about the time that the tax subsidy is about to evaporate, how do any of you in the GSHP biz in cold climates think the industry as a whole will do? It was one thing for GSHP marketing pitched against $3 propane or $4 oil, made easier when Uncle Sugar was covering 30% of the up front cost. At the same time it was pretty tough against buck-a-therm (or cheaper) gas. But now even the ducted mini-splits are competitive with condensing gas on marginal operating costs in much of New England, despite elevated wintertime electricity pricing in the region. As tough as it is to close the sale on modestly sized GSHP systems now, on January Fools Day 2017 it's going to be considerably tougher. If it's a boutique biz now, it'll be even more so then. Ten years ago I was SO hoping it would be a commodity by then, a new paradigm for heating & cooling in N. America, but that's not the way it seems to be playing out.

GSHP seems to have traction in Europe, where hydronic heating is the incumbent paradigm, air conditioning rare, and people build houses for the long term, not 7-years max, but even there competition from mini-split technology is eating some of the cake. In the swampy Netherlands where most homes aren't more than 3 meters above the water table, a large Net Zero Energy retrofit program went from initially standardizing on small GSHP solutions to air-to-water heat pumps, less than two years since the initial concept roll out. http://blog.rmi.org/blog_2015_04_16_taking_dutch_housing_from_energy_hog_to_net_zero

Yes, good design and installation is crucial for geo, but so is it for mini splits. They get buried in snow easily, and the lack of whole house distribution makes mini splits not applicable in many applications.
While mini splits get much better and efficient, their fantasy rating system is misleading professionals and consumers. You simply have to overcome a much higher lift, especially when you need it most, both in heating and cooling modus.


Prices for geo will unlikely get so much less, since the labor is significantly more than air source, so is the equipment costs to make a higher capacity system needed for the northern part of the country. Variable sped technology is more expensive, manufacturers have to recoup their development costs, and the higher efficiency equipment commands larger ground loop capacity. On the other side, the efficiency has doubled in the lat 25 years, so has the system life expectancy. More efficient variable speed DC inverter circulator last much longer and use up to 85% lesser pumping energy, but cost 4 times as much, but also pay for themselves within a few years, similar like LED light bulbs.


I can also search around and can find a many examples where air source was switched out for geo.


http://blog.rmi.org/blog_2015_04_16_taking_dutch_housing_from_energy_hog_to_net_zero


May be you could elude why they switched out geo versus air source, I could not find any reasoning following your link. Not enough room, bad geology, too high of a price?

Plus us humans need a healthy, fresh air circulated environment, even HRVs don't do 100%.

The RMI article link didn't really explain how they settled on air-to-water systems, but it was a change. A couple of years ago when they launched the program I was reading about it on a Dutch newspaper's website, all of the original units were (to my surprise) water-to-water heat pumps. But all the current press & bloggery on that program ( in English or Dutch) have the air-to-water solution. The only recent exception I've found is here:

http://www.renda.nl/nieuws/nieuws/s-morgens-naar-het-werk-s-avonds-een.416160.lynkx

"En we hebben de bodembron voor de warmtepomp geboord in de parkeervakken voor de deur."

"We drilled the ground source for the heat pump in parking area in front of the door"

and

"Met de toevoeging van een grondgebonden warmtepomp zijn de huizen straks energieneutraal.

With the addition of a ground coupled heat pump the houses are soon energy neutral."

(my translation- shoot me if I'm wrong- I'm not a native speaker :-) )

So the 18 row houses they retrofitted in Tilburg there were all done with GSHP solutions. But it seems to be the exception that proves the rule(?).

I suspect that they did the financial math to come up with the pre-packaged air-to-water solution, given the low loads of any one row-house unit, and the temperate outside design temps. Even if it's less efficient, as long as it has capacity and the PV to get to Net Zero still fits on the roof, it's a done deal. Spending the time to properly design a GSHP system for a miniscule load just isn't worth it (?). Their pre-packaged air source solution mentioned in the RMI piece (and elsewhere) is a pre-plumbed 100 cubic foot blob that plops in the yard- no wells to drill or soil to analyze. The standardization of the installation package probably saves them more money in installation costs than any efficiency improvements would, given the magnitude of the loads.

I too find it pathetic how many mini-splits in New England get installed at ground level, often directly under the path of roof avalanches or ice-dam falls. It's neither expensive nor difficult to bracket mount them on walls under the protection of roof overhangs. They got over 10' of snow this year in Worcester MA, where a deep energy retrofit I was involved with a few years ago has the three mini-splits (one per floor) bracket mounted on the wall, 4' off the ground, and despite near-record snowfall they never missed a beat. Simply not having an idiot-attack, treating it as if it were an air conditioner that only needed to work in mid-summer seems sufficient. It's not a hard concept to understand that it snows, or how deep it gets.

The notion that recirculated air is necessary for human health & comfort is tough to sell in the land of hydronic heating, eh? :-) In the Netherlands continuous exhaust-only ventilation in both the kitchen & bath is required by code, and I've NEVER seen an HRV there (but they may exist.) In New England at least half the homes have hydronic heat (either steam or hot water), and NO automatic or continuous ventilation, but I've seen HRVs in tight high-R construction here. ASHRAE 62.2 is a pathetic excuse of a standard, barely more than a collective WAG of a bunch of middle aged guys based on little, that drives comfort down by excessively drying homes to unhealthy levels in winter, and increasing the latent loads in summer. The Building Science Corp alternative to ASHRAE 62.2 takes a more pragmatic approach. I'm not sure how GSHP is supposed to solve any ventilation or indoor air quality issues (especially hydronic GSHP). Ventilation needs are independent of the magnitude of heating & cooling loads, and should be treated separately.

It seems that no one knows what the reason was behind some of the dutch's decision to install air source. Drilling conditions? Collapsing boreholes? open floor plans? You suspect financial reasons, but you don't know.


Air quality is independent of delivery system. The point was that once you tiger up the houses to make them more efficient, it becomes necessary to ventilate fresh air in, with the need to heat up the make up air, which starts to counter all the efficiency efforts. Even ERVs don't recover 100%. If you have never seen an HRV how do the dutch heat up the make up air? More tightness gets to the point of no return.

There are really only three major soil types & conditions in NL:  boggy topsoil/peat, clay, and sand.  In any individual location there will be layers of all three, an artfact of being an ancient & ongoing river delta (the Rhine).  A large fraction of the country is below sea level, and with the exception of the southern hills district around Maastricht, everyone is VERY close to the water table.

It's DEAD EASY stuff to drill, but the bottom of a well casing would have to be embedded in a sand layer to not sink out of sight over time. Nearly all foundations for buildings are built on pilings, and code requires that the pilings terminate in sufficiently dense & thick sand layers to support the load of the building.   As a geo-pro, you are in a much better position than me to speculate on what the other technical issues might be around drilling in those conditions.

Given the brevity (non-existence) of the cooling season there, and the close proximity of the wells in a row-house development there may be issues of over cooling the soil too.  If  (as in Tilburg) the wells are under a paved parking area, with sufficient paved area they may get sufficient solar gain out of it to prevent that from being a problem (or not.)

SFAIK the Dutch don't pre-heat ventilation air.  While the climate has HDD numbers comparable to US zone 5 locations, it's only true because of the 12 month heating season.  It's a very temperate climate, with 99th percentile temperature bins in the mid 20s F, similiar to the warmer parts of the Puget Sound region or Vancouver BC.  The mean January temp in Tilburg NL (as in the rest of the country)  is about 37F, and the July mean temp is about 63F.  Zoom out and eyeball it with the cursor cross hairs:  

See:  https://weatherspark.com/#!dashboard;q=tilburg%20netherlands  

No pre-heat or heat recovery at low cfm isn't a very serious heat load, nor is it much of a comfort issue in NL. The mid-winter lows are nothing like say Pittsburgh PA or Columbus OH, despite the comparable annual heating degree-day numbers.  If you zoom in to the weatherspark link you'll see that the coldest hour of the coldest day in Tilburg this past winter was +19F (8PM, 28 December 2014).  Most winter weeks the WEEKLY low was about 30F.  The coldest hour of the prior winter was +27F.

In very tight houses  I'd assume (pure speculation) that ventilation inlet ports/valves are added so that the code-required exhaust venting still works.

That's also a climate where modulating air source heat pumps don't have much of an efficiency or capacity penalty the way it does in most US climate zone 6 or higher locations.

Here is the quote I got for my home.. TWO system totaling $79,998.00
no info on actual BTU.. I told them about spray foam etc... they said it only dropped 1/2 Ton so the equipment stays the same....

FOR THE INSTALLATION OF 3 ZONE CLIMATE MASTER WATER TO AIR GEOTHERMAL
SYSTEM TO HEAT AND COOL HOME DESIGNED FOR FINISHING BASEMENT IN FUTURE
FIRST FLOOR
-Tranquility 30 two stage variable speed 410A heatpump will be installed in basement
-Unit will be equipt will desuperheater to assist in making of domestic hot water
-Unit will be equipt with electric back-up heat
-Ductwork for first floor will be ran throughout basement suppling first floor through floor registers
-Ductwork will be mastic sealed and insulated to code standards
-Ductwork will be done to Energy Star standards with less than 5% air leakage from duct system
-Standard Hart & Cooley white or brown register package will be installed
-System will be setup as 2 zones using electronic zone dampers
-Low voltage wiring will be done
-2 programmable thermostat will be installed
-Drain will be run into condensate lift pump and pumped to daylight
-Piping from where loop field was brought into house by others will be connected to pump pack
SECOND FLOOR
-1 Tranquility two stage split systems 410A heatpump will be installed in basement
-1 Bryant variable speed air handler will be installed in attic with electric back-up heat
-Unit will be placed on emergency drain pan with float switch
-Drain will be piped to daylight
-Refrigeration piping will be done between basement and attic unit
-Ductwork will be ran throughout attic to supply second floor
-Ductwork will be mastic sealed and insulated with R-8 insulation
-Standard Hart & Cooley white or brown register package will be installed
-Low voltage wiring will be done
-1 Programmable thermostat will be installed
-Piping from where loop field was brought into house by others will be connected to pump pack

GEOTHERMAL SYSTEM 55,998.00

CLOSED LOOP WELL FIELD INCLUDING-
(3) BORE HOLES AT 400ft, 40FT OF CASING PER BORE HOLE, LOOPING OF EACH WELL,
GROUTING OF EACH WELL, 50 OFFSET TO HOME .
This is a estimated cost only and price can change depending on ground conditions, casing depths over
40ft, if bore hole becomes watered out and drilling cannot continue,if water removal from site is needed, if
bore hole has collapse additional charges will apply
24,000.00
All excavation by others, not included



THOUGHTS?

Even if those installers are geniuses and deliver something that has an all-in COP of 5 and a $10-12K ducted mini-split solution only delivers a COP of 3, and even after discounting the $80K quote to $55K to account for the Federal Tax Credits how many decades does it take to make up the $45K difference in upfront cost on electricity use savings?

If you spent the $45K difference on rooftop solar instead (and got a 30% tax credit bringing that down to $32K) you would likely come close to hitting Net Zero Energy, since that would buy you something like 13,000 watts-DC of PV, delivering at least 17,000 kwh of annual electricity. At a COP of 3 the 17,000 kwh used in the minisplit delivers 58 MMBTU of heat. A house with a 30KBTU/hr heat load at +10F use about 13,000 BTU/HDD to keep it toasty 24/7. So, at a coastal RI climate of ~5500 HDD it uses 72 MMBTU for space heating. That's not Net Zero, but it's covering 80% your heating bill. With the perfect GSHP with a COP of 5 the heating costs would only be 40% less. If you increased the PV array to match the same after-tax-credit spending level you'd be 100% covered on heating, with something left over to run the lights with.

In the real world you'd do better than a COP of 3 with Fujitsu mini-duct units in a coastal RI climate. In the real world almost nobody get's an all-in COP of 5 out of their GSHP.

This has been my point all along: At that type of system pricing it's really REALLY hard to make a case for GSHP on the marginally better efficiency. Both mini-splits and PV are fairly low-risk commodities of known performance at this point. At half the money GSHP would have at least a remote chance of competing, with perfect design, but even then it could be a close call.

You told them about the spray foam, but you didn't tell them about the insulating sheathing foam, so they're quoting for more heat pump than you need. It's not doing you or them any favors by holding half the cards close to your chest, since they over-spec the system, which boosts the quote considerably. But it's still unlikely that the reduced system would hit a price point that makes financial sense against a mini-split + PV alternative.

Kleach, I my market, a dual stage 5 ton HP with zoning system and vertical loop field, DSH and hot water tanks would run in the high 30s. That is a price we guarantee no matter the difficulties with the loop field. But I cannot speak for the RI market.


We continue to monitor SEASONAL COP of dual stage units at 4.4, whereas variable speed units can run average COPs of over 5. Keep in mind that the only seasonal variation to have a major influence on the heating efficiency is the entering water temperature (EWT) and that starts at around 65F at the beginning of the heating season, and ends at 32-35F at the end of the heating season. Name plate efficiency rating is at 32F in full load and 41F in part load. The part load rating is a more realistic number since HP run (in our climate) 85% in part load, and the 41F reflects more the average seasonal EWT.


At the same moment I do question a seasonal COP of 3.0 in RI climate for the mini splits. In the real world you want your bedrooms heated, your water heated, not a single point distribution. What you should seek is another quote. And good insulation, which should have a higher impact than 1/2 ton.

The Fujistu xxRLFCD series DUCTED mini-splits test in the 11s for HSPF-  significantly more efficient than the Mitsubishi  FExxNA wall-coil types that test in the low to mid-10s.

A fleet of 10 field-monitored FE12NA (HSPF=10.6) delivered a fleet average COP of 2.81 in Idaho Falls in NEEAs third party testing program a handful of years ago, with comparable ~COP 3 averages in the Montana clusters. (See Table 12 of the addendum on p.138 , PDF pagination).

These are US climate zone 6B locations, which are MUCH colder (more than 10F colder winter averages) than coastal RI, which is on the warm edge of US climate zone 5A.  If a mini-duct cassette unit with 10% higher tested efficiency can't beat the performance of the lower efficiency mini-splits at outdoor temperature averages more than 10F warmer it means the ducts are leaking as much air as a tennis racket!

These mini-ducted units have all of the heat distribution advantages of any ducted system, and WILL beat a seasonal COP of 3 in RI (but probably not 3.5.)  The 1.5 tonner (HSPF=11.3) is good for ~20,000 BTU/hr down to -5F, which is about 15F colder than the 99th percentile temperature bins for any location in RI.

The newest  best-in-class wall-coil types might hit a COP of 4 in RI, but unless you're going to R40 whole-wall R for the walls, and carefully down-size sub-U0.2 windows everywhere they aren't going to cut it for room-to-room temperature deltas.

The straw-man heat load calcs I ran earlier showed that the exterior foam cuts something on the order 15,000 BTU/hr off the design heat load, well over a ton of load reduction from a code-minimum build. Until you run the real numbers with the actual house & insulation design, it's just silly to be out there getting quotes for heating systems.  I'm not impressed with the load-analysis skills of the contractors who did the last quote, but if you don't really tell them what your wall construction is you can't blame them for taking a WAG based on code-minimums.

You told them about the spray foam, but you didn't tell them about the insulating sheathing foam, so they're quoting for more heat pump than you need.

Dana1, I just told them an R factor for the walls..etc. you tell me what I should telling them the R factor should be for the walls, ceiling and basement if I use the wall model we spoke about. Open Sprayfoam on the inside.. polyiso on the outside.. Maybe I low balled it?

Until you run the real numbers with the actual house & insulation design, it's just silly to be out there getting quotes for heating systems

I need to get quotes for all subs and complete home costs for the bank.. I can't get a loan without it if I am the GC. It is not realistic on a new construction home to build it without heating and AC in the design... I need SOMETHING! just having a hard time swallowing 80K ... and yes.. I did contact a solar person.. it is $50K but would be a pay back of under 4 years.. not bad...

I have an open floor plan and three stories if you count the walk out. I don't want to see a wall unit inside and not a huge fan of the system being visible from the outside unless it can be covered and look nice... so having heat/cooling come from one spot for the floor will not work.. this means some form of ducting.. how do you see a ASHP working in that model? The cassette is large and ugly .. the admiral (wife) would never go for that .. How do you get the abilities of a ASHP you have outlined in a 4000 sq/ft open floorplan home? Seems to be targeted towards smaller lower end homes and apartments? I am sure that just pulled the pin on the grenade ...

Last question.. do you work for or get paid by or are in any way affiliated with any of the ASHP companies? You are SO pro air source .. I had to ask...

-Ken

"...I don't want to see a wall unit inside and not a huge fan of the system being visible from the outside unless it can be covered and look nice... The cassette is large and ugly ... the admiral (wife) would never go for that " ------------ From my very simplistic position, these were EXACTLY the points that I had in my head while the technical discussion was in full session. Sometimes it's all about the $$, but sometimes there are other factors to consider as well. There's a house near me with a Mitsu split with 3 heads. The line sets climb like ivy up the outside walls ------------- Sorry for the lack of line breaks. Anyone know how to allow better control over post formatting?

Posted By Dana1 on 13 May 2015 04:00 PM
The Fujistu xxRLFCD series DUCTED mini-splits test in the 11s for HSPF-  significantly more efficient than the Mitsubishi  FExxNA wall-coil types that test in the low to mid-10s.

A fleet of 10 field-monitored FE12NA (HSPF=10.6) delivered a fleet average COP of 2.81 in Idaho Falls in NEEAs third party testing program a handful of years ago, with comparable ~COP 3 averages in the Montana clusters. (See Table 12 of the addendum on p.138 , PDF pagination).

These are US climate zone 6B locations, which are MUCH colder (more than 10F colder winter averages) than coastal RI, which is on the warm edge of US climate zone 5A.  If a mini-duct cassette unit with 10% higher tested efficiency can't beat the performance of the lower efficiency mini-splits at outdoor temperature averages more than 10F warmer it means the ducts are leaking as much air as a tennis racket!

These mini-ducted units have all of the heat distribution advantages of any ducted system, and WILL beat a seasonal COP of 3 in RI (but probably not 3.5.)  The 1.5 tonner (HSPF=11.3) is good for ~20,000 BTU/hr down to -5F, which is about 15F colder than the 99th percentile temperature bins for any location in RI.

The newest  best-in-class wall-coil types might hit a COP of 4 in RI, but unless you're going to R40 whole-wall R for the walls, and carefully down-size sub-U0.2 windows everywhere they aren't going to cut it for room-to-room temperature deltas.

The straw-man heat load calcs I ran earlier showed that the exterior foam cuts something on the order 15,000 BTU/hr off the design heat load, well over a ton of load reduction from a code-minimum build. Until you run the real numbers with the actual house & insulation design, it's just silly to be out there getting quotes for heating systems.  I'm not impressed with the load-analysis skills of the contractors who did the last quote, but if you don't really tell them what your wall construction is you can't blame them for taking a WAG based on code-minimums.

You forgot to mention that in the NEEA study participants were using wood supplement heat, and unknown amounts (and unaccounted for) of electric resistant heat to keep their houses warm. The data also shows that this supplement heat was used more the colder the outside temps were. Supplementing the ASHP's with unaccounted supplement heat at the time when they run least efficient skews the results significantly.
You continue to present wonderful reports to support efficiency claims of ASHP's without mentioning the flaws in those reports, or the flaws in the ASHP's rating game overall.