<DrumBeat: February 7, 2008The Oil DrumA Vision Splendid or Selective Myopia: Exploiting the Australia 2020 Summit>

141 comments on Ground Source Heat Pumps

Comments can no longer be added to this story.

HereinHalifax on February 9, 2008 - 3:51am Permalink | Subthread | Parent | Comments top

This conversation is especially timely for me as I will be meeting with an electrical utility to discuss various DSM initiatives now under consideration, including the retrofit of air source and geo-exchange heat pumps in electrically heated homes. As I've stated here before, I've always considered high efficiency air source heat pumps a better value overall, at least in our milder Maritime climate, but I haven't looked closely at the numbers until now.

To better prepare myself for this meeting, I've downloaded ten year's of hourly temperature data for the Halifax area and built a spreadsheet to test various scenarios (it's 673 pages long, but the first two pages are available in PDF format here: http://www.datafilehost.com/download.php?file=d4474884). According to the Nova Scotia Department of Energy, the spacing heating demands of a conventional new home based on our construction standards and local climate is approximately 50 million BTUs (older homes are rated at 80MM BTUs and an energy efficient R2000 home is pegged at 30MM BTUs). In the standard scenario, I've assumed internal heat gains from lighting, appliances, passive solar, occupants, etc. would be sufficient to maintain indoor temperatures until outside temperatures fall below 15C/59F. I've also assumed heat loss below this point averages 200-watts per degree C (I appreciate heat loss is not linear and other factors such as wind play a large role, but this level of detail goes well beyond my abilities to model here and probably wouldn't alter the final results appreciably).

I selected the Fujitu 12RLQ and 15RLQ as our air source units and estimated their installed cost at $3,500.00 and $4,000.00 respectively (an amount roughly double their wholesale cost).

The ten-year average space heating requirements of our reference home is 15,024 kWh/year. If the results are valid, the smaller of the two units can supply roughly 76 per cent of overall demand and the larger, 79% -- this assumes the heat supplied can be adequately distributed throughout the home, which is unlikely, but that's something I'll put aside for now. Backup heat, to be provided by current heating system, is estimated to be 3,602 and 3,126 kWh/year respectively.

The financials, as I expected, are strong, with annual savings in our base year of roughly $840.00 for the 12RLQ and $880.00 for the 15RLQ. This puts the simple pay back at under four years for the former and five years for the latter, assuming a modest 6% escalation in electricity costs. The internal rates of return are 26 and 23 per cent and the corresponding 10-year NPVs are $4,665.00 and $4,504.00, assuming a cash discount rate of 5%. Overall, a pretty solid investment.

Surprisingly, the numbers for the geo-exchange system were not nearly as good and I'm wondering if I've made some poor assumptions or if my calculations are flawed. I've assumed a capital cost of $18,000.00, which includes the installation of ductwork, an average COP of 4.0 and that the heat pump can supply 100 per cent of the home's space heating and domestic hot water needs. The combined annual savings in our standard scenario are $1,482.00. This provides us with a pay back of just under ten years (again, assuming a 6% escalation in utility rates), an internal rate of return of 1.4% and a ten-year NPV *loss* of just over $3,100.00. I had thought the inclusion of the DHW component would minimize the gap between these two systems but that doesn't seem to be the case. So I'll pose the same question I asked in another forum: Am I missing something obvious or are the numbers I used unrealistic? I don't want to unfairly criticize a technology if it can help customers save money and assist the utility in meeting its goals.

Bear in mind the target homes are electrically heated and would be, in most cases, reasonably energy efficient; again, the space heating requirements are likely to be in the order of 50MM BTUs/year or less. The vast majority would be heated with conventional electric baseboard units, although a smaller number could be in-floor or radiant panel, ETS, electric boilers and forced air furnaces – with the exception of the latter, there would be no existing ductwork.

Any feedback would be appreciated as residential heating systems are not my speciality and I don't wish to publically embarrass myself or my company. And if anyone wants to examine the spreadsheet internals, I'd be happy to email them a copy if they so desire.

Cheers,
Paul

0
Comments can no longer be added to this story.
AlanfromBigEasy on February 10, 2008 - 2:25pm Permalink | Subthread | Parent | Comments top

I think that I found a flaw. Air source heat pumps output declines significantly at cooler temperatures. More electricity AND less heat as the temp drops. This adjustment is not apparent in your spreadsheet.

In New Orleans, I found that heat pumps sized for a/c cooling load could provide adequate heat down to about +3 C (with interior heat from office building). GREAT for us (rarely below 0C), minimal gas heat supplement.

On an province wide basis, this has strong implications. Minimal demand at 8C (air source works wonderfully), MUCH higher demand (and resort to resistance heat) at, say, -20 C. TOOOO much for grid :-(

If you would like to talk, send me an eMail (click my name and it is in my profile).

Best Hopes,

Alan

0
Comments can no longer be added to this story.
DaveMart on February 10, 2008 - 4:00pm Permalink | Subthread | Parent | Comments top

Check out information in this thread on the new Eco-Cute CO2 air pumps - they are not yet in the States, Japan only, but they are more efficient and good for down to -20C

0
Comments can no longer be added to this story.
HereinHalifax on February 10, 2008 - 6:16pm Permalink | Subthread | Parent | Comments top

Hi Alan,

Thanks for your comments and for your kind offer to assist; both are much appreciated and I might just take you up on that.

Actually, the spreadsheet makes adjustments for both output and power consumption based on outdoor ambient temperature. At 8.3C/47F, the Fujitsu 12RLQ produces 4.68 kW of heat and its power consumption is 1.25 kW (COP = 3.75). At 24C, heat output climbs to 6.18 kW, but so too its power demand -- maximum demand is said to be 2.14 kW. At -15C, we're told heat output falls to 0.9 kW; I don't honestly know the exact numbers, but I'm guessing at this point its COP runs in the range of 1.75 to 2.0 and that periodic defrosting of the outside coils kicks us closer to 1.5 or perhaps 1.8. I wish I had better numbers to work with and as soon as I find them I'll incorporate them into the model.

That said, based on published specs, we would expect heat output to rise an average of 0.094 kW per degree C and for our purposes, I rounded that down to 0.09 kW/C. Likewise, for each degree above 8C, power consumption should increase by no more than 0.059 kW and I rounded that up to 0.06 kW. On that basis, I'm reasonably confident our performance estimates are accurate for temperatures 8C and above. When temperatures fall below 8C, we assume heat output drops by 0.16 kW/C which is in line with published specs. With regards to power demand, one would expect it to fall largely in proportion to heat output, but this would be tempered by defrost demand; in our model, I assumed power demand would only fall by just 0.004 kW/C which is far more pessimistic than need be. For example, at -15C, we know heat output is 0.9 kW, but my calculations have power demand at 1.16 kW, giving us a negative COP when, in fact, we know it would be positive. I figured it would be better if I intentionally underestimated performance rather than the other way around so, if anything, the numbers should be even better than what we show here.

Best regards,
Paul

0
Comments can no longer be added to this story.
AlanfromBigEasy on February 10, 2008 - 8:13pm Permalink | Subthread | Parent | Comments top

at -15 C... but my calculations have power demand at 1.16 kW, giving us a negative COP when, in fact, we know it would be positive.

Actually not. It is entirely possible for a heat pump to generate less heat than electrical resistance heat (COP < 1.0). Given the stress on the equipment, and defrosting, it is better to turn off the heat pump and go to resistance heat (or oil) before this happens (at COP 1.5 or so). 28 F or so depending upon the model.

Alan

0
Comments can no longer be added to this story.
HereinHalifax on February 10, 2008 - 10:03pm Permalink | Subthread | Parent | Comments top

It is entirely possible for a heat pump to generate less heat than electrical resistance heat (COP < 1.0).

Hi Alan,

I'd be shocked if a heat pump's COP would be allowed to fall below 1.0 within its normal operating range; presumably manufacturers would avoid this for all the obvious reasons. As mentioned, I don't have the operating specs on the Fujitsu 12RLQ (HSPF = 10.55), but I do have them for a York BHX024 which is a less efficient unit with an HSPF of 8.0. At -23C and with 21C dry bulb temperature over the evaporator coil at 800 CFM, the BHX024 produces 2.43 kW of heat and has a power draw of 1.25 kW, which includes the blower. So even at -23C, a full 8 degrees below the -15C cut-off of the Fujitsu, the COP for this particular heat pump is a still respectable 1.95. Defrosting will obviously take the final number down somewhat, but I couldn't imagine a scenario short of entombing the outdoor compressor in a thick block of ice where more energy would be expended performing this task than what would be gained through normal operation.

I tend to believe my numbers are, if anything, unfairly conservative but, again, this isn't my area of expertise, so I would encourage you and anyone else to challenge my assumptions and poke holes in my arguments.

Cheers,
Paul

0
Comments can no longer be added to this story.
Saratoga Peak on February 11, 2008 - 9:36am Permalink | Subthread | Parent | Comments top

Actually,
Air Source Heat Pumps are designed to fall below a COP of 1.0 when the outdoor temperature gets near or below freezing. What happens is the outdoor coil begins to Freeze up. Then, to combat this, by design, is the Unit switches to Air Conditioning mode to generate heat on the Outdoor coil, thereby cooling indoors. Then, since it is winter, and you want heat, the resistance coil turns on, thereby taking cooled air and reheating it, and heating it more in order to heat your home. This is painfully inefficient. And is what in fact has given the Heat Pump industry a serious black eye in the majority of North America. And sadly, Ground Source Heat Pumps have had to work hard to rid this stigma, since they are entirely different and not prone to the same problem.

Now I don't know about this fujitsu model. It must use a different refrigerant to make this possible.

0
Comments can no longer be added to this story.
HereinHalifax on February 11, 2008 - 12:31pm Permalink | Subthread | Parent | Comments top

Air Source Heat Pumps are designed to fall below a COP of 1.0 when the outdoor temperature gets near or below freezing

Hi Saratoga Peak,

Frankly, I don't see how this is possible and it certainly doesn't reflect my own experience. Air source heat pumps are rated by their HSPF (Heating Season Performance Factor), which is a ratio between how much heat they produce over the heating season versus the amount of energy they consume, in total; obviously, higher numbers are better. The Fujitsu 12RLQ has a HSPF of 10.55 (Zone 4). To convert this to its "seasonal COP", you divide this number by 3.4, which gives us a COP of 3.1. The York product I mentioned above has a HSPF rating of 8.0, so its seasonal COP is 2.4. Just to be clear, these numbers take into consideration the energy used to defrost the outside coils. I should also add that Halifax, N.S. is located in Zone 4 and our heating degree days number 7,800, which means our winters are as cold as those of Minneapolis, MN (not exactly tropical by any means).

Prior to installing my ductless heat pump, I used, on average, a little over 2,000 litres of heating oil a year for space heating and domestic hot water purposes. The following winter, this number dropped to 827 litres and last year it came in at 830 litres. My records show my DHW related consumption during the summer months averages 1.2 litres/day and about 1.5 litres/day during the winter months when water inlet temperatures are lower, I do more laundry (bulker and heavier clothing) and when longer (and hotter) showers are preferred. On this basis, I can reasonably assume 500 or so litres a year can be attributed to DHW needs, with the balance related to space heating. Thus, with the addition of my heat pump, my space heating consumption has fallen from about 1,500 litres/year to 330 litres, for a net savings of 1,170 litres/year. [My home, btw, is a 2,500 sq. ft., 40-year old Cape Cod that has been extensively upgraded in terms of its thermal efficiency, with a space heating demand that places it somewhere between a conventional new home and a R2000 equivalent.]

My oil-fired boiler has an AFUE of 82%, which means I net about 8.77 kWh of heat from each litre of heating oil. Multiplying 1,170 litres x 8.77 kWh/litre, tells me my heat pump is providing me with an average of 10,260 kWh of heat over the course of the heating season. My electrical consumption averages 17 kWh/day during the summer months and climbs to 40 to 43 kWh/day during the coldest winter months when the poor little guy is working flat out. Taking a look at my most recent power bill, here's how the numbers break out (total consumption / days in billing cycle / kWh/day):

For the period ending:

January 08 -- 2,540 kWh, 59 days, 43 kWh/day
November 07 -- 1,527 kWh, 62 days, 25 kWh/day
September 07 -- 1,136 kWh, 62 days, 18 kWh/day
July 07 -- 1,043 kWh, 62 days, 17 kWh/day
May 07 -- 1,848 kWh, 62 days, 30 kWh/day
March 07 -- 2,397 kWh, 58 days, 41 kWh/day
January 07 -- 2,332 kWh, 58 days, 40 kWh/day

Past Year: 10,491 kWh, 365 days, 29.7 kWh/day

Our heating season basically kicks off October 1st and eventually tapers off towards the latter part of May, so if we look at the consumption for just this period, I used a total of 7,548 kWh over the span of some 210 days, which is an average of 35.9 kWh/day. From that, I can subtract what would be used for other household needs (i.e., lighting and appliances) which, based on my summer usage, seems to be in the range of 17.5 kWh/day. If these numbers are more or less correct, my heat pump consumes a little less than 3,900 kWh/year but provides me with just over 10,000 kWh/year in heat. On this basis, my seasonal COP should be in the range of 2.5. Note too that my heat pump has a HSPF of 7.2 and the Fujitsu has a HSPF of 10.55, so the Fujitsu should be, in theory, 1.5 times more energy efficient than my own.

My apologies for the long post, but I wanted you to understand my own "real world" experience with air source heat pumps. I'd be happy to answer any questions you have and provide you with more information if it would be helpful.

Cheers,
Paul

0
Comments can no longer be added to this story.
docscience on February 12, 2008 - 2:18am Permalink | Subthread | Parent | Comments top

Greetings; I am in Sydney, NS and was wondering if you know anyone else in halifax who is researching peak oil ?
You do not have any email contact info in your personal info section. Can you email me ?

0
Comments can no longer be added to this story.
HereinHalifax on February 12, 2008 - 12:12pm Permalink | Subthread | Parent | Comments top

Hi Gilbert,

I've send an e-mail to your hot mail account.

Cheers,
Paul

0
Comments can no longer be added to this story.
DaveMart on February 12, 2008 - 9:25am Permalink | Subthread | Parent | Comments top

Assuming that the 'Halifax' in your handle refers to Halifax, Nova Scotia there is actually an air-source heat pump designed specifically for the Canadian climate, although I realise of course that your climate is more maritime than many areas.

This air-source pump is OK at down to -30C.
Efficiencies should approach ground source pumps, they say.

Here are the details:
http://www.gotohallowell.com/technical.html
http://www.thestar.com/article/302301
http://www.thestar.com/article/302300

The site also includes a cost calculator for different towns in Canada and the US, although the one for Halifax has a glich, as it is under 'Halifax Int'l Airport, which crashes the program.

Hope this helps.

0
Comments can no longer be added to this story.
HereinHalifax on February 12, 2008 - 11:58am Permalink | Subthread | Parent | Comments top

Hi Dave,

Many thanks for the links. I've been following the development of this heat pump fairly closely and I think it holds tremendous promise. As you may know, some of the first generation "cold weather" heat pumps in utility field trials were plagued with quality control issues, but that's not uncommon with any new technology. I hope it will be a huge success for them.

The narrow strip of land that hugs the south-eastern portion of the province stretching from Yarmouth in the south to Halifax in the north is considerably milder than other parts of the province; we're rated as Zone 4 whereas the rest of Nova Scotia is classified as Zone 5. In fact, our temperature here at harbour side are commonly two to three degrees warmer than even the airport readings just a few km inland.

I log every single hour my heat pump operates in a spreadsheet and calculate its relative performance based on these airport readings. I estimated my seasonal COP last year at 2.48; in reality, it's higher than this due to our slightly milder micro-climate.

The nominal COP of the Fujitu 12RLQ is 3.75 (at 47F/8.3C) and based on airport data for the past ten heating seasons, I've calculated its seasonal COP to be 3.26 (and as I've stated above, I believe my estimates are decidely conservative). I suspect one reason why our performance is so good is that given our truly maritime climate, we seldom get sharply bitter cold weather, and when we do, it doesn't last very long. In addition, we have unusually long, cold spring. Whereas Toronto come May can be basking in 30+C temperatures we consider ourselves lucky if we break 15C. Looking at the rolling COP as each day passes, you can clearly see how our extended heating demand during the months of April and May move our seasonal average upward.

Cheers,
Paul

0
Comments can no longer be added to this story.
DaveMart on February 12, 2008 - 12:27pm Permalink | Subthread | Parent | Comments top

Hi Paul.

They are not available outside Japan yet, but if you have concerns regarding the reliability of the Canadian model you might possibly have more confidence in Japanese engineering, with the added fact that they have installed very many of their new carbon dioxide based Eco-Cute heaters for several years.

The big thing is that they have a COP of up to 4.9.

Here is the data:
http://www.r744.com/knowledge/faq/files/ecocute_all.pdf
Technology and Market Development of CO Heat Pump Water Heaters ...

I don't know how that would fit into your schedules but it might be worth waiting, as I believe they might be available outside Japan in the next year or so.

That they are good for down to -15C can't be bad either, even if not strictly needed in Halifax.

0
Comments can no longer be added to this story.
HereinHalifax on February 12, 2008 - 2:02pm Permalink | Subthread | Parent | Comments top

Hi Dave,

I think they're just now hitting the European marketplace and I suspect they'll eventually make their way here, but it likely will be a few more years yet. Someone in another thread spoke of "technological hard ons" and I confess there are two things that stir deep passion; one is this: http://www.allpar.com/cars/dodge/challenger.html and the other (don't laugh) is the Eco-Cute. As someone who abhores energy waste, I'm ashamed to admit the former, but the '74 Challenger was my first set of wheels and thirty-five years later, it still holds tremendous emotional appeal... chalk it up to that left-side, right-side of the brain thingy.

In any event, I would dearly love to replace my oil-fired boiler with an Eco-Cute. I believe Sanyo recently announced an enhanced version that works efficiently at temperatures at or below -20C. Pardon my Japanese, but that really "蹴りのろば!

At this point, almost two-thirds of our fuel oil consumption is DHW related. Five hundred litres/year is a trivial amount compared to most households, but since it's the only low hanging fruit remaining, it's the logical place to target. I'm struggling with this, but I'm thinking of adding a Nyle heat pump to take on this responsibility, assuming I can somehow attach it to plumbing that connects my boiler and the SuperStor Ultra cylinder.

For information on the Nyle heat pump, see: http://www.nyletherm.com/waterheating.htm

Right now, I can shoot down to Bangor and throw one in the back of the Chrysler for a little over $800.00 CDN. With a COP of 2.0 to 2.4, it would cut our water heating costs by more than half, plus minimize or even eliminate the need to run the dehumidifier during the summer months (after our heat pump, probably our next biggest power draw). Between May and October, our dehumidifier averages between 5 and 10 kWh/day, so the Nyle could assume full responsibility for this task and, in the process, provide us with free hot water. Even though our DHW requirements are extremely modest, once you factor in the dehumidifier savings, our simple payback is less than three years. My unnatural lust for the Eco-Cute is the only reason why I'm hesitating. ;-)

Cheers,
Paul

0
Comments can no longer be added to this story.
DaveMart on February 12, 2008 - 4:09pm Permalink | Subthread | Parent | Comments top

You obviously know a great deal more than I on all these subjects!

On top of that, the requirements are radically different between America and Britain - no need for de-humidification here, and not much for air-conditioning.

One thing which caught my eye though was reclamation of heat from waste water via a coil - at the cost of your bills it won't pay-back in a reasonable time though.

0
Comments can no longer be added to this story.
HereinHalifax on February 12, 2008 - 5:59pm Permalink | Subthread | Parent | Comments top

Hi Dave,

I had considered adding a heat recovery device to our shower drain but there's only the two of us and our low-flow shower head has an on/off control that allows us to conveniently turn off the water as we soap up, so a typical shower might consume 20 to 25 litres of hot water at most, and I suspect the actual number is closer to 15L. That's less than 1 kWh of heat demand and if a recovery device could recoop 40 per cent of that, our savings would be less than $3.00 a month; strictly on economic terms, a non-starter.

As an alternative, I heat our wash water during the summer months with a 50 metre garden hose that I roll out on the back patio. An hour exposed to direct sun can raise water temperatures by 40 or 50C. And by the time the front loader has finished its first load, the hose has come back up to temperature and is ready to do the next. By scheduling laundry on the days when the sun does shine (admittedly a daunting task given our maritime weather), I've trimmed our fuel oil consumption between May and October by an average of 6.0 litres/month, and at no cost to boot! It's enough to bring tears to any Scot's eyes. :-)

Cheers,
Paul

0
Comments can no longer be added to this story.
Retsel on February 13, 2008 - 3:16pm Permalink | Subthread | Parent | Comments top

The efficiency of these devices is limited, according to thermodynamics, to the temperature differences between the house and the medium from which the heat is being extracted. Sure air pump heat pumps are as efficient as ground source heat pumps when the heat source has about the same temperature ( i.e., 50 degrees F). But as the air temperature drops, then air source heat pump efficiency and capacity drops through the floor. Employing tweaks to improve the efficiency of air source heat pumps should help ground source heat pumps as well.

Retsel

0
Comments can no longer be added to this story.
HereinHalifax on February 14, 2008 - 1:11am Permalink | Subthread | Parent | Comments top

Hi Retsel,

I've been discussing the performance of GSHPs with a professor of architecture and engineering at the University of Waterloo. He's done extensive in-field evaluations of these products and tells me the COP numbers are often significantly lower than expected, particularly where heating and cooling demands are not well balanced (in my province, for example, our heating season spans late September/early October and runs through late May/early June and we have no cooling requirements to speak of). In addition, during the shoulder seasons, daytime air temperatures routinely exceed ground temperatures, especially late spring when ground temperatures are at their lowest due to natural thermal lag and where the earth in the immediate area of the supply lines has been further chilled by the operation of the GSHP.

Along these lines, the ten-year mean air temperature for Halifax for the months of October and November and April and May is 7.2C (as noted above, the Fujitsu 12RLQ has a COP of 3.24 at 8.3C and 7.2C is within spitting distance of that mark). The ten-year mean temperature for the full heating season which, for our purposes, I've designated as October 1st through May 31st is 2.2C. According to Natural Resources Canada, our average "deep ground temperature" is 9C and I presume this number is somewhat lower during the winter months due to normal seasonal variations and would fall further as heat is extracted over a seven or eight month period. Looking at the entire heating season, the spread between air and ground temperatures may not be as great as one might think.

In any event, if we assume a heat demand of 15,000 kWh/year, at $0.10 per kWh, a homeowner would expect to pay $1,500.00 a year to heat with electric resistance. A high efficiency air source heat pump with a HSPF of 10 would lower this cost to $500.00/year and a ground source heating system with a COP of 4.0 would get us to down to $375.00. The additional savings, in this case, are $125.00, and if we add another $250.00 for domestic hot water, our net savings are $375.00. If we double heat demand to 30,000 kWh/year and double electricity costs to $0.20 per kWh, our incremental savings reach $1,000.00/year ($500.00 for space heating and a further $500.00 for DHW production). It sounds great, but if the installation costs are $10,000.00 or more above what I would expect to pay for a conventional air source heat pump, how do I stand to benefit?

Cheers,
Paul

0
Comments can no longer be added to this story.
Retsel on February 14, 2008 - 3:05pm Permalink | Subthread | Parent | Comments top

You live in a similar latitude as me as I live in Ann Arbor, Michigan. The efficiency benefit of a ground source heat pump (GSHP) over air source heat pumps (ASHP) are obvious and you seem to agree with that, although I did not verify your numbers. I will then address several points that you make.

One is that with a closed loop GSHP, the ground will tend to be cooler at the end of the winter (perhaps approaching freezing or 32F) and thus an ASHP would actaully be more efficient than the GSHP. That is potentially a true statement for the daytime but as long as the nightime temperatures are low enough, the GSHP would still be more efficient. If you are talking about when the nightime temperatures are also higher than 32 degrees even at night, the energy gain from solar heating though is likely high enough that neither system would run much at these higher temperatures (remember that insulation is sized to deal with zero F degree days), thus this warmer part of the year would have very little impact on costs. Just a sidenote, my lot is adjacent to a pond so the water table is VERY high. I doubt that the ground temperature will decrease to under 40F for my system because of the very high water content in the soil.

An important point to make is that the impact on global warming will tend to shift our climate. We will spend more of our energy on cooling going into the future compared to heaating, thus at our latitude, the heating of the ground will be more balanced with the cooling of the ground. Also, the solar affect tends to increase the cooling load for the summer months greater than what the average temperatures would suggest.

All this discussion is moot if the GSHP is an open loop system, which has improved thermal efficiency but trades off with pumping losses.

I will not agonize whether your cost numbers are right or wrong. Using them on their face value, the economics suggest that the payout for a GSHP at current energy prices over an ASHP is on the order of 30 years. This is not that much different than a GSHP over a natural gas furnace with air conditioner. It all depends on whether you want to trade higher capital costs for operating costs.

The second part of your message gets closer to the issue for me, and that with energy prices expected to increase, the payout is expected to be, using your simply adjusted cost numbers, 10 years or less. That is a much more easy step to take when installing a system cost that is expected to last over 30 years. The other part of this is that I am an environmentalist. Thus I gain a sense of satisfaction on the fact that the GSHP will reduce greenhouse gas emissions over a natural gas furnace or an ASHP. By that way, assuming coal-fired electricity generation, the ASHP will have a larger CO2 impact than both GSHP and natural gas furnace/air conditioner. Even assuming coal-fired electricity, the GSHP will have lower CO2 emissions than a natural gas furnace/air conditioner.

Retsel

0
Comments can no longer be added to this story.
HereinHalifax on February 14, 2008 - 5:03pm Permalink | Subthread | Parent | Comments top

Hi Retsel,

Thanks for your comments. As is true with most things in life, we're often forced to make trade-offs and, in this case, I'm willing to sacrifice some efficiency for lower price -- the exact numbers we could probably toss about for days. I decided my limited resources would be better spent elsewhere (i.e., improving the overall efficiency of my home's thermal envelope), but if someone is willing to spend more for a system they percieve to be better for whatever reason then, obviously, price may not be the best metric by which to judge such investments. I certainly applaud you for taking into consideration these other factors. However, as valid as these other points may be, if we are to recommend a particular technology and especially if we are to recommend it over a competing technology, we can't ignore or simply gloss-over the financials. No one has properly addressed this aspect, at least to my satisfaction, and in the absence of such, I can't in good faith recommend these systems.

BTW, just as one more random data point... earlier today I asked a contractor who installs these products in the Moncton area (in the neighbouring province of New Brunswick) how much a 3 tonne GHSP might cost. He said a typical closed loop system in the case of new construction runs in the range of $25,000.00 and an open loop version might push us closer to $30,000.00. I'm curious, do these numbers strike you as high, low or just about right?

Cheers,
Paul

0
Comments can no longer be added to this story.