Is GSHP justified over ASHP at todays prices

KCross

Hi
I have a GSHP and was recently talking to someone who is about to start a new build and deciding on heating system.

He seems to have decided on ASHP rather than GSHP eventhough he has the space, conditions and funds to install a GSHP, if he so wished.

It is, of course, an appropriately insulated house and using underfloor heating etc.

His theory is that the ASHP's are now efficient enough and, crucially, "cheap" enough that the return on investment is not there for installing a GSHP. He understands the issues around the ASHP will struggle at low temps(<0C) but he figures the extra electricity cost for the few days/weeks wouldnt justify paying for a GSHP.

He isnt an expert so I'm assuming he is getting his info from sales folks.

I dont have the figures he had calculated but I am interested to hear from folks on this forum whether the ASHP technology and cost (both initial and maintenance) today is better (over say 20years) than GSHP for a new build scenario?

Or is this one of those questions that just cant be answered definitively?

KCross

Condenser

KCross wrote: »

Hi
I have a GSHP and was recently talking to someone who is about to start a new build and deciding on heating system.

He seems to have decided on ASHP rather than GSHP eventhough he has the space, conditions and funds to install a GSHP, if he so wished.

It is, of course, an appropriately insulated house and using underfloor heating etc.

His theory is that the ASHP's are now efficient enough and, crucially, "cheap" enough that the return on investment is not there for installing a GSHP. He understands the issues around the ASHP will struggle at low temps(<0C) but he figures the extra electricity cost for the few days/weeks wouldnt justify paying for a GSHP.

He isnt an expert so I'm assuming he is getting his info from sales folks.

I dont have the figures he had calculated but I am interested to hear from folks on this forum whether the ASHP technology and cost (both initial and maintenance) today is better (over say 20years) than GSHP for a new build scenario?

Or is this one of those questions that just cant be answered definitively?

KCross

Despite the recent surge in popularity in ASHPs the reality is they are no more efficient than they were 8 to 10yrs ago. The main difference is that some big brand names have entered the market from the airconditioning sector with HP's based on the same platform as their AC units and in doing so can manufacture to a difference price point because of economies of scale.

ASHPs are no where near as efficient as a GSHP on a year to year basis and have much more volatility in their running costs due to being dependant on the outside air temp. They also won't last as long, having a much shorter life than a GSHP, more parts to go wrong and more exposed to weather resulting in a higher cost of ownership.

One factor also overlooked is the cost of defrosting. The unit is drawing air through a coil filled with refrigerant gas which is usually at a temp about 7-8c below the air temp. Air touching this coil will lose moisture to the coil through condensation. The moisture in colder weather will freeze to the coil, which impedes airflow and heat transfer and needs to be removed. This is normally done through reverse cycle defrost where the hot gas that normally heats your water/ufh is sent out to the coil to defrost the ice while the cold gas absorbs heat from inside. This is energy being used with no benefit to the owner and this defrost cycle is usually most intensive between air temps of 2-8c as the air can hold alot of moisture while the refrigerant gas is below 0c.

In short, yes your initial costs will be lower with an air source unit but the lifetime costs will be much higher and the ROI will be lower than if you installed a GSHP on day one. The mantra buy cheap, buy twice applies just as much to heat pumps as it does to any other product.

KCross

Condenser
Thanks for your response.

Do you have any details from your service history as to what the costs are like for each system, on average?

I dont think anyone disputes that the ASHP's are cheaper to buy and are more expensive on electricity, particularly at lower temperatures. The argument really is whether the figures add up when you put it all together and you have clearly said GSHP is better long term.

I'm looking for some figures…. there are several elements to owning the system:

1) Initial purchase price
2) Installation cost
3) Running costs, i.e. electricity
4) Maintenance, e.g. general servicing and likelihood of breakdowns (compressors etc)

1) and 2) are easy enough to determine. I'd estimate there is about somewhere between €2500-€5000 in the difference between the systems for those two items with, obviously, GSHP's being more expensive primarily on the installation cost since you have to dig the collector(either well or trench).

Am I about right on that figure?


I dont have any direct experience of 3) and 4) for ASHP's.
Do you or anyone else on the forum have direct knowledge of 3) and 4) for ASHP's?
e.g. Do compressors have a shorter lifespan in ASHP's? How short, on average?

Can someone give examples of what their electricity usage is in their house for an ASHP?
Can someone give examples of what maintenance issues they have had for ASHP's?




Bottomline, even though ASHP's are less efficient, if the buy/install price difference between ASHP vs GSHP is, say, €5000 for a particular house and if the extra electricity used for ASHP per year is, say, €200 and maybe factor in an extra compressor over 20years it appears there is very little difference between them…. €200x20=€4000 and add in the extra maintenance (e.g. compressor) they work out about the same.

These somewhat "out of the air" figures are assuming the GSHP doesnt breakdown!

Could anyone give some facts/figures to confirm or refute what I have given above?

Condenser

KCross wrote: »

Condenser
Thanks for your response.

Do you have any details from your service history as to what the costs are like for each system, on average?

I dont think anyone disputes that the ASHP's are cheaper to buy and are more expensive on electricity, particularly at lower temperatures. The argument really is whether the figures add up when you put it all together and you have clearly said GSHP is better long term.

I'm looking for some figures…. there are several elements to owning the system:

1) Initial purchase price
2) Installation cost
3) Running costs, i.e. electricity
4) Maintenance, e.g. general servicing and likelihood of breakdowns (compressors etc)

1) and 2) are easy enough to determine. I'd estimate there is about somewhere between €2500-€5000 in the difference between the systems for those two items with, obviously, GSHP's being more expensive primarily on the installation cost since you have to dig the collector(either well or trench).

Am I about right on that figure?


I dont have any direct experience of 3) and 4) for ASHP's.
Do you or anyone else on the forum have direct knowledge of 3) and 4) for ASHP's?
e.g. Do compressors have a shorter lifespan in ASHP's? How short, on average?

Can someone give examples of what their electricity usage is in their house for an ASHP?
Can someone give examples of what maintenance issues they have had for ASHP's?




Bottomline, even though ASHP's are less efficient, if the buy/install price difference between ASHP vs GSHP is, say, €5000 for a particular house and if the extra electricity used for ASHP per year is, say, €200 and maybe factor in an extra compressor over 20years it appears there is very little difference between them…. €200x20=€4000 and add in the extra maintenance (e.g. compressor) they work out about the same.

These somewhat "out of the air" figures are assuming the GSHP doesnt breakdown!

Could anyone give some facts/figures to confirm or refute what I have given above?

You're making the assumption that ashp's will last 20yrs. I would say only the very high end units costing as much as a gshp will last this long. The more economical models will last between 10 and 12yrs.

Typically a very good ashp will cost approx 30-40% more to run than a gshp in an identical installation. Lesser units could cost 100% extra or more depending on the year. You then have to factor in the rise in energy prices over 10yrs. Lets say the cost of electricity rises 3% per year and the gshp runs for €500 and the ashp runs for €800. In year two the cost to run the gshp would be €515, the ashp would be €824. After 10yrs the gshp would cost €652.38, the ashp would cost €1047.81.

When you add up the extra running costs, cost of replacement due to shorter lifetime plus the likelyhood of higher servicing costs due to more moving parts and exposure to the weather, I can guarantee you it will cost much more in the long term.

Yes you can get a gshp that runs like a pig and costs a fortune but thats mostly down to the installer you used and its just as likely to happen with an ashp.

Borzoi

I opted for ASHP for our 300mtr house, bills are about €1300 for the year. The unit would not be one of the best in terms of efficiency - look at the SEI website for very good info and comparison.

I looked at GSHP, but based on the unit cost and the ground works and water loop costs, the increase in efficiency didn't justify the costs.

Do the research yourself, or employ a competant engineer, because a lot of the information on the Web is pure drivel

Borzoi

I opted for ASHP for our 300mtr house, bills are about €1300 for the year. The unit would not be one of the best in terms of efficiency - look at the SEI website for very good info and comparison.

I looked at GSHP, but based on the unit cost and the ground works and water loop costs, the increase in efficiency didn't justify the costs.

Do the research yourself, or employ a competant engineer, because a lot of the information on the Web is pure drivel

KCross

Borzoi wrote: »

I opted for ASHP for our 300mtr house, bills are about €1300 for the year. The unit would not be one of the best in terms of efficiency - look at the SEI website for very good info and comparison.

I looked at GSHP, but based on the unit cost and the ground works and water loop costs, the increase in efficiency didn't justify the costs.

Do the research yourself, or employ a competant engineer, because a lot of the information on the Web is pure drivel

Borzoi
Is that €1300 for just the HP or does it include all other elec usage(lights etc)?
If it's all in, do you know how much the HP is using?

Condenser

Borzoi wrote: »

I opted for ASHP for our 300mtr house, bills are about €1300 for the year. The unit would not be one of the best in terms of efficiency - look at the SEI website for very good info and comparison.

I looked at GSHP, but based on the unit cost and the ground works and water loop costs, the increase in efficiency didn't justify the costs.

Do the research yourself, or employ a competant engineer, because a lot of the information on the Web is pure drivel

The HARP database is a terrible indicator of efficiencies. Its heavily weighted towards A2W allowing test conditions that have more favourable parameters than gshp's are allowed and totally ignores the requirement for defrosts or how your ufh or dhw system is designed. Its merely a box ticking process and bares no reflection as to what your actual real world performance will be.

Calahonda52

Borzoi wrote: »

I opted for ASHP for our 300mtr house, bills are about €1300 for the year. The unit would not be one of the best in terms of efficiency - look at the SEI website for very good info and comparison.

I looked at GSHP, but based on the unit cost and the ground works and water loop costs, the increase in efficiency didn't justify the costs.

Do the research yourself, or employ a competant engineer, because a lot of the information on the Web is pure drivel

Not a completely rigorous basis for decision making.

There are many reasons for making such decisions outside the tech and financial so Borzoi live and enjoy the system. Am just posting this so as to highlight to others that might pass this way that simple apparent efficiency comparatives is not enough.

Borzoi

KCross wrote: »

Borzoi
Is that €1300 for just the HP or does it include all other elec usage(lights etc)?
If it's all in, do you know how much the HP is using?

That would be heating costs only, I don't run the HP over summer, so can roughly take summer as my baseline for electrical loads.

Borzoi

Condenser wrote: »

The HARP database is a terrible indicator of efficiencies. Its heavily weighted towards A2W allowing test conditions that have more favourable parameters than gshp's are allowed and totally ignores the requirement for defrosts or how your ufh or dhw system is designed. Its merely a box ticking process and bares no reflection as to what your actual real world performance will be.

I'd would agree that Harp should only be used to select within a category. I never intentionally alluded to anything else.

Borzoi

Calahonda52 wrote: »

Not a completely rigorous basis for decision making.

There are many reasons for making such decisions outside the tech and financial so Borzoi live and enjoy the system. Am just posting this so as to highlight to others that might pass this way that simple apparent efficiency comparatives is not enough.

I don't follow the point of your post? What are these other considerations that you allude to?

Condenser

Borzoi wrote: »

That would be heating costs only, I don't run the HP over summer, so can roughly take summer as my baseline for electrical loads.

What energy rating is the house?

Borzoi

Condenser wrote: »

What energy rating is the house?

Haven't a clue. I'd guess high B or low A. I wasn't prepared to pay for a rating that I have zero faith in.

In the spirit of full disclosure. ..
I'm an engineer with 20 years experience in heating/cooling/energy calculations for industrial/commercisl and residential projects. Ive designed heat pumps from component level and had them installed - successfully.

Condenser

Borzoi wrote: »

Haven't a clue. I'd guess high B or low A. I wasn't prepared to pay for a rating that I have zero faith in.

In the spirit of full disclosure. ..
I'm an engineer with 20 years experience in heating/cooling/energy calculations for industrial/commercisl and residential projects. Ive designed heat pumps from component level and had them installed - successfully.

€1300 for that size of house I'd consider expensive. A well installed gshp should have a running cost of €500-600 per year on that house ran on day rate electricity with hot water all year round. That is why imo ashp's are not the unit that people should look at when choosing unless you have no choice. They're being oversold at the moment and we haven't even had a hard winter in 5yrs.

Borzoi

Condenser wrote: »

€1300 for that size of house I'd consider expensive. A well installed gshp should have a running cost of €500-600 per year on that house ran on day rate electricity with hot water all year round. That is why imo ashp's are not the unit that people should look at when choosing unless you have no choice. They're being oversold at the moment and we haven't even had a hard winter in 5yrs.

Any calculations to back that up?

Then compare the extra capital investment, come back with a rate of return on that money.

Take your time. I did it. I made my decision.

Borzoi

Condenser wrote: »

€1300 for that size of house I'd consider expensive. A well installed gshp should have a running cost of €500-600 per year on that house ran on day rate electricity with hot water all year round. That is why imo ashp's are not the unit that people should look at when choosing unless you have no choice. They're being oversold at the moment and we haven't even had a hard winter in 5yrs.

Any calculations to back that up?

Then compare the extra capital investment, come back with a rate of return on that money.

Take your time. I did it. I made my decision.

Borzoi

Condenser wrote: »

€1300 for that size of house I'd consider expensive. A well installed gshp should have a running cost of €500-600 per year on that house ran on day rate electricity with hot water all year round. That is why imo ashp's are not the unit that people should look at when choosing unless you have no choice. They're being oversold at the moment and we haven't even had a hard winter in 5yrs.

Any calculations to back that up?

Then compare the extra capital investment, come back with a rate of return on that money.

Take your time. I did it. I made my decision.

KCross

Borzoi
These calculations are exactly what I'm looking for when I started the thread. There are loads of threads out there with people arguing over and back as to what the correct choice is but no calculations. I think everyone agrees on the following...

1) GSHP is more expensive to install
2) GSHP is cheaper to run once installed
3) ASHP is likely to have a shorter lifespan and higher maintenance than a GSHP.... this point might be debated somewhat, but it seems logical based on the fact that the ASHP will have to work harder than a GSHP to achieve the same result in an indentical house.

So, if everyone can agree on the above it is really down to the actual money figures and return on investment after that.

I'm interested in your figures since you calculated it and made an informed decision for yourself and not a salesman doing it for you.


Can you share your calculations?


thanks, KCross

Condenser

Borzoi wrote: »

Any calculations to back that up?

Then compare the extra capital investment, come back with a rate of return on that money.

Take your time. I did it. I made my decision.

I could give you 100 real world examples.


The extra capital cost is not significant enough to overcome this difference in running cost especially when you consider you'll have to buy a replacement in less than half the time. You'll have the difference paid back in 5-6yrs on running cost difference alone.

KCross

Condenser wrote: »

I could give you 100 real world examples.


The extra capital cost is not significant enough to overcome this difference in running cost especially when you consider you'll have to buy a replacement in less than half the time. You'll have the difference paid back in 5-6yrs on running cost difference alone.

Condenser
One real world example would do me!

Could you share one?

Condenser

KCross wrote: »

Condenser
One real world example would do me!

Could you share one?

PM'd

Borzoi

Condenser wrote: »

PM'd

So not for public scrutiny.

I declare that the emperor has no clothes!

Condenser

Borzoi wrote: »

So not for public scrutiny.

I declare that the emperor has no clothes!

Nope I make it a policy not to promote any products on this site. I believe its a rule also. I'll pm you if you like. Ask KCross if I fed him a sales pitch

Borzoi

Condenser wrote: »

Nope I make it a policy not to promote any products on this site. I believe its a rule also. I'll pm you if you like. Ask KCross if I fed him a sales pitch

Please do.

I'll take out the names and just examine the numbers

rampantbunny

Condenser wrote: »

PM'd

I don't want to start an avalanche of PM requests, but I'd appreciate the same example Condenser if you have time.

bargaret

rampantbunny wrote: »

I don't want to start an avalanche of PM requests, but I'd appreciate the same example Condenser if you have time.

Really sorry but could you pm me too Condenser!

murphaph

Condenser wrote: »

€1300 for that size of house I'd consider expensive. A well installed gshp should have a running cost of €500-600 per year on that house ran on day rate electricity with hot water all year round. That is why imo ashp's are not the unit that people should look at when choosing unless you have no choice. They're being oversold at the moment and we haven't even had a hard winter in 5yrs.

But isn't the problem with ASHPs in Ireland that they enter the defrost cycle "too often". Here in Germany they are more popular than ever and Germans tend to run the numbers on these things really carefully. We generally do have longer, colder winters here, so ASHPs possibly function better here because they are not icing up as the temp hovers just above zero? If it gets down below zero the air is drier, right, and the units don't have to enter defrost cycle as often, right?

galwaytt

Condenser wrote: »

€1300 for that size of house I'd consider expensive. A well installed gshp should have a running cost of €500-600 per year on that house ran on day rate electricity with hot water all year round. That is why imo ashp's are not the unit that people should look at when choosing unless you have no choice. They're being oversold at the moment and we haven't even had a hard winter in 5yrs.

I disagree.

Disclaimer: I have only indirect experience with either -and cursory at that - but for any complete non-technical people that may read this, that's €1300 for a house that's 3 times the size of a typical 3-bed Semi D house.

Which, very very approximately means a 3-bed semi fully heated for €433 a year- €8.75 a week ?

Imho I think that is good value, and a straw poll of Joe Public would probably agree.

True, to half that would be fantastic (and I see that regularly too), but claiming the above figure is 'expensive' is wide of the mark.

KCross

galwaytt
I suppose "expensive" is relative here. In the context of this being the "renewable energy" forum it could be argued it is "expensive" and Condenser gave an example of €600.... thats half the cost, so it would appear "expensive" from that perspective.

The purpose of this thread is to determine whether the extra cost of GSHP justifies the overall cost of both systems over the lifetime of the products.

Of course, the vast majority of Joe Public who are probably using oil/gas, and maybe paying 2-3k per year on oil, would see €1300 as very cheap.

KCross

Borzoi

KCross wrote: »

galwaytt
Condenser gave an example of €600.... thats half the cost, so it would appear "expensive" from that perspective.

KCross

No he didn't, he produced a number and declared it as fact. He hadn't sent on the case study either.

Borzoi

KCross wrote: »

galwaytt
Condenser gave an example of €600.... thats half the cost, so it would appear "expensive" from that perspective.

KCross

No he didn't, he produced a number and declared it as fact. He hadn't sent on the case study either.

KCross

Borzoi wrote: »

No he didn't, he produced a number and declared it as fact. He hadn't sent on the case study either.

galwaytt already agrees that he has seen running costs in that range as per his own post.... "and I see that regularly too".

So, what is your point? Are you saying that the figure of €600/yr as a running cost for a GSHP in a 300sqm house is a lie?



Again, the discussion is whether the extra capital cost of GSHP is worth it in the long term. If you cant agree that a GSHP can deliver running costs of €600 for a 300sqm house then there is no point in discussing the purpose of the thread.

You also mentioned that you calculated your own figures and decided on ASHP based on rate of return. Can you share your figures?

Hallowed

Just for added info on the running costs.
I have a gshp vertical bore in a 3000 sqf house (icf), mhrv also with an A2 rating.
I don't have figures for heating only but all electric bills for first 13 months including drying outhe house which I'd imagine would have burned more electricity than normal, came to 1400 euro.
As I said that's for everything. Lighting, heating, hot water cooking etc

New Build 2015

Hallowed wrote: »

Just for added info on the running costs.
I have a gshp vertical bore in a 3000 sqf house (icf), mhrv also with an A2 rating.
I don't have figures for heating only but all electric bills for first 13 months including drying outhe house which I'd imagine would have burned more electricity than normal, came to 1400 euro.
As I said that's for everything. Lighting, heating, hot water cooking etc

That's really good performance however what was the installation cost of the system? What would the system cost to run with ASHP or Oil even in your energy efficient home?

Condenser

Borzoi wrote: »

No he didn't, he produced a number and declared it as fact. He hadn't sent on the case study either.

Apologies for having a life outside of boards but I finished work at 2am the night before last and 9pm last night so didn't feel much like posting here then.

I will send the example to those who asked tomorrow or sunday and I'll add further examples in the next 10days.

The example above is further evidence of gshp,s far outstripping the running costs of ashp's. His total bill is close to your heating bill alone.
I was at a C1 270sqm house with horizontal collector today built in 2006 with a heating cost of €760 and a new build A2 rated house of 200sqm running for about 6 euro per week at the moment. All day rate electricity.

Condenser

galwaytt wrote: »

I disagree.

Disclaimer: I have only indirect experience with either -and cursory at that - but for any complete non-technical people that may read this, that's €1300 for a house that's 3 times the size of a typical 3-bed Semi D house.

Which, very very approximately means a 3-bed semi fully heated for €433 a year- €8.75 a week ?

Imho I think that is good value, and a straw poll of Joe Public would probably agree.

True, to half that would be fantastic (and I see that regularly too), but claiming the above figure is 'expensive' is wide of the mark.

When people buy a heat pump they are doing so expecting two things in my experience, high levels of comfort and low running cost to see a return on investment. I would call anything over €1000 for any new house below 500sqm expensive.

Borzoi

Condenser wrote: »

Apologies for having a life outside of boards but I finished work at 2am the night before last and 9pm last night so didn't feel much like posting here .

Fair play. It will probably take me as long to look at it properly

Borzoi

Condenser wrote: »

Apologies for having a life outside of boards but I finished work at 2am the night before last and 9pm last night so didn't feel much like posting here .

Fair play. It will probably take me as long to look at it properly

KCross

All
Anyone else have first hand experience with the cost of installation/running-cost of air source or geothermal heat pumps?

Looking for:
1) Cost of heat pump (optionally make/model)
2) Cost of collector if you have a geothermal system
3) Cost of install/commissioning
4) Running cost per year (i.e. electricity)
5) Size of house
6) Any maintenance issues you have had and costs for same.

I dont want to get into details about level of insulation, air tightness values etc as every house will be different. What I'd like to get to is a general idea of how ASHP stacks up against GSHP.

PM me any figures and I plan to put them all together in one post on this thread. I have some figures already but not enough to call it a good sample.


thanks, KCross

murphaph

That strikes me as pointless. You will be comparing running costs for systems installed in totally different houses, so the data will be worthless. You'd need to install the systems in the same property or at the very least "identical" properties to have any idea if system A is cheaper to run than system B.

A huge well insulated and airtight house may cost less to run a heat pump in than a tiny one with little or no insulation and no airtightness...comparing apples and oranges as they say! It is already known that ASHP's are generally less efficient than GSHP's and that's sort of intuitive. Anything beyond that will be down to the particular installation.

galwaytt

Condenser wrote: »

When people buy a heat pump they are doing so expecting two things in my experience, high levels of comfort and low running cost to see a return on investment. I would call anything over €1000 for any new house below 500sqm expensive.

I agree with your former statement, but not the latter. It's laudable, desirable even, but that's just plucking a number out of thin air.

And, a 500m2 house ??

KCross

murphaph wrote: »

That strikes me as pointless. You will be comparing running costs for systems installed in totally different houses, so the data will be worthless. You'd need to install the systems in the same property or at the very least "identical" properties to have any idea if system A is cheaper to run than system B.

A huge well insulated and airtight house may cost less to run a heat pump in than a tiny one with little or no insulation and no airtightness...comparing apples and oranges as they say! It is already known that ASHP's are generally less efficient than GSHP's and that's sort of intuitive. Anything beyond that will be down to the particular installation.

True, to a point!

If you look at my original post you'll see where I'm coming from.

If you take a newbie, building their first house, learning about renewables for the first time, they will have lots of information to absorb and sales men giving conflicting figures, prices, COP's etc... its a lot to take in and difficult to decide which is the one for them. The simple answer is to just tell them go hire a professional to give them the info but ultimately they still have to decide for themselves. Getting true life examples to compare against is better than any COP figure in a sales leaflet. You also have the variable of a cowboy installer... I cant address that either.

There seems to be(based on my op) a perception that ASHP is the way to go because its cheaper to buy day one, but no long term figures to validate it one way or the other.

Your example gives the wildly different ends of the spectrum of what responses I might get but I'm hoping the reponses wont be that different. My assumption(and I'll have to wait and see) is that most people who install HP's(AS or GS) are somewhat informed and will have "reasonable" insulation and build structure. I wont know until I see the responses.

What I'm trying to achieve is to give some indicative figures from the ordinary unbiased punters out there who have these systems in their homes. The more responses I get the more valid the data will be. If I only get a few responses then its trash.

If I get any reasonable amount of responses I'll post it and you can by all means trash its validity then!

Condenser

galwaytt wrote: »

I agree with your former statement, but not the latter. It's laudable, desirable even, but that's just plucking a number out of thin air.

And, a 500m2 house ??

Its not really. That in my experience is what I would expect from a house built to current regs of about that size. Much more than that and I wouldn't consider that it was performing very well. It might be €100 either side depending on finish and usage but that would be average.
500m2 houses aren't that uncommon. I was in 3 this week alone. One 560sqm that had been running 4 months and had consumed €320 including the dryout phase. I'd be surprised if that house exceeds €700 this year.

New Build 2015

Condenser wrote: »

Its not really. That in my experience is what I would expect from a house built to current regs of about that size. Much more than that and I wouldn't consider that it was performing very well. It might be €100 either side depending on finish and usage but that would be average.
500m2 houses aren't that uncommon. I was in 3 this week alone. One 560sqm that had been running 4 months and had consumed €320 including the dryout phase. I'd be surprised if that house exceeds €700 this year.

Can we assume for the purpose of this question though the house is 280m2 built to Part L compliance only of 10 kWh/m2/annum contributing to energy use for domestic hot water heating and heating? Surely there is some excel sheet that will carry out a system appraisal of ASHP vs GSHP (but collector and vertical) based on this info. I can't do it but I'm sure someone can.

Condenser

New Build 2015 wrote: »

Can we assume for the purpose of this question though the house is 280m2 built to Part L compliance only of 10 kWh/m2/annum contributing to energy use for domestic hot water heating and heating? Surely there is some excel sheet that will carry out a system appraisal of ASHP vs GSHP (but collector and vertical) based on this info. I can't do it but I'm sure someone can.

Theres too many variables. How do you calculate the energy used during the defrost cycle of the ashp and how many times it defrosts. This is not only be affected by the temperature but also by humidity which also affects COP as with a ASHP the COP gradually decreases due to the build up off ice and thus lower air flow until the next defrost initiates.
Also if its windy the defrosts can be less effective as the wind drives the heat out of the coil so the coil might not be fully defrosted when the unit restarts.
None of this is applicable to a GSHP. The only way to do it is to put a ASHP and a GSHP on two identical houses and monitor the energy they produce and consume. Then you can compare and contrast

New Build 2015

Condenser wrote: »

Theres too many variables. How do you calculate the energy used during the defrost cycle of the ashp and how many times it defrosts. This is not only be affected by the temperature but also by humidity which also affects COP as with a ASHP the COP gradually decreases due to the build up off ice and thus lower air flow until the next defrost initiates.
Also if its windy the defrosts can be less effective as the wind drives the heat out of the coil so the coil might not be fully defrosted when the unit restarts.
None of this is applicable to a GSHP. The only way to do it is to put a ASHP and a GSHP on two identical houses and monitor the energy they produce and consume. Then you can compare and contrast

Does anyone know if this study has been done anywhere? Possibly by some research insitute?

I am aware met office data is available for the year to show temperatures daily. Could this help answer should of the potential running costs of an ASHP?

Calahonda52

Before delving too far into this A Vs G debate, the lifetime costs, along with no service backup on some kit seems to be mindboggling.
See this threadhttp://www.boards.ie/vbulletin/showthread.php?t=2057091531&page=2

murphaph

New Build 2015 wrote: »

Does anyone know if this study has been done anywhere? Possibly by some research insitute?

I am aware met office data is available for the year to show temperatures daily. Could this help answer should of the potential running costs of an ASHP?

You'd need even more than that because the ASHP has to defrost when it ices up....it ices up because of low temps coupled with humidity in the air. I strongly suspect that an ASHP in Ireland will perform less efficiently than one in central Europe because with the continental climate it gets cold and stays cold in winter (cold air has less moisture in it) whereas in Ireland it will generally hover around zero, allowing ice to build up more frequently and requiring more regular defrost cycles.

In Ireland you have the huge issue of support and (IMO) many more cowboys installing heat pumps without a clue how to properly commission them. Even getting parts seems to be a nightmare sometimes.

Even on the continent you have differences in what is favoured where. In France for example, heat pumps are very widely used (probably because electricity has historically been very cheap in France as the are almost self sufficient due to nuclear). They commonly install direct expansion systems (no brine, the refrigerant itself circulates in the buried pipework) but these are almost NEVER installed in Germany for some reason!

Condenser

Calahonda52 wrote: »

Before delving too far into this A Vs G debate, the lifetime costs, along with no service backup on some kit seems to be mindboggling.
See this threadhttp://www.boards.ie/vbulletin/showthread.php?t=2057091531&page=2

That particular company left a huge trail of crap in their wake and then closed up shop when things started to catch up to them. Another example of how our laws in this country are completely inept. No one should be allowed profit from poor work and just walk away.

Condenser

murphaph wrote: »

You'd need even more than that because the ASHP has to defrost when it ices up....it ices up because of low temps coupled with humidity in the air. I strongly suspect that an ASHP in Ireland will perform less efficiently than one in central Europe because with the continental climate it gets cold and stays cold in winter (cold air has less moisture in it) whereas in Ireland it will generally hover around zero, allowing ice to build up more frequently and requiring more regular defrost cycles.

In Ireland you have the huge issue of support and (IMO) many more cowboys installing heat pumps without a clue how to properly commission them. Even getting parts seems to be a nightmare sometimes.

Even on the continent you have differences in what is favoured where. In France for example, heat pumps are very widely used (probably because electricity has historically been very cheap in France as the are almost self sufficient due to nuclear). They commonly install direct expansion systems (no brine, the refrigerant itself circulates in the buried pipework) but these are almost NEVER installed in Germany for some reason!

Installing Dx units requires specialist refrigeration knowledge if it is to be completed correctly unless you buy the precharged kit type which is popular in france but not necessarily very good quality and usually means having the HP out in the garden which isn't ideal.