Geothermal Piling

[Caroline]

Hi all

 

I am trying to get a quote for Geothermal Piling and having difficulty finding contractors.  All those advertising on their websites that the do it, when I email they come back and say they don't.

 

The site doesn't have mains gas, we would prefer GSHP over ASHP, only due to reviews I have heard about ASHPs, we plan to have multi fuel heating in two rooms, so other alternative will be LPG or oil?

 

Any my advice appreciated 

 

Thanks in advance

[ProDave]

What is it about ASHP's that has put you off?

 

The other side of the coin is GSHP's require rather a lot of antifreeze, which is supposed to be replaced after a few years with a disposal cost.  That was what put me off them.  I have no doubt they work but the extra eficciency compared to an ASHP appeared to me to be lost in additional costs.

 

Another factor which is not often discussed, the "workings" of an ASHP usually go outside. but the workings of a GSHP usually go inside which is more likely to be a noise nuisance in the house.

[Caroline]

5 minutes ago, ProDave said:

What is it about ASHP's that has put you off?

 

The other side of the coin is GSHP's require rather a lot of antifreeze, which is supposed to be replaced after a few years with a disposal cost.  That was what put me off them.  I have no doubt they work but the extra eficciency compared to an ASHP appeared to me to be lost in additional costs.

 

Another factor which is not often discussed, the "workings" of an ASHP usually go outside. but the workings of a GSHP usually go inside which is more likely to be a noise nuisance in the house.

Thank you. Did worry about noise of ASHP but know it can be away from house, outside space not an issue. Also worried that they are not efficient when weather falls below freezing.

[Jeremy Harris]

We have an ASHP about four feet from the back door, and you can't hear it from there when it's running normally, so noise isn't really an issue with modern inverter controlled ASHPs.  The noisiest heat pump I've ever heard was a GSHP, that was so noisy that the owner ended up moving into an outbuilding to reduce the noise level in the house.

 

In terms of efficiency, then the worst case for ASHP is just above freezing, with damp air, where it may start to run defrost cycles unless it's set up properly.  Set up is key to getting good performance I found.

 

Cold air makes very little difference to performance; air at -5 deg C only has about 5.3% less heat in than air at 10 deg C, not enough to make any noticeable difference in performance.  I worked out that there was no way to ever recover the much higher, purchase, installation and maintenance cost of a GSHP (running from a borehole) over the very much lower cost of an ASHP over its lifetime.

[Caroline]

1 hour ago, JSHarris said:

We have an ASHP about four feet from the back door, and you can't hear it from there when it's running normally, so noise isn't really an issue with modern inverter controlled ASHPs.  The noisiest heat pump I've ever heard was a GSHP, that was so noisy that the owner ended up moving into an outbuilding to reduce the noise level in the house.

 

In terms of efficiency, then the worst case for ASHP is just above freezing, with damp air, where it may start to run defrost cycles unless it's set up properly.  Set up is key to getting good performance I found.

 

Cold air makes very little difference to performance; air at -5 deg C only has about 5.3% less heat in than air at 10 deg C, not enough to make any noticeable difference in performance.  I worked out that there was no way to ever recover the much higher, purchase, installation and maintenance cost of a GSHP (running from a borehole) over the very much lower cost of an ASHP over its lifetime.

I think maybe ASHP is the way to go then. Just need recommendations of manufacturer/good set up (as you say), once we can obtain this info we will be good to go?

[pdf27]

1 hour ago, Caroline said:

Thank you. Did worry about noise of ASHP but know it can be away from house, outside space not an issue. Also worried that they are not efficient when weather falls below freezing.

If you're worried about noise (I am - continuous fan noise in particular makes me really tense) you can look into acoustic louvers and either fit it into a standalone box or integrated into something like an attached garage (which I'm thinking about doing). That should knock the noise down by about 10 dB(A), making them quieter than a GSHP anywhere you are likely to spend any time. Noise levels will also scale with heat demand (more heat needed = more air flow), so again better insulated houses should be quieter.

[Jeremy Harris]

38 minutes ago, Caroline said:

I think maybe ASHP is the way to go then. Just need recommendations of manufacturer/good set up (as you say), once we can obtain this info we will be good to go?

 

Pretty much any of the big name brands (Panasonic, Mitsubishi etc) inverter controlled ASHPs will be reliable and easy to setup.  If you want really hot domestic hot water, then the Daikin hybrids are worth a look - they have a gas boiler internally that boosts the DHW temperature, and can run on LPG.  The advantage of them is they don't use a lot of gas, as they use the ASHP to preheat the water and only use the gas boiler to add an extra 10 deg C or so.

 

Fan noise from our inverter controlled ASHP is really low; we've had people stand next to it and not realise it's running.  Ours is a re-badged Carrier (another really big name in heat pumps - Willis Carrier was the chap who first introduced air conditioning using heat pumps over 100 years ago) and several companies sell the same unit with a different badge on the front (ours is badged Glowworm, but identical units were badged Kingspan and a few other names).

 

In terms of cost, our ASHP (self installed) cost around £2k all in.  The cheapest borehole GSHP quote we had was £8k, not including the cost of drilling the hole.

[Mr Punter]

Good advice as per from @JSHarris.  I can understand - if you are having piled foundations - that the GSHP seems attractive but there are several drawbacks and the ASHP systems seem to be where the investment is.  Mitsubishi and Viessman both have good reputations but there may well be more suitable manufacturers.  Why are you having multi fuel in 2 rooms?  If this is new build it won't be needed / wanted.

[Caroline]

Hi thanks to both of you really helpful stuff.  

 

The  reason for two multi fuels one in lounge amd one in family/dining room, will prob spend most time in family room but want the opportunity to have one in lounge when we use that room. I know it's extravagant and hopefully if house is well insulated may not need it but we are in a chilly spot, not a lot of sunlight into the house due to the many trees, and don't want to fit later.

 

we had them for years usually only in lounge but we have a large open plan kitchen/dining/family area too, with quite a lot of glazing.

[Mr Punter]

Your ASHP with UFH will heat the house easily.  With lots of trees around it may at times be difficult to get rid of combustion gasses with the multi fuel heaters.  You will probably need to create a fairly big inlet through the wall or floor as well.

[pdf27]

Worth looking into how small a stove you can practically run - they really don't like being run smouldering (lots of smoke and creosote), and when run hard most will put out at least 5kW which will be 2-3 times what you might need for the whole house. Again, a lot depends on how well insulated you're looking to go for - at building regulations minimum then you'll be fine with a couple of stoves, if you're anywhere near Passivhaus then you'll have overheating problems.

[Jeremy Harris]

I've told this tale before, but it's worth repeating.  We had an open weekend where around 40 people came to look around our house.  One of them was a lady who had finished building a Touchwood Homes house a year or so before.  She'd insisted on having a wood burning stove in the living room, the smallest room sealed model available, which I think was rated at about 4 kW.  They lit it for the first time on a Christmas Day, and within an hour the living room was over 30 deg C and they had to leave the room, even with all the windows open.  it took several hours for the room to cool down enough for them to use it, and messed up their Christmas a bit.  Since then they've never used the stove again and last time I heard she was looking at getting an LCD monitor installed in it to display a flame effect.

[Nickfromwales]

@Caroline

What spec are you building to? Just before we all stray off on different tangents.  

Are you having solar PV ? With some thought and commitment early on, you should be able to avoid the need to set fire to ANYTHING.

[pdf27]

1 hour ago, JSHarris said:

I've told this tale before, but it's worth repeating.  We had an open weekend where around 40 people came to look around our house.  One of them was a lady who had finished building a Touchwood Homes house a year or so before.  She'd insisted on having a wood burning stove in the living room, the smallest room sealed model available, which I think was rated at about 4 kW.  They lit it for the first time on a Christmas Day, and within an hour the living room was over 30 deg C and they had to leave the room, even with all the windows open.  it took several hours for the room to cool down enough for them to use it, and messed up their Christmas a bit.  Since then they've never used the stove again and last time I heard she was looking at getting an LCD monitor installed in it to display a flame effect.

My cousin lives in a Passivhaus in Hamburg, fitted with a log-burning stove. It's usable, but you've got to be careful - you burn one small log (sticks are no good - too much surface area so they burn too fast: they burn short fat logs) at a time, keep the doors open to spread the heat around the house and it's fitted with some hefty soapstone slabs on the top and sides. From memory the room ended up at 27 or 28C after a few hours - actually quite nice in that part of the world in winter, but definitely not a routine occurrence.

[Caroline]

4 hours ago, Nickfromwales said:

@Caroline

What spec are you building to? Just before we all stray off on different tangents.  

Are you having solar PV ? With some thought and commitment early on, you should be able to avoid the need to set fire to ANYTHING.

Hi there

 

We are building an oak frame with SIPS not PH standard (I think) but more insulated than we are used to (living on site in converted stables at mo!).

 

We intend having PVs as long as we can have them in the grounds, don't want them on the roof. Our PP says we have to reduces energy by 10% and suggests PVs, however, if we are having ASHP we should managed the 10% without PVs. Of course want to make fuel bills as small as possible, as we only have electric available (no mains gas).

 

Thank you

[PeterW]

6 minutes ago, Caroline said:

Our PP says we have to reduces energy by 10% and suggests PVs

 

I love those sorts of statement..!! 10% of what..??! If you replaced all of your lights with LED from CFL you would easily make 10% but it’s meaningless for a new build.... 

 

Ground mount PV lend themselves to tracking systems so think about placement and exposure. 

[Nickfromwales]

1 hour ago, PeterW said:

Ground mount PV lend themselves to tracking systems so think about placement and exposure. 

They also are a doddle for DIY non-MCS registered installs ( e.g. cheap ) so look at what you need and aim to self-consume all, or as much of, what you generate. If you have electric only, then I'd look at a Sunamp + Willis ( immersion heater ) based UFH system with a second Sunamp as the DHW ( domestic hot water ) provider. Look to store as much of the pv generation as you can by employing a good pv diverter and once you've got a year under your belt, if necessary, you could add a few more panels if so required. 

Id forget oil or lpg and put the cash into something smarter.  

An ashp would be a cheap way to solve space heating but when you need it most, the pv won't really be up to providing what you need anyway so £'s per kW ( taking maintenance and lifespan ) the Sunamp + Willis solution has the most appeal imo. That lot fortified with grid electricity for any time the pv hasn't cut it and you've got a clean, simple, and uber-low maintenance solution. 

[Nickfromwales]

You can always use lpg for gas cooking btw.   

[SteamyTea]

Or an induction hob, which is much, much better.

 

Re: PV

You can have roof integrated, you will hardly notice it and it can be cheaper than tiling.

Ground mounted which can track the sun, is not really worth it, easier and cheaper to add a few extra modules.  Just check with your DNO how much you can fit.

 

The mismatch between maximum generation times and space heating times is often used as a negative against having PV.  This is why FiT payments were introduced.  For the 3/4 of the year that you export some power you get payment, you then, in effect, use that cash to import power.  The FiT is just under 10p/kWh in all at the moment, so not to be sniffed at.  Maximizing self consumption can get costly and may not be worth while over all.

[Ferdinand]

 

Which, summarised, says expand your knowledge and do your homework up front, even if it takes longer.

 

Because most of us are only building one house and will have to live with mistakes forever rather than have the opportunity to learn from them. Like Icarus and the practical implications of the melting point of wax vs the temperature it can reach in the sun.

 

Which is what you are doing ?. Cool.

 

F

Edited June 18, 2018 by Ferdinand

[pdf27]

5 hours ago, Caroline said:

Hi there

 

We are building an oak frame with SIPS not PH standard (I think) but more insulated than we are used to (living on site in converted stables at mo!).

 

We intend having PVs as long as we can have them in the grounds, don't want them on the roof. Our PP says we have to reduces energy by 10% and suggests PVs, however, if we are having ASHP we should managed the 10% without PVs. Of course want to make fuel bills as small as possible, as we only have electric available (no mains gas).

 

Thank you

• As I understand it, most oak frame/SIPs combinations now have the oak frame inside and the panels wrapped around the outside of it to avoid cold bridging through the oak. The thing is, SIPs are themselves a structural option, which makes the oak frame largely redundant. If you do follow this route, then I would suggest thinking exactly where in the house you actually want to be able to see the oak - it may for instance be possible to work some oak timbers into the structure of a timber-framed building without needing an entire oak frame, saving £££££.
• More importantly, if the SIPs are on the outside then the only real limitation on thickness is the internal and external dimensions of the building. That means any insulation level up to Passivhaus is possible with a full structural timber frame - see https://www.oakwrights.co.uk/siteI/cfbc0416c099a39a8bd816131025b2d8/press/39935ffd63b49558c7873a6fea6f430e.pdf - but the best way of doing it may not necessarily be with SIPs (the couple in that example didn't use them, for instance).
• If I'm understanding things correctly, the UK building regulations at the moment should limit consumption to about 50 kWh/m²/year for space heating - about 9,000 kWh/year for your proposed buildings. For comparison Passivhaus is defined at 15 KWh/m²/year with a rather more rigorous modelling system to back it up - about a 70% saving over building regulations even before you start looking at heat pumps. By the time the heat demand gets that low even electric resistance heating (which is really cheap to install) is economical to run.
• Don't feel forced to go down the heat pump route - I happen to think it's a pretty good one, but the better insulated your house the better it works. If you're planning on only meeting the minimum PP target, then I would think seriously about alternatives like LPG or Oil: they're well understood, cheap to install and deal well with increasing the output temperature a bit because say your radiators were a bit too small. Personally I think heat pumps are the best solution for a low-energy house, which is why I want to go down that route, but don't make the assumption that they're the best option for every house. Good performance is critically dependent on them supplying heat at a low temperature - the worse the insulation, the harder this is to actually achieve.
• Assuming total annual consumption is about 14 MWh (plug loads, hot water, etc.) then you need about 1.5 MWh/year from PV to meet the PP specification. As a rule of thumb, a 1kW panel facing south in the UK will give about 1 MWh/year of generation - so you could meet it with a 6 x 250W panel system costing maybe £2k for a ground-mount system. That's almost certainly the cheapest way to meet the target, and will be why the PP suggested it.

I would suggest taking a step back and thinking through (in order):

1. What your energy target is going to be - the minimum to meet PP, minimum cost to live in afterwards, or something else. This will define the insulation levels in the structure, which will make clear what else is practicable. If you want to have a play with that, @JSHarris has written a pretty decent heat loss calculator at http://www.mayfly.eu/wp-content/uploads/2017/01/Fabric-and-ventilation-heat-loss-calculator-Master.xls
2. When you know this, work out how you want to deliver the heat - radiators, underfloor heating, warm air, something else? Underfloor will work with just about anything, but warm air and radiators don't play well with heat pumps.
3. Then you can do a meaningful trade-off between ASHP, GSHP, electric resistance, LPG, etc. - knowing the annual heat consumption and peak heating load is critical here because it changes the design of a heat pump system radically, while a traditional boiler system really doesn't change a lot.
   1. If you want building regs minimum and radiators, then you should probably look at LPG or oil - you need quite a bit of heat delivered at a high temperature.
   2. Building regs minimum plus underfloor might well be the sweet spot for a GSHP as demand will be high enough for the COP gain to be worthwhile. It's worth running some calculations on this though - the SCOP figures published by the manufacturers should be good enough for this, divide heat load by SCOP to give electrical consumption and work out if it ever pays back over an ASHP.
   3. If you want Passivhaus or close to it - particularly with underfloor heating - then you should probably look at an ASHP like @jack as the heat load will be so small that there is no point to a GSHP. Resistance heating is feasible at this point, however, and gives you low installation cost with bombproof reliability: at 15 kWh/m2/year and 15p/kWh then your heating bill for a 180m² house is only going to be £400. @TerryE has gone down this route and it has worked very well for him.
4. When you've done all that, then is the time to think about renewables (PV, realistically) - more insulation or underfloor heating is an utter nightmare to add by retrofitting, while a ground-mount PV system is incredibly easy. Make sure you've got the things that are locked in done early, and worry about the rest later.

[Ferdinand]

What @pdf27 said, plus this:

 

Do your models incorporating at least a 20 year period to give a lifecycle assessment. You will need to do that for an assessment of FiT anyway. Just assume a reasonable value for inflation and sensitivity test with higher plus lower.

 

F

 

 

[Nickfromwales]

Couldn't agree more about the fabric first approach. Why spend money building a less insulted house with a high temp heating system, with your income going towards tracking the cost of fossil fuel, when you can spend once on more insulation / MVHR / airtightness detailing and live cheaper forever? It need not cost a fortune with planning and a good degree of curiosity. 

[Onoff]

You only pay for insulation ONCE.

 

 

[Jeremy Harris]

There are potential gotchas in Part L1A of the building regs for an all-electric house, that can make it challenging to not use a heat pump or fit PV.  I know we often say that Part L1A isn't a great standard for modern house performance, but in real terms it isn't that bad, either.  In terms of whole house heating requirement it's about 3 to 4 times higher than a passive house, which is massively less than a house built 20 or 30 years ago, and much of that difference comes from the much higher ventilation heat loss.

 

More importantly, though, is the penalty imposed for all-electric heating with no renewable generation.  This would almost certainly rule out resistance heating unless the house was made airtight and insulated to close to passive house levels.  Adding some PV makes a big difference as far as getting the energy use down in SAP is concerned, and is one reason why many new builds have a few panels on the roof - they are there to get an adequate SAP score without needing to air test new houses (which really means not having to make them properly airtight).  Airtightness is, if anything, more important than insulation.  If our house just met the Part L1A airtightness requirement, so had no MVHR, it would need about three times more heat in winter.

 

It's very well worth looking at the trade offs between construction cost (better insulation and airtightness), heating requirement, heating options and how these all impact on the SAP score, particularly for an all-electric house where it's already challenging to meet the requirements now.  You may well find that you're driven to use an ASHP with a house built to just meet building regs, because it would not pass if fitted with electric resistance heating.

 

On the topic of oak frames, I know at least one passive house company that can supply oak internal frames for their passive house kits, so it may well be an option to consider.  I suspect it's a cheaper approach than the structurally wasteful SIPs over oak frame option, which always struck me as being just an idea that one oak frame company came up with as a way to continue to sell their standard oak frames yet still meet current building regs requirement (there are issues with oak frame movement over time that make it easier to have two structurally independent "frames" like this).