Does a GSHP make sense in a Grade 2 listed building in need of complete renovation

fizio

Just bought a property and would like to go GSHP for max efficiency and environmental reasons but not sure I am making a good decision. Facts are :

• Grade 2 2/3 bed detached property in 0.75 acres. Brick and rendered with slate roof plus lime plaster walls and ceilings. Some concrete floors downstairs and some wood joist floors
• Surrounded by trees but 2-300m space around the property that could be utilised
• Plan is to insulate best I can given LBC restrictions so loft insulation, maybe rafter insulation, wood fibre type wall insulation, floor insulation where possible and secondary glazing.
• Previously was oil boiler plus radiators and fireplaces in every room with 3 chimneys.
• 1 person resident with modest requirements

Purely financially I get the impression that an oil boiler with radiators will be most cost effective but not sure as I am unsure how much the cost of GSHP is given the land is a bit of a mess so the digging part will by messy. Environmentally speaking, it's my preferred solution. Secondly I am unsure whether a GSHP is upto the job given the building is limited in its ability to be tightly insulated and is in 'the middle of nowhere' and, although it has trees pretty much all around, its still exposed to the colder temps of the countryside.

I am trying to get some quotes so will see how they stackup - assuming I get the 7.5k grant - but will be very unhappy if, after a costly installation, I find the place isn't as warm as I would like - though the option of a wood burning stove is very do-able.

Any advice/comments from those with experience appreciated..

QrizB

fizio said:

Secondly I am unsure whether a GSHP is upto the job given the building is limited in its ability to be tightly insulated and is in 'the middle of nowhere' and, although it has trees pretty much all around, its still exposed to the colder temps of the countryside.

This bit is a myth. You don't need a well-insulated home with a heat pump, any more than you do with a conventional boiler. The National Trust have used heat pumps to heat huge buildings without having to compromise their historic character.

For example:

https://www.nationaltrust.org.uk/services/media/palace-of-art-leaves-oil-in-the-past-as-national-trust-switches-on-historic-heat-pump

The "30000 litres of oil" used by the old boiler per year is 300,000 kWh (300 MWh) of heat.

FreeBear

A heat pump is just another source of heat. As long as it is appropriately sized for the property, it will be no worse than gas or oil. Coupled with a suitable tariff, running costs should be comparable too.

If you were thinking of excavating trenches for slinkies, you might find yourself having to do an archeological survey and might get caught up in paying for proper excavations. If this is the case, that will add considerably to your installation costs. With good access to the site, it may be worth looking at drilling a couple of boreholes rather than using slinkies.

matelodave

As said above, a properly configured system whether it be oil, lpg or a heatpump (ASHP or GSHP) will be capable of heating the place. We've stayed in several LandMark TRust places with heatpumps and they all work better than places with storage heaters.

In the end it only you who can decide whether the outlay is worth it, Ground Source are significantly more expensive to install than air source, but can be more efficient and probably cheaper to run but it could take a lot longer to realise any peyback

matt_drummer

matelodave said:

As said above, a properly configured system whether it be oil, lpg or a heatpump (ASHP or GSHP) will be capable of heating the place. We've stayed in several LandMark TRust places with heatpumps and they all work better than places with storage heaters.

In the end it only you who can decide whether the outlay is worth it, Ground Source are significantly more expensive to install than air source, but can be more efficient and probably cheaper to run but it could take a lot longer to realise any peyback

The top performing systems on www.heatpumpmonitor.org are actually air source heat pumps.

It would seem that a well set up ashp can outperform a gshp in terms of efficiency.

Reed_Richards

I reckon for a GSHP with a ground collector you need a "paddock", that is a large area of clear ground that can be easily dug to bury the collector pipe but which you will never want to dig afterwards.  Boreholes are an alternative but very expensive to drill.  It's worth making a cost comparison between and ASHP and a GSHP.

You presumably have a sight of an EPC for the property which should give you an estimate of how much heat it requires per annum.  What is that figure?  

Strummer22

matt_drummer said:

matelodave said:

As said above, a properly configured system whether it be oil, lpg or a heatpump (ASHP or GSHP) will be capable of heating the place. We've stayed in several LandMark TRust places with heatpumps and they all work better than places with storage heaters.

In the end it only you who can decide whether the outlay is worth it, Ground Source are significantly more expensive to install than air source, but can be more efficient and probably cheaper to run but it could take a lot longer to realise any peyback

The top performing systems on www.heatpumpmonitor.org are actually air source heat pumps.

It would seem that a well set up ashp can outperform a gshp in terms of efficiency.

There's only three GSHPs on there, not really a good sample size. Mine has a SCOP of 5.0 for 2024 so would be the best performing GSHP, and second best overall, if it were on there. 

What really matters is: which would be better for your needs? In any given situation a GSHP will probably achieve a better COP but will cost more to install. You'll need to crunch the numbers.

It's worth mentioning that minimising thermal loss will make any heating system cheaper to run, but this is especially true of heat pumps where efficiency is much higher at low flow temps and decreases significantly for higher flow temps. Efficiency really drops above about 42°C in my experience. A well insulated house with large radiators or underfloor heating means you don't need to blast heat to warm it up and a gentle heat will do the job; therefore the heat pump will rarely need to run at those inefficient high flow temps.

FreeBear

Strummer22 said:

matt_drummer said:

matelodave said:

As said above, a properly configured system whether it be oil, lpg or a heatpump (ASHP or GSHP) will be capable of heating the place. We've stayed in several LandMark TRust places with heatpumps and they all work better than places with storage heaters.

In the end it only you who can decide whether the outlay is worth it, Ground Source are significantly more expensive to install than air source, but can be more efficient and probably cheaper to run but it could take a lot longer to realise any payback

The top performing systems on www.heatpumpmonitor.org are actually air source heat pumps.

It would seem that a well set up ashp can outperform a gshp in terms of efficiency.

There's only three GSHPs on there, not really a good sample size. Mine has a SCOP of 5.0 for 2024 so would be the best performing GSHP, and second best overall, if it were on there.

Before getting too hung up on the "who has the best SCOP" argument, you need to ask "how much energy is being used for DHW" If you are using a lot of hot water in comparison to generating heat for the house, that is going to knock the SCOP right down. And if you want really hot water (60°C or more) out of your tap, that is going to knock the SCOP down even further.

https://protonsforbreakfast.wordpress.com/2023/11/01/heat-pumps-cop-envy-is-pointless/

matt_drummer

Strummer22 said:

matt_drummer said:

matelodave said:

As said above, a properly configured system whether it be oil, lpg or a heatpump (ASHP or GSHP) will be capable of heating the place. We've stayed in several LandMark TRust places with heatpumps and they all work better than places with storage heaters.

In the end it only you who can decide whether the outlay is worth it, Ground Source are significantly more expensive to install than air source, but can be more efficient and probably cheaper to run but it could take a lot longer to realise any peyback

The top performing systems on www.heatpumpmonitor.org are actually air source heat pumps.

It would seem that a well set up ashp can outperform a gshp in terms of efficiency.

There's only three GSHPs on there, not really a good sample size. Mine has a SCOP of 5.0 for 2024 so would be the best performing GSHP, and second best overall, if it were on there. 

What really matters is: which would be better for your needs? In any given situation a GSHP will probably achieve a better COP but will cost more to install. You'll need to crunch the numbers.

It's worth mentioning that minimising thermal loss will make any heating system cheaper to run, but this is especially true of heat pumps where efficiency is much higher at low flow temps and decreases significantly for higher flow temps. Efficiency really drops above about 42°C in my experience. A well insulated house with large radiators or underfloor heating means you don't need to blast heat to warm it up and a gentle heat will do the job; therefore the heat pump will rarely need to run at those inefficient high flow temps.

My point was that ashps are now so good if installed and operated properly that they can match gshps with much lower installation costs and no chance of leaks in the ground.

Granted, there aren't many gshps on that site but gshps should be easier to get good performance from?

Mine also has a SCOP of over 5.0 but doesn't show on the default screen view yet. It will in a few days time.

Others are coming too, they may well be better than the current best performer in terms of efficiency.

Reed_Richards

Strummer22 said:

What really matters is: which would be better for your needs? In any given situation a GSHP will probably achieve a better COP but will cost more to install. You'll need to crunch the numbers.

You mean "In any given situation a GSHP will probably achieve a better SCOP", surely.

If the outside air temperature is higher than the ground temperature then an ASHP should achieve a better COP than a GSHP (or should be capable of doing so).  It's when the outside air temperature is lower than the ground temperature (and so your house needs a lot of heat energy to keep warm) that the GSHP beats the ASHP on COP.  And by all accounts the SCOP average works out in favour of the GSHP, although if you lived somewhere warmer in winter than the UK is then it might not do so.  

Strummer22

Reed_Richards said:

Strummer22 said:

What really matters is: which would be better for your needs? In any given situation a GSHP will probably achieve a better COP but will cost more to install. You'll need to crunch the numbers.

You mean "In any given situation a GSHP will probably achieve a better SCOP", surely.

If the outside air temperature is higher than the ground temperature then an ASHP should achieve a better COP than a GSHP (or should be capable of doing so).  It's when the outside air temperature is lower than the ground temperature (and so your house needs a lot of heat energy to keep warm) that the GSHP beats the ASHP on COP.  And by all accounts the SCOP average works out in favour of the GSHP, although if you lived somewhere warmer in winter than the UK is then it might not do so.  

I probably should have written SCOP, but even so I'm not sure the statement highlighted bold is true. Wouldn't the higher heat capacity of the ground source can transfer more heat energy to the brine and then to the refrigerant than can be transferred from air at the same temperature? As an example, consider the speed of melting an ice cube in 10°C air vs in a glass of 10°C water. This would make the GSHP still more efficient than the ASHP for a given source temp, all else being equal, although the brine circulation pump might reverse some or all of the difference.

I'd be interested to hear other's thoughts.