Solar Options with EUFH instead of plumbed heating

[damocoleman]

I'm going to be doing an extension to my derelict stone cottage.
Im using limecrete floors and lime for the repointing but with these types of buildings obviously, its best to keep things warm internally to allow the stone to breath and not hold the damp.

To give context, the extension is going to be 100sqm and done in ICF and double glazed.

Generally I have heard a lot of people say that even in winter, there isn't normally much demand for heating with ICF because of the insulation.

Now, instead of traditional wet UFH and radiators etc, I'm leaning towards putting electric UFH around the house (both old and new), zone it with thermostats and install Solar panels with battery packs. Might work out cheaper especially with the drive to move away from fossil fuels

Does anyone have any thoughts, ideas or perhaps experience in this at all?

 

[oldbutnotdead]

Thoughts- heating consumes lots of energy. A standard caravan leisure battery will store 100Ah or so- sounds impressive but that would run a 1 bar electric fire (1kw) for 1.2 hours.
Obviously battery technology is moving on but a decent sized energy store (20kwh or so) is still a fairly big financial outlay.
Solar panels- depends where you live but at the moment the payback time on panels, inverters etc. is in the years, maybe even a decade. Yes that may change with rising energy costs but that's a gamble & relies on long term reliability of the installation.
Disadvantage with electric heating is you are tied to electricity. If you install a wet heating system you can (with the addition of a thermal store) power it from gas, electricity, oil, a woodburner, wet solar, rotting horse manure, ASHP, gshp....choices are endless if you have the room

 

[lostinthelight]

Ive just finished installing a limecrete floor with wet ufh and going to line the stone walls with wood fibre insulation boards which will be lime plastered.
I dont intend using ufh but the pipes are there which gives the option in the future to hook up to a heat pump.

 

[damocoleman]

Ive just finished installing a limecrete floor with wet ufh and going to line the stone walls with wood fibre insulation boards which will be lime plastered.
I dont intend using ufh but the pipes are there which gives the option in the future to hook up to a heat pump.

Thats exactly what I am doing. I have spent the past weekend putting NHL2 on the walls to flatten it as much as possible for the wood fibre. I'm waiting on planning decision so I can remove chimney and then the floors!

 

[damocoleman]

Thoughts- heating consumes lots of energy. A standard caravan leisure battery will store 100Ah or so- sounds impressive but that would run a 1 bar electric fire (1kw) for 1.2 hours.
Obviously battery technology is moving on but a decent sized energy store (20kwh or so) is still a fairly big financial outlay.
Solar panels- depends where you live but at the moment the payback time on panels, inverters etc. is in the years, maybe even a decade. Yes that may change with rising energy costs but that's a gamble & relies on long term reliability of the installation.
Disadvantage with electric heating is you are tied to electricity. If you install a wet heating system you can (with the addition of a thermal store) power it from gas, electricity, oil, a woodburner, wet solar, rotting horse manure, ASHP, gshp....choices are endless if you have the room

Thats good to know. With this, the budget is tight so I would only be doing 1 or the other. I felt that using something like Nilan MHRV for the the hot water, the heating could be covered with eufh and excess heat in the winter for the cottage part would be provided by the stove.

Rather than an ROI, I am looking at the outlay costs and what I can do myself to reduce that

 

[oldbutnotdead]

Usually the initial outlay on electric is lower but your running costs are much higher. Think the scheme outlined by @lostinthelight has many merits- long as it's only pipe that's buried not couplers, manifolds etc. the initial outlay will be quite low (you can buy manifolds, pumps etc later on).
Since you're planning on stored hot water you're halfway to a thermal store anyway, if you have access to cheap or free timber for your woodburner (is that what you mean by stove) then get a burner with a water jacket connected to the store & you're away.
EDIT Your heat pump can dump energy into the store, you could use wet solar to warm the store or PV solar to warm it via an immersion heater. Thermal store will be a lot cheaper than the equivalent energy capacity in batteries and it'll last a lot longer.

 

[lostinthelight]

Thats exactly what I am doing. I have spent the past weekend putting NHL2 on the walls to flatten it as much as possible for the wood fibre. I'm waiting on planning decision so I can remove chimney and then the floors!

How much insulation are you putting down or haven't you dug any trial holes at the base of the walls to see how far you can go down without undermining them?

 

[damocoleman]

How much insulation are you putting down or haven't you dug any trial holes at the base of the walls to see how far you can go down without undermining them?

I'm gonna put 400mm of glass rock and compact it down to 300. I'll dig the edges at an angle to avoid disturbing the walls.

 

[lostinthelight]

You'll have to do that thickness in layers then and don't be surprised if you don't get that much compaction, very difficult to do. I spoke to the manufacturer in Germany who said it had to go down By a third but was told that, not the manufacturer, was German over caution as in domestic situations its not subject to the loadings as in industrial use. I dug down the the bottom of the walls on 3 sides which allowed 200mm compressed Glapor but the end around the fireplace the wall ended at the bottom of the original flags so had to excavate ot 45°