Aggierockdoc

Many thanks to everyone for their cogent responses. I'm now wondering what my best options are... At the moment my thoughts are that I should: clad the North side of the house if the planners will let me, in order to up-rate the U-value for that side of the house insulate the hell out of the floor so that I can limit heat loss through the floor... (maybe 150mm?) accept that on the South side of the house I have a high U-value and maybe mitigate heat loss slightly by way of a 25mm interior perlite/lime render and shutters on the windows insulate the hell out of the roof to limit heat-loss out the top (?250mm) install a MVHR system and find/close up all the little draught holes that I can find - invite a local shaman/smudging expert with a blower door to help install a wood burner to provide another heat source that mitigates the cost of the all the electricity I'm going to need for my ASHP Any other suggestions gratefully received. In terms of answers and comments... Firstly for saveasteading: I believe our walls are 600mm thick and in 3 layers, but the layers are: c.40mm lime plaster; c.400mm cob; 150mm stone (killas not granite). Message understood re: builders... and studying hard. For TerryE: Apologies for not referencing your code and diagram correctly... Also, I got a U-value of c. 1.0 from ubakus for a close approximation to my wall. I up-rated (ie raised) the default U-value for clay blocks to 1 W/m2.k to approximate to cob, which makes it around 4x worse than building regs. Better than solid stone, but still not great. SAWWall_South-1.pdf For ProDave: Duly noted. And finally for SteamyTea... Re knock it down and start again... funny you should say that... I'm trying to convince my wife we need to knock down the bit on the East side and rebuild that at least. But that's going to take a lot of persuading and a metric shit-tonne of money (notice that's a metric shit-tonne not an imperial shit-ton)... I like to get my units right.

Unfortunately I won't be back until September at the earliest. 🤔... so my pump-action super-soaker will have to stay under wraps for another year. Are water pistols still banned? I'm wondering if we know each other... ever met anyone who used to work at the old "hot-rocks" project, then disappeared to warmer climes? Anyhow thanks for confirming my suspicion regarding thermal storage and size. and I guess I'm going to be digging some trenches.

That was quick... my dual location has already been figured out! (cf Steamy Tea - good to see some Cornish representation...). As regards house placement... if you know Goonvrea you might well know the house. But the last comment is the important one ... I've always considered GSHPs as a better option because of the physics of heat transfer... ie water is around 20x better at moving heat from a surface than air. Plus, I have the space for a slinky loop that I can install myself. Plus I'm assuming our climate and ground heatflow is better suited than other areas in the UK because of our "southerly" latitude and minor temperatures swings. But, and there's a big but... GSHPs are sooo much more expensive. Also I'm intrigued by an older thread that I found from SteamyTea, TerryE and JSHarris. (I commend JSHarris for his code and suggest he can bore me anytime with such work). His wall temperature profile that shows how stable the interior temperatures are whilst the exterior wangs about betwen 10 and zero. Anyhow let me try to set out a cogent message that relates my interest in the consensus on AHSP vs GSHP and also the concept of seasonal heat storage, thermal inertia and thermal penetration. I'm keen to understand some of the fascinating comments made within this thread. In particular from StormyTea, TerryE and JSHarris. When I click on the youtube link I get a message describing this as private and I need to sign in on Youtube, which I try to avoid... is there any other way to get this? I'm assuming the lack of thermal penetration is because fourier's law (-k.dT/dx) tells us that heat flow will be much greater up than down? But what if the heat source is under an insulator? I bet every non-technical person now mentions the guy in Grand Designs, with his heat storage system. I suspect his design is a very special case. From my back of a fag-packet calculations I was thinking that the problem with storage is just size. EG. If you had a house with footprint of radius r, the notional heat island under the house would have a volume of half 4/3. pi. r^3. If this hemisphere touches the water table where the water just whisks away your heat and never goes above 12C. You'd chop your volume at the base ... a bit like an upside down egg. Assuming for this exercise that it doesn't ... a half 4/3. pi. r^3 would give a volume of around 1000 m3, for r=8. Multiply that by heat capacity of say 800 J/kg.k and density of 1500 kg/m3 and delta T of say 5 degree on average gives c. 1800 kwh of heat storage. (Is this right?) If so, this aint much when you consider a stone/cob home will need about 15,000 kwh a year to stay warm. My 1800 kWh estimate for storage doesn't really factor in how much heat buggers off out the bottom of the storage volume and leaks out the sides. The only utility I could see with trying to inject summer heat under your house to create a heat store, would be for relatively short time scales - say between sunny periods and cloudy periods... and even that doesn't account for whether you could realistically get much of the heat back... Hmmmm.... I'm convincing myself of the futility of heat storage: you can't put enough heat in to store on the time-scale that you want, and even if you did, you might only get a small proportion of it back. Comments welcome on whether the issue with storage is just size and also the ASHP vs GSHP angle. Regards Stephen

Firstly many thanks to those who have both set up and contribute to this forum. I'm a geophysicist turned builder who is returning to the UK from overseas and about to start a Cornish Cottage Renovation and Extension project. I'm very much interested in all things heating related especially GSHP technology, insulation, UFH and heat storage. I look forward to some sound evidence based discussion that cuts through all the cowpoo associated with some of this technology. All the best Stephen