General > General Technical Chat

EV-based road transportation is not viable

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Monkeh:

--- Quote from: tszaboo on February 21, 2023, 04:13:00 pm ---
--- Quote from: mikeselectricstuff on February 21, 2023, 04:10:48 pm ---
--- Quote from: tszaboo on February 21, 2023, 03:57:36 pm ---
--- Quote from: tom66 on February 21, 2023, 03:48:28 pm ---Good diagram.  But, does it account for the difficulty in insulating UK homes to support heat pumps?  Having embarked upon the process of insulating our 1930's detached home, it is definitely not a trivial process usually requiring bespoke techniques for each property.

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Heat is heat. There is no difference for heat pump heat or heat from a boiler or gas.

--- End quote ---
Not true. optimum working temperature is different between different systems - heat pumps don't produce the higher temperatures needed to overcome poor insulation. Replacing a traditional pumped water/gas CH system with HP usually requires radiators to be up-sized to get the same output at a lower temperature drop.

--- End quote ---
If it works for Norway, there is really no reason why it wouldn't work for the UK or here.

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But it requires significant remedial work to the properties.

My house would be quite impractical to heat with a heatpump: The floors are leaky, and the existing pipework is microbore and fairly severely contaminated by iron oxide buildup. Every radiator and every pipe would require replacement, along with lifting the entire ground floor and insulating and sealing. Oh, yes, all the windows upstairs also need replacing, along with a properly sealed loft hatch.

By the time you've done all this you've not only tripled the cost of the installation, but required the occupants and their belongings to be removed from the house for at least several weeks.

I'd love to go this route. Hell, I'd take the opportunity to fit some AC to a couple of rooms. You supplying the £30,000?

nctnico:

--- Quote from: Ice-Tea on February 21, 2023, 07:28:22 pm ---
--- Quote from: nctnico on February 21, 2023, 07:00:26 pm ---
--- Quote from: Ice-Tea on February 21, 2023, 06:36:29 pm ---So, uhm, that's your argument then? You disregard any data that doesn't fit your narrative and call all those that run with it idiots?  :o

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There is no narrative and there is no argument. Just the fact that heatpumps are not economic to run when it is cold. This is obviously clear from looking at specifications from actual heatpumps. There is no need for yet another fantasy number that is invented to compare heatpumps because it says nothing about the suitability of heatpump for a less insulated home.

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But.... it does. Nobody is arguing that the efficiency of a heatpump goes down when temperature does. That's why you have the SCOP value. It tells you what your seasonal efficiency will be. And it does say something about suitability for less isolated houses as you typically have this value for 35C and 55C feed temperatures. And if 55C doesn't suffise: get crackin' on isolating your barn, please.

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If you look at what SCOP actually means, you'll notice it is not a number that tells you something about the suitability of a unit. Seasonal efficiency doesn't mean that a unit will be able to heat a home when it is cold. The COP might be too low and SCOP doesn't tell you that at all.

Also, you don't need high water temperatures perse. It is relatively easy to retrofit an existing home with underfloor heating (been there, done that) which doesn't need high water temperatures at all.

tom66:
What I do find nuts is that the UK government is allowing new homes to be built (a) with gas boilers and (b) without good insulation, such that when they do get heatpumps fitted, they will need additional remedial work to make it work properly.  It's bonkers.

tggzzz:

--- Quote from: nctnico on February 21, 2023, 06:30:47 pm ---
--- Quote from: tggzzz on February 21, 2023, 06:12:50 pm ---
--- Quote from: tom66 on February 21, 2023, 03:48:28 pm ---Good diagram.  But, does it account for the difficulty in insulating UK homes to support heat pumps?  Having embarked upon the process of insulating our 1930's detached home, it is definitely not a trivial process usually requiring bespoke techniques for each property.

--- End quote ---

And external insulation is very easy to get badly wrong, e.g. https://www.walesonline.co.uk/news/wales-news/victims-home-insulation-scandal-scandal-26076372.amp

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One of my relatives is an advisor for people who seek to improve the insulation & lower the carbon footprint of their homes. His conclusion is that it is not worthwhile to re-insulate older homes because the basic structure doesn't allow for it. Better insulation also means adding air treatment to manage the moisture inside a home which means adding ducts and mechanical ventilation. So the only option is to use hybrid heaters (heatpump + boiler) in order to get enough heat into such homes. Heating is not just necessary to keep the people inside a home warm, but also to keep the home itself dry in order not to get problems with mold and wood rot. It is pretty complicated to get right from the start. Let alone trying to do a retrofit.

--- End quote ---

All plausible, and questions I would want answered before doing anything like that.

IIRC the S Wales situation was exacerbated by grossly incompetent work, allowing driving rain to enter the external insulation. Even if done competently, it sounds like a fragile installation which is certain to deteriorate over the decades.

tggzzz:

--- Quote from: tom66 on February 21, 2023, 07:55:16 pm ---What I do find nuts is that the UK government is allowing new homes to be built (a) with gas boilers and (b) without good insulation, such that when they do get heatpumps fitted, they will need additional remedial work to make it work properly.  It's bonkers.

--- End quote ---

There's always a balance to be struck w.r.t. planning for a future that might not come. I've known people that put RS232 everywhere in their house so they wouldn't have to retrofit it.

Having said that, the lack of good insulation does seem unsupportable.

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