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Lewis Bowick @l-bow.bsky.social · 26/07/2025

A secondary frustration with the "solar makes HPs make sense" concept is that upfront cost is HPs' greatest challenge IMO. To mainstream this for ordinary households, the last thing we need is to say "you just need to drop a further £8k for it to be worthwhile"

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Lewis Bowick @l-bow.bsky.social · 26/07/2025

What's screwey is that fixed cost are recovered via the energy consumption charge. As a result, electrifying makes you overcontribute to fixed costs, while generation lets you undercontribute. The two cancel each other out, causing the illusion that micro solar complements heat electrification.

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Lewis Bowick @l-bow.bsky.social · 26/07/2025

The idea that micro generation, costing 2-3x as much as grid-scale generation, with a generation profile inversely correlated to the heating season, makes electric heating more economic than using the grid should tell you something's screwey with the price signals

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Lewis Bowick @l-bow.bsky.social · 26/07/2025

I'm pretty sure it does more harm than good. Only one third of the retail price of electricity is for energy, so the "true" saving of rooftop PV must be about 8p/kWh of self consumption. The other two thirds are just shifted to everyone else's bills, making electrification even less appealing.

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Lewis Bowick @l-bow.bsky.social · 25/07/2025

Ooft. Hadn't thought it might get that bad

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Lewis Bowick @l-bow.bsky.social · 24/07/2025

The whole reason for CP30 was, I think, that in 2022 it looked like any additional renewable capacity would bring down bills. Now that wholesale has come down and CfDs have risen, I'm not sure there's any merit to a 2030 sprint (besides being the right direction of travel for carbon overall)

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Lewis Bowick @l-bow.bsky.social · 13/07/2025

District cooling is a thing, though I'm not convinced that would be easier than an individual building approach, given the need for co-ordination across many building owners and civil works. It would still need fan coils to be installed indoors. New build is an ideal opportunity for A2A I'd say

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Lewis Bowick @l-bow.bsky.social · 13/07/2025

Efficiency of air-to-water is very sensitive to the water temperature required by the radiators. If you've got underfloor heating or very big radiators then great, but if not you can get COPs much worse than you would with warm air. I think retrofitting refrigerant pipes more likely!

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Lewis Bowick @l-bow.bsky.social · 13/07/2025

Yep air-to-water is the default path for our homes. Just seems like a shame to be rolling out heat-only systems right when we realise we're gonna need AC. If we could combine the cooling perk with decarbonisation it would be a much easier transition.

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Lewis Bowick @l-bow.bsky.social · 13/07/2025

UK here, been trying to figure out if mini-splits could work for us at scale. The trouble is we all have whole house hydronic systems, so would need to double up with splits in every room. And how do you deal with bathrooms? More likely is people just put splits in bedrooms and keep using gas heat

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Lewis Bowick @l-bow.bsky.social · 13/07/2025

You can have fan coils connected to the pipework as well as radiators, which can provide effective cooling with proper moisture removal. The pipework needs to be insulated to avoid condensation. Probably quite hard to find installers who will do it atm

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Lewis Bowick @l-bow.bsky.social · 07/07/2025

True, heat pumps will only introduce about 30% as much additional heat to the environment as other forms of heating. So no cooling, but a reduced contribution to urban heat island in winter

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Lewis Bowick @l-bow.bsky.social · 07/07/2025

I'd be interested to know if these studies have taken into account that the portion of heat being blown onto the street which has been removed from the building is being cancelled out by that building absorbing heat through its leaks. Only the portion covered from electricity is a net addition.

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Lewis Bowick @l-bow.bsky.social · 07/07/2025

In both heating and cooling mode, heat is moved between indoors and out, plus heat is generated by electricity being burnt off as friction. So in both cases there's a net addition of heat. The hot air blown out is a combination of the heat moved from indoors and the heat added from electricity.

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Lewis Bowick @l-bow.bsky.social · 06/07/2025

Heating just adds heat to a building at the same rate it escapes to outdoors. It's an equilibrium to maintain a steady temperature, so there's no net removal of heat from the environment.

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Lewis Bowick @l-bow.bsky.social · 30/06/2025

Raises the question of whether we should be insulating pipes at installation to make them cooling-ready

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Lewis Bowick @l-bow.bsky.social · 19/06/2025

Not sure about easy. Freeholder permission needed, and often difficult to pass noise limits due to being close to neighbours' windows. Maintenance at height could be awkward. Feels like flats need fully indoor HPs which duct to outside air

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Lewis Bowick @l-bow.bsky.social · 19/06/2025

I suppose you can have bypass for the cool night air, then heat exchange to *cool* the fresh air in the afternoon, right? Whereas I have to seal up in the afternoon if I want to keep peak temperatures out, which feels weird!

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Lewis Bowick @l-bow.bsky.social · 19/06/2025

I suppose I'm basically describing PIV, except timed to run only during cool hours in a heat wave

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Lewis Bowick @l-bow.bsky.social · 19/06/2025

I'm not sure how much relief extract would provide, pulling air into the rooms from other warm rooms? Having supply at outdoor night time temperatures sounds nicer! I guess some of the extract makeup might come through the trickle vents though

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Lewis Bowick @l-bow.bsky.social · 19/06/2025

I reckon all it would take would be a fan to duct cool night air into the bedrooms from a quiet side of the house

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Lewis Bowick @l-bow.bsky.social · 19/06/2025

What I notice in heatwaves is we'd be able to keep cool if we weren't so restricted with ventilation. Security overnight, road noise, curtains to block 5am sunrise (also blocking cool air) and outdoor temps above indoor between midday and 9pm. Precious little opportunity for passive cooling!

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Lewis Bowick @l-bow.bsky.social · 18/06/2025

Poor bloke should have just followed the handy steps on his EPC. Move out of his downstairs to do underfloor insulation, stick a wind turbine on the back wall and put in flue gas heat recovery to save 2% emissions and get a 150 year payback

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Lewis Bowick @l-bow.bsky.social · 08/06/2025

Does reducing output on a within-day timescale meaningfully reduce fuel costs? I've been wondering if the renewables which displace French nuclear actually have value. Had it in my head nuclear is virtually all fixed cost

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Lewis Bowick @l-bow.bsky.social · 05/06/2025

I'd assume there's some crossover point with the design flow temperature of A2W where it becomes more efficient. Like maybe it beats A2A at 35C design but not at 50C

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Lewis Bowick @l-bow.bsky.social · 05/06/2025

Looking at the datasheets for A2A products, they usually have a tested heating SCOP above 4

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Lewis Bowick @l-bow.bsky.social · 05/06/2025

Do you have any sources for that? HP efficiency is mainly about the temperature of the condenser, and if anything A2A can probably run cooler than A2W in many cases

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Lewis Bowick @l-bow.bsky.social · 05/06/2025

I put a heat pump in my 1900 terrace. Works great. Does the same thing the boiler before it did

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Lewis Bowick @l-bow.bsky.social · 04/06/2025

It's sometimes suggested you could use A2A to displace the bulk of gas heating cheaply, leaving the boiler to pick up periphery rooms on very cold days and hot water. It's a nice idea but you'd have to move the thermostat, which is often hardwired

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Lewis Bowick @l-bow.bsky.social · 04/06/2025

I mean that if your starting point is electric resistive heating, heat pumps offer a very attractive running cost saving. But if you're starting from gas, there isn't much saving

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Lewis Bowick @l-bow.bsky.social · 04/06/2025

I think it's more to do with having lots of electric resistive heating, so heat pumps are a slam dunk on running cost savings.

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Lewis Bowick @l-bow.bsky.social · 04/06/2025

It's not obvious to me how you'd integrate air-to-air with existing central heating. Easier if you've got individually controlled electric heaters in each room, and you just run air-to-air to one or two main rooms, as I think is often the case in Scandinavia

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Lewis Bowick @l-bow.bsky.social · 04/06/2025

I think there's a lot of electric heating in Scandinavia. It's cheap and easy to put air-to-air in a couple of main living spaces, and leave electric heaters in other rooms and hot water alone. Really strong payback against electric heating too! Replacing gas central heating is harder!

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Lewis Bowick @l-bow.bsky.social · 29/05/2025

Enter your postcode into the design tool to automatically populate design temp and background noise!

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Lewis Bowick @l-bow.bsky.social · 29/05/2025

Background noise makes a massive difference. How could that be accounted for in the calc on a simple way without the need for an expensive and slow noise assessment at each site? Some kind of national background noise database?

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Lewis Bowick @l-bow.bsky.social · 29/05/2025

Yeah passing the noise calc is still pretty difficult for many flats, with neighbour's windows immediately above/below/beside

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Lewis Bowick @l-bow.bsky.social · 25/05/2025

France is like wow great thanks, let me add this to the rest of my summer Sunday oversupply

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Lewis Bowick @l-bow.bsky.social · 10/05/2025

Seems disproportionate! Like "we really can't be bothered dealing with this country" pricing

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Lewis Bowick @l-bow.bsky.social · 10/05/2025

Found out my phone doesn't do eSIMs 😞 But yeah a local physical SIM would be the way for a longer stay.

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Lewis Bowick @l-bow.bsky.social · 10/05/2025

and no, there's absolutely nothing you can do about it. My travel insurance should cover mountain rescue but maybe not Googling their phone number

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Lewis Bowick @l-bow.bsky.social · 10/05/2025

I pay £7/mo for 12GB mobile data. Graciously my provider let me use that data for no extra charge in Spain and France. Dipped into the Spanish speaking principality of Andorra for some hiking and all of a sudden they're charging me £9830 per GB!!!

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Lewis Bowick @l-bow.bsky.social · 30/04/2025

But electrification is about to increase the units of consumption. So we can recover the same costs from the current levy rate on the current amount of consumption, meanwhile making the additional consumption levy-free

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Lewis Bowick @l-bow.bsky.social · 30/04/2025

AFAIK PD is still in the pipeline; this is alongside sorting out PD, not instead of

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Lewis Bowick @l-bow.bsky.social · 30/04/2025

Consultation launched today on including air-to-air heat pumps in the Boiler Upgrade Scheme! The proposal is for a grant of £1000-2000, which would allow hot water to be provided separately, but would exclude fossil fuel hybrid setups

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