General: Saving energy versus saving carbon - new building regs

1 to 28 of 28

- CommentAuthorWillInAberdeen
- CommentTimeMar 23rd 2022 edited
Reducing "Primary energy" is going to be the main criteria in the updated Building Regs and Standards, replacing the previous focus on reducing CO2 emissions.

Coal, oil and gas heating fuels will have the most favourable primary energy factors, around 1.1 .

Electricity will have the least favourable primary energy factor, of 1.5, irrespective whether renewable or not.

So choosing direct electric heating or hot water, will make it more difficult to meet your primary energy target.

If you add insulation, it will reduce your Primary Energy according to the factor of your heating fuel - so adding insulation will be more encouraged in an electric-heated house, than for a gas-heated house.

Changes will not be permitted that increase your Primary Energy, so you cannot switch over say from gas to direct electric heating.

This might discourage electrification of heat, despite electricity now carrying lower carbon emissions than gas. The English regulations will continue to use CO2 emissions and fabric energy efficiency as additional metrics, but the Scottish standards will no longer consider CO2 emissions targets for electrified houses.

In the English consultation, 76% of responses disagreed with this new approach.

Interested what others think about this? I've always thought that saving carbon was the goal, and saving energy is just a means to that end.

For example, if one house has big roof windows to gather light and solar heat, and another has PV panels instead, the second house is treated as consuming more primary energy, but both use the same photons and emit no CO2.
- CommentAuthorPeter_in_Hungary
- CommentTimeMar 23rd 2022
Posted By: WillInAberdeenChanges will not be permitted that increase your Primary Energy, so you cannot switch over say from gas to direct electric heating.

So you couldn't go from gas to direct electric heating supplied by PV ?? Presumable a heat pump supplied by PV would be permitted.

On the face of it it sounds as if they haven' got it quite right.

Over here from July any new house has to have 20% of its calculated energy demand supplied by renewables - That's the good news, the bad news is that pellet boilers count as a renewable source.
- CommentAuthorWillInAberdeen
- CommentTimeMar 23rd 2022 edited
PV is to be treated as no better or worse than any other kind of electricity, because the focus is shifting off CO2 and onto saving Primary Energy.

You could switch from gas to a heatpump powered from any source of electricity, because the heatpump uses one unit of electricity (counted as 1.5 units of Primary Energy) to gather typically two units of (ultimately solar) heat from the air (solar heat is not counted as Primary Energy, unlike solar electricity). So overall that's a reduction in Primary Energy usage, compared to 3 units of gas.

Likewise if you switch from gas to electric heating or hot water, you'd need to reduce usage substantially (eg insulate) so you end up using less Primary Energy overall, despite electricity having a worse Primary Energy Factor than gas.
- CommentAuthorPeter_in_Hungary
- CommentTimeMar 23rd 2022
Posted By: WillInAberdeenPV is to be treated as no better or worse than any other kind of electricity,

So PV is no better or worse than a coal fired power station !
- CommentAuthorEd Davies
- CommentTimeMar 23rd 2022
Posted By: WillInAberdeenFor example, if one house has big roof windows to gather light and solar heat, and another has PV panels instead, the second house is treated as consuming more primary energy, but both use the same photons and emit no CO2.
AIUI, the Passivhaus standards also have this oddity.
- CommentAuthordjh
- CommentTimeMar 23rd 2022
Posted By: Ed Davies
Posted By: WillInAberdeenFor example, if one house has big roof windows to gather light and solar heat, and another has PV panels instead, the second house is treated as consuming more primary energy, but both use the same photons and emit no CO2.
AIUI, the Passivhaus standards also have this oddity.

I don't believe so, unless you have a reference? Windows are part of the thermal envelope and large roof windows are notorious for the losses they can introduce (same with windows on the north elevation). They are evaluated as part of the PHPP energy demand assessment. PV panels are not. They introduce no losses and are not part of the energy demand assessment. They are assessed as part of the energy supply assessment for the more esoteric PH classes (Plus & Premium) and I confess I find the PER mechanism used for that very confusing.
- CommentAuthordjh
- CommentTimeMar 23rd 2022 edited
Will, do you have a reference (or more than one if necessary) for the material in your first post, please?

edit: One reason I ask is that https://www.bregroup.com/wp-content/uploads/2019/10/Briefing-note-on-derivation-of-PE-factors-V1.3-01-10-2019.pdf disagrees about the windows and PV panels for example. It shows PV generation used in the house directly reduces the energy demand of the house and any exported also reduces the demand but at a reduced factor (the numerical value looks suspicious to me) presumably to reflect grid losses, although I think those will also be accounted for by whoever consumes that electricity so it somewhat looks like double counting.

edit2: Just to comment on the scale of the problem I think we need to deal with: SAP 10.2 has a section 'A3 Dwellings with inadequate heating systems' and that has a special section 'A3.3 Highly insulated small dwellings' which says "In the case of highly insulated small dwellings, item (1) in A3.2 may not be realistic, for example a 3 kW gas fire could suffice to provide most of the heating needs. Accordingly, if the design heat loss (DHL) is less than 3 kW, the heating in the main room is the main system irrespective of the number of rooms heated." Note that my house is not especially small (around 150 mÂ²) and the design heat loss according to PHPP is less than 1.5 kW. My main room has no heating, unless you count the MVHR terminal and the post heater in the plant room :)

edit3: Reading SAP 10.2 is just depressing; it saps my will to live. The assumptions it makes simply aren't close to true for the house I live in. Assumptions about water usage, about when we use electricity etc etc. With such faulty assumptions it's no wonder EPCs are rubbish.
- CommentAuthorWillInAberdeen
- CommentTimeMar 23rd 2022 edited
https://www.gov.scot/publications/scottish-building-regulations-proposed-changes-energy-standards-associated-topics/pages/2/ (start at section 2.2)

https://www.gov.uk/government/consultations/the-future-homes-standard-changes-to-part-l-and-part-f-of-the-building-regulations-for-new-dwellings (start at page 30)

Posted by DJH: "the numerical value looks suspicious to me"
Yes, that's where the trick is! But TBh I was more interested what people think of the broad principle of regulations to save Primary Energy, rather than to save carbon. Even if that favours using coal heating over renewable electricity, in order to reduce distribution losses of Primary Energy . Perhaps shouldn't have included the roof window example.

Edit: from the Scottish consultation paper:
"A requirement of the 2018 amendment to the EU Energy Performance of Buildings Directive... is that Member States adopt Primary Energy as the principal metric for compliance ... This is ... being considered for implementation across the four UK administrations."
- CommentAuthorPeter_in_Hungary
- CommentTimeMar 24th 2022
The Scottish paper talks about delivered energy
Quote
Delivered energy is the amount of energy that needs to be supplied to the building from external sources. This is the calculated energy demand for the building less any offsetting of that demand from the generation of energy or heat onsite from renewable sources. It is the delivered energy total for each fuel supplied to a building to which primary energy and emissions factors are applied.
end quote
This makes (much more) sense than just measuring all primary energy used by the dwelling.

It begs the question about a block of flats, could a PV farm installed as part of the flats construction but not actually 'on site' because of practicalities be counted. The same could apply to town houses where space may be too limited for a decent amount of PV.

Posted By: WillInAberdeenA requirement of the 2018 amendment to the EU Energy Performance of Buildings Directive... is that Member States adopt Primary Energy as the principal metric for compliance ... This is ... being considered for implementation across the four UK administrations."

What happened to Brexit ???
- CommentAuthorEd Davies
- CommentTimeMar 24th 2022
Posted By: djhThey are assessed as part of the energy supply assessment for the more esoteric PH classes (Plus & Premium)â€¦
OK, but for â€œvanillaâ€ PH (whatever it's called these days) my understanding is that energy as photons coming through windows doesn't count towards your 15 kWh/(mÂ²Â·a) or 10 W/mÂ² limits whereas energy as photons hitting a PV panel then running down wires into the house does. Is that wrong?
- CommentAuthordjh
- CommentTimeMar 24th 2022
Posted By: Ed Davies
Posted By: djhThey are assessed as part of the energy supply assessment for the more esoteric PH classes (Plus & Premium)â€¦
OK, but for â€œvanillaâ€ PH (whatever it's called these days) my understanding is that energy as photons coming through windows doesn't count towards your 15 kWh/(mÂ²Â·a) or 10 W/mÂ² limits whereas energy as photons hitting a PV panel then running down wires into the house does. Is that wrong?
It's called 'Classic' - that's what we are. Energy coming in through windows is assessed on the heating (and cooling) demand side, since it reduces the heating energy required and can increase the cooling required. PHPP works out a pretty accurate assessment in my experience. Electrons from my PV don't enter into it. I don't know exactly what current PHPP does, but power from PV doesn't affect the heat demand. PHPP is a fabric first standard - it's the building itself that decides whether you pass or fail. PV might be incorporated in the power supply calculations (most likely is in current PHPP).
- CommentAuthorWillInAberdeen
- CommentTimeMar 24th 2022 edited
Peter, for a block of flats, henceforth none of the individual flats will be credited with any Primary Energy savings (or cost or carbon savings) from PV panels on the shared roof.

For a house, SAP AppM calculates a Beta factor for how much rooftop PV can be instantaneously self-consumed in the daytime (typically less than 30% unless there's a battery) and how much is deemed to be exported and reimported later in the evening (typically 70%). As DJH spotted, the export is assigned a punitive low Primary Energy Factor, which might be further reduced in Scotland. But the reimport is assigned the usual high Primary Energy Factor, so the net effect is that PV has much reduced benefit.

If the same PV panels were installed in a neighbouring field, or the homeowner bought a matching share of a windfarm in Wales, then that might be a much better solution economically but it wouldn't count towards passing the Primary Energy target in Building Regs.

It just seems to be a feature of Primary Energy that you are supposed to minimise your use of PV electricity, but you are encouraged to use solar heat gathered through windows or heatpumps or evac tubes.

By convention, Primary Energy is defined as the output electricity of a PV panel or wind turbine, which ignores their low conversion efficiencies, which are due to physics constraints (Betz etc). So the inputs (sunshine and wind) are not defined as Primary Energy and you can collect as much as you like, so long as you don't convert them to electricity.

But for a thermal or nuclear power station, Primary Energy is defined as the input fuel, so the physics constraints in their cases (Carnot etc) mean their output electricity will have poor Primary Energy factors. You are encouraged to burn the coal etc directly in your house to avoid these losses.

In future, the grid mix will change to more renewables and possibly more nuclear/hydrogen/CCS, so the Primary Energy of electricity used in houses will change during the lifetime of the building. So a design that optimises Primary Energy when built, might turn out to be suboptimal in future. TBF this also applies to Carbon factors which also have conventions about what is/isn't included.
- CommentAuthordjh
- CommentTimeMar 24th 2022
Posted By: WillInAberdeenBut TBh I was more interested what people think of the broad principle of regulations to save Primary Energy, rather than to save carbon. Even if that favours using coal heating over renewable electricity, in order to reduce distribution losses of Primary Energy . Perhaps shouldn't have included the roof window example.
FWIW, I agree with the reasoning in the consultation response that measuring carbon emissions becomes useless as a tool as the grid is decarbonised. Primary energy seems like a reasonable condidate for a replacement metric, although there are lots of details in the definition that I'm not sure about. I do agree that the total quantity of electricity used is a real world constraint just as important as the carbon emissions, unless and until we get portable fusion generators that consume fish bones :) That constraint is simply a practical matter of how much generation capacity there is.

If the choice is burning coal in a power station or burning it in a fireplace then I'd guess the fireplace wins. But where that choice can be applied is limited by other rules about smokeless fuels and emissions. And I'd guess that producing coke or smokeless fuels involves their own emissions and PE factors.

Regarding roof windows vs PV, I didn't see that case mentioned in the document. Did I miss it somewhere? I don't understand the point.
- CommentAuthorWillInAberdeen
- CommentTimeMar 24th 2022 edited
The carbon factors in SAP for 2020-25 are still far from zero, so while the argument is fair that restricting carbon will eventually become meaningless, it seems to me that we are not nearly there yet, and it is not yet the time to take the focus off reducing carbon from the building stock, or to discourage electrification of heat.

There's no restrictions on smokey fuels where many of us live. Where it is restricted, the PE factor for smokeless coal is 1.26 which is now more attractive than electric heating (PE factor 1.5).

More widely, this approach encourages people to design around gas central heating (PE factor 1.13) which is then difficult to get off later (radiators too small, etc)

Roof windows vs PV : see all three posts above - heat and light gained through windows and evac tubes, are not defined as Primary Energy, so their consumption are unlimited under building regs/stds, nor it seems by PH. Whereas PV electricity is defined as Primary Energy, and SAP penalises it via the low PE factor on exports mechanism as discussed above. Sounds like PH is more straightforward by just restricting the total primary energy supply and counting the self-consumed PV against that. Was just an example of the quirky effect of 'details in the definition' of Primary Energy.

Edit: if the national supply of electricity or PE is considered the constraint that BR must regulate, then logically the builder should have the choice to build a higher-consuming building and to provide extra renewable generation on site, or off site if that is cheaper. The effect on the environment/society/homebuyer would be the same or better.
- CommentAuthorEd Davies
- CommentTimeMar 25th 2022
Posted By: djhI don't believe so, unless you have a reference?
You just wrote it for me, http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17427&page=1#CommentBody_295484 , thanks.

If you're trying to reduce the amount of â€œprimaryâ€ energy used by a house you might well find yourself balancing up extra windows or extra PV to harvest solar energy. Extra windows are likely more effective when the sun is shining but on balance at the time of year that it matters they make much less efficient use of your money (Â£/W) because of the higher losses the rest of the time. Still, if I understand your description correctly, PH Classic regards them as a gain whereas it ignores the more cost effective PV.

In other words, it arbitrarily regards windows as fabric but PV as not fabric.
- CommentAuthorWillInAberdeen
- CommentTimeMar 25th 2022 edited
Think it goes back to the definition of what is Primary Energy. The UK gov have set out their version in the BRE doc that DJH linked, but I cannot trace back their references other than vague suggestions that it all started from the UN or IPCC.

Other governments have different interpretations, although seems they all consider that PV Electricity is Primary Energy and so should be conserved, whereas Solar Thermal is not Primary Energy so can be used unrestricted. Yes it is bizarrely arbitrary, but seems that PH just follows that rule.

Some EU governments put quite different values on different kinds of Primary Energy, by including/excluding different parts of their supply chain. There seems to have been an unsuccessful attempt to agree a common definition

https://energy.ec.europa.eu/review-default-primary-energy-factor-pef-reflecting-estimated-average-eu-generation-efficiency_en Annex2

Another quirk is that wood pellet boilers were previously favoured in building regs for rural homes, because they are assigned a low carbon intensity vs the alternative LPG or Oil boilers. However they are assigned a high Primary Energy factor, so henceforth will be discouraged. (Edit: wood pellets are still attractive if consumed via a community heat network or CHP - another quirk!). Log and woodchip burners still have attractive Primary Energy factors.

There is no factor yet for Hydrogen but it will be higher (less attractive) than the natural gas or electricity from which it will be made, making it difficult to switch natural gas boilers to hydrogen.
- CommentAuthorMike1
- CommentTimeMar 25th 2022
Posted By: WillInAberdeenMore widely, this approach encourages people to design around gas central heating (PE factor 1.13) which is then difficult to get off later (radiators too small, etc)
Subject to the Government's supposed ban on gas boilers in new housing from 2025.
- CommentAuthorWillInAberdeen
- CommentTimeMar 25th 2022 edited
That's right Mike, this current 2022 set of building regs are supposedly 'interim' and will be in force until at least 2025. They now apply to retrofit as well as new-build.

In the UK consultations (link in post 8 above), the gov said "we intend to set the performance standard of the [proposed 2025 update] at a level which means that new homes will not be built with fossil fuel heating, such as a natural gas boiler... we expect heat pumps will become the primary heating technology for new homes"

In other words, once Primary Energy is established as the new metric in these 2022 regs, they plan to crank the Primary Energy target tighter after 2025, such that gas boilers will not be able to comply economically, but heat pumps will. That way, they will avoid actually 'banning' gas boilers. At that level of Primary Energy, it will also mean that direct renewable-electric heating will not be able to comply, nor will biomass/oil/lpg etc.

Obviously it remains to be seen whether they follow through on this plan in 2025, who knows, fingers crossed!
- CommentAuthordjh
- CommentTimeMar 25th 2022
Posted By: Ed DaviesIf you're trying to reduce the amount of â€œprimaryâ€ energy used by a house you might well find yourself balancing up extra windows or extra PV to harvest solar energy. Extra windows are likely more effective when the sun is shining but on balance at the time of year that it matters they make much less efficient use of your money (Â£/W) because of the higher losses the rest of the time. Still, if I understand your description correctly, PH Classic regards them as a gain whereas it ignores the more cost effective PV.

In other words, it arbitrarily regards windows as fabric but PV as not fabric.
We're at cross purposes somehow and I'm too preoccupied with other matters at the moment to diagnose it exactly. But no, the distinction isn't arbitrary.

If you don't have a window then there's a hole in the side of the building and your airtightness is shot to hell. Alternatively you can't see very well inside the house and have to install more lighting. Windows are fundamentally a part of the fabric of a house. None of that applies to PV; they're just a bolt-on that can just as well be in the garden or miles away but sometimes it's more convenient to mount them on the opaque parts of the house.

Windows generally aren't a gain in PHPP. They lose more heat than they gain when heating is needed and they may gain more heat than they lose when cooling might be needed. PHPP can and usually does measure everything on a monthly basis. Windows are tolerated because of the light they admit and the escape possibilities they introduce.

PV always makes electricity, but in varying quantities throughout the year. What it is used for is another subject.
- CommentAuthorEd Davies
- CommentTimeMar 25th 2022
Posted By: djhWindows generally aren't a gain in PHPP. They lose more heat than they gain when heating is neededâ€¦
Interesting, I thought good south-facing windows were typically a small gain.
- CommentAuthorRobL
- CommentTimeMar 25th 2022
Yes, I too thought decent South windows were a net win in winter in the UK.
I tried PVGIS, got 40kWh/month in winter from a 1m^2 (ok, I used 1kWpk of solar) vertical south admittedly unshaded surface. Simple calc suggests it looses around 20degC*1*24*30/1000 = 14kWh/month. Why is that wrong?
- CommentAuthordjh
- CommentTimeMar 25th 2022 edited
South-facing windows gain heat on sunny days. They lose it on overcast ones. Most houses, even PH, need some heat on the overcast days. Averages don't mean much.

niggles:

design temp is -10 not 0. Though U-value is less than 1.

https://www.jojusolar.co.uk/faqs-solar-power/
"For standard modules of 16% efficiency, each kWp takes up about 6.25m2 of roofspace. More efficient modules are available, and because they convert light more efficiently, they take up less space. 1kWp of high efficiency 20% modules only take up 5m2 of roofspace." No idea whether that is correct or not.
- CommentAuthorEd Davies
- CommentTimeMar 25th 2022
Posted By: djhNo idea whether that is correct or not.
It is by simple arithmetic: 1/16% = 6.25, 1/20% = 5.
- CommentAuthorWillInAberdeen
- CommentTimeMar 26th 2022 edited
My fault! The windows example was to illustrate that the quirky accounting conventions in Primary Energy, can push you to suboptimal design choices. Sorry if it sent everyone off track!

Maybe a less confusing example would have been to compare a PV panel against a Solar Thermal flat plate collector. Neither are 'fabric'. Let's imagine both collect 1kWh, which is used to heat DHW, so displacing mains electric heating.

- the previous building regs/stds would have treated both collectors equally, as giving equal CO2 savings, based on the grid CO2 intensity;

- the new building regs will favour the Solar Thermal, as it is treated as displacing 1.5kWh of Primary Energy. The PV will be treated as being mostly exported, the exported portion will be given a heavily reduced Primary Energy credit, or zero credit in Scotland;

- AFAICT the passivhaus standard will favour the Solar Thermal by treating it as a credit against the 60kWh/mÂ²/yr Primary Energy Renewable target for heating+dhw+appliances. The PV would not be credited against any of the primary energy targets. Maybe someone with PH experience can confirm/correct this?

- ref recent thread and Ed's blog, the PV would be cheaper than the Solar Thermal, for the same amount of hot water (IE more CO2 abated per Â£, and more electricity saved per Â£) and could sell electricity once the cylinder was hot enough. The same PV would be even cheaper if installed in a solar farm nearby.
- CommentAuthordjh
- CommentTimeMar 26th 2022
Posted By: WillInAberdeen- AFAICT the passivhaus standard will favour the Solar Thermal by treating it as a credit against the 60kWh/mÂ²/yr Primary Energy Renewable target for heating+dhw+appliances. The PV would not be credited against any of the primary energy targets. Maybe someone with PH experience can confirm/correct this?
I'm not that person I'm afraid. My house was designed with PHPP 7, before the PER (primary energy renewable) stuff came in so I think the rules now are somewhat different. FWIW, the PE factor for electricity was 2.6 in my PHPP and we still passed using all electric resistance heating. Also the PE factor for PV is 0.7, presumably reflecting the emissions or whatever in the production of solar panels. The current version is PHPP 9. Maybe others know more about the details.

Maybe interesting , there's an example PHPP results printout at https://passivehouse.com/downloads/04_phpp_V9.6b_Passive_House_End_of_Terrace.pdf and other details at https://passivehouse.com/04_phpp/04_phpp.htm The example shows the results, but you need the actual spreadsheet to see how everything is calculated.
- CommentAuthorWillInAberdeen
- CommentTimeMar 27th 2022 edited
Thanks for the links!

The quirky definition of Primary Energy for certain renewables, means that PE factors for UK electricity have reduced a lot since you built, lots more PV and less nuclear in the grid mix now. Fusion is defined as better than fission!

The Primary Energy Renewable measure for electricity seems even quirkier, as it is based on time of year as well as on the grid mix. Electricity scores less well for space heating, because of space heating being concentrated in certain months.

The example PHPP pdf includes Primary Energy and PER factors on page 40. As expected, heat from Solar Thermal is treated much more favourably (Primary Energy Renewable = 0 to 0.2) than PV electric heat (PER= 1.0 to 1.8 based on Germany). So much so, that the example house has an astonishing 13kW (edited) of grid-tied PV panels, but still could not have passed its Premium certification level without a magic 5mÂ² of Solar Thermal to gain that favourable accounting treatment for the DHW energy!

I was slightly gobsmacked to read that the passivehouse PER measure is defined against a hypothetical grid which uses renewable energy to synthesise "P2G Methane" and store it underground. The original 'Mr Passivehouse' is apparently very keen on this idea. If a passivehouse uses electricity at the wrong time of year, then more synthetic P2G Methane would have to be used, so it would be assigned an unfavorable PER score and would need more insulation to compensate. I think the PH concept has high credibility for its building science, but they might have gone a bit far off-piste for me with the synthetic Methane storage...

https://passipedia.org/basics/passive_house_-_assuring_a_sustainable_energy_supply/passive_house_the_next_decade/determining_application-specific_per_factors
- CommentAuthordjh
- CommentTimeMar 27th 2022
Posted By: WillInAberdeenThe quirky definition of Primary Energy for certain renewables, means that PE factors for UK electricity have reduced a lot since you built, lots more PV and less nuclear in the grid mix now. Fusion is defined as better than fission!
Yeah, it's good news on that front.

The Primary Energy Renewable measure for electricity seems even quirkier, as it is based on time of year as well as on the grid mix. Electricity scores less well for space heating, because of space heating being concentrated in certain months.
I think that reflects reality doesn't it? I always liked PHPP's monthly method. The PHPP output for the example house illustrates the level of detail that PH uses.

the example house has an astonishing 91mÂ² of PV panels
p37 says 89 mÂ² does it not? (65.9+23.1) Still fairly astonishing.

I was slightly gobsmacked to read that the passivehouse PER measure is defined against a hypothetical grid which uses renewable energy to synthesise "P2G Methane" and store it underground. The original 'Mr Passivehouse' is apparently very keen on this idea. If a passivehouse uses energy at the wrong time of year, then more synthetic P2G Methane would have to be used, so it would be assigned an unfavorable PER score and would need more insulation to compensate.
Ha! I've either never read that or forgotten it. But Feist's brain seems to work a little bit like mine in some respects. In my view a constructive proof is as good as an analytical one - my teachers didn't always agree :( That's how I view the P2G methane idea. It's a constructively provable method of solving a problem (seasonal storage). So if reality turns out to be better then so much to the good, PHPP will be shown to be somewhat pessimistic. And if reality turns out to be worse, well how can it?

(PS don't forget there are two 'Mr Passivehouse' - Adamson and Feist)

I thought the PH concept has high credibility for its building science, but they might have gone a bit far off-piste for me with the synthetic Methane storage...
I agree. The building science stuff is very solid, but all the rest seems a bit more speculative. But I trust these guys a lot more than I trust our politicians and bureaucrats.
- CommentAuthorWillInAberdeen
- CommentTimeMar 27th 2022 edited
Quite right about the rooftop solar farm area!

Don't think synthetic Methane is a constructively provable solution to seasonal demand, any more than fusion toruses! Because of the deployment time - there is no way to scale that up from zero to multi-hundred-GW in time to control global warming, you need to start with something that already exists at least at multi-GW scale. On the plus side, the energy system is an awful lot more than just heating houses (which they based all the numbers on) - mostly it's transport and industry which are not seasonal, so they have greatly over-stated the seasonality problem with electricity.

The issues I have with (all) this are that a) by arbitrarily making electrified heating/DHW seem unattractive vs primary fossil fuels, you drive people to keep burning things in their homes; and b) all the arbitrary accounting definitions leave loopholes wide open for clever accountants to play accounting tricks, such as the solar thermal loophole deployed here (even by the PH people themselves on their own website!).

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