Posted By: dazdreadSIPs ... speedy construction for a DIYer

You probably need a crane for SIPs. Do you consider that DIY?

What is "EMI"?

Tom , Is the being shown in long energy analysis and resultant polution, as the best way forward or a trend brought about by other geo political concerns?

>1. Is don’t do it!
2. Make it smaller
3. Straw bales,
4 cob
5. DiY
6. So.id wall using s/h stuff with thick EWI

Roof, not flat roof using s/h everything

Difficult to build eco, I like low energy demand, built in as best opportunity is while building it.

Edit to clarify:
The emissions due to heat loss were the same for each wall type because the U values were set to be the same.
The emissions from manufacturing, delivery, construction, demolition and disposal were 2x to 3.5x worse for cement/polystyrene based construction compared to timber/cellulose.

Thanks for the link, Will.

Plant based materials do seem to have less lifecycle impact than cement or petroleum based materials.

If we include demolition and disposal in the complete lifecycle, then they are not carbon negative, they release their carbon when they are incinerated or rot down in landfill at end of the building's life. They also have some overall net carbon emissions from transport, kiln-drying, renders, fixings etc.

Their suppliers seem curiously keen to talk only about the manufacturing/construction and occupancy phases, and forget about the disposal phase!

Not sure any material can be actually carbon negative over the whole building lifecycle (so sequesters carbon for geological time)?

Posted By: WillInAberdeenIf we include demolition and disposal in the complete lifecycle, then they are not carbon negative, they release their carbon when they are incinerated or rot down in landfill at end of the building's life. They also have some overall net carbon emissions from transport, kiln-drying, renders, fixings etc.

The life-cycle standards are somewhat immature and biased though, IMHO. The house next to mine is about 400 years old and is built using similar materials but in a less "advanced" form than mine. But my house is supposed to last only 60 years according to the standards! Plus there's said to be a "crisis" at the moment, so storing carbon even for just 60 years might be worth while.

Which I see is what Tom kind of goes on to say

My recent single-storey extension was post (150 x 100) and beam, just because I like building P & B frames. Walls wrapped in 160 rigid wood-fibre (with lime render/silicone silicate finish) with a further 80mm flexi wood-fibre internally, residual cavity, Intello and 15mm wood-wool boards and lime plaster finish. Vaulted ceilings: 50mm battens to form ventilation void for cold roof. 20mm rigid W-F to maintain that, taped in with A/T tape. 280 flexible W-F in Larsen trusses. Floor: 200 x 50 joists, 11mm OSB, taped, 200 rigid W-F, 18mm OSB and 18mm for final finish (which, due to a change of plan, ended up as varnished OSB, so there's a superfluous layer there!).

Not necessarily a suggestion for 'best, but an option. Approx U values: Roof: 0.13; Floor (est'd): 0.18; Walls: 0.17. If I had not been watching the ££s flying away I could have got the walls down to about 0.13.

Posted By: WillInAberdeennuclear power plants, designed without thought of their end-of-life, which is why the 1950s nukes are proving so expensive to demolish!

Not only that, but still shoved under the carpet and not mentioned in debate, are the piles of radioactive waste, some of it as lethal as a nuclear war would be, which nations still have no strategy for 'safe' storage, which would have to be proof against multi-thousands of years of future mad warlords. As the saying goes - if the Romans had nuclear power, we'd still be guarding their waste.

I think I'd not taken on board, or perhaps lost sight of

Posted By: WillInAberdeenthe 10000-100000 year timespan for the climate system to reabsorb CO2

and indeed have come to rely a bit on

Posted By: WillInAberdeenthey will ... remove the equivalent number of tonnes of carbon from the atmosphere

which may in fact be credible, but only if technical/industral society survives and thrives and can handle today's 'carbon bomb' as its delayed and slow-motion explosion kicks in. Hmmm ... thinking. Not to mention the other bomb - accumulating loads of all the other bio-active pollutants (other than GHGs) which have barely entered the discussion yet.

Posted By: WillInAberdeenSo it does seem that the days of 'fabric first' are over, and we need to get heads around 'building lightly' as well.

What do you mean by 'building thinner' and 'building lightly' in this context? Light in Embodied Carbon or just physical weight?

The majority of low carbon and renewable building materials (woodfibre, structural timber etc.) tend to be less efficient structurally and thermally, but much more benign in environmental terms. So they often end up thicker in section than the status quo.

Building thinner can be achieved by light gauge steel and aerogel, but it isn't going to save on embodied carbon or pollution during production and is often more difficult to dispose of at end of life.

By all means promote not building wastefully (I think we all agree on that), but the reality of low carbon construction is probably still to have fairly thick walls, and I don't think we can claim that "fabric first is over".

Posted By: WillInAberdeenSo it does seem that the days of 'fabric first' are over

Except that it's not a choice between
a 'fabric first' approach at 8-10t embodied + 3t in use
vs 'build lightly' at 4t embodied + (greater loss > say) 5t in use.
To pay off convincingly, 'build lightly'' has to be 4t embodied + 0t in use
i.e. a greater in-use loss has to be supplied from renewable not fossil energy, from the start.

In other words 'build lightly' means a greater demand for in-use renewable energy than 'fabric first' (but eventually converted to renewable fuelled) does. Are we confident that the renewable supply will provide the increased in-use expectation of 'fabric first'?

>>>> a choice between
a 'fabric first' approach at 8-10t embodied + 3t in use
vs 'build lightly' at 4t embodied + (greater loss > say) 5t in use

No, all the example walls had the same U value U=0.18 so the same in-use energy and carbon, 3t. NB is not a high-fabric-efficiency buildup such as the U= 0.1 often associated with fabric-first.

It's (8-10t embodied + 3t in use) for block versus (4t embodied + 3t in use) for timber.

The 3t in-use can be reduced by a couple of tonnes with PH-style insulation and/or heatpump, but with increased embodied carbon, so may or may not be better overall. But point is: by far the biggest game in town is swapping the blocks for timber, saving 4-6t.

<blockquote><cite>Posted By: Doubting_Thomas</cite>There's a good paper on Retrofit by the Passivhaus Trust where they explore the impact of switching to electricity for space heating:

<a href="https://www.passivhaustrust.org.uk/guidance_detail.php?gId=51" rel="nofollow">https://www.passivhaustrust.org.uk/guidance_detail.php?gId=51</a>

"If all existing homes switched from gas to electricity without demand reduction, an additional 6.5kW average peak load per home would be added to the electricity grid - 68GW in total. However, the National Grid ESO’s Future Energy Scenario (Consumer Transformation), allows for only 30GW to heat our homes at the coldest peak in winter."

Now this does assume a pessimistic ASHP COP of 2.5, but it goes on to demonstrate that deep retrofit can get the additional average heating peak load down to 1.3kW per home, resulting in a 14GW additional load (80% reduction on ASHP only).

In other words we can't just rely on a decarbonising grid to provide guilt-free heating while we put up paper thin walls. We need to be improving fabric as well. And doing with the lowest embodied carbon materials that we can.</blockquote>

There is another aspect to electrification of heat.

I can't remember the exact acronym but local sub-stations are specified to a maximum average demand level, the most that all connections will draw as a probability, not to the physical maximum that they could draw. So by adding just a few heat pumps on a very cold day when they are working on an almost 1:1 efficiency they can easily exceed the sub-station capacity... according to an EON employee I spoke to, their test was with 15 heat pumps.

Posted By: WillInAberdeenSeems like electric vehicle charging is the main concern now for distribution, not so much heating.

https://www.nationalgrid.com/stories/journey-to-net-zero-stories/can-grid-cope-extra-demand-electric-cars

Hmm, the headline of that article is "The transition to EVs is happening … and we’re ready" which seems a little disturbing when I read other stories about the length of time that EV charging stations are having to wait for grid connections! Along with delays for solar farms and wind turbines. Doesn't sound very ready to me!

edit to add: having now skimmed the article it seems to be completely bogus with rose-tinted spectacles firmly in place :(