Quite how the UK will achieve its stated objectives given the state of the housing stock, lord knows. Perhaps this is what Hammond was banging on about.
Replacing the UK's domestic energy demand for methane with heat pumps running on a de-carbonised grid and hydrogen in the gas pipes from non carbon sources, the latter being a straight reversal of the high speed gas project in the 60"s. That gets round having to insulate and draft proof to the nth degree.
Insulating cavity walls as a peculiarly UK problem as they aren"t really found anywhere else as they were a cheap, simple and material saving answer to constructing rain resistant masonnary walls with a lack of skilled labour in Victorian times.
Blown bonded expanded polystyrene (EPS) beads is best for block/stone facing as it will resist penetrating rain (more likely with a stone facade) from crossing the cavity. Blown fibre gets soggy in such applications and PU foam presents a risk of water penetration at the joins between the individual globs of foam meet as it cannot be injected as a continuous mass.
Any plastic insulation on a potentially exposed element of a building, particularly a dwelling is basically a no no, Grenfell just being the latest in a long series of tragic errors probably starting with the EPS tiles of the 60's.
Build tight (airtight), ventilate right (MVHR), insulated foundations (the perfect application for EPS) avoid heat bridge and aim for an insulation package with a high decrement delay (~12 hours).
Trouble is UK house buyers are grossly uninformed about what a good house should be and therefore developers face no pressures to change their offer as they are providing what the customer wants and can't build enough of the crap fast enough to keep up with demand.
Tod28, what about internal insulation of solid walls in older buildings - i.e. vast swathes of London, Manchester, Liverpool, Birmingham etc. I have no relevant background/training, but it seems to me that an awful lot of these buildings won't be externally cladded for eons because of a long list of reasons:
- landlord won't pay and doesn't care
- owner-occupier won't pay and doesn't care
- buildings are divided into flats and the occupants won't come up with a shared plan to pay a contractor
- the disruption and expense of scaffolding, dust, noise etc are a huge disincentive. People will shrug their shoulders and wait for nanny state to come up with a plan. But we are cursed with a barely functional government which won't borrow/invest
- cladding will completely change the look of the buildings. Owners and planners will object
So the reason I got excited about recycled plastic tiles is that occupants can insulate gradually at almost no cost. Hardly any disruption. Landlords needn't even be involved. Thin plastic tiles allow skirting boards, carpets, electrical fittings, cornices and so on to be left as is - the tiles can just be trimmed with scissors to fill in the gaps. The wall ends up only 80 or 90% insulated, but perhaps that's enough? And the building can still breathe a bit through the untiled areas, reducing condensation/mould issues which could be very expensive and disruptive to fix...I imagine they require new ducts or air bricks or an electricity-consuming dehumidifier going all the time.
Recycled plastic tiles have many disadvantages - they're flammable, ugly unless painted, the recycling and 3D printing uses lots of energy and emits toxic fumes. Can you think of better ways, or am I really just barking up wrong tree?