Cost effectiveness of insulation?

silverwhistle

I've never had a problem of general mould in my house except on some silicone sealant, but I think my single occupancy makes a difference. Style of house also ,makes a difference on heating cost, my terrace being warmer than a detached or semi, even with the through passage between me and next door. I reckon 1100 kwh per annum for gas for heating and hot water is pretty good, but I won't get an idea of true fuel costs until I'm no longer able to scrounge and prepare wood for the stove..

Incidentally JoeFizz, you mentioned using your oil boiler the other day. Have you ever considered doing what I occasionally do in the shoulder months which is to shove on an oil filled heater using surplus PV power? It raises the temperature and puts a bit of heat into the house without me having to put the central heating (or logburner) on. It's now in the loft unneeded, but I'm a lot lower and further south!

Petriix

markin said:

Petriix said:

Insulation is pretty intangible when it comes to ROI. Beyond adding loft insulation, it's not something you can easily buy or install without serious disruption or expense.

We've got an area of flat roof which is poorly insulated. To bring it up to modern standards I would have to remove the ceiling along one edge to insulate between the ends of the joists, then add 130mm of rigid insulation above the deck before adding a second deck and felting on top. That's a massive job that would cost £thousands and save £tens from my heating bill.

It makes sense to insulate properly when building or extending but it's much less clear when thinking about retrofitting. 

Cant you just cut open the roof to insulate between the ends of the joists.

.......

Yes, you're right. I'd not though it through. I could just remove the external boards and insert insulation from outside. My point about cost vs benefit still stands.

joefizz

silverwhistle said:

Incidentally JoeFizz, you mentioned using your oil boiler the other day. Have you ever considered doing what I occasionally do in the shoulder months which is to shove on an oil filled heater using surplus PV power? It raises the temperature and puts a bit of heat into the house without me having to put the central heating (or logburner) on. It's now in the loft unneeded, but I'm a lot lower and further south!

Ive bolded the important bit ;-) Its what I bought the ASHP for but if the battery doesnt charge I dont use it. The oil boiler is not just for heat but hot water as well.
This year has been strange so far, a couple of weeks ago even emptying my battery twice a day I was still getting surplus PV. This morning Im down below 40% with no real excess use at all (big storm here yesterday evening/last night) Looking at the weather forecast for the next couple of days it looks like battery could be emptied ;-)

silverwhistle

Ha, looking at our forecast I reckon my PV production could be down this coming week due to overheating!

It certainly gets to be a complicated equation when ASHP and batteries are brought into play. Mine is simple enough as I divert spare power to the immersion (currently HOT), occasional heater use and demand management. I will be getting an EV next month but as it's a bicycle it won't be mopping up too much of my production.. That should assuage my EV itch for a bit and then next year get a bigger battery on 4 wheels..

joefizz

silverwhistle said:

Ha, looking at our forecast I reckon my PV production could be down this coming week due to overheating!

It certainly gets to be a complicated equation when ASHP and batteries are brought into play. Mine is simple enough as I divert spare power to the immersion (currently HOT), occasional heater use and demand management. I will be getting an EV next month but as it's a bicycle it won't be mopping up too much of my production.. That should assuage my EV itch for a bit and then next year get a bigger battery on 4 wheels..

I wish! Im going back to thinking about putting a mini tubine in my rainwater downpipes!

I have to say I didnt think buying the ebike would have made as much of a difference as it has (when not constantly raining of course). Well that and companies/shops being a bit more generous with deliveries in lockdown.

Certainly every time I take it out (foldable version so does look a bit odd) people stop and ask what its like and where I got it.

When the sun eventually does come out again here Im going to do a run into Belfast city centre on the ebike as it is probably just about the end of its range to get there and back (fully expect to be walking part of it home!) and have already looked at how I can add another battery in a pannier bag to give a 50 mile range.

Just waiting to see if they do anything in the budget to help promote this sort of thing over cars, although they are making noises (and about reducing VAT etc to help instead of subsidies), it does appear to be government by twitter at the minute and make it all up at the last minute.

Going back to insulation, with all the home renovations going on at the minute, seeing steady stream of people offering odd rolls of insulation on gumtree cheaply so if anyones interested in topping up, get looking!

Greenglockenspiel

Hi everyone, sorry to revive a dormant thread. I’m trying to improve the efficiency of my home and have no idea about any of it. Could anyone give any advice?

I’ve got a Victorian mid terrace with a single storey extension (kitchen & bathroom) at the back. The loft is already insulated and we’re already having extra insulation put in as part of replacing the flat roof on the extension (needs replacing anyway as it had leaked) so those aspects are already sorted.

The main part of the house is solid wall and the extension is cavity wall. The bathroom in particular is very cold in winter.

Is having the cavity walls insulated (3 external walls) likely to be beneficial/cost effective?

We are having one of the bedrooms replastered - would it be a good idea to get internal insulation put on the one external wall as part of this refurb? There’s a window and a radiator on that wall and the airing cupboard door also opens towards it so how much space would we lose?

I’m also hoping to do up the bathroom in a couple of years. The floor is really cold because of the concrete base to the extension and there’s laminate flooring in there at the moment which I am thinking of replacing with karndean type stuff. Would floor insulation be effective/take up a lot of depth? Or likewise underfloor heating? There isn’t much space under the door to lose! Before I had clocked the possibility of cavity insulation I had thought about putting internal insulation before re-tiling the walls - would doing both be overkill? Can you even do internal wall insulation in a bathroom due to weight of tiles, sink, heated towel rail etc?

Thanks to anyone who read this essay 😂

Martyn1981

Hiya Green....etc.
Is this news any use to you:

Sunak to unveil £2bn home insulation scheme

Under the Green Homes Grant, the government will pay at least two-thirds of the cost of home improvements that save energy, the Treasury said.
For example, a homeowner of a semi-detached or end-of-terrace house could install cavity wall and floor insulation for about £4,000 - the homeowner would pay £1,320 while the government would contribute £2,680.

joefizz

Greenglockenspiel said:

We are having one of the bedrooms replastered - would it be a good idea to get internal insulation put on the one external wall as part of this refurb? There’s a window and a radiator on that wall and the airing cupboard door also opens towards it so how much space would we lose?

I’m also hoping to do up the bathroom in a couple of years. The floor is really cold because of the concrete base to the extension and there’s laminate flooring in there at the moment which I am thinking of replacing with karndean type stuff. Would floor insulation be effective/take up a lot of depth? Or likewise underfloor heating? There isn’t much space under the door to lose! Before I had clocked the possibility of cavity insulation I had thought about putting internal insulation before re-tiling the walls - would doing both be overkill? Can you even do internal wall insulation in a bathroom due to weight of tiles, sink, heated towel rail etc?

Thanks to anyone who read this essay 😂

Very similar to what I did although Im in a 1980s timber framed bungalow.
When I was getting the bathroom redone I removed the bath and put in a big shower and then moved the sink and toilet around. The best way to fit all the plumbing in etc was to fit false walls rather than pull of the originals and then possibly balls up other stuff. When fitting the false walls you do lose a bit of space but I had plenty to play around with so went with space that would allow extra insulation on the outside walls. You have to be careful though with exisiting vapour barriers, particularly in kitchen and bathroom in a timber framed house but builder should know all about that and in your house that might not be an issue.

My biggest issue with the floor insulation is what you mention. I wanted to keep my doors (for some weird reason - keeping something original in the house!), old cheap sapele doors, and there was a limit to how much could be trimmed off the top and bottom and rehung. This was trial and error (fair bit of error on my part) and the limiting factor in the depth of the underfloor insulation. I was already replacing the skirting board, door frame surrounds etc so that wasnt an issue. All concrete floors here and only when doing it myself realised there wasnt a straight line or level floor in the house! I was originally planning underfloor heating (electric) in the bathroom under the floor tiles but space for doors and avoiding noticeable step up into the bathroom was advised against it. Now there is a slight drop (couple of mm) into the bathroom but no tripping at night walking in ;-) To do it all properly would have meant cutting out and redoing the bathroom floor and Ive sort of got used to (even welcome at times) the colder feel of the bathroom floor.

None of the above would be an issue if you were replacing the doors with solid wood ones that could be trimmed (my ultimate fall back position) but had enough leeway in my house for IIRC 6mm solid board insulation and in different rooms put one or two layers of the 2mm flexible on top of that. In an outbuilding I did from scratch I have 50mm jablite, ply sheeting then 2 layers of 2mm flexible insulation and laminate floor. It rarely needs heating.

On the internal wall/tiling issue I dont really know anything except to say that when I was getting it all retiled and the false walls were put in the builders advised waterproof plaster sheets (some may have come with extra insulation?) and then tanking it so that was done instead of extra insulation. Timber framed with no internal insulation so may not apply to your circumstances. My bathroom radiator is the overflow one so didnt want to overly insulate the bathroom internally (useful to have the extra heat 'leak' into the bedroom if that makes sense?)

Greenglockenspiel

Thank you both!
Martyn - I am definitely hoping so, it would be good to use it for the cavity insulation and maybe also towards a new composite front door if permitted. We were also already planning that as ours is a wooden one which is very draughty/badly fitting in the frame. 

Joefizz - that is good to know. I may well use this as an excuse for new internal doors as ours have such deep moulding that I have to dust them which is not how I’d rather spend my time 😆 We don’t have much space to lose in the bathroom and I want to keep the tub so I don’t think false walls will be an option but I’ve made a note of what you’ve said so that I can ask the bathroom people about the waterproof plaster and tanking. This house was rented out before we bought it so I don’t think it’s had anything much done to it for quite a while and it’s our first house so a learning curve 😊

joefizz

Greenglockenspiel said:

 We don’t have much space to lose in the bathroom and I want to keep the tub so I don’t think false walls will be an option but I’ve made a note of what you’ve said so that I can ask the bathroom people about the waterproof plaster and tanking. This house was rented out before we bought it so I don’t think it’s had anything much done to it for quite a while and it’s our first house so a learning curve 😊

Re-reading the plaster and tanking comment I think I left some info out. I had this done in areas around the large shower, so it probably makes more sense when that is added in! Originally Id wanted a wetroom but that would have needed serious digging into the concrete floor or raising the floor with a step up into the bathroom.
The waterproof plaster and tanking around the shower (one full wall and one half of one wall) dictated really how the rest of the bathroom went (rather than a step in the wall).