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Author Topic: Advice needed on 'greening' an existing building  (Read 11559 times)
M
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« Reply #15 on: October 03, 2019, 08:41:32 AM »

OK, a bit more meat to put on the bones. May be a bit hap dash I think of things.

The property is slightly on the large side at approx 15m across the front and 9m deep. Two storey. Large roof and no plans/need to use it.

It is currently served by two oil boilers, reflecting the extension (approx 1/3rd), but both boilers are questionable at this stage.

Old building may well be single skin, extension is double skin, probably no CWI, though of course it envelops/removes the original single skin end wall on that side.

A lot of work is needed on the building internal and external. Including a complete new septic tank, re-wire and kitchen, probably around £100k.

Now for the good news, I hope. My sister is open to ideas and major work. they will be storing the vast bulk of their 'stuff' and will, as she describes it, be camping out in the new house to keep it all empty and available. She's also aware that a lot of time will be needed and when I suggested a second winter might break them, she said that was their plan too to hopefully be complete by Sept 2020.

From there, plus the fact that all rooms need redecorating, plus walls and ceilings are simple no complicated architrave, I suggested that IWI of 100mm PIR would be ideal across the external walls of each room - seems like the right time to do it?

I mentioned no plans for the loft, so that should simply be a matter of chucking 400/500mm(?) of 'fluffy' insulation down, and issues there?

Onto leccy supply, it is single phase but she took some photos of the pole across the road from her where the wire comes in, and it also has about five lines all going into the farm/business/yard whatever it is they are/do, which suggests to me that that pole has three phase, would that be a fair assumption? Obviously a bit more research needed though.

Next we move on to PV. The front roof is one single long roof, faces SSE, with two chimneys at the top/back (so north to panels. It is 15m wide and at a guess, from the depth of 9m and the average looking pitch (30-40d) I'd suspect 6m or more in height. So at 14 panels wide and 3 panels high and lowish (now) 300Wp, that would be 12.6kWp, so a figure around 10kWp would look easy, again depending on three phase. I've seen more Pv quotes (on MSE) getting closer to £1k per kWp, and a few going under when installs are 6 or 7kWp, so I've suggested a price for 10kWp of around £8k, possibly £10k.

The economics of the PV are surprisingly good, I guessed at 10,000kWh's, with 3-4k consumed, as the house will have leccy heating (back to that later) and DHW, so around 3,000 x 15p savings, £450, and export, hopefully of 7,000 x 5p, £350, giving £800 pa.. They almost certainly will be moving to BEV(s) in the future, so additional benefits possible.

Now for heating. Obviously we need to do more research but ASHP could be good. Especially combined with IWI and plans for one or two wood burners anyway, but which are not planned for heating the house, just top up. Looking at photos some rads are doubles, but closer look needed, and whilst it's tricky to work out from photos, the pipework certainly doesn't look like microbore to me, possibly 15mm, could be 22mm. Good chance rads (or at least some) need replacing anyway, and back to the empty house / camping, all seems to fit nicely as the time to do it, and do it properly.

Regarding ASHP costs, excluding rad work, i simply stuck a wet finger in the air and said that suggestions are £6-£8k, so given property size, and erring on side of caution, perhaps £12k to £15k as a guide. I did explain that a bigger size will push up costs, but bigger size means more heating needs, which in turn pushes up the RHI side.

So where am I going wrong? What am I missing? Does the entirely basic plan at this stage make sense? what else could we consider (she would like a WT, but I'd guess it neds to be a biggish one so that she can forget about it (to a degree), and this might be something for the future?

All thoughts welcome. Thanks guys and girls.
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Just call me Mart.     Cardiff: 5.58kWp PV - (3.58kWp SE3500 + 2kWp SE2200 WNW)
Countrypaul
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« Reply #16 on: October 03, 2019, 09:31:21 AM »

Whats the construction, you mention single and double skins, but nowhere I spotted indicates what these are made of or how thick they are etc. Are the ground floor suspended or concrete onto earth (or insulation) or stone tiles onto earth? How do services enter/leave the house, if there are lots of pipes going through the walls much more possibility of air leakage. What are the windows like (again I didn't see any comments about them but may have missed any).

Have you created a spreadsheet to work out estimated heat requirements and what effect the various changes might make?  Best to model the effect of any changes before deciding whether to implement or not.
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benseb
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« Reply #17 on: October 03, 2019, 10:21:26 AM »

Our House is twin walled stone and brick with 50mm IWI and is toasty, except for the lounge which is a bit drafty so need to fix that

If you can, it might be worth leaving some stone work revealed to help with thermal mass. Then when you get a very cold day you have a chunk of stone at say 20c radiating heat. Assuming youíve kept the room up to temp constantly

Ideally an internal wall so itís not bridging cold from outside.
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bxman
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« Reply #18 on: October 03, 2019, 11:05:12 AM »

 I suggested that IWI of 100mm PIR would be ideal across the external walls of each room -

 Sorry to disagree Mart .

  BUT all internal walls running off the the exterior wall will be a thermal bridge as will be  any of  the floors and ceilings joined to the external walls.

If at all possible go with EWI .

The structure of the house then becomes a  thermal store helping to modulate the house temperature through out the year .

good luck cheers Patrick
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M
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« Reply #19 on: October 03, 2019, 12:20:10 PM »

Thanks guys.

The construction of the extension (lhs 1/3rd of house) is brick outside finish, so presumably cavity wall, but an inspection will be needed to see if it's insulated. the rest of the house has a roughcast finish so uncertain.

Personally, I thought EWI would be a good idea, but it's an awful lot of surface area, so costs might be too high, hence the IWI compromise as decorating is needed anyway. But, I need to read the surveyor's report as some (possibly a lot) of external work is needed, in which case that would be a time to consider EWI, I think.

I'm hoping to go with them next time they visit, but my sister has said floors are solid and sound when I suggested underfloor heating, but we will see.


Sorry this is so bitty, but I'm learning as i go along, and sharing on here, and using ideas, points and suggestions to raise questions for more feedback etc..

Thanks to all, again.
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Just call me Mart.     Cardiff: 5.58kWp PV - (3.58kWp SE3500 + 2kWp SE2200 WNW)
todthedog
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« Reply #20 on: October 03, 2019, 01:55:38 PM »

 We used internal insulation to retain the look of the house (traditional Breton) also way way cheaper and I could do it DIY.
 CM did likewise different system easier to do if the walls are square.

Navitron share or used to the same address as Burley and the wood burners sold by Burley were rebadged by Navitron excellent fires worth a ring. Super efficient.

We found air/air ASHP really good. No rads.

We had concrete floor downstairs did not have the will to take it up for underfloor heating.
Ended up toasty and cheap to run.

On current Welsh pad CWI strongly  advised against by Building Research Establishment being in High penetrating rain environment .
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Kidwelly South Wales
M
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« Reply #21 on: October 04, 2019, 09:11:42 AM »

More info.

Start off, completely forgot to mention, despite being asked (sorry), it looks like all windows need replacing, some old wooden, and old tired UPVC. My initial suggestion/guess to Sis was that the many, and large south facing windows should be good quality but DG, to benefit from the most solar gain as possible, but the smaller number (and size) of north windows might benefit from triple glazing. Anyone have any strong thoughts on this, DG v's TG, solar gain v's heat loss, and so on?

Having read the surveyors report, it seems the old structure is around 140yrs old and single skin, but all walls are in reasonable condition, not great, a few cracks that need attention, but certainly no major works that would help to justify EWI, so I'm thinking the IWI with redecorating is the best course of action. I used a plasterboard coated 80mm type in one room in my house when we stripped out the bay and found it was single skin. Great stuff. Any thickness recommendations, success with 50mm sounds good, but if there are no space issues, would it be best to go towards 100mm?

Tod, to avoid confusion (mine), contact Nav about wood burners, is that what you mean? They already fancied one or two, and when I explained heat pump may have limitations some years, and that a back up was a good idea, that seemed to cement the idea. Also they have a lot of trees, and apparently two or three dead ones to remove, so whilst a little concerned about longer term and age, I think they could be semi-sufficient if it's only as a part role in the house.

I shall interrogate Sis again on Sunday, and she welcomes help from the forum, and importantly is well aware that I'm simply the one-eyed man in the land of the blind, so learning as we go along.
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Just call me Mart.     Cardiff: 5.58kWp PV - (3.58kWp SE3500 + 2kWp SE2200 WNW)
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« Reply #22 on: October 04, 2019, 10:27:54 AM »

I agree with the N-S DG V TG viewpoint.

On the South facing, backalong i worked out the solar isolation for the month of JAN was almost equal to a good DG windows losses for JAN.  This was without the effect of curtains and assumed up to temp 24/7 .  My conclusion was that it did not justify the expense but then TG prices may have dropped and become amore available.

Are you still thinking you can get RHI on the HP?  I have grave doubts.

Ken
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Moxi
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« Reply #23 on: October 04, 2019, 10:35:56 AM »

Hi Mart,

Don't be too quick to rule out the EWI, there are a lot of DIY kits for it now and it really does have great benefits over the IWI.

as an example here's a link to a companies guide - I have no affiliation they were literally the first that had a good guide to look at - also Mods I cannot see that this is in conflict with our host but if I have erred then please remove the link and accept my apologies.

https://www.theecostore.co.uk/install-external-wall-insulation-system/

I cant do the posh links like others so maybe copy paste?

Moxi
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Iain
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« Reply #24 on: October 04, 2019, 10:45:04 AM »

Hi
I have a solid wall brick house. the external render was cracking. Went for EWI as it killed 2 birds with one stone.
If you do IWI and damp is still getting through you will have problems.
At least with EWI you get an external waterproof coat, the rooms don't loose any size, the structure of the building becomes a heat store, penetrating damp is eliminated and can really improve the looks of some external finishes.
Noticeable difference on my house. cooler in the summer, warmer in the winter.
Heating requirements have dropped dramatically.

Iain
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« Reply #25 on: October 04, 2019, 10:50:59 AM »


Personally, I thought EWI would be a good idea, but it's an awful lot of surface area, so costs might be too high, hence the IWI compromise as decorating is needed anyway. But, I need to read the surveyor's report as some (possibly a lot) of external work is needed, in which case that would be a time to consider EWI, I think.


Hey Mart Smiley

We're fitting IWI in our house because it's listed but I'd definitely have preferred EWI. I don't see the costs as being cheaper with IWI as it involves major works internally that are above and beyond normal decorating. You'd have to remove skirting boards, radiators, electrical sockets, floor boards, window reveals and sills, ceiling boards. Then you have to worry about dew points and whether the joist ends that go through the insulation will start to rot away. You have to ponder what to do with internal walls that connect to the outside walls, ideally you insulate these too.  You can spread the costs of all this work by doing it a room at a time, but that just means you're living in a building site for years and it costs more as you don't get bulk discounts for materials and tradesmen always seem to cost more when they come out to smaller jobs.
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« Reply #26 on: October 04, 2019, 03:21:46 PM »

Again, thanks to all, I think my Sis is going to appreciate all the help and advice, and also rue the day she mentioned it to me, as she just wanted an easy life.  Grin

I don't know how much she can do, but she's in the perfect situation to do the best job possible if funds allow, and a few people have now mentioned converting the external walls into a thermal store (via EWI) which I completely agree with, especially if she does go down the route of a heat pump and needs to avoid peeks and troughs in energy demand.

Just today and yesterday I've been using the ASHP (A/C) to add warmth to the house, utilising some of ~1kW of PV generation in poor weather. If they were able to go with around 10kWp of south facing, then I'd suspect they'd be getting approx 4x the power I am, which is an awful lot of daytime semi-free heat.
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Just call me Mart.     Cardiff: 5.58kWp PV - (3.58kWp SE3500 + 2kWp SE2200 WNW)
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« Reply #27 on: October 04, 2019, 03:34:24 PM »

Wood burners ring navitron to see if they any contacts (do a deal type of contact) with Burley or do a deal themselves.

Wood burners do eat a lot of wood, which requires cutting, transporting, drying,stacking, restacking,storing , etc I reckon I was on first name terms with some logs prior to burning.
Our house was 150m2 and we burnt 9m3 a year.
 Mrs T said. dust levels have dropped since we no longer have a wood burner, but we have 1 dog not 3.

Double glazed in France, triple glazed in Sweden.  Triple glazed definitely better, for sound as well. Is there a huge difference in cost if installing a whole house.
-A mixture of the two if costs are tight. We have DG in Wales with no view  to  replace. Rarely hits -20c in Kidwelly facepalm


Both CM and I went 100mm insulation + pb.
EWI a no go as it would have changed the look of the house, DIY not an option at the time.







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Kidwelly South Wales
Countrypaul
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« Reply #28 on: October 04, 2019, 04:11:38 PM »

With repsect to windows, I went with Tripple glazed on the north side and double on the others when we renovated this house. The tripple glazed is also darker than double glazed (which is darker than single glazed) but since our Tg face North and into trees about 10 metres away the lower transmission levels make little differnce. In our case there are two sets of bay windows on the north side, each about 3m wide and 1m deep, the glazed area being about 1.5m high so a significant amount of glass which I felt could also lead to significant cold air falling from the windows (we have UFH) and causing "draughts".

It was more expensive than double everywhere, but in the total scheme of things the cost difference seemed minor.

We have only been through one winter and it is difficult to tell how much difference it makes, but there is no condensation on the inside - we do frequently see condensation on the outside though.
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« Reply #29 on: October 04, 2019, 06:15:51 PM »

One of the biggest difference makers I found and it was late in the process was the search for air gaps. It made a huge difference to our comfortable environment. Got a clipboard out, assessed every room and sealed up all the weird and wonderful found. Instadifference. Doesn't cost much and enhances the inside/outside border hugely.
« Last Edit: October 05, 2019, 07:18:10 AM by pantsmachine » Logged

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