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Author Topic: Advice needed on 'greening' an existing building  (Read 12433 times)
desperate
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« Reply #30 on: October 04, 2019, 07:28:56 PM »

Hallo Mart, me again facepalm

Have you considered an entire rebuild? IE knock it down and start again to modern specs.  We are planning something similar and TBH refurbing the existing is soo bloomin expensive and nowhere near as good in the long run we may well demolish the existing building and recycle as much of the materials as poss.
Re-build costs come in at about 1200-1600/m2, food for thawt??

Desp
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kristen
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« Reply #31 on: October 04, 2019, 07:47:57 PM »

I've not been here for a while ... sorry, got a number of ideas, sorry for long diatribe that follows

I do not believe a solid house made from stone,concrete etc needs AC. The thermal mass makes a good job of stabalising temps.
We have Passive House extension,and all internal walls dense-block, so very little temperature fluctuation day-to-day and high thermal mass.

In the 2018 heat wave (went on for weeks) the temperature climbed to 25C (extternal was well over 30C day after day for a couple of weeks), that's quite uncomfortable to "just sit still" in. We used night-venting to cool, but in order to achieve that you have to be there, to open windows / security, so if we went away for a couple of days there would be no night-cooling. and we would gain a degree or two, which we then couldn't lose the following night. Lets the flies in too.

Personally, if I was putting UFH heating in, I would have reversible heat pump and cool in summer (when PV would be plentiful)

Including a complete new septic tank

We put anew digester thingie in when we were having major work done, on the grounds that the septic tank was old and might well fail in near future. We were able to re-pipe all downpipes, which just went to soakaways nearby (too nearby maybe??) to the old septic tank, and now use that as rainwater harvesting

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re-wire

did that too in the old part of the house. 4 x CAT5 to each room, and HA for the light switches. Seemed like a huge expensive luxury, but having now lived with it for a number of years very pleased to have done it. The main benefit was to reprogram the switches after we moved in and only then realised what we would actually want each switch to do. And we have added some "master switches" for things like all lights off when going to bed; and also all upstairs lights off at 10AM - I have no idea why visiting kids turn on a light in the morning, and leave it on, rather than open the curtains ...  also "pathway" switches to light all the way to kitchen (from upstairs; from the patio when coming in with an arm full of dishes after day turning to night on a balmy summer's evening, and so on. Alarm brings on all the lights in the house; "vacation mode" makes it look like we aren't away (ironically ..). Basically it just gives us flexibility over what the switches do. We haven't actually changed any circuits since a month or two after we moved in, but we changed lots in that period. We have at least half a dozen lighting circuits in the kitchen, individual dimmers for those would be an a nightmare to set each time, we just have 3 switches for 3 different "scenes" - Cooking (full blast!), Chill (subdues) and then Gentle (a coupe of steps down from Full Blast)

We also put in a whole house, plumbed-in, vacuum cleaner. We like that. "Bag" is in the garage, empty less than once a quarter, and all the "recirculated dust" that makes it through the filter of a conventional Hoover is confided to the "bag location"

Another suggestion: put a single isolating switch, with "neon light", for all the white goods in the utility room. These days they all use some parasitic power when "off", which annoys me even if 1W, but so many stories of fires, recalls, and even recalls-after-fixed ... I'm more comfortable with everything physically off when not in use / when we are away.

Alarm, including Fire Alarm (rather than a battery one that you might not hear ... our Fire Alarm sets off the Burglar Alarm sounder, no way of sleeping through them!)

CCTV?  Seems excessive, to me, but I would prefer that either the blighters do over someone else or, if they come in here, I have some nice piccies to give to Boys in Blue. We have both overt and Covert cameras, and in the sheds, and where yobs might come over the fence at the back and muck about smashing stuff.

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ceilings are simple no complicated architrave

We put in pukka plaster architraves in all the rooms after rewire/redecorate. Made a lovely improvement, and was one of the least-cost, best-feel-good, things we did

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Next we move on to PV. ... export, hopefully of 7,000 x 5p, £350, giving £800 pa

Battery and self-use, rather than export?

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They almost certainly will be moving to BEV(s) in the future, so additional benefits possible.

BEV has to be at home during the day to benefit ... Our primary BEV goes to work each day; we have debated having 2nd BEV and toggling them each day, so that "the other one" is at home charging from PV, and doing that instead of Battery (or instead of 2nd battery). Shifts £7,500 from battery-budget to 2nd-car budget

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Now for heating. ... ASHP could be good

My staring point for ASHP (or GSHP) is UFH, and thus hard floors throughout and no carpets.  Also very high levels of air tightness and insulation, so that the low temperature heating easily copes and the house is toasty warm for piddly-little amounts of energy.  Having, personally, gone for "zero energy" I now advise "Go for max comfort, but still tiny amounts of energy" instead.

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one or two wood burners anyway, but which are not planned for heating the house, just top up

We use, solely, the Wood Burner Stove at the shoulder Autumn/Spring ends, instead of boiler. House well insulated, MVHR moves the heat around, and the "fire" is a very cheering sight.

Our Wood Burning Stove is Passive House certified - it has its own external air supply, so as not to compromise the air tightness layer (by Building Regs requiring a wide open air-brick in the room!)

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some rads are doubles, but closer look needed ...

With Heat Pump if you don't go UFH then likely to need much bigger RADs (for lower temperature CH water). If you insulate much better then original sized RADs may well turn out to be right-sized

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So where am I going wrong? What am I missing?

As others have said, I too would aim for "no heat" rather than "not much heat". I would still install heating, in order to be comfortable. But well insulated, air tight, the heating requirement is tiny (Passive House has design requirement for peak heating to not exceed 10W / sq.m., so a one-bar-fire would be sufficient for an average 3 bedroom house Smiley )

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she would like a WT

I've considered that, each time I raise it on this forum the general advice has been that amateur sized ones are relatively high commitment, and I don't really want that sort of solution. PV, by comparison, is install-and-forget (but the wind blows during the dark of course ...).  Solar Thermal IME is high-maintenance, but subjectively from posts here I would say that for 50% of people it is zero maintenance, and the other 50% is more maintenance than makes economic sense.  I would NOT bother with Solar Thermal again, I would install extra PV and convert that into hot water only when I wanted it, and use the extra PV juice for something else the rest of the time.

Personally, I thought EWI would be a good idea, but it's an awful lot of surface area, so costs might be too high

I'm in the EWI camp too. The real gains come when you have good insulation, air tight, and zero cold bridging.

If your external brickwork is beautiful its a difficult decision. If not then cheapest is bang the insulation onto the outside of the walls and render over that.  The insulation join at the top, "under" the roof eaves and joined to the loft insulation, is the tricky bit - kinda "jack up the roof, put the insulation in, and lower the roof back again"!

Cold bridging becomes exponentially more problematical as the rest of the building is improved. If it gets to the point where it starts rotting things its very expensive to sort out.

If it causes convection draughts it wrecks the whole "comfort" benefit (Passive House wants window inside surface to be no more than 4C colder than air, in order NOT to get falling air / convection / draught / turn up thermostat / exacerbate!)

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hence the IWI compromise

Get a Passive House consultant in and see what they say.  I reckon the money, spent on the advice, will rule out (or in) some choices, and focus your mind on things that have a more certain outcome.

IWI steals all your, internal, thermal mass, so you can't "store" solar energy from the sun when it is helping in Autumn, Winter and Spring, and you are back to "lumpy" temperature swings.

many, and large south facing windows

You need to keep the sun off them in Summer, but encourage it in during Winter - eg. with overhang.

Helpful to also keep the sun off the West facing windows too - deciduous trees some distance away are ideal.  East side too, but sun / air temperature cooler in mornings, so of the three I think that least important to protect.

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the smaller number (and size) of north windows might benefit from triple glazing

Triple glaze the lot. Price differential DG / TG unlikely to be significant Pay attention to the frames and avoid and cold bridging etc. and make sure installation integrates with the insulation layer so that is "continuous". You need to be aiming for the inner surface to not get cold and induce convection, and therefore draughts; I doubt you can do that with DG.

We bricked up 50% of our North windows. They weren't really needed, and were hugely disproportionately cold. Those rooms , which were Arctic in Winter Sad, are now snug. Of course if that is the only window in that room its not a good choice!

One of the biggest difference makers I found and it was late in the process was the search for air gaps.

We had air tightness test of the main house, before we ever thought about building a Passive House extension or major insulation initiatives. Also had Ivan round one freezing cold Winter evening, with his Thermal Camera, having had the heating on full blast all day. That was helpful to see heat-leakage (pleased to say we didn't have much).

We blocked up all the air leakage - amazing some of the places that blower-pressurisation smoke test found gaps to escape through ...

Have you considered an entire rebuild? IE knock it down and start again to modern specs.  We are planning something similar and TBH refurbing the existing is soo bloomin expensive and nowhere near as good in the long run

This is excellent advice. Wish we had new-built, rather than improving. And our outcome was that even with a relatively easy building to convert (1960, mostly "poured concrete") it was still far too difficult, so we built Passive House extension to hibernate in during Winter.

Knock down and Rebuild, to Passive House standards, will create a fantastically comfortable building, with the associated known additional health benefits, and capable of being heated on diddly squat of energy.
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todthedog
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« Reply #32 on: October 05, 2019, 06:27:14 AM »

I think the knock it down start again school has a lot in it's  favour .  Certainly  worth doing the sums. You get exactly what you want.
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Kidwelly South Wales
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« Reply #33 on: October 07, 2019, 07:05:52 AM »

Make sure there are underground ducts to any outbuildings from to where the location of the fuse board.

Same to where the boiler will be, it may allow you to pull in cables and pipework later without disrupting already finished areas.


You could live with the  oil boiler during the works until the insulation has been upgraded then install heat pump with a lower demand.

And wire up some cat 6 cabling in the house, helps with fixed appliances and helpful for additional Wi-fi access points
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M
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« Reply #34 on: October 07, 2019, 12:55:52 PM »

Hello again peeps.

Had another good chat with Sis. She was explaining that whilst they have access to the property, nobody will come out and look at anything (apart from the septic tank guys) until transfer is complete - which is fair, they don't want to waste their time.

I mentioned the knock it down suggestion, and it wasn't, shall we say, favourable. But it did raise a few chuckles. And as half of it is 140yrs old, Sis thought that would be a shame.

Regarding current boilers, whilst they are old and haven't run for a few years, the plan is to get them inspected and serviced if they are viable to get some heat this winter, otherwise, over to leccy heating (oil rads etc) and warm clothes. The two boilers and heating systems are separate, serving the old and new sections respectively, so, so long as one works, they can simply live in that part of the house.

EWi, whilst a bit scary, is certainly of a lot of interest. Sadly, the outside walls etc are in reasonable condition, so no killing of two birds, and part of the structure is very nice to look at, but certainly the possibility of doing some of the front/sides, and all of the back (north).

The property is licensed for caravans/motorhomes and has some power points in 'the field', so that's another big tick for PV, and 3-phase if possible. Plus Sis/BiL will be home most of the time, and also plan on getting an EV, so big PV and possible batt in future all getting ticks too.

Looking at the EPC, it's rated as needing up to 39k kWh's of heating, i assume that's based on a bad winter, as mine suggests 13k but we use around 6-7k kWh's of gas including DHW and oven.

Again sorry for the bitty nature of all this, and if things go well, should be able to give much better info in approx 3 weeks.
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Just call me Mart.     Cardiff: 5.58kWp PV - (3.58kWp SE3500 + 2kWp SE2200 WNW)
Countrypaul
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« Reply #35 on: October 07, 2019, 02:29:45 PM »

Can you clarify the point about needing 39k kWh of heating, is that per day? or 39kW for the whole property when its -2C or something entirely different?
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A.L.
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« Reply #36 on: October 07, 2019, 04:38:03 PM »

hello,

Can you clarify the point about needing 39k kWh of heating, is that per day? or 39kW for the whole property when its -2C or something entirely different?

Probably 39000 kWh per annum.
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Countrypaul
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« Reply #37 on: October 07, 2019, 08:05:10 PM »

hello,

Can you clarify the point about needing 39k kWh of heating, is that per day? or 39kW for the whole property when its -2C or something entirely different?

Probably 39000 kWh per annum.

Yep, how did I miss the fact it was 39000 rather than just 39?  wackoold
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M
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« Reply #38 on: July 25, 2020, 07:26:10 AM »

[Spoiler alert - help/advice needed on 3phase.]

Hiya all, been a long time, and thanks to C19 everything has been delayed, slowed etc etc.. Quick update and ASHP is the chosen winner for the property, and the original solid walls of the first build (over 100yrs old) that are external will be getting IWI. These only make up one half of one side, and approx 40% of the front wall. The rest will be getting CWI.

Now on to the fun bit. I went down yesterday as they had a PV company out to look at an install, and we wanted to discuss all options, such as asking for permission for high export, export limitation (not inverter capping) and potential of 3phase. Whilst we were chatting and with regard to this bit I posted ages ago:

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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.

my sister got a text message from the DNO who'd she'd asked for info on the location of 3phase, and they confirmed it is at the pole from which her leccy supply cable comes from, and if no transformer upgrade is needed then the cost of 3phase would be ~£1,700.

Now, I thought that sounded damn good, and would remove all concerns (hopefully) about ASHP spike loads, big PV, and even potential for higher leccy demand in the future, such as rapid BEV charging (7-22kW), the possibility for campervans etc to stay at the property. I mention rapid charging as the property will also be a small business, as my sister runs training, well being and mental health programs etc, and I thought that being able to offer BEV charging may be useful in the future.

So ..... sorry for the waffle ..... what are the problems, hassles, etc of having 3phase, and especially with regard to PV, and 3phase inverters? Am I right to think that at this price 3phase is a great investment as they are building out a 'greenish' future that will lean very heavily on leccy, with the removal of two oil boilers, and almost certainly BEV transport in the next 1-5yrs?
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brackwell
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« Reply #39 on: July 25, 2020, 08:37:41 AM »

Ones commitment to 3Ph ends where the incoming cable terminates in the house from there on in everything can be 3Ph or 1Ph.  3Ph stuff always costs more but is cheaper to run but would only really get used for high powered stuff perhaps the HP and EV charger say. It may help to get more on the PV front as well.

3Ph could allow you to do more things particularly there is a far chance the the incoming supply is fused at 60A which does not cut it in the modern picture compared to 100A/Ph.   Put like that it sounds like the 3Ph is a necessity.

« Last Edit: July 25, 2020, 08:44:41 AM by brackwell » Logged
kdmnx
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« Reply #40 on: July 25, 2020, 08:50:20 AM »

Pros of 3-phase:
 - That is about as cheap as you will ever get 3-phase power.
 - EV charging will be fast on 22kW chargers and enable better use of cheap ToU tariffs (the thought of pulling 44kW to charge 2x EVs during an Octopus plunge period might just be too exciting for some members).
 - You can have a 3-phase heat pump if you want. This shouldn’t be a factor because if you insulate correctly you’ll only need a small HP.
  - The DNO will be happier to approve a bigger PV system if it is 3-phase.

Cons of 3-phase:
 - Makes self use of PV more difficult. You can be exporting on 2x phases (at 5p/kWh) while importing on the other (at 15p/kWh).
« Last Edit: July 25, 2020, 08:51:57 AM by kdmnx » Logged

12x JA Solar 340Wp panels (total 4080Wp)
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benseb
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« Reply #41 on: July 25, 2020, 08:55:52 AM »


Cons of 3-phase:
 - Makes self use of PV more difficult. You can be exporting on 2x phases (at 5p/kWh) while importing on the other (at 15p/kWh).

In theory this shouldn’t be an issue as your meter should net the import across all 3 phases. In practice some meters don’t do this and trying to explain to your electric supplier what type of meter you need is near impossible (looking at you Bulb)

If you get a SMETS2 meter this won’t be an issue but 3ph versions not really available yet

We’re on a mission with Octopus currently to get a non-smart meter fitted that works with our solar.
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brackwell
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« Reply #42 on: July 25, 2020, 10:48:28 AM »

The 39kwh is the energy rating for heating  ie 39kwh/m*2/yr  so for a building of 200m*2  is 7800kwh/yr.   For the average house it is 6676kwh/yr so perhaps your EPC is after mods?
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Mostie
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« Reply #43 on: July 25, 2020, 01:47:39 PM »


Cons of 3-phase:
 - Makes self use of PV more difficult. You can be exporting on 2x phases (at 5p/kWh) while importing on the other (at 15p/kWh).



We’re on a mission with Octopus currently to get a non-smart meter fitted that works with our solar.

ABB spinning disc meter, say 4kw generated across 3 phases, switch on kettle, meter stays still  Smiley
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« Reply #44 on: July 25, 2020, 06:27:24 PM »

Thanks everyone, lots of positive comments. I think, given they will be re-wiring, that taking the opportunity now to go up to 3phase is just too good a deal to miss. The property is huge, hence the 39,000kWh figure for heating, though that will come down with the work they are doing, and these figures seem to be worst case, is that correct(?) as ours is around 13k but we use about 7-8k kWh of gas pa. for heating, DHW and oven.

I think they have a 100A fuse, but I learned recently that whilst you might have an upto 100A unit, the DNO prefers to fit 80A (this happened to us going from 60A to 80A), and whilst of course 80-100A is fine for most homes, in a leccy future with heat pumps and BEV's, a co-located business, and perhaps, maybe hook ups for campers, I think 3phase opens up so much potential.

Also, they have a good sized SE roof, so 8kWp looks easy, and I think in the future as they plan to build a small barn, it might be a good idea to give it a SW facing mono-pitch roof and slap on another load of PV.

Lots of potential. I'll pass on the comments.
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Just call me Mart.     Cardiff: 5.58kWp PV - (3.58kWp SE3500 + 2kWp SE2200 WNW)
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