Muellar

Thank you all for the input. Hope you've managed to have a lovely Christmas and New Year... I've put the effort in too and @SteamyTea i've adapted what you sent to me but only because I'd got the devices and loadings already mapped out given the room layouts and my thinking behind what would be used in each area. So here's my workings, warts and all on the basis of @SteamyTea and his rationale as well as applying BS7671 methodology to what I would suggest as being the ring ciruits just from my gut feeling using a video I saw. As a summary of the sheet: Using @SteamyTea principles I get total daily KW of 7.3 in winter and 4.5 in summer Applying the same number/wattage of devices and using BS7671 I get a total need of 42kVA If i take into account all the considered opinions, i'd take 25% of BS7671 as being most likely demand, so about 10kVA say in winter... It does show the demand that comes out from ASHP purely due to it's wattage rating alone and the application of the code. Heating and cooking is about 50% of the kVA using the code and applying the diversity rules. Maybe i've got it wrong, but without taking a course I feel i've applied it fairly closely. Interestingly, I found this really useful videa on youtube, https://youtu.be/7MhH-k6pEgI and the big takeaway I took from this was as the guy points out, that even in BS7671 it states it's impossible to work out. There's been other things i've seen where an electrician even pointed out that using the code his home installation woudl be illegal, but in reality it actually consumes about 1/3 of what the code would produce, even on a winter day with his kids leaving lights on! So I'm going to stop now and share my workings, but this has all given me the logic to go to NIE and state I don't need a 40kVA 3 phase supply and may maybe not need one at all if I go off-grid, but what would they charge for a 100amp supply and see what they come back with. However the more I've looked at this the keener I am to try and not connect to grid, have a mixed supply (PV, Ridgeblade, Log burner with heat exchanger and a back-up generator etc) and to log it all so anyone can see how well it works. Hope this is helpful/useful to others as i'm very grateful for your input. Electrical workings and key figures_01.01.25.xlsx

Now I'd originally thought of having something like that, but was told 'don't be silly'. i'd seen a Woodfire EX15 that i'd quite liked, and had seen that not only would it be a nice feature, but we'd also have back up should things go bad - like recently during the storms and power went down. This whole experience with the cost of power has really made me think that maybe i'd dump the whole induction hob thing and go with Calor gas tank for cooking use and also a boiler to be used now and then, with adding in the Woodfire EX15 for use during winter and as a back-up. Then go back to NIE and ask 'how little can you give me' just for small power and other items.

Yes, Northern Ireland Electricity. I've made my own attempt at a sheet but I got an even larger figure... duh. Thanks for offering to knock one up for me, i'm very grateful.

lol... you've reminded me of a Father Ted sketch @Conor, thank you! And yes, it's how I felt when I saw the calcs come through I just couldn't believe the figures being presented but they stood by their calcs and this is an area I get confused in so I left them to their stuff being told by the architect they were good and could 'work wonders with NIE'.... unfortunately not the wonder I'd hoped for.

I assume so as the engineer did all the dealings. I've seen he's said that NIE will want to upgrade the transformer to a 50kVA regardless of what we want as it's currently at capacity. He said that a home such as ours from his experience would need 35-40kVA and we can have that but as single phase, not 3 phase. My conclusion is that NIE are holding a gun to my head now as they want me to pay for a transformer upgrade even though i'll only be 1 of say 20 properties drawing off it of which several are farms with milking parlours!

hope you're sitting down.... engineer came up with peak demand of 40,000 watts, so suggested a 3 phase supply of 41 kVa. I'm being told that I can have all the supply needed but as a single phase and not three phase supply. I reckon this is why the cost is as high as it is.

I tried this and got myself in a pickle. Created various spreadsheets and am now completely confused by the whole thing which seems to be a bit of a dark art to me. My current view though is given the feedback, is that i'm very tempted by the micro CHP route and getting a Calor gas tank put in. That way I transfer all the heating load and electricity gen to that particularly during the winter months when the PHPP calcs show the need. Once we are outside of Nov/Feb the heating need drops off, then CHP would decrease till we get sufficient from the PV/Batteries.

It is up on a hill but NIE have said they need to replace the whole transformer and want to charge me for that as opposed to just adding in my portion so they are playing a game in my view with me as i'd heard the transformer was up for replacement in any case. Now i've been looking into this seriously I'm tempted to go the CHP route that @SteamyTea mentions and using that at least for all the heating. To me it makes sense as winter months is when I would need the heating and is when PV output would be lowest, so having CHP doing that at least would be the way to go. If that get's me below a threshold then great, maybe NIE will see sense. Moving the house isn't possible.

We've got 300m2 so I guess size is maybe the issue as we've got a very low overall need for heating as a result of the ICF/Flooring/Roof and glazing (most glazing on South/West). All indications were we only needed a 6-7kw ASHP. The micro CHP may be the way to go given the cost NIE are wanting to upgrade the transformer and lay in the new supply @£35k. it may be that I just have to 'suck it up' but I feel they want a silly amount for what is a well designed home.

Thanks @SteamyTea... i've already got a quote for 5.22kw PV array with 2x batteries/inverters etc, but that won't deliver that amount all the time so I'd thought of adding in a wind turbine as we are on a hillside. I see there's micro CHP which could be a route as that would supply the heating/hot water so woudl offset what the ASHP would have consumed. Ideally I need to find someone who can do a proper calculation on the power needed so I have that with more certainty that the bowl of porridge it currently is for me!

£35k to have the connection to the grid via NIE who want to upgrade the local transformer.

Hi I've had a crazy quote for power supply and wondered if anyone has had experience of going totally off-grid at least for electricity supply and if there's someone you've known of who's been able to solution up a whole system? I'd already got plans to put in a 5.2kW pv array with battery packs etc and I'm thinking i'd be happy to go with the extra cost of a wind turbine (which will need planning) and then a back-up generator, but i'm lost as to how to work out the calculations with any degree of accuracy. Merry Christmas and best wishes for 2025. David

I should have added that I the main bed will have a balcony so the windows are quite set back, same for the larger 8.4m so we'll also look at practicalities of shading as we get more into it but I guess you can only design so much out/in. Not sure if you saw my original post when I joined, but we've got these windows all there becuase of the view out over Lough Neagh. We did toy with reducing window area, but we felt we'd just ruin the point of building where we would be, and thermal gain/overheating was on the top of my worry list. But great that you mentioned it. Thanks.

I did wonder about that JohnMo, however the PHPP came up with no issues on overheating when I put in the stats for natural ventilation and as we're on a hillside outside Antrim we can readily open up and ventilate - fly screens needed! I'd seen more benefit from the heat gains in late autumn/winter/spring than a risk on overheating given location (temp/wind) and the limited days of sun/warmth we have. lol

@Nickfromwales@JohnMo sound advice and is what i've done previously, it'll be intersting to see the relvative cost difference between D/TG from the same supplier, that is where I'd be looking at the pricing in detail than purely going for a cheap set of windows. Interesting comments on bi-fold v sliding. My head was in the place that sliding would be more water/air-tight than bifold (fewer moving parts/less seals etc).. Your 'bifold over sliders every damn day' has got me thinking. Just to give you some context, we have 3 main large openings. Main bed = 5.5m, Kitchen/Dining/Lounge = 8.4m and Rear onto patio = 4.4m. Our SE has managed to design in a beam so the 8.4m opening can be clear span.

@Russell griffiths @Nickfromwales DG/TG conundrum is really down to weight and value for money on the extra cost of TG against benefit gained. We will decide when we get quotations. Should be easy for a supplier to give us both once they've got the sizes and type entered. @Conor being in tropical Co Down you've made me think about resizing up our heat pump as we'll be up on a hill outside Antrim (210m above sea level) so it'll be a lot cooler than where you are is my guess. I thought i'd accounted for this but your comment re running it for 20hrs has made me think... we were going to have a wood stove but removed that, now I'm wondering! In terms of the glazing thanks for the comment re Feneco; the largest sliding doors we'd have would be 2.3m wide, we've got a few sets of them.

Hello It’s been a while since I posted as we’ve been busy with design updates, as well as being busy working to save money for a new build! I’ve also been reading articles here (thank you all) as well as doing my own attempts at calculating loads as there’s quite a mixed view and now I’m in a position to share what I did in the hope that maybe it’ll be helpful for someone else and to discuss on this forum. Some key figures about the house are: 1. New build ICF on a hillside outside Antrim 2. Nearest weather station is Aldergrove but I adjusted for exposed site 3. Zinc/Ali clad for 30% of the perimeter then timber cladding for the remainder 4. Total NIA is 290m2 and habitable (excluding garage and plant room) is 243m2 5. Internal volume is 946/822m3 respectively. It’s large as we have a few vaulted ceilings to make the most of the views out towards Lough Neagh 6. There’s 186m2 of external walls with 91m2 of glazing 7. U values I’ve got are walls will be 0.14, floor 0.13 using TLA, vaulted ceilings/roof is coming out at around 0.1 and windows will be a mix of DG/TG – DG purely for sliding doors due to weight 8. Will install UFH with an ASHP, maybe GSHP as there’s a lot of digging anyhow Using the spreadsheet provided by Jeremy Harris I got a total heat loss of 6394 watts. I then went a decided to buy the PHPP software to learn more, and put in all the data needed. That took a lot of effort and I had to fiddle the windows section but that came up with a lower figure so I’m having to work through it again when I get some free time. The profile from PHPP looked right however, max heating in Jan/Feb/Nov/Dec and correlated with what a couple who built an ICF home in the area back in 2019 have found with their GSHP. Here’s a copy of the PHPP losses profile: The initial PHPP results are coming out at 28 kWh/(m2a) and a heating load of 15 W/m2 which was arrived at from a max total of 65.7 kWh/(m2a) which was then reduced by solar/internal heat gains of 38 kWh/(m2a). I need to spend more time on this PHPP sheet to ensure I’ve got it right as the figures just seem too low, and I’ll do that when I get the time. We are now producing the necessary working drawings and will get the electricity load calculated on the basis of a 7kW heat pump unit.

I've never been a timber frame person, grew up in a home of builders and played with blocks as a kid and then along came timber frame, all the damp issues, rot etc... I know things have come a long way but I like that mass/heavy build. Now I know NI isn't Florida so we don't get hurricanes, but to get the view we'll have well we aren't in a sheltered location in a valley basin... we'll get whatever the Westerly throws at us and you only have to look at the orientation of the main runway at BFS airport to see what way those prevailing winds come. Oh, and that's pretty much our entire front orientation. And it'll be windy (noise) so I'm factoring that into my thinking here too. It wasn't my reason for ICF, I helped a friend out who built with it back in 2017 and the finished units he and his wife have built are really nice to be in, quiet and just darned comfortable and solid. They ticked all the boxes for me. And like you i'd love to see some real stats on ICF v Timber frame v SIP v Clay v Block/brick cavity... Controversial; do you think that owner builders take a longer term view than a builder/developer who wants to flip and move on so see the value in ICF beyond that initial build cost? I only say that as I've had this in office builds as the client where i wish the developer had just spent a bit more and made my ongoing costs and functionality better for me as the occupier/user. We're looking to build and live in our home for as long as we can, so our 'payback' horizon is say 8+ years.

Thanks @JohnMo it was a conclusion an ill informed me had come too after picking up initial hesitation of NIE and also reading up about power issues generally where ASHP was mentioned. But I also recognise that we need to have some decent calcs on it all and that is now the next path - take the outline design and work it up more thoroughly so we know what losses/loads we'd have so we can decide. But feedback from you and others is making ASHP look more viable - thank you and all. Sounds like we may have a similar design at least in part as we'll have valuted ceilings - at least in the living/kitchen/dining area. Most post of those plans I have....

This is very interesting and helpful thanks. It is changing my thinking in a good way as if a HP is viable then we could go all electric. Yes, there is a pole transformer that NIE have said will need upgraded, I estimate that it's about 250 metres from from where it would eventually terminate. Unfortunately I can't find the original documents that I asked for when we were looking at whether the site was viable in terms of getting utilities to it and the cost of these. I made initial enquiries just over a year ago and then concentrated on the site legals/planning as there were a number of issues to overcome that could have killed the whole project, so they took priority. In case it helps we will be 120 metres away from 2x 5 bed detached houses and about 200 m from a farm. One of the houses has a Tesla and a charge point.

NIE haven't given a thing, it was early stage enquiry so I can see how @Conor advice is the way to go. I'll need to get calcs done etc then go to NIE and have a sensible discussion I guess with some figures to hand to help. Funny you should mention induction, a friend has gone that way and I'll pop over to see it. At present we have a Neff hob with a wok burner and I use it all the time.... old habits eh. Thanks for the point re U values. I was wondering about just how insulated they are and cold bridging with the larger ribs from inside to outside but was told 'that's not an issue with the way the thermal dynamics work'. So essentially I need to set some time aside and see what I can work out, possibly with my architect who is new to ICF but keen to understand it as he believes it will become used more frequently than it is now.

@Alan Ambrose it certainly looks that way, there's also some healthy debate as well which I liked. I've uploaded a couple of images now I've found the 'quote' functionality.... cropped as there were people to the left but the view does go around. For context the water in the image is Lough Neagh and you can just about make out the hills in the distrance - can't decide if they are actually the Mournes or not but I'm told on a clear day you can make them out. I spent a lot of time in this part of the county and always dreamed of having a view like this so when the site became available I moved fast.

@Conor ahhh, County Down, was very tempted to find a site there but North Coast and family drew me to Antrim area and then a site with a view that ticked a number of boxes became available. Woodcrete was attractive to me as the idea of making somehting more natural appealed (used wood, cement, lime... ok, not 100% natural but aside from building a mud house with fallen dead wood I ran out of options) and the blocks have a nice weight but easy to handle and reduced the risk of blow-out. Also they looked to be more viable for rendering onto without special additives, then being able to fix into anywhere and/or chase also appealed. Yes, that was an issue a friend of mine had who's an architect... who would build as there's not many ICF builders around. I've done a few projects over the years and build an extension as well as PM'd some small house builds, so I thought that if there was something I could do then I would. Clearly the gas is an issue, and maybe NIE will come through, but for now they are 'No way' so I need to explore options. I'd come to the conclusion (purely on my own) that I will need some sort of backup for heating, and that meant oil/gas/wood.... preference is gas/wood gasification, and as the Mrs wants a wok burner then I veered towards gas feeling that it would have to be there in any case. So many bad stories of wood chip and pellets that I discounted that option.

@Iceverge Thank you for the welcome. A friend built with ICF and I liked the feel. The site is fairly exposed on a hillside, so I wanted somehting solid and the more I looked at options the more I felt that ICF was a viable and good option. Then I say the woodcrete blocks and they appealed to me. I'd even looked at the clay building blocks and liked them over SIPS, purely for the mass and solid nature of the build. I've always believed that cavity wall has had it's day and we need to have more mass on the inside, so ICF appealed. Wood supply is not an issue and we do like a modern wood fire, however whilst it's a 'nice to have' we will assess it's viability. There are a number of things we'll have to take into account and whilst it suits where we live now it may not in the future. Would I just post the plans as a separate posting or as a new topic here? Sorry, maybe a dim question but I'll claim newbie learning as my excuse 🙂 lol

I'm looking at doing a self-build in Northern Ireland, hillside overlooking Lough Neagh and we have planning permission approved for a 1.5 storey (as part of it will be basement to make the most of the slope and eaves height restriction). It will be about 280m2 in area. To make it minimal impact we decided to go with a dark metal/zinc cladding on the main front/side and we would have a simiple render on the rear as this will be east/north orientation. Due to the location and exposure I was going towards ICCF and the woodcrete blocks - I've read the various pros/cons and love/hate with Durisol which still baffles me. The more I read the more I feel that even Isotex has issues as well. I may end up just going with one of these EPS blocks, but I liked the idea of a more natural product onto which I could render and have some breathability. The search goes on..... As for energy and heating my current view is to have UFH, a wood burning stove in the main living/open plan area with a heat exchanger to get some input to a hot water cylinder/thermal store. I am also considering PV both on the roof and nearby as we have a large plot and maybe even throw in a Ridgeblade to make the most of the likely winds we will get. I'm not sure if I'll be able to get a heat pump in, be either gound or air sourced, due to the draw and notice by electricity provider that it's unlikely they'll support the draw, so I am considering having a tanked gas system if I need it and supplementary boiler. Whilst we have planning permission we are now moving to detailed working drawings. We need to dig and lay foundations in August 2025 so there is a bit of time, but not loads. Hence I joined this forum as I'd read some contributions and felt that it woudl be good to learn more and also where possible provide some input and lessons learnt along the way to others.