ProDave Posted December 7, 2020 Share Posted December 7, 2020 27 minutes ago, Mr Punter said: The outside terminals on mine have backdraught flaps and the fans have an iris that opens when the fan runs. Not as good as MVHR but I could not find space for the unit and all the ducting, plus over 4 storeys there would need to be lots of acoustic and fire stopping. Also, I like an externally ducted kitchen extractor. The recirculating ones don't do it for me. Our extractors all had the backdraught flaps. They just clattered and banged annoyingly when it was windy. I agree changing the fans for those with an iris would have helped a lot. Link to comment Share on other sites More sharing options...
Bitpipe Posted December 7, 2020 Share Posted December 7, 2020 I haven't worked out per m2 but last time I looked we were spending £1/day for gas and £1.50 for electricity (once FIT taken into consideration) for a just under 400m2 house. My supplier (Tonik) has just gone pop and been taken over by Scottish Power so once that's complete I'll be digging into the details again. Link to comment Share on other sites More sharing options...
MikeGrahamT21 Posted December 7, 2020 Share Posted December 7, 2020 All my figures are in my signature, I have electric hob for cooking, so gas is purely hot water and space heating. 1 Link to comment Share on other sites More sharing options...
JamesP Posted December 7, 2020 Share Posted December 7, 2020 (edited) Great topic @Oz07 All electric here in the new build, no gas or oil. We have MVHR, Solar PV with a PV diverter. A cat flap is the weak point in the fabric of the building. A bit difficult to be exact at the moment as our electricity usage is for 2 homes, 2 families with 9 people. The ASHP figure for the new build is approximately 4500kWh per annum. About 4500kWh for all other electric items. 9000 / 275 = 32.7 kWh.m2 Edited December 7, 2020 by JamesP 1 Link to comment Share on other sites More sharing options...
TonyT Posted December 7, 2020 Share Posted December 7, 2020 You do get a fan grill that has a shield that, fits into the external wall and the air has ton travel downwards to effectively escape the grill, also means the fan is less prone to wind blowing directly into the duct. Mine are black but along the general lines of https://www.cef.co.uk/catalogue/products/1740725-100mm-4-cowled-outlet-with-damper-cotswold Link to comment Share on other sites More sharing options...
AliG Posted December 7, 2020 Share Posted December 7, 2020 On 06/12/2020 at 11:54, Oz07 said: My god I'll have to knock this place down and start again. @AliG what are you all totted up heat and water per m2? My heating cost use is roughly 50kWh per sq metre per year. I am not sure it is worth putting hot water and the pool into square metres, you water cost would fall as you house gets larger. I also would struggle to split these two out, but at a guess we use around 14000 kWh a year for DHW and 22000 kWh for pool heating. If I added the DHW and heating I would get around 70 kWh per sq metre per year. Our hot water usage is a little heavy due having a circulating hot water system and also a wife who often takes more than one bath a day or a shower then a bath! My old place which was a pretty standard early 2000s timber frame developer house used around 125kWh per square metre a year in heat - Biggest contributors to this were probably a draughty raised timber ground floor and a large double glazed conservatory. Before we bought the new place we looked at a late 1800s stone built 600sq metre house. It was coming in at I think 4-500kWh/metre/year from what they said their gas bill was! Link to comment Share on other sites More sharing options...
SteamyTea Posted December 7, 2020 Share Posted December 7, 2020 30 minutes ago, AliG said: and the pool into square metres There are evaporation losses to consider, these can be quite substantial. https://dengarden.com/swimming-pools/Determine-Evaporation-Rate-for-Swimming-Pool Link to comment Share on other sites More sharing options...
AliG Posted December 7, 2020 Share Posted December 7, 2020 1 hour ago, SteamyTea said: There are evaporation losses to consider, these can be quite substantial. I just meant I am not sure it is worth dividing these costs by the area of the house as they are fixed and unrelated to the size of the house. The heating cost for the pool is actually quite low (Around 2200kWh/yr or £500), however the dehumidifier and pump use a lot of electricity. Between them and the Tesla my electricity bill is larger than my gas bill. Link to comment Share on other sites More sharing options...
Oz07 Posted December 7, 2020 Author Share Posted December 7, 2020 Yes @AliG as @ProDave said earlier if you can seperate water out its a more accurate reflection really. I was disappointed at high 60's all in if I can be bothered I may see how many units the meter clocks up on a shower and boiling some veg - how sad! I think I need to get that new MVHR unit on and balance and temper it down a bit, is yours all tuned up @AliG? By rights they do say that anything above 3 on an air test and the MVHR is uneconomical but your heating figures are not to OTT @MikeGrahamT21 how old is your place? @JamesP i'd seperate out the other electric usage if I was you, not really relevant to house performance. At the 4500 figure your m2 rate looks good! Link to comment Share on other sites More sharing options...
Mr Punter Posted December 7, 2020 Share Posted December 7, 2020 40 minutes ago, Oz07 said: I think I need to get that new MVHR unit on and balance and temper it down a bit I did not think MVHR had much impact on SAP and energy consumption. More a thing of better air quality and no draughts. Link to comment Share on other sites More sharing options...
Oz07 Posted December 7, 2020 Author Share Posted December 7, 2020 I got told occasionally MVHR can make a SAP score worse, but perhaps that is with a crap assessor? Also I remember reading at any air score below 3 they should start to save more energy than they consume but perhaps this is just for the leccy they use? Not allowing for increasing standing losses? OK I am getting seriously sad, just looked at meter before and after my shower difference of .253m3 is 2.874 kWh on the online convertors this is bringing my total kWh down by over a 1000 a year. Thats excluding the missus and and hob cooking and washing pots. I'm feeling better about it now! Link to comment Share on other sites More sharing options...
joe90 Posted December 7, 2020 Share Posted December 7, 2020 9 hours ago, Bitpipe said: £1/day for gas and £1.50 for electricity I like that kind of statistic ( even i can understand it!!,), all electric here, ASHP, MVHR, no PV (plus bottled gas fir hob) and my last bill was higher because the heating has just come on this month, and it works out at £3 per day. Link to comment Share on other sites More sharing options...
Oz07 Posted December 7, 2020 Author Share Posted December 7, 2020 3 minutes ago, joe90 said: I like that kind of statistic ( even i can understand it!!,), all electric here, ASHP, MVHR, no PV (plus bottled gas fir hob) and my last bill was higher because the heating has just come on this month, and it works out at £3 per day. c'mon @joe90 make the effort just look at a couple of bills! mind I suppose you'd have to estimate heating/other split usage @Declan52 you and @ProDave have the best performing up to now. Yours is pretty traditional construction isn't it declan? What width cavity do you have and what's in floor and roof? @tonyshouse post your numbers here @PeterW cmon I bet you know your figure? Link to comment Share on other sites More sharing options...
ProDave Posted December 7, 2020 Share Posted December 7, 2020 I bet if @Jeremy Harris was still posting here his would be the best. 1 Link to comment Share on other sites More sharing options...
Oz07 Posted December 7, 2020 Author Share Posted December 7, 2020 @JamesP figure is pretty good as well actually if that includes DHW? Whats your construction method and rough insulation details? Link to comment Share on other sites More sharing options...
Oz07 Posted December 7, 2020 Author Share Posted December 7, 2020 @ProDave i've dangled the carrot for him! Link to comment Share on other sites More sharing options...
SteamyTea Posted December 7, 2020 Share Posted December 7, 2020 23 minutes ago, Oz07 said: .253m3 For a shower, a quarter of a tonne. You are not in Cornwall, that would cost you £2. Link to comment Share on other sites More sharing options...
Oz07 Posted December 7, 2020 Author Share Posted December 7, 2020 those the figures on the meter Link to comment Share on other sites More sharing options...
SteamyTea Posted December 7, 2020 Share Posted December 7, 2020 5 minutes ago, Oz07 said: c'mon @joe90 make the effort just look at a couple of bills! mind I suppose you'd have to estimate heating/other split usage I have an energy monitor on @joe90's meter. Not sure where the data is as I have backed it all up, but did upload it once, so may check Drive/Onedrive and see if it is still there. Link to comment Share on other sites More sharing options...
Oz07 Posted December 7, 2020 Author Share Posted December 7, 2020 I'm pretty impressed with @AliG number tbh thats what started this thread. To have an air score of 9 or 10 and still to be coming in at 50kwh on the heating made me question all the hard work I did getting this place air score at 1. For the boffins - is it a case of the more volume the better efficiencies you get with heating - 900m2 is probably the biggest place on here! Link to comment Share on other sites More sharing options...
SteamyTea Posted December 7, 2020 Share Posted December 7, 2020 1 minute ago, Oz07 said: is it a case of the more volume the better efficiencies you get with heating - 900m2 is probably the biggest place on here! Yes, as the volume increase, the volume to surface area decreases, so large houses use less energy when measured by square metre. This is party because fixed loads are similar i.e. cooking, refrigeration, bathing. One of the reasons mine seems to high, but my total usage is pretty reasonable. Link to comment Share on other sites More sharing options...
JamesP Posted December 7, 2020 Share Posted December 7, 2020 6 minutes ago, Oz07 said: @JamesP figure is pretty good as well actually if that includes DHW? Whats your construction method and rough insulation details? Yes that includes DHW. Stick built timber frame, From the outside : Cedar cladding, Counter batten, Batten, Breather Membrane, 40mm Pavatherm, 260mm Rockwool cross layered, VCL, OSB, Batten, Plasterboard, Skim. Link to comment Share on other sites More sharing options...
Oz07 Posted December 7, 2020 Author Share Posted December 7, 2020 Similar in roof too then? Do you have an insulated foundation? Link to comment Share on other sites More sharing options...
jack Posted December 7, 2020 Share Posted December 7, 2020 Mine's hard to work out due to the 8.5kW of PV on the roof, but looking at the two meters, covering almost exactly 5 years: Electricity: 35598 kWh (= around 7100 kWh/a) PV: 37583 kWh (= around 7500 kWh/a) House is 289m2 If I assume we used all generated energy locally, that's 14,600 kWh/a, or about 50 kWh/m2/a If I assume we used none of the generated energy locally, it's roughly 25 kWh/m2/a The truth is probably somewhere in the middle. We don't try that hard to time our usage of electricity, and my wife's a massive user/abuser of the dryer (which at least is a decent condensing model), so on balance I don't think the numbers look too bad. I did look into this a while ago and I seem to recall that our feed-in tariff payments just covered our electricity bill. One day I'll get around to measuring how much of our generated PV we self-consume. Link to comment Share on other sites More sharing options...
Oz07 Posted December 7, 2020 Author Share Posted December 7, 2020 That's lock stock though isn't it @jack like steamy tea includes even appliances etc etc. Heating alone is the most accurate measure as Dave says Link to comment Share on other sites More sharing options...
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