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Simon R

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Simon R last won the day on May 6 2021

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  • About Me
    Retired form the computer industry. Like getting involved in projects, between my wife and I we have restored cars, built a boat, a done limited house renovation, new electrics, central heating and plumbing.
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    Lee on Solent - Hampshire

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  1. Your SAP calculations have a W/m2 and a W/structure per degree C values. Multiplying these by the HDD (Heating Degree Days) for your location or any other location will give you an idea of the annual energy cost.
  2. I'd put it in as late in the project as you can manage. Our went in after we had painted! Yes, it was a pain having to use ladders internally but it was also good having the open voids to get material in. Installing as late as possible also reduces the risk of damage which you want to avoid as much as possible. Fontanot do a very nice modular stair case with a good rage of different wood treadles which won't break the bank. It's a very minimalist staircase so not to everyone's taste .
  3. We also went this route having decided that an ASHP was an overkill for a property that didn't require much more than 2kW heat input. We're into our second year and it has worked out very well for our place which is open plan as the one A2A unit takes care of the whole house for both winter and summer. Our annual consumption for the house was 538kWh last year which included cooking , lights etc BUT not hot water which is provided by a small combi boiler. Installation cost less than 2K and it's a very comfortable way of heating and cooling. Considerably simpler than an ASHP and underfloor heating.
  4. It may be worth considering an outfit like Beastons https://www.beatson.co.uk/ they do all sorts of fan work.
  5. Well, I'm unashamedly in favour of home storage, even though it doesn't make much financial sense at the moment. It's just a year now since my 9.5kWh battery got commissioned, with a 3.6kw solar installation. So I have a full years data to go on. House is a well insulated 180m2, pretty much passive build. Our heating is from a 3.5 kW split air to air unit and has no problem keeping the house at 22c summer and winter. Electrity consumption total from grid 2814kWh, of which 339 was charged at peak rate and 2475 at low rate.. So I've used 2138 kWh at low rate that I would otherwise have paid the higher for. Of that 2,138 I estimate 1,600 ended up in the car so just 538kWh went into the house. .3794 - .0714 = .308 x 538 = £165.70 which sounds pretty dire. But that calculation ignores the 7mWh of solar generation. Of that 7mWh I only managed to use 4mWH the remainder went into the grid at of give away prices. So adding the 4mWh of solar I was able to use all of which was generated during the day 0.308 x 4000 = £1232 Annual saving is in the region of $1232 + £165 = £1397 given my system outlay was 6.5K that's not such a bad return. More importantly the energy exported added to the renewables component of other peoples electricity, helping to reduce co2 production. Regarding battery cycles. It's still an emerging technology but the data on Lithium Phosphate suggests they are going to last a long time. 12 year unlimited charge/discharge warranty is not exceptional. The company I got my battery from is now trialling a battery to grid pilot to use home storage to help balance out grid loads. This has to be the way forward in decarbonising the grid. True 9.5kWh is tiny but hopefully in the future the 50kWh in my EV will also be able to help. Tesla use Phosphate in the base model 3 and the data so far is suggesting that they may well last the 20 year life of the car. A figure of 2 to 4 times the number of cycles expected from the NCA batteries used in the other Tesla models GivEnergy have an integrated inverted battery package (13.5kWh) for £6650 just as an example of the current solution costs.
  6. Perhaps we should follow the Germans and make it law. https://www.renewable-ei.org/en/activities/column/REupdate/20220721.php Having no experience of house building, with the aid of the folks of on this forum have managed to build a very low energy house, so it's not rocket science. I had the choice of multiple build methods all of which could deliver a low energy solution. I also don't believe it costs appreciably more that traditional methods. We all know the story of the motor manufactures who pushed back against the cost of fitting seat belts....the same is true of the building industry today. The consequences of not fixing this is bad for the planet and bad for the economy.
  7. Have you considered a small air to air AC unit? there are lots of options in the 2.5kw power range are very efficient, cheap to install and run.
  8. Our MVHR input is typicaly 1.5-2 C below the output air temperature and as others have mentioned they don't move heat around as much as you might expect. Our build is upside down, with the bedrooms downstairs and this has had more effect than anticipated with a 2 to even 3 degree cooler temperature downstairs in the bedrooms. Heating inputs to a well insulated airtight structure are incredibly low. Have you considered small split air to air AC units to either heat or cool? they provide a very economical and efficient solution. I suspect that in many smaller (ours is 180m2) low energy builds heat pumps and underfloor heating are more than is actually required.
  9. This is just an altogether rather depressing thread, especially given the implications for lifetime C02 associated with the build. As several people have pointed out nothing is going to change until home buyers become aware of the real cost of not building airtight structures. It may help if buyers started demanding airtightness tests as part of their surveys. The test cost next to nothing in real terms and tell you so much about the cost to heat a structure. Certainly U values are important but nothing like as easy to verify as airtightness. I don't believe the big building firms will do a darn thing until buyers start holding them to account and to do this airtightness needs to be part of sales contract.
  10. Don't forget to look at solar gain. It can be a real problem if you don't get your window shading correct.
  11. Our south facing sun room roof (30degrees pitch) has two Roof Maker 2440x1200 windows with white internal blinds. They do a pretty good job of keeping the heat out.
  12. I think I hit on the Goldilocks zone by good fortune and a bit of calculation. Daily consumption runs in the region of 15kWh (including EV) Our battery is a 9.5 kWh GivEnergy unit coupled to a 3.6kW GivEnergy inverter and two PV strings of 6 panels each. The inverter will only deliver 2.4kW from the battery the remainder coming from solar. Octopus provide our electricity with a cheap overnight rate between 23:30 and 5:30. In winter we run a 3.5kW A2A unit at 22C to heat i our living area on the cheap rate electricity and bring the battery to 60%. In summer the battery is set to charge to 20% on the overnight rate but it's rare for this to happen as there is nearly always more charge left in them. The 3.5kW A2A keeps the house at 22C and runs from 7:00 until 21:00. The result is that we run almost exclusively on the cheaper overnight rate in winter and in summer barely take from the grid at all. For June: cheap rate 67.3 kWh £4.80 peak rate 31.4 kWh £11.88 (mainly due to charging the EV at 10amps during the day and using appliances while it's charging) standing charge £12.32 For February: cheap rate 339.5 kWh £24.24 peak rate 9.6 kWh £3.63 standing charge £11.50
  13. You're absolutely right about efficiency, but again if you're not using much you're not wasting much...back to the mantra of always minimise your inputs. Utilita have a gas options that has no standing charge, just a higher rate of 23.7p a kWh making it a very good option for users who don't use much gas. Regarding annual service, essential for a rental property but optional for your home. If the boiler is undisturbed and working properly it should not be an appreciable safety risk provided you have good mains connected CO alarms fitted. Rightly or wrongly I work on the principal of if it's not broke then don't fix it. I didn't plan solar into our build, but having added it I can't imagine trying to run without a battery, even given how expensive the battery was.
  14. Very true but storing hot water is a losing game in energy/CO2 terms, you may get a lot of hot water, but how useful is it in practice. Given there is already a gas boiler heating water on demand is far better in energy/CO2 terms. With two in our household we're using 22kWh of gas a month , pretty much all on showers and the occasional bath. The washing machine and dishwasher both heat there own water. I don't get paid for the surplus electricity exported but it does reduce the total CO2 production, every little helps....All the energy from the heated water just wicks away over time.
  15. I could not operate our 3.6kW PV effectively without a battery as we gather energy during the day and then use it overnight. With a 9.5kWh battery I'm still exporting energy despite having A2A cooling and an EV (which has been running on sunshine for the last couple of months).
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