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    • CommentAuthorStuartB
    • CommentTimeJan 18th 2008 edited
     
    Is it possible to be 100% off grid for a maximum capital outlay of £15k? Location - rural, exposed south facing half acre plot in Scotland with am average wind speed of 6.1.

    What renewable technology would you use to provide all your heating and power needs for a 4 bed house? If it can't be done for less than £15k how much do you think it would cost?
    • CommentAuthorstephendv
    • CommentTimeJan 18th 2008
     
    It largely depends on your electricity consumption. I will be going 100% off grid in Spain with a PV array and backup generator and have put together a spreadsheet for sizing and pricing the system at: http://www.casanogaldelasbrujas.com/blog/?p=9
    Double check those values though, as I'm new at this!

    I calculated that for my wife and I in a 2 bed house, we'd use about 6.7kWh per day using new energy efficient appliances and CFLs. No skimping on electricity either as I've included running a bunch of electronics 24/7 and powering a MVHR. The PV panels are designed to supply electricity March through to October and we'll be relying on some help from the generator in the winter months. It's just not economical to size the array for the whole year. Estimated about 24k Euro for the complete setup.
    • CommentAuthortony
    • CommentTimeJan 18th 2008
     
    Insulate and get airtight then work out heat loss then think about how much solar heat you can use then think about an inter-seasonal thermal store (needn't be expensive) then see what you maximum base load will be then look at reducing that then size your generation or storage capacity.

    we cant say yes or no without a lot more info.
    • CommentAuthorhowdytom
    • CommentTimeJan 18th 2008
     
    I hope your using the heat from the generator in winter stependv or is it wind ?. If you dont need it in the house you could grow summer crops out of season with the spare heat ?.
    tom
    • CommentAuthorGBP-Keith
    • CommentTimeJan 18th 2008 edited
     
    No. Stuart but it really depends on how frugal you want to be when the wind does not blow. I know someone offgrid (electric )with just a 2.5kw proven but i think they are using bottle gas etc for cooking.

    To be truly off grid for energy, you will need to spend £25,000 if you self install or £35,000 + if you use installers. You will need a tri or quad-hybrid mix or massive batteries. Tri-hybrid would be wood, wind and solar (active, passive and PV). Quad-hybrid would include some water power input.

    Lots of hands-on too. If you are in a really windy site than a large wind turbine 6 or 15kw will give you a good proportion of your annual power but not complete.

    Frighteningly rough breakdown.
    Wood boiler and system - £7,000 self install or £12,000 installed

    Inverter, batteries etc for electricity - £4,500 self or £6,500 installed

    Wind turbine - 2.5kw £16,000 self install may not be an option

    Micro water turbine if water available (include for pipes, ponds and lots of wasted time playing with water) - £4,000 self install or thousands and thousands if installed

    Solar PV - how deep are your pockets? best technology though so budget as much as poss - say £5,000

    Solar thermal - £2,500 self install or £4,500 installed

    Solar passive can go into your design at little extra cost.

    Dont forget the logging equipment and the land needed for planting trees - grants available though

    But it is the best fun you will ever have though and I've got energy coming out of my ears at the moment. Energy price increases - what are they?
    • CommentAuthorrichardt
    • CommentTimeJan 19th 2008 edited
     
    My setup cost around 22k net of grants. Thats roughly 1kw wind, 2kwPV, generator (backup and workshop loads), woodburner for heat, cooking, DHW, Solartwin. And camp stove for summer cooking. PV and turbine via 'approved installer' as required by SCHRI, everything else self-installed. Don't bother with wood unless you have your own timber or can get it at or near cost.

    That doesn't include an old Unimog for hauling firewood (which does other work too)and 3pl splitter btw.

    Scottish Shower quoted us around 18k for a mains hookup.
    • CommentAuthortony
    • CommentTimeJan 19th 2008
     
    Sounds like a good name for them!
    • CommentAuthorGBP-Keith
    • CommentTimeJan 19th 2008
     
    Think on.
    Put in a good woodstove now. In ten years time they will be difficult to obtain due to over-demand.

    If you only have half an acre of land, plant half of it now with ash trees in a semicircle around the north of the other half. You will need the rest to grow food on later.
    • CommentAuthorStuartB
    • CommentTimeJan 21st 2008
     
    Thanks for the responses! I had thought that it may run into the low £20k's but had hoped for less! Keith - can you expand on the ash trees in a semi-circle??
    • CommentAuthordazdread
    • CommentTimeJan 21st 2008
     
    Ash, our fastest growing native tree in the UK... how about hazel coppice?
    • CommentAuthorGBP-Keith
    • CommentTimeJan 21st 2008 edited
     
    The semicircle is to protect the other ground from the harsh north weather and create a suntrap to help warm the ground. As Dazread has said some hazel in the outer edges will grow less high so would allow low morning and evening sun in.

    Have you taken a look at the Skystream 3.7 wind turbine from Southwest Windpower Stuart. It looks really quite economical and could help you keep nearer your budget. The guide prices seems to be about £6500 + groundwork. That's about half the installed price of the Proven! (Plus batteries etc of course).
    • CommentAuthorchipedwood
    • CommentTimeJan 22nd 2008
     
    I'm not too up on my Green Building, but i agree with what tony said, before you start trying to save power with your own sources you should ensure you are using as little as possible with insulation and low energy consumption products.

    Also I wouldn't recommend any solar equipment in the UK as it is not efficient enough to pay for itself even in the long run. They normally are out of their lifespan by the time they would of become useful.
    • CommentAuthorchrisc
    • CommentTimeJan 22nd 2008 edited
     
    Posted By: chipedwoodAlso I wouldn't recommend any solar equipment in the UK as it is not efficient enough to pay for itself even in the long run.


    But I guess you are comparing with the cost of fossil fuels and perhaps you haven't appreciated that peak oil is probably in the past (or if not will be in a few years at most) and peak gas isn't going to be far behind and peak coal might be as soon as 2025 -- annual 10 to 20% fossil fuel prices rises are probably going to be the norm for the next few years...
    • CommentAuthorStuartB
    • CommentTimeJan 23rd 2008
     
    Its a gimmie that the house will airtight and very well insulated before attempting to reduce power and use renewable resources. I too am very sceptical about cost/benefits resulting from solar. My father in law paid about £8k for a DHW system which gave him about 10-15% hot water last summer (although I think he was ripped off with the price) and that is south facing in sunny Surrey. We are in Scotland!

    stephendv - 6.7kwh seems very high for a 2 bed house! We are currently burning 7.9kwh in a not particulary efficient 4 bed home, I would hope to get this down considerabley with a new build.
  1.  
    Posted By: StuartBstephendv - 6.7kwh seems very high for a 2 bed house! We are currently burning 7.9kwh in a not particulary efficient 4 bed home, I would hope to get this down considerabley with a new build.


    I think you're getting mixed up between kWh and kW - 6.7kWh is very little over a 24 hour period - equivalent to less than 3 100W lightbulbs. At the electrical rate I pay, that would be equivalent to around Can$140 a year. If, as I suspect, your load is 7.9kW, you'd consume around 190 kWh in a day which sounds more like it for an inefficient 4 bedroom house in winter in Scotland!

    Paul in Montreal
    • CommentAuthorStuartB
    • CommentTimeJan 23rd 2008
     
    Paul, you are correct, excuse my maths. It was 70,000kwh for the year.
  2.  
    Posted By: StuartBPaul, you are correct, excuse my maths. It was 70,000kwh for the year.


    Wow, that is an astounding electricity consumption! You're right that it's not very efficient! We scrape by on 25,000kWh per year in a much colder climate than you for what is probably a similar sized house. What form of heating system do you have?

    The original poster was talking about lighting and appliance consumption only so 6.7kWh per day is not too bad. My baseload is around 10kWh per day (measured during the period between the heating season and the cooling season) - and a good part of that is the computer equipment.

    Paul in Montreal
    • CommentAuthorStuartB
    • CommentTimeJan 23rd 2008
     
    My dual fuel supplier gave me these figures. 4,681mWh for electric and 22,300 kWh for gas which is how I got to 70,000 for the year. Does this sound excessive/incorrect anyone? They charge me £100 per month for both.

    Paul - I was in Ontario and Quebec last summer and had a fantastic time, Canada is definitely somewhere I could live. The quality of life is so much higher than the UK. Lovely hot summers too which I guess helps you get through the freezing winter!
  3.  
    Posted By: StuartB4,681mWh for electric and 22,300 kWh for gas which is how I got to 70,000 for the year. Does this sound excessive/incorrect anyone?


    I'm not sure how you summed these to 70,000kWh. The sum is 26681kWh which is much more reasonable.
    Posted By: StuartBCanada is definitely somewhere I could live. The quality of life is so much higher than the UK. Lovely hot summers too which I guess helps you get through the freezing winter!


    Yes, the summer certainly make up for the winters - though last summer was not particularly hot, though it was sunnier and average and also wetter too - though most of the rain was at night. It gets as much above freezing in summer as it goes below freezing in winter - it's like there's a big +30C / -30C switch that gets thrown twice a year :wink:

    Regards,

    Paul in Montreal.
    • CommentAuthorvalasay
    • CommentTimeFeb 1st 2009
     
    I'd appreciate any help you can give on my planned project.
    Water sourced heat pump from sea loch 100m from house with a 50m drop to sea level and 20kw wind turbine to replace 10000kwh electricity and 5000l of oil
    We live in an exposed location in the Outer Hebrides of Scotland in a timber framed house built 11 years ago. It makes total sense to insulate more effectively as the building regs which applied at the time of our build were the same whether in the centre of Edinburgh or on the coast, next stop America.
    There are vents under the floor, in the walls, along the soffits and in the roof space, hence draughty house with 180 mms insulation in walls but huge energy bills. This is probably a silly question but how do I improve insulation/air tightness without compromising the ventilation required for the timber frame?
    All suggestions gratefully received!
    • CommentAuthorrobJH
    • CommentTimeFeb 2nd 2009 edited
     
    I'd just like to reiterate getting your consumption down as the first place to start.

    I'm sure you can drastically reduce your consumption below those values! Just for info, here's how we do it.

    I have a 1930s semi (110m^2 total floor area) in Sheffield and this year the house has been occupied 24/7 due to the arrival of our baby in Jan 08. We have used around 6000kWh of gas and 5.2kWhr/day of electricity in the last year - and we have an electric cooker (not my choice, I'd like to add!). We have a new combi boiler and a wood burning (5kW) stove.

    Central heating is only on for around 45mins in the morning and only ever on in rooms that we use. It is on for around in hour in the evening, but most importantly of all, the thermostat is set to around 13-14 degrees. It gets the kitchen warm enough for breakfast and the stove is then lit which keeps the lounge at between 17 and 20. The stove keeps the dinning room to around 16-18 degrees as well.

    So I would think it is probably possible to significantly reduce your energy consumption and as a result, significantly reduce some of the costs of your renewable energy generation.
    • CommentAuthorpmcc
    • CommentTimeFeb 3rd 2009
     
    Valasay, I have a similar project with an uninsulated timber frame house. In rural central Scotland rather than the isles, so although I class my place as windy it's nothing compared to you!

    Completely agree that before looking at how to generate heat you should first look at how to keep it.

    There seem to be well understood techniques for lofts, although it can be rather messy and complicated for timber frame houses with many voids. Lots of threads on this forum discussing them, plus lots of materials on the web. I just so happen to have these links open, but many others explain in more detail.

    http://www.xtratherm.com/products/saferpitchedroof.php
    http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3466&page=1#Item_0

    The walls are the biggest problem. I'm looking at external insulation, but the cost would make your eyes water. Other options are to rip off plasterboard for external facing walls and stuff insulation into the gap. Or to put up some insulating wallpaper type of stuff.

    For under the floor, I'm afraid the only options I've seen discussed seem to be cutting rigid insulation board and fixing between the floor joists. The joists are a cold bridge, but must be ventilated to avoid condensation and rot.

    I have a whacky idea, but I'm not a builder so it will probably be silly. In essence, put insulation above the foundation concrete, block off the under-floor air vents to the outside, and install wall vents on the inside. The space between the internal walls and external wall becomes warm. Insulation is outside the external wall so heat is not lost too fast.

    Probably this deserves its own thread...
    •  
      CommentAuthorfostertom
    • CommentTimeFeb 3rd 2009
     
    Posted By: tonyInsulate and get airtight then work out heat loss then think about how much solar heat you can use then think about an inter-seasonal thermal store (needn't be expensive) then see what you maximum base load will be then look at reducing that then size your generation or storage capacity.
    That should be on a banner across the top of every GBF and AECB page! Says it all.
    • CommentAuthorMarkH
    • CommentTimeFeb 3rd 2009
     
    pmcc - we chose to have Warmcel blown behind our plasterboard between the timber frame. We already had 25mm of EPS (and then a 75mm gap). This seems to have been effective (we think the walls now have a u value of 0.35 or better), and although just as messy as ripping off plasterboard to fill the stud work with rigid insulation, it was about 20% of the cost if my memory serves...
    • CommentAuthorpmcc
    • CommentTimeFeb 3rd 2009
     
    Posted By: MarkHpmcc - we chose to have Warmcel blown behind our plasterboard between the timber frame. We already had 25mm of EPS (and then a 75mm gap). This seems to have been effective (we think the walls now have a u value of 0.35 or better), and although just as messy as ripping off plasterboard to fill the stud work with rigid insulation, it was about 20% of the cost if my memory serves...



    Interesting - from various conversations and general reading I had formed the impression that blown-in insulation wouldn't work for timber frame. Could that be because there is sometimes a vapour control layer outside the studs, which would trap moisture and cause rot?

    Also, for some reason I thought there had to be some sort of gap immediately behind the plasterboard to allow for electric wires and other services. In my house making such a gap that would mean ripping the plasterboard off anyway.

    Did you fill up the whole space between the foil back of the plasterboard and the wood on the outside of the studs? Presumably you drill a hold in the plasterboard and spray it in? If so what happened to stuff like wiring - just trapped inside the insulation? Warmcel is supposed to have effective fire suppressants, but I wonder about fire risks from loose electrical connections...

    Sorry for so many questions - I've not seen a good explanation of this elsewhere.
    • CommentAuthorMarkH
    • CommentTimeFeb 5th 2009
     
    pmcc,

    I'm no expert, relying mainly on the Warmcel technical people and the installers - very helpful.

    Drilling the holes through the plasterboard meant going through the vapour barrier. The company installing the Warmcell ran a calculation to show that the risk of condensation was below the levels required. As a belt and braces approach we have used a sealant overs the patched holes to minimise vapour transfer. Also, the Warmcel was blown in dry not sprayed in wet.

    Regarding electrical cables - yes we do have a few in the external walls, and yes the cables are now buried in Warmcel. Again there is some building software which showed no problem. (If you have cabling that is pre PVC covered that might be a problem).

    We have assumed no electircal cable connections in the Warmcel - connections are in the wall socket boxes or in the loft.

    Hope that helps. If you want more its worth speaking to the Warmcel tech guys. If I remember when I'm at home I'll dig out the name of the installer for you.
  4.  
    Posted By: StuartBIs it possible to be 100% off grid for a maximum capital outlay of £15k? Location - rural, exposed south facing half acre plot in Scotland with am average wind speed of 6.1.

    What renewable technology would you use to provide all your heating and power needs for a 4 bed house? If it can't be done for less than £15k how much do you think it would cost?


    You could go down the biomass CHP route especially as it is eligible for ROC's and RHI when it comes in.

    10kw solution for $16995 20kw for $25995 plus shipping and import duties.

    http://www.gekgasifier.com/gasification-store/gasifier-genset-skids/
    •  
      CommentAuthorfostertom
    • CommentTimeFeb 17th 2011
     
    Posted By: renewablejohnWhat renewable technology would you use to provide all your heating
    I answered you that but you poured scorn on it, poss because it wasn't a bolt-on 'technology' but something more integral in the (re)design of the house's fabric.
  5.  
    Posted By: fostertom
    Posted By: renewablejohnWhat renewable technology would you use to provide all your heating
    I answered you that but you poured scorn on it, poss because it wasn't a bolt-on 'technology' but something more integral in the (re)design of the house's fabric.


    Fostertom

    Just to clarify it was StuartB who posed that question even though the system suggests that it was posted by me.
    •  
      CommentAuthorfostertom
    • CommentTimeFeb 17th 2011
     
    Ah OK. So, Stuart, do you see what I mean about going off-grid for the space-heating bit of it is not a matter of 'renewable technology' as in an alternative mechanical system to be purchased, but more a matter of (re)design of the building's fabric?

    That is, about enabling the building to collect, store and use 'renewable' energy in an extremely lo-grade form:
    Collecting solar heat by collectors operating at very low flow/return temp, about 21C, which reduces re-radiation loss to cold outside scenery, so that even in Jan/Dec there's useful and sufficient nett gain
    Transporting that heat to very massive heat store e.g. all the walls of the building - massive enough to store enough heat in lo-grade form for long enough to bridge over Jan/Feb sunless spells
    Inputting that heat to the interior over large enough radiant area e.g. all the walls of the building, that very low delta-t is sufficient.
    So if desired inside temp is 17C, inside radiant wall temp needs to be 17.5C, outside temp of same walls 20C, thermofluid inputting heat into outside of walls @ flow temp 22c, return temp 20.5C.

    Only space heating can make user of solar heat collected at such lo temp (tap water, electricity etc can't) - so at least do your space heating that way, which makes it possible right thro Dec/Jan - and is inherently off-grid.
   
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