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Other Garden office - help me make it self sufficient.....

Discussion in 'Hardware' started by Goatee, 19 Nov 2019.

  1. Goatee

    Goatee Well-Known Member

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    I'm hoping to move into a new house in the new year. One of the first things i need to tackle is the creation of a home office down the end of the garden.

    The property we are trying to buy has a big garden, part of which down the end has been earmarked for the new office space.

    I could run power down to the site but this would require digging a trench about 40 to 50m long. I'm looking at an insulated, composite building that comes relatively prefabbed. I will need to create a concrete / brick base.

    [​IMG]


    I'm looking to figure (and cost) out:

    Heating - Electric Underfloor heating, suggestions on brands, controls (as it will be used with solar / battery). This can be built into the concrete base.

    Cooling - AC for the few hot weeks a year and supplementary heating if needed. Potentially de-humidification may be nice too. Something to be run off batteries so suggestions if you have any?

    Power (generation) - Solar panels on the roof to generate enough electricity. Suggestion on size, brands ect.

    Power (storage / conversion) - Battery bank and distribution / conversion requirements. All that jazz.

    Other Stuff - Need to extend my home network to the office, I'm thinking some form of antenna / receiver to connect the office. I will be running a TV and office computer so they will need powering too.

    I'm a competent DIY'er, builder of watercooled PC's so I think I can tackle all that's needed in terms of the fit out but I need some advice and experience so I have everything planned out for before I start.

    Thoughts, feedback, ideas?
     
  2. VipersGratitude

    VipersGratitude Well-Known Member

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  3. wolfticket

    wolfticket Downwind from the bloodhounds

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    I think unless it's exceptionally well insulated (or you're wearing exceptionally warm clothes) I think you're going to struggle with heat/AC without external power.
     
  4. Gareth Halfacree

    Gareth Halfacree WIIGII! Staff Administrator Super Moderator Moderator

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    This. There's no way you're going to be able to run all that off rooftop solar. If you turned the rest of the garden into a solar farm, maybe; rooftop? Nah.

    Trench it, then you can run power *and* proper wired networking.
     
  5. Spraduke

    Spraduke Lurker

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    If its very well insulated and you have south facing tripple glazing you might get away with virtually no heating (research passive houses for more ideas) but these often require a large 'thermal mass' to store any heat - think lots of concrete - and incredibly good air change control (lots of silver tape on joints etc).

    I suspect this doesn't easily scale down to small office spaces though (less thermal mass and worse volume to surface area ratios). You could also look into air source heat pumps or MVHR (mechanical ventilation heat recovery). The first is a comparatively efficient way of heating with electrics. The second would recover as much heat (or cold in the summer) from the space so you don't piss it into the universe whilst also doing humidity control etc. Be warned these aren't small units (2-3 times bigger than a gas boiler) and normally belong in a plant room.

    As for Solar / batteries / inverters. I have had an SMA inverter for a year and its been flawless at a reasonable price. Ultimately find a good local company to advise / give quotes. I used Atlantic Renewables (if you're in the north west) and they were reasonable price, good workmanship and non-pushy advice.
     
  6. Xlog

    Xlog Active Member

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    +1 to Gareth.
    For solar, you are looking at ~2kWp setup (with storage prob cost you 10000+), in winter months that would result in 60-70kWh/month of electricity (https://re.jrc.ec.europa.eu/pvg_tools/en/tools.html), not counting losses in storage. Maybe enough to run a PC, not for heating.
    For a trench - two of us dug ~50m one in less than two days and that was in the area full of rocks and other construction crap, if soil is good and you can rent a trenching tool, you could do that in couple hours. For underground cable + pipe you would be looking at ~200 currency (50mm pipe, 5x16mm2 alu XLPE cable (enough for ~10kw), outside boxes, ethernet).
    If you are thinking about AC, get a split system and use it for heating/dehumidifying (600-2000 currency, depending on manufacturer)
     
  7. Goatee

    Goatee Well-Known Member

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    You guys are no fun! However its what I asked for and thinking about it a bit more, you may well be right about a trench. I could rent something to do the buildings foundation block at the same time. Also if i'm doing a trench, I could then run water down there too (allowing me to put a loo and sink in). Waste access is down the end of the garden anyway.

    The building is south facing with a total roof area of of 21 sq M, that should allow something like a 2kw PV system which I guess could run a small A/C off a battery during the summer months for a couple of hours but maybe not worth it. I could always get a wood burner for the colder months and stick some underfloor in to take the chill of in the morning.

    Thanks for the feedback guys
     
  8. bawjaws

    bawjaws Well-Known Member

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    Prepare to freeze your baws off in the winter and swelter on the summer, mains power or not. A small, poorly-insulated space like that is going to be super difficult to maintain at a comfortable temperature year-round.
     
  9. MLyons

    MLyons Half dev, Half doge. Staff Administrator Super Moderator Moderator

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    I live in a summer house at the bottom of the garden and we went with mains from the house. With good insulation and some of those electric oil filled radiators it's fine pretty much any time of the year. The only time I sometimes have an issue is during the summer with the flat black roof but now I've got a portable AC unit.
     
  10. Arboreal

    Arboreal Keeper of the Electric Currants

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    That may bring planning consent and building regs into play, adding £££ to the plan :worried:
     
  11. edzieba

    edzieba Virtual Realist

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    If you have a fence you can nail to (and occupants who do not mind a Big Honking Cable nailed to said fence) then the trench can be skipped entirely.
    Then there's the Faff But Technically Compliant option of an external socket on the house, and a roll-up extension lead run out to the shed that Honest Guv I Roll It Up When I'm Done For The Day, meaning it is not a permanent installation so no electrician required to add a new mains spur and install the exterior run (or to jump through the Part P hoop).
     
  12. cobalt6700

    cobalt6700 Active Member

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    Electric underfloor heating is great for keeping your feet warm.... That's about that.

    If you can properly insulate the building and run elec radiators you will be in a better position.

    Having a south facing large window has benefits and drawbacks. In the winter you get some solar gain (radiation) which helps heat the space, in the summer you get a lot of solar gain which doesn't help you cool the space. You will also have the inverse for conducted heat transfer.

    You could very well run mains power and solar and only use the mains when needed - but this very much depends on your budget - e.g. how much you are willing to invest in solar.

    Whilst running a water supply isn't an issue, once you look to install a toilet you essentially make it a habitable building, which means you may have to seek planning permission etc.
     
  13. nimbu

    nimbu Well-Known Member

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    A fried of mine sent me some links to battery solution that he has put in, I'll dig it out, but mines cheaper then the tesla / varta options.

    He has gone ham on batteries and panels. As a result his day production runs the house and the excess is enough to keep the house ticking over at night. Mind you he is still wired up to the grid!

    But as I said he has made a serious investment into it all.
     

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