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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

PLEASE NOTE: A download link for Volume 1 will be sent to you by email and Volume 2 will be sent to you by post as a book.

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    • CommentAuthorbogal2
    • CommentTimeNov 26th 2019 edited
     
    My house is 100m2 on 3 floors. Maximum heat load of 1000W and heat demand of 1600kWh/pa. Currently using 7yr old efficient condensing combi to supply 3 rads and HW. Is there anything suitable to move away from gas? A 5kW ASHP seems a bit overkill and expensive!
    •  
      CommentAuthorDamonHD
    • CommentTimeNov 26th 2019
     
    Solar + storage to cover DHW most of the year, and possibly DHW and SH partly or fully in the winter?

    The solar could be thermal or PV or PVT.

    And I am trying to get Sunamp wrapped round my combi for its low losses to reduce grid flows.

    Rgds

    Damon
    •  
      CommentAuthordjh
    • CommentTimeNov 26th 2019
     
    Solar PV to heat water most of the year with mains immersion for winter and direct electric space heating is simplest and cheapest. You could just heat water and feed it to the radiators, though I'd use a separate heater rather than combine DHW storage and space heating.
    • CommentAuthortony
    • CommentTimeNov 26th 2019
     
    Direct electric heating has a very poor efficiency, all be it 100%, compared with a heat pump at 300 or 400% efficient and so in terms of running costs can be justified. Gas is likely a cheaper option at present though, but that will change.
    • CommentAuthorRobL
    • CommentTimeNov 27th 2019
     
    2kW air conditioner - these are about £800, say £1200 installed. Cheap heat pump, as most of the worlds cities need cooling, uses A2A as it’s better for cooling air than A2W or W2W, and can dehumidify. For that money you get inverter drive, remote control, A++ efficiency, good brand (Fujitsu, Panasonic,) etc. One unit in a central location is likely good enough. If they’re on low, I think they’re fairly quiet (that would be my only concern). Direct elec DHW.
    • CommentAuthorCWatters
    • CommentTimeNov 27th 2019
     
    Is the gas boiler still reliable? If it's still working fine I think I'd stick with it. Mains gas is still pretty cheap to run.
    • CommentAuthortony
    • CommentTimeNov 27th 2019
     
    +1
    • CommentAuthorWeeBeastie
    • CommentTimeNov 27th 2019
     
    Posted By: CWattersIs the gas boiler still reliable? If it's still working fine I think I'd stick with it. Mains gas is still pretty cheap to run.


    What would you recommend if the gas boiler was on its last legs?
    •  
      CommentAuthordjh
    • CommentTimeNov 27th 2019
     
    Posted By: WeeBeastie
    Posted By: CWattersIs the gas boiler still reliable? If it's still working fine I think I'd stick with it. Mains gas is still pretty cheap to run.

    What would you recommend if the gas boiler was on its last legs?

    But is your house the same size and as apparently well-insulated as bogal2's?
    • CommentAuthorWeeBeastie
    • CommentTimeNov 27th 2019
     

    But is your house the same size and as apparently well-insulated as bogal2's?


    No! Smaller and not well insulated. But insulation will be improved. I don't wish to hijack the thread but am interested in thoughts on options if the gas boiler is on its way out. Plus other renovations/upgrading planned which provide a good opportunity to change things.
    • CommentAuthorbhommels
    • CommentTimeNov 27th 2019
     
    Posted By: WeeBeastie
    No! Smaller and not well insulated. But insulation will be improved. I don't wish to hijack the thread but am interested in thoughts on options if the gas boiler is on its way out. Plus other renovations/upgrading planned which provide a good opportunity to change things.


    Another reason to stick with the boiler: once you know the final heat demand of the house post-insulation, the HP can be properly sized relative to heating/DHW demand, making the system more efficient.
    • CommentAuthorjamesingram
    • CommentTimeNov 27th 2019 edited
     
    I've got an 18 year old A rated combi at a property, never touched it other than annual gas safe check . Works fine.
    When things change a bit? Solar with something like a heat battery (sunamp) might be the solution as Damon mentioned , currently they're pretty pricey though.
    •  
      CommentAuthordjh
    • CommentTimeNov 27th 2019
     
    Posted By: WeeBeastieNo! Smaller and not well insulated. But insulation will be improved. I don't wish to hijack the thread but am interested in thoughts on options if the gas boiler is on its way out. Plus other renovations/upgrading planned which provide a good opportunity to change things.

    Well, the answers will be different if your house is different, so it doesn't make sense to try to address two separate questions on the one thread. And as already hinted, the answers will probably change on your own house pre- and post- renovation/upgrading.
    • CommentAuthorSimon Still
    • CommentTimeNov 28th 2019 edited
     
    >>Direct electric heating has a very poor efficiency, all be it 100%, compared with a heat pump at 300 or 400% >>efficient and so in terms of running costs can be justified.

    Surely depends on the load.

    >>Maximum heat load of 1000W and heat demand of 1600kWh/pa

    Does 1000w mean that's the max input you need? Ie a single 1kw electric radiator would do the job?

    1600kWh is only about £250 of electricity a year and electric radiators are cheap, zero maintenance and long life compared to anything that needs installation. If you're sufficiently low energy resistive heating and solar PV could well be lowest lifetime cost.
    • CommentAuthortony
    • CommentTimeNov 28th 2019
     
    How long is this lifetime?
    •  
      CommentAuthordjh
    • CommentTimeNov 28th 2019
     
    Posted By: Simon StillIe a single 1kw electric radiator would do the job?

    Or a hairdryer on low-power setting :bigsmile:
    • CommentAuthorgyrogear
    • CommentTimeNov 28th 2019 edited
     
    Posted By: bogal2My house is 100m2 on 3 floors.


    sounds like a tall house: where are the rads ?
    Do you get any stack effect ?

    FWIW, it might be useful to heat the bottom of the staircase as a priority - then see where the heat goes.
    (preferably you'd have a high-mass lower flight, say RC, with ceramic tiling...).

    What fraction of your total energy bill goes on heating ?

    1600 kWh p/a does not sound that bad to me, for 100 m2.
    (I use twice that, for 180 m2) (I think that this is a "C" on the EPC, for all the worth *that* is ) :devil:

    Posted By: WeeBeastieWhat would you recommend if the gas boiler was on its last legs?


    If it will fit, to start with, a DHW immersion tank, underneath bottom flight of stairs, driven off PV. Unlagged pipes serving the various wet rooms.

    Otherwise a groundfloor (= stair lobby...) electric storage radiator, running on off-peak tariff, for low installation cost and zero maintenance charges, as already specified by others). Then hot water from point-of-use heaters.

    gg
    • CommentAuthorWeeBeastie
    • CommentTimeNov 28th 2019
     
    Windmill :wink:

    https://solar.lowtechmagazine.com/2019/02/heat-your-house-with-a-water-brake-windmill.html
  1.  
    >How long is this lifetime?

    I'd expect a resistive radiator to still be working long after some part has broken in a heat pump or gas boiler and rendered it unfixable.
    • CommentAuthorbogal2
    • CommentTimeNov 29th 2019
     
    I like the idea of a hot water tank heated by an immersion powered by our 4kw of pv. Is this the sort of ASHP that would be suitable? The house is two storeys and a loft conversion I would put the heater on the wall in the living room and I think the upper storeys would stay warm enough.

    https://www.saturnsales.co.uk/Panasonic-Wall-Mounted-Heat-Pump-CS-FZ35UKE.html
    • CommentAuthorjamesingram
    • CommentTimeNov 29th 2019 edited
     
    Posted By: bogal2I like the idea of a hot water tank heated by an immersion powered by our 4kw of pv. Is this the sort of ASHP that would be suitable? The house is two storeys and a loft conversion I would put the heater on the wall in the living room and I think the upper storeys would stay warm enough.

    https://www.saturnsales.co.uk/Panasonic-Wall-Mounted-Heat-Pump-CS-FZ35UKE.html" rel="nofollow" >https://www.saturnsales.co.uk/Panasonic-Wall-Mounted-Heat-Pump-CS-FZ35UKE.html


    id say yes
    • CommentAuthorbogal2
    • CommentTimeNov 30th 2019
     
    By my reckoning with carbon intensity of uk electricity generation and distribution at 300g CO2/ kWh ( amazing how this has come down) and for 1 kW of gas heating 200g CO2 approximately, a ASHP with a COP of 3 would mean for 1 kW of heat an ASHP would produce 100g CO2 as opposed to the at least 200g from a gas boiler. Please correct me if I'm wrong! If a bit of solar is thrown in too even better.
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