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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.

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    • CommentAuthorsaillandc
    • CommentTimeMar 23rd 2008
     
    This is my first post. I'm trying to modernise the heating system of a large house in cornwall and I cannot really get my head around the heat pump advantage. If my electricity is 4 times more expensive than the gas then a heat pump with a real life COP of 4 will not reduce my energy bill but should cost more to install, is it right or is there something I'm missing?
    • CommentAuthorCWatters
    • CommentTimeMar 23rd 2008 edited
     
    See Table..
    http://www.nottenergy.com/energy-costs-comparison2

    This is the only place I've found a comparison that includes "boiler" efficiency. See middle column.
    • CommentAuthortony
    • CommentTimeMar 23rd 2008
     
    The heat pump will cost more to install but in both cases you should air seal and insulate the house first then IF you need a heating system size it appropriately.

    Future energy prices should be taken into account too.
  1.  
    Posted By: tonyair seal and insulate the house first then IF you need a heating system


    ...hot water....?

    J
  2.  
  3.  
    ...so how do you 'Quote' and paste a link in one post......?

    J
    • CommentAuthortony
    • CommentTimeMar 24th 2008
     
    You cant!

    Solar for hot water and dont throw away the heat from it either.
  4.  
    ...in the winter....?
    • CommentAuthortony
    • CommentTimeMar 24th 2008
     
    U use hot water in winter?
  5.  
    The point is how do you heat your DHW in the winter (particularly on cloudy days) with only Solar water heaters and no boiler backup...?

    J
    • CommentAuthortony
    • CommentTimeMar 24th 2008
     
    Ah - I have an interseasonal thermal store so I am OK. Solar works in the winter a bit and I m not afraid of cold showers either.
  6.  
    sailandc you right

    I'd have thought if your on mains gas you'd be mad to use anything else to heat your home
    for the next 20 year or so , other than solar for hot water and perhap wood , though if
    we all used that we'd probably have a smog problem

    Heat pumps could make more sense when put up against oil and lpg , but again the cost difference is high
    and as mentioned if you spend the money on air tightness/insulation then get the cheapest heating system you can
    as hopefully it wont need to be used much
    • CommentAuthorRonnieS
    • CommentTimeMar 24th 2008
     
    James,

    Might electricity prices uncouple from gas prices?
    What if wind (in Scotland) and nuclear in England helped keep electricity prices down but gas supplies were physically constrained by political events in Eastern Europe? Most users can't readily switch from gas.

    BR

    R
  7.  
    Ronnie,

    What about an immersion heater element in the multi coil thermal store?

    J
    • CommentAuthortony
    • CommentTimeMar 24th 2008
     
    Way better off with a heat pump than anything direct.
    • CommentAuthorjamesingram
    • CommentTimeMar 24th 2008 edited
     
    good point Ronnie

    The need to import more/all our gas is certainly a problem regarding energy security
    Generally we have electric to most home , perhap when the above problem become more of a issue
    the technoligy/price of ASHP/GSHP and electric heating systems will have improved
    also the renewable generation input into the national grid will have increased
    I'm guessing this to be in around 20 years time perhaps it will be sooner
  8.  
    Posted By: James NortonWhat about an immersion heater element in the multi coil thermal store?


    Purely as inexpensive future proofing in relation to Ronnies point:

    Posted By: RonnieSJames, Might electricity prices uncouple from gas prices?


    Wasn't thinking about plugging the thing in !.

    J
    • CommentAuthorFootprints
    • CommentTimeMar 25th 2008
     
    Hi Gang,
    I posed a similar question a few days ago and never really came to a satisfactory conclusion.
    Am I to understand from this series of comments that I am up a gum tree?
    I am using LPG Ideal Mexico 75000 btu`s, my heating engineer suggests a wall mounted LPG , I`m using £200 per month at the moment he says I will reduce radically, but gets cagey when I ask by how much
    Has anybody any ideas?
    I want to get rid of dangerous gas anyway and just learned of ASHP, would it be cheap to run, could I reduce installation cost by doing it myself?
    Would oil be cheaper?
    I`m floundering around in the dark, I`m an OAP, i`ve little money, but I`ve obviously got to do something and fast.
    Is there a plan of action I can follow
    Footprints
  9.  
    did you look into the insulation options
    there was a link I posted for you

    jim
  10.  
    plan of action

    draught proof
    insulate
    these may be free have a look here

    http://www.energysavingtrust.org.uk/proxy/view/full/2019/grantsandofferssearch

    try and get some more quotes on a new boiler/heating system , lpg/oil/ASHP
    • CommentAuthortony
    • CommentTimeMar 25th 2008
     
    Footprints -- If you are an oap there are fuel subsidies available for you from HMG.
  11.  
    Footprints,

    ASHP would not save you money when compared to mains gas. it would be approximately the same when you compare kWh for kWh. A smallish ASHP would set you back £7k. A new gas boiler would be a fraction of this. I am not sure of current lpg gas prices but this form of heating used to be more expensive than oil.
    If it was me, I would only replace the lpg gas boiler with another one if the first one was bust. You would be better making sure you had spent the money on air tightness improvements, cavity wall insulation, loft insulation and double glazing. When you have done all this your running cost should be much improved
  12.  
    Footprints, can you explain briefly the size and layout of your house, what level of wall and loft insulation you have, what fuel you cook with, how you heat your water and if you have a cylinder? I would not go for LPG or oil, neither would I be rushing to spend £7k on an ASHP. There may be other options that would cost you less and give a better financial pay back.
    • CommentAuthortony
    • CommentTimeMar 26th 2008
     
    Small ashp for one/two rooms less than a grand fitted!
    • CommentAuthorchipedwood
    • CommentTimeMar 26th 2008
     
    Another thing if your an O.A.P. Have you applied for heating allowances and insulation grants from the government.
    • CommentAuthorFootprints
    • CommentTimeMar 26th 2008
     
    Chris Wardle,James Ingram Tony,Chiped Wood,Timevans,
    Thanks for comments,
    To save time I have copied and pasted the information I gave in the previous discussion, apologise for the longwindedness
    James - I am following up insulation and cavity fill and will do from OAP aspect, but while I will expect better results, I cannot believe I couldn`t get by without some method of heating house and Hot water
    Chris - Size of house below.
    Layout - difficult, but it was an old cottage said to be 600 years old in parts, used as a post office,3 small rooms at the front and dormers above them, which I guess were bedrooms (they are still there,but dormers now roofed over - so in fact it is just roof space)
    The 3 rooms are now bedrooms, 2 singles and a decent sized double.
    If you imagine looking from the road, driveway is to the right and front door between thew first and second room to the keft.
    Still looking from the front a wing at the left was probably added after the war and now houses 2 bathrooms and a bedroom (enormous 20x15ft)
    To the right hand side an extension has been made year 2000 parallel to the driveway and this houses the kitchen approx 7`6 wide (i.e.it is the new end to the old cottage) a side entrance/hallway /lobby and behind that the sitting room (approx 15x15)
    so we are now at the rear of the house, between the enormouse bedroom and the sitting room lies the dining room (open plan to the hallway and with sliding patio door to the outside rear garden)
    Insulation - see below
    Hot water cylinder heated by primary flow & return from boiler below, it has an immersion heater but no connection to it
    Present Boiler Ideal Mexico 75000btu - Age - the ark I think - free standing, flue through roof - air supply iffy
    Corgi fitter says it will have to go anyway - costing £200 per month at 37p per litre usage 7-9am,5.30 - 10pm, present weather temperature indoors approx 62 deg F.
    Fitter suggests LPG balanced flue boiler fitted to outside wall, says easy job approx 2 days £2k and definite saving in usage costs, but gets very cagey when asked figures or even likely proportionate reduction.
    Anyway reason I am searching around for alternatives is
    Don`t like Gas, don`t like the supplier (he charges what he thinks he can get away with) treats us as captives and I`m sure prices will go through the roof , and I don`t know the technology of how the stuff is produced, but I bet they don`t pipe it from a hole in the ground without refining it in some way.
    House insulation approx 4" + some loft boarding over some of it
    Solid floor/ Carpet (mostly) approx 1350 sq ft , it`s a bungalow so thats the ceiling area as well
    Ceiling height varies from 7`10-8`6" (say avg 8`3")
    Outside wall length approx 190 lin ft of which 80 lin ft is cavity (doubtful if there is any infill)
    Radiator area (measured both sides ) 104 sq ft, singles with fins on the back & foil pushed down
    No Thermostatic valves, but I doubt if it was a designed system anyway.
    I have done a heat loss calculation and it comes out at 44000 btu`s plus allowance for DHW.
    One supplier asked me what the ambient temperature was, sorry I don`t know, but during the last few days the lowest I got hereat 8AM at Torksey was 32 degrees F., what should I quote?
    Is this enough info?, if you want to check my heat loss calculation I would let you have room sizes
    This is an old much extended cottage and we moved in here in September, we have had a few frosts and got by heatwise with the addition of fan heaters, without switching on central heating all day ( mainly for the reason that it is eating into our savings and frightening me to death!)
    Sorry just one final thought, you mentioned 24/7 5months usage, I wouldn`t expect to do this, but I know so little about the ASHP system that I don`t know it`s capabilities,or how it is meant to work
    Also remembered my electricity supply co. can give me economy 10 - should I have it anyway, even if I don`t go ahead with an electrical heat system?
    Thanks for watching,
    Footprints
    • CommentAuthorwogone
    • CommentTimeMay 19th 2008 edited
     
    Posted By: CWattersSee Table..
    http://www.nottenergy.com/energy-costs-comparison2


    Just to update, the link is now: http://www.nottenergy.com/energy-costs-comparison3

    So, to answer the first question, they think a heat pump with a COP of 3.5 will save money relative to gas, which I think is pretty realistic to expect.
    • CommentAuthorCWatters
    • CommentTimeMay 19th 2008
     
    Seems the URL for my favorite comparison web site has changed to..

    http://www.nottenergy.com/energy-costs-comparison3

    Scroll down to the table. The only thing cheaper than mains gas is a GSHP or a wood fire. An ASHP is 50% more expensive to run than mains gas at the moment.
    I would suggest that the capital cost of a GSHP would make that unattractive for an OAP. Overall I think I would go for mains gas if the connection costs aren't too great. Perhaps get a quote for that.
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