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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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    • CommentAuthordereke
    • CommentTimeSep 3rd 2018
    Check this out - these people are growing citrus in Nebraska with pretty impressive results. https://www.youtube.com/watch?v=ZD_3_gsgsnk

    They have pipes going under the ground that the blow air through and use the heat from that in winter to warm the green house and the cool for cooling in summer.

    I'm a bit surprised they get enough heat out of it to keep the temperature stable but hey they are doing it and it seems work. What I am interested in is whether a similar thing would be possible to supplement an ASHP for a house. I've read all the stories about them freezing up in winter and having to run defrost cycles and the COP dropping off. Surely this would be a better source of air. I imagine it is much cheaper to install as well (I was recently quoted £10k for ASHP vs £20k for GSHP).

    What do you all think?
    • CommentTimeSep 3rd 2018
    Pipes underground for 'tempering' incoming air (to warm or cool it) can work but can accumulate all sorts of nasties (eg mould) growing in them, eg:



    • CommentTimeSep 3rd 2018
    How many kW to blow the air end up warming it?
    • CommentAuthordereke
    • CommentTimeSep 4th 2018
    tempering - that is a good word :-)

    Yes I suppose it could get a bit horrible down there. Though if the air was just going through a heat exchanger (ASHP) maybe it wouldn't matter?

    I wonder how it is OK in the greenhouses though? Maybe there is so much air going through it that it keeps it dry and fresh?

    I've no idea how much energy is involved @fostertom!
    • CommentTimeSep 4th 2018
    It could account for quite a bit of the air warming.
    • CommentTimeSep 4th 2018
    Posted By: fostertomHow many kW to blow the air end up warming it?

    There are numbers on their website if you want to read it. I don't remember them, sorry.

    It's just a big fan recirculating air. It cools in the summer as well as warms in the winter. They have separate ventilation. Note that Nebraska's climate is quite different to here.

    Keeping a greenhouse a few degrees above freezing is a whole different ball game to heating a house. Forget about any ideas of pre-warming air for an ASHP.
    He states the ground temp is 52 F = 11.11 deg C, and rising to 62 F =16.67 deg C somewhere not that far away.
    I did note the easily excavated, but stable, dry sandy ground, so less moisture, ergo perhaps less moulds?
    Also the glasshouse/greenhouse is dug-in, and the soil simply held back by timbers, as far as I could tell, guessing a metre deep, so effectively pretty well insulated in conjunction with the relatively limited South facing twin wall polycarbonate glazing, and perhaps some added insulation from winter snowfall.
    Still very impressive.
    He states they use the same technology to heat their 4000 sq ft dwelling, if I recall correctly.
    Perhaps they simply wear jumpers.
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