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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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    • CommentAuthorTomasz_P
    • CommentTimeFeb 2nd 2021
    Ok, I feel quite happy with my rough plans for the floor (pending limecrete quotes!)

    I have had the first of a few initial quotes for heat pumps. It has been a point of discussion with my father in law as well. He is very much of the approach of doing as little as possible. The first ASHP quote has 2x 7-22kW Mastertherm BoxAir Kits. Does this seem overkill or is it ultimately more economical to overspec even if it means spending an extra £7k+ initially?

    I am tempted to complete the floor insulation and UFH along with other improvements and run that on oil for a year to get a true idea of what I am using.

    The EPC (from quite a few years ago now) suggested 69842 kWh per year for space heating but I know these are not always a very good representation of what will actually be used.

    I am still toying with the idea of a hybrid oil/ashp option because it gives me assurance that I will stay warm but the option of becoming less and less reliant on oil as I improve the insulation. Grant have quite a neat looking option.
    Remember to get Listed Building Consent before you commit to anything.

    In the farmhouse I am a big fan of 2 jumpers whilst working from home, to avoid having the (oil fired) heating on, and have also recently discovered the comfort that "quilted overalls" brings. A bit like an adult baby-grow, or practical one-sey!
    • CommentAuthorTomasz_P
    • CommentTimeFeb 3rd 2021
    Ha, yes i have been using quilted overall recently. Not for my desk work yet though. I don't think the two jumpers approach will go down all that well my my wife unfortunately.

    I have been thinking of approaches to low energy home working recently. radiant panels mounted to desks etc. Quite a fun project (if i had time).

    I just has another quote come through for ASHPs. this one was 2x16kW Nibe units. It came in around £23k for the ashps, buffer and 300l cylinder including installation (but not including rads and ufh). I think i will have to do that bit myself to try and keep costs down.
    • CommentAuthorphiledge
    • CommentTimeFeb 3rd 2021
    Is the rough estimate of 24kw heat demand based on the existing house, or on with the insulation ideas you have planned?

    It may be worth running the heat demand calc a bit more accurately and size the heat pump to deal normal heat losses for most of the year. Add in a woodburner with a backboiler to top up the TS when its exceptionally cold- your wife will soon warm up lugging logs into the house:)
    • CommentAuthorTomasz_P
    • CommentTimeFeb 4th 2021
    Haha. I will definitely have a wood burner as we have a good supply of wood. It is for the existing house so i can make some improvements on that.
    • CommentAuthorTomasz_P
    • CommentTimeMar 18th 2021
    Just to keep this thread up to date....
    I have dug out all of the floors. Sooo many different floor coverings in the area that was the stables. I am now digging down. Almost two weeks in now and only about a 1/5th dug out. Total floor area is 142sqm. I will be going for roughly 200mm glapor and 100mm slab.
    1/5 dug out - lots more to go. Is galpor the only way to go? From what I read you would get the same insulation value (or perhaps a bit more) with 100mm of EPS for a cheaper price with less digging out
    • CommentTimeMar 19th 2021
    Posted By: Tomasz_PAlmost two weeks in now and only about a 1/5th dug out.
    Sounds like you need a machine.
    • CommentAuthorTomasz_P
    • CommentTimeMar 19th 2021
    We have a micro digger and dumper now (and labourers!).
    @Peter it certainly would have been easier and cheaper but I would like to go for a breathable system. Past owners have raged several battles against the damp in the house and i would like to work with the house rather than fight it. I hope it pays off. I think that just consistently heating it and living in it will help a lot too.
    • CommentAuthorEd Davies
    • CommentTimeMar 20th 2021 edited
    Posted By: Tomasz_P: “@Peter it certainly would have been easier and cheaper but I would like to go for a breathable system.”

    The “breathability” of EPS isn't terrible: about half of that of lime plaster, for example. Neil May in his “Breathability in Buildings” paper gives min, typical, max figures of:

    Lime: 45, 75, 200 GNs/kgm
    EPS: 100, 150, 750 GNs/kgm

    Jablite EPS250 is 238 GNs/kgm - I don't suppose it's surprising that the strong stuff is on the lower end of the permeability range. https://www.jablite.co.uk/wp-content/uploads/2016/01/Jablite-EPS.pdf

    Of course, you're not likely to have 100mm of lime plaster but a) I imagine with UFH you won't be to far short of that and b) limecrete is I also imagine a bit less vapour permeable.
    • CommentTimeMar 20th 2021
    The main reason I used foamed glass in places was that it provides a capillary break as well as being 'breathable'. So there is no need for a DPM above or below it. There are lots of breathable materials that do not provide a capillary break.
    Posted By: djhThe main reason I used foamed glass in places was that it provides a capillary break as well as being 'breathable'. So there is no need for a DPM above or below it. There are lots of breathable materials that do not provide a capillary break.

    EPS doesn't wick up water, which is why it is generally accepted to EWI over a DPC without problems.
    • CommentTimeMar 20th 2021
    edit: You're quite right. I forgot to mention my other constraint, which was that the material must be freely draining.
    • CommentAuthorEd Davies
    • CommentTimeMar 21st 2021
    I guess the key is whether there's a risk of liquid water immediately under the floor. If it's just vapour then EPS should be OK, if it's molten ice then, yes, something non-wicking and free draining seems wise.
    I would have thought a french drain around the building (with a good outflow) to keep water out of the underfloor would be a better bet than having a free draining sub floor. Unless you are expecting periodic floods. If you are expecting the floods I'm not sure how limecrete would cope with the soaking.
    • CommentAuthorTomasz_P
    • CommentTimeMar 28th 2021
    To be honest I only just discovered that EPS is more breathable than I would have imagined. Most of the limecrete suppliers/installers seem to suggest expanded glass but I guess they would as they also supply it. There is potential for the earth to get damp under the house although I will be re-digging the French drain too.
    Anyway, too late to change my mind as the digging is complete and the glapor coming next week!
    • CommentAuthorTomasz_P
    • CommentTimeMar 28th 2021
    • CommentAuthorTomasz_P
    • CommentTimeMar 28th 2021
    @peter can you also please tell me that I don't need to bother stripping of this modern paint on these walls before iwi and lime plaster because it will be breathable enough?! (See me other thread)
    It very much depends upon what the paint is/was. Vinyl silk paint won't be breathable whereas e.g. Dulux trade emulsion is breathable and can be painted over drying out plaster.

    The wall looks like it has a texture which could be a pain to strip however if the paint is matt then perhaps sanding with a very coarse sandpaper or a going over with a wire brush on an angle grinder would damage the paint surface enough to open it up to the base wall to make it sufficiently breathable for the purpose. To get a breathable surface yo don't need all the paint off, just enough to let any moisture through to the next layer. Actually thinking about it, even if the paint is non-breathable then scratching through the paint surface to the wall should be enough, just that you would need a bit more scratching through for the more plastic type paints.

    Edit to say look like a nice place - even before it's finished!!
    • CommentAuthorTomasz_P
    • CommentTimeMar 30th 2021
    Thanks Peter! The upper floors are certainly looking better than the ground right now.
    I thought about scratching it. I think this seems like a good option and I think it is more likely something like a trade matte too.
    • CommentAuthorTomasz_P
    • CommentTimeMar 30th 2021
    Ground floor Glapor going in!
    • CommentAuthorTomasz_P
    • CommentTimeSep 9th 2021
    Just a quick update on this. I ended up going for ashp ufh for just the ground floor, which is now finished. The rest of the hot water and heating are supplied by the boiler for now. I insulated all of the external walls with 60mm wood fibre then an insulated undercoat lime plaster and top coat. Still loads to do but we are now living on the top floor!
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