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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
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  1.  
    I'm about to move our renovations across to the living room. The renovations will pretty much follow the pattern of the other room I have done with 100mm of acoustic rockwool insulation in the ceiling void, 25mm woodwool boards, 2 coats of lime plaster to form the ceiling, 100MM woodfibre boards on two external walls (with window reveals covered with aerogel) with 2 coats of lime plaster. The South facing wall will be exposed stone as a feature wall and lime pointed. The window reveals in this wall will remain as exposed stone (mullions). The floor will have 100mm of acoustic rockwool beneath 22mm engineered oak and the windows are all A-rated double glazed units. The walls are solid (outer and inner stone face with rubble in-fill) and are 400mm thick. The room is 10m long and 4m wide and has 4 stone mullioned windows (one at each at each end and two along the long (east facing) side. The chimney breast is on the east side and so has a window either side of it.

    I'm tempted to fit underfloor heating in this room to replace the two existing cast iron radiators but I'm worried that it might be too cold in there? We have kids (and a dog and cat) that seem to all have to enter a room by pushing the door wide open and don't understand the concept that doors can also be closed. Do people think that the level of insulation in the room is adequate for UFH? Bear in mind that I would be fitting 50mm kingspan between the floor joists to mount the UFH pipes if I install UFH (with the rockwool underneath that).

    The other question is around our wood stove. We currently have a Coalbrookdale Severn multifuel stove in there, which gives 15kw to the room. I'm assuming that this will be way too big once the insulation is fitted, so will be looking to replace it. My missus hates the stove because of all the mess and the pain of lighting it (and carying wood/coal up to the middle floor). She is asking for a gas stove instead (one that looks like a cast iron wood stove). I'm pushing for a dedicated woodburner as I think we would hardy use the stove except for the effect and so the pain of lighting and cleaning it will be vastly reduced. The other option would be to fit a multifuel stove again, but with a smaller output.

    Does anyone have any thoughts? I guess I'm hoping for advice from someone who has retrofitted similar levels of insulation to let me know what sort of difference it made to the room.

    EDIT: The other room I have renovated only has one external wall and was quite warm and cozy (compared to the rest of the house) before I started, so isn't really a good comparison.
    • CommentAuthorFlubba
    • CommentTimeJul 11th 2016 edited
     
    I'm no expert compared to many of the folk on here but I probably wouldn't go with underfloor heating since your flow temps would probably need to be reasonably high and it's not tied into any thermal mass e.g. floor slab. Even without the thermal mass I'd imagine it would still have a fair bit of lag before the room temperature increased by a noticeable amount. The question I have is, how is the room or house occupied and heated e.g. is everyone out all day?

    As for the stove, we have a multi-fuel (wood or coal) stove for diversity in heating sources as well as for aesthetic and comfort reasons but maybe I'm just a bit more paranoid than some. Lighting it depends on how you build it, we quite often pre-build fires and all that's needed is a single match to get it going, either that or use a blow torch. For cleaning we just vacuum it out and empty the ash pan although the dust the thing tends to spread is rather annoying :|

    Anyway hopefully someone with more direct experience pops along :)
    • CommentAuthorsmudger
    • CommentTimeJul 11th 2016
     
    Ditto no to u/fh. It restricts location of furniture / rugs etc (ok for bathrooms and kitchens where furniture is fixed) - apart from any technical issues regarding heat loss calcs and thermal loss through floors.
    • CommentAuthorgyrogear
    • CommentTimeJul 11th 2016
     
    Posted By: Flubbaempty the ash pan although the dust the thing tends to spread is rather annoying


    I cover mine with a piece of 3mm plywood (that I stash behind my ready-use logs): it does not lose any dust on its way to the compost heap !

    gg
    • CommentAuthorCWatters
    • CommentTimeJul 11th 2016
     
    If you decide to risk UFH I would also install the pipes for rads just in case.
  2.  
    Thanks guys. The remarks about UFH echoed my own misgivings. I'll retain the radiators!

    Does anyone have any feelings about multi-fuel / wood or natural gas stove?

    I know wood is renewable, but having read about the issues with wood smoke I'm wondering whether to go with natural gas?

    I have my eye on a Burley Brampton 6kw as it's Defra approved and seems to be very efficient and we wouldn't be walking downstairs with ash pans full of hot coals! My missus just wants a fire that she can turn on, but I'm trying to move away from fossil fuels if I can.
    • CommentAuthorJonG
    • CommentTimeJul 11th 2016
     
    With the level of insulation that you describe I would guesstimate (from years of MCS level heat loss calcs) that your heat loss is in the region of 40-45 watts a sqm or less, which puts it at 1600-1800 watts.

    It would depend on floor covering, but at circa 40 degrees MWT and 200mm centres with a stone, tile or similar covering the floor would be giving 92 watts a sqm according to CIBSE, which is 3640 watts, with a design room temperature of 20 degrees.

    You could easily flex the design for greater output or more efficiency by adjusting MWT and pipe centres, but it is eminently doable.

    Depending on your system though, hydraulic separation may be required to accommodate differing flow rates through cylinder coil, rads etc.

    UFH doesn't really affect furniture placememt, because it is designed to heat everything in the room, which then also radiates that heat into the air if a differential occurs between the air and the heated thermal mass or masses.

    Rugs aren't a good companion though, unless suitably holey.
  3.  
    A simple no brainer, underfloor heating as a background heat source, so no worries re response times, then a wood burning stove for instanteanous response.

    We already, over 20 years run this set-up in our 25m2 living room, and I am also installing the same arrangement in our 28m2 garden room, a Myson 40m2 kit for about £500.00, no sophistacated thermostats or controls needed, and a Clearview stove.
    Bugger faffing about with heat loss calcs, keep it simple, and cheap.
    PS
    Woodburner to be spliced into the same flue as the Morso the other side of the wall.
    cheers
    m
  4.  
    Posted By: JonGWith the level of insulation that you describe I would guesstimate (from years of MCS level heat loss calcs) that your heat loss is in the region of 40-45 watts a sqm or less, which puts it at 1600-1800 watts.

    It would depend on floor covering, but at circa 40 degrees MWT and 200mm centres with a stone, tile or similar covering the floor would be giving 92 watts a sqm according to CIBSE, which is 3640 watts, with a design room temperature of 20 degrees.

    You could easily flex the design for greater output or more efficiency by adjusting MWT and pipe centres, but it is eminently doable.

    Depending on your system though, hydraulic separation may be required to accommodate differing flow rates through cylinder coil, rads etc.

    UFH doesn't really affect furniture placememt, because it is designed to heat everything in the room, which then also radiates that heat into the air if a differential occurs between the air and the heated thermal mass or masses.

    Rugs aren't a good companion though, unless suitably holey.


    The floor would be engineered oak and the UFH would have 200mm centres (this is the best I can achieve with the joist spaces). I was considering running two loops into the living room, but could run more if that would provide increased heat.

    We would have a rug in front of the fireplace, but it would be a hessian backed one, not rubber.

    One wall (4m wide, standard height) would be exposed stone. Would this have a major impact on the heatloss calcs? Would installing additional insulation help (I don't want more than 100m in the walls, but if push comes to shove, I'd consider installing earogel blankets beneath the ceiling joists, sandwiching them between the joist and woodwool boards).

    I basically want to make sure that the room is warm enough from the central heating only, rather than the current situation where we have to have the heating on and multifuel stove at full blast to warm the room in winter.
    • CommentAuthorJonG
    • CommentTimeJul 12th 2016
     
    Ok, in terms of the heat loss, we completed a project for the PDNP with very similar insulation and achieved around 30-35 watts but didnt have an exposed wall, hence the uplift.

    In terms of the floor, we would recommend a pug screed (25mm of sand and cement) around the pipework, then screed board as the structural floor for thermal transparency and finished floor on top.

    You could then play with FT and FST, but you should still see around 50-60 watts a square meter which would cover the heat loss.

    It is usually feasible to get 150 centers between joists, if you butt up either side but calcs above are on 200mm.
  5.  
    I'd actually be looking at this product to carry the UFH pipes rather than using a screed:

    https://cdn.plumbnation.co.uk/site/prowarm--in-joist-system-boards/in-joist-batten-system.jpg

    I don't want too much weight on our elderly joists, plus these look straightforward to fit. The question is whether they would provide enough insulation and heat transmission to provide enough heat under an oak floor to heat our room.

    As I said, the priority is to have the room heated adequately by a single heat source (central heating), rather than having to have both the central heating and a wood burner on at the same time (which is the issue we have currently).
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