Home  5  Books  5  GBEzine  5  News  5  HelpDesk  5  Register  5  GreenBuilding.co.uk
Not signed in (Sign In)

Categories



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.

Buy individually or both books together. Delivery is free!


powered by Surfing Waves




Vanilla 1.0.3 is a product of Lussumo. More Information: Documentation, Community Support.

Welcome to new Forum Visitors
Join the forum now and benefit from discussions with thousands of other green building fans and discounts on Green Building Press publications: Apply now.




  1.  
    Got an opportunity to purchase what we would call our forever home.... Property needs a complete refurb 50s 60s brick cavity)

    We would be going from a mid terrace Victorian house with EWI/IWI, double glazing, lift insulations and running an ASHP

    The house we are looking at is detached, bigger and has single glazed windows, cavity walls with no sign of insulation....


    As such, my first thoughts are loft insulation, triple glazed windows to front, bead cavity insulation and maybe open up the rear windows being South facing to take into account the solar gain.

    We would then choose a heating system based on u-values etc. The floor is concrete and assumed un-insulated. Probably another ASHP or perhaps even direct electric in each room and then invest in solar panels etc.

    Any immediate thoughts? We would like to maintain the brick facade so EWI probably out of the question
    •  
      CommentAuthorfostertom
    • CommentTimeNov 19th 2021
     
    Posted By: VictorianecoWe would like to maintain the brick facade
    Seems heavy consequences. Any photos?
  2.  
    • CommentAuthorSimonD
    • CommentTimeNov 20th 2021 edited
     
    With such a large overhang, you do have an ideal candidate for EWI. It would make your life a lot simpler than having to deal with IWI and associated thermal bridging. EWI with brick slips maybe? You could even look at installing your ewi with a cavity and carrier board that then holds clay brick slips. Not sure what the costs are but there are options.

    If you were to look at a lime render for the ewi then Lime Green is the only company I know at the moment who have develoed a lime render system for woodfibre ewi.

    Good luck with it, looks like an exciting project.
  3.  
    The bricks don't look anything special to me. I would not be precious about these. House looks a good size though.
  4.  
    What is the floor construction, how will you insulate it? Suspended floor possibly easier to retrofit insulation than a slab?


    Been some previous threads about EWI retrofit on cavity walls, the questions were about

    - stopping any residual air movement in the cavity that would bypass EWI, and

    - how to join the wall insulation onto the floor insulation so there's not a cold bridge all around the wall/floor junction -much easier with IWI than EWI. The wall/ceiling junction is also difficult with EWI especially on gable walls. But making IWI continuous depends on the internal partition wall construction, difficult with solid partition walls, and

    -what to do about airtightness between the inside and the wall cavity, if you need to plaster internally for airtightness then you might want to IWI while you are at it.


    Is becoming more important to think about the embodied energy/carbon of material/insulations we use, a few years ago that was insignificant compared to energy/carbon from heating, but now ASHP heating is becoming quite low in primary energy and carbon so the balance is shifting. Might be good to avoid too much polystyrene/cement/lime if you can use glasswool/timber instead.

    Edit to add: we sank a huge amount of time effort and emotion into retrofitting our previous 'forever' home, however illness in the extended family meant we unexpectedly had to sell it, to move closer to them. We are now retrofitting our next 'forever' home but our learning point was not to commit extravagant effort in the expectation of getting decades of satisfaction/comfort/luxury, we are trying to stay more level headed this time, life is too unpredictable to make plans for 'forever'!
  5.  
    With decent properly installed cavity wall insulation the benefits and cost effectiveness of EWI are IMO marginal especially because, as mentioned above, the primary energy and carbon output for an ASHP in falling and likely to fall further in the near future. So IMO forget the EWI and spend the considerable thousands of pounds on extra PV. For the floors I would put 20mm of EPS then engineered wood over and cut the bottom of the doors to account. Most doors can take a 30mm off the bottom without affecting the stability. This would make a big difference to the floor heat loss. I would be inclined to leave the kitchen as slab with tiles over (I don't like wood floors in kitchens due to the wet spillages)

    Is there a heating system at the moment (radiator CH perhaps) ?
    • CommentAuthorJohn Walsh
    • CommentTimeNov 20th 2021 edited
     
    It's all going to come down to what your take is on energy consumption reduction. As noted on the "Circular economy for rare elements" thread, reducing energy consumption is critical with reducing heating need a main priority. If it's going to be your forever home then I'd argue that piecemeal measure - 20mm floor insulation / fill the 2 inch cavity / accept the ASHP sell - will not provide long-term satisfaction.

    It's a philosophy thing and if you want to significantly reduce consumption then, I'd go with EWI as it will be much more effective. Looks like there's the potential to slightly reduce ground level and thus EWI below ground floor level. EWI means a much neater thermal envelope, e.g. re triple glazing. Look into lightweight fill of the cavity - not insulation - so as much of the existing walls become part of the thermal mass. Look into digging out the existing concrete floors - much 50s floor construction is poor quality and thus easy to take out (is the garden big enough for 'spoil' landscape features?).

    Above all, it's not easy. But don't decide on the basis of opinion, get it modelled, maybe with an EnerPHit plaque as a finishing touch?

    EDIT: are you certain there's a cavity? Lots of examples of 50s brick build with all stretchers so it looks like a cavity wall but actually it’s around 10 inch of solid wall.
    • CommentAuthorEd Davies
    • CommentTimeNov 20th 2021
     
    Posted By: Dominic CooneyThe bricks don't look anything special to me. I would not be precious about these.
    Agree. The large eves overhang is just crying out for EWI. Best done while the windows are being replaced.
    • CommentAuthorMike1
    • CommentTimeNov 20th 2021
     
    I agree with John, and I'd also be looking to install UFCH in those new floors.
  6.  
    Also good to look at the building standards/regs for where the house is (Wales? Sorry I don't know exactly what the stds are).

    They will set a (minimal) baseline for insulation levels for major retrofits, which might help decision making by quickly ruling out shortcut options. Then if you are directed towards deeper options to meet regs, it might be easy to beat the regs baseline, eg by putting a thicker insulation in while you're already at it.
  7.  
    SimonD said ''If you were to look at a lime render for the ewi then Lime Green is the only company I know at the moment who have developed a lime render system for woodfibre ewi."

    SimonD, are you ruling out the Baumit products because the EWI render (MC55) apparently contains a very small proportion of cement? I don't know the proportions but I think it is predominantly llime, but not pure lime? It's great to use.

    Fassa do a lime render for use with graphite EPS.
    • CommentAuthorAshley
    • CommentTimeNov 20th 2021
     
    we undertook a similar project on a 1950s detached house over the past year. Our house has CWI, but the cavity is only 50mm so, whilst I'm sure it helps, I didn't think it was enough.

    In the end, we went with IWI, 3G windows, huge amounts of loft insulation and concentrated a lot on airtightness (when new windows / doors installed, around as many floor joists as I could, wet plaster walls etc.). It has made a huge difference compared to what it was.

    Just one really important thing with a house of this age, and that is to watch out for asbestos. We had to have some fairly innocent looking garage ceiling panels professionally removed, floor tiles also had asbestos but lower risk.

    Ashley
    • CommentAuthorSimonD
    • CommentTimeNov 21st 2021
     
    Posted By: Nick ParsonsSimonD said ''If you were to look at a lime render for the ewi then Lime Green is the only company I know at the moment who have developed a lime render system for woodfibre ewi."

    SimonD, are you ruling out the Baumit products because the EWI render (MC55) apparently contains a very small proportion of cement? I don't know the proportions but I think it is predominantly llime, but not pure lime? It's great to use.

    Fassa do a lime render for use with graphite EPS.


    Hi Nick,

    Yes, mentioned Lime Green as it's a pure lime (NHL) render and I know some people are keen on this. I do agree with you about Baumit, I myself have woodfibre rendered, well actually I'm still rendering it myself, with Baumit MC55W! :smile:

    I chose the Baumit because it was the only product available to me in the UK that was an European Technical Assessment approved alternative render to the woodfibre manufacturer's own product. It is really nice to work with.

    Good to know about Fassa, that's handy, thanks.
    • CommentAuthorJohn Walsh
    • CommentTimeNov 23rd 2021
     
    Puzzled by IWI suggestions above - I must be missing something here?

    Primary concern (especially with a 'forever home'): reducing heating need to as close to zero as possible.
    Method: Insulation/ thermal bridging/ air tightness/ MVHR / solar gain (if possible) / thermal mass (given Victorianeco says SG is available). NB 'solar gain' = a calculated SG strategy.

    The above method means the heating season (broadly, given UK latitudes) is reduced to around early Nov - mid Feb (i.e. the period when max sun altitude is below 20 degrees). How can IWI compete with that?
    •  
      CommentAuthorfostertom
    • CommentTimeNov 23rd 2021 edited
     
    Posted By: John WalshLooks like there's the potential to slightly reduce ground level and thus EWI below ground floor level
    No need, for downstand insulation purposes - much more effective is to dig a trench right down to bottom of foundation (but abs no deeper, to avoid undermining the found or reducing its bearing area) and run the EWI right down as deep as that allows. This creates a 'coffer dam' of insulation around a large block of subsoil, which then becomes a slow-changing stabilising thermal mass, part of the house's internal environment. To maximise insulation value, you can prevent standing water in the trench by putting a french drain in the bottom, with sharp clean aggregate and geotextile to prevent silting.
    Posted By: John WalshLook into digging out the existing concrete floors
    And it goes a long way to making that unnecessary, which is a boon when you don't have to rip out kitchen, cloakroom etc, not even carpets.

    This floor insulation won't be as good as you could achieve with a new replacement floor, but could be a worthwhile trade-off. See latter part of http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6562 where an02ew applies Therm to quantifying it.

    I used to think that the underground EWI needn't be as thick as above - but now realise that the reverse is true - make it at least as thick if not more.

    There's more detail on how to do this - search GBF.
    • CommentAuthorgravelld
    • CommentTimeNov 23rd 2021
     
    Very similar situation to me. Although we had a bit more insulation to start with, and crap 2G (which needed replacing anyway). Plus, I'm envious of that hipped roof and overhang.

    Would this be an incremental or all in one retrofit?

    Might have to do something custom around that attached garage?
  8.  
    Posted By: fostertomdig a trench right down to bottom of foundation (but abs no deeper, to avoid undermining the found or reducing its bearing area) and run the EWI right down as deep as that allows. This creates a 'coffer dam' of insulation around a large block of subsoil, which then becomes a slow-changing stabilising thermal mass, part of the house's internal environment. ... This floor insulation won't be as good as you could achieve with a new replacement floor, but could be a worthwhile trade-off. See latter part of http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6562 where an02ew applies Therm to quantifying it.

    I used to think that the underground EWI needn't be as thick as above - but now realise that the reverse is true - make it at least as thick if not more.


    Reading back on that thread, I said at the time that didn't really look like enough insulation - the figures An02ew came up with, were equivalent to about U=~0.9 W/m²K for the floor area of the example house.

    Maybe further tweaking of the Therm could get a bit more out of it?

    The contours show that the heat wasn't getting through the insulated trench, so it didn't need thicker insulation. Instead the heat was just flowing underneath it. If we think about the 8m width of the house floor slab, compared to the 0.6m-ish depth of the trench, the 'aspect ratio' isn't in favour - really the trench needs to be metres deep if it's going to meaningfully lengthen the heat flow path from the floor to the outside air.

    I think if you are going to the trouble of wall insulation, you'd also want floor insulation and you don't want a gap between the wall and the floor insulation.
    •  
      CommentAuthorfostertom
    • CommentTime7 days ago
     
    Posted By: WillInAberdeendidn't really look like enough insulation
    True but as I say
    Posted By: fostertomwon't be as good as you could achieve with a new replacement floor, but could be a worthwhile trade-off ... when you don't have to rip out kitchen, cloakroom etc, not even carpets.


    Posted By: WillInAberdeenthe heat wasn't getting through the insulated trench, so it didn't need thicker insulation
    Not getting through *because* of the insulation - there must be an optimum thickness.

    Posted By: WillInAberdeenthe trench needs to be metres deep if it's going to meaningfully lengthen the heat flow path from the floor to the outside air
    0.6m is questionably not worth it - 0.75m is minimum found depth for postwar houses, now 0.9m. Even 0.6m increases path length from almost nothing (if the wall is thermally 'part of' the floor slab) to about 1.7m - but the path length is always partly short-cut by heat leakage through the downstand insulation.

    At shallow found depth i.e sub-0.6m, maybe think more in terms of an under-garden horizontal wing of insulation around the perimeter - but that creates only half the path length benefit compared to downstand.
Add your comments

    Username Password
  • Format comments as
 
   
The Ecobuilding Buzz
Site Map    |   Home    |   View Cart    |   Pressroom   |   Business   |   Links   
Logout    

© Green Building Press