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Fundamentals: Recommended U-Values in the UK

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  1.  
    • CommentAuthormrben
    • CommentTimeApr 13th 2010
     
    Hi there,

    I have recently bought an old leaky (and, to make matters worse, listed) 4-story victorian end-terrace and am scratching my head over how to evaluate its various amounts of leakiness in order to work out how to most effectively spend my limited cash (whilst not upsetting my listed building control "officer").

    I think I am OK-ish with caluclating U-values of existing/ propsed materials, but I've had a pretty good look on a couple of occaisions but I can't seem to find a straight forward recommendation on the target (R- or) U-Values for specific aspects of insulation (roof/ floor/ walls/windows/ doors/ etc...) for specific UK regions (I'm in North Yorkshire).

    This site in the US has a really useful step-by-step approach - and I think pretty much exactly what I'm after for roofs - http://www.oldhouseweb.com/how-to-advice/insulation-the-facts-part-3.shtml - but I think I'd need to know which HDD zone (1-5) I'd equate to here in the UK. Carbon Trust have a bit on Heating Degree Days here http://www.carbontrust.co.uk/cut-carbon-reduce-costs/calculate/energy-metering-monitoring/pages/weather-effects.aspx but the figures don't seem to tally (can't believe Yorkshire equates to Florida - I've never been there but I've seen Baywatch and it ain't like Ripon :bigsmile:) Do I need a Farenheigh vs Celcius conversion perhaps?

    So any advice on that would be handy, please, plus any other recommendations on how to figure out (scientifically!) the most heat lossy aspects of the house first would be most appreciated.

    Thanks & excellent forum BTW!

    Ben

    P.S. Anyone got any better prices on SapcethermF than this - seems high - but I am only buying 50 odd sheets...
    2400x1200x10F/35mm Spacetherm @ £105.50m2 = £303.84 per sheet
    2400x1200x10F/20mm Spacetherm @ £59.80m2 = £172.44 per sheet
    • CommentAuthortony
    • CommentTimeApr 13th 2010
     
    Draught proofing is way and away most cost efficient first step, ceilings, floor, windows and doors

    then consider EWI

    as low as you can with the U values,
    •  
      CommentAuthorSteamyTea
    • CommentTimeApr 13th 2010 edited
     
    Have you worked out what your place is currently using? Always a good place to start.

    And draught proofing first every time, will be the best 100 quid spent.

    Baywatch was California :bigsmile:

    Try this
    http://www.planningportal.gov.uk/wales/professionals/buildingregs/technicalguidance/bcconsfppartl/
  4.  
    Ben

    Degree Days are useful when attempting to precisely calculate your future energy consumption & size your heating system, but not particularly useful when working out how much insulation to put into your home.

    Assuming this is part of a renovation then as a minimum you need to go for the elemental U values called up by Building Regulations, this sets an upper boundary in the range 0.2 to 0.3. You will start to hit practical & structural problems beyond 300mm insulation in floors/walls & 400mm insulation in roofs. Using affordable insulation, this sets a practical lower limit somewhere around 0.1 for floors/walls & 0.08 in roofs.

    Most people on this site would recommend aiming for these lower values, but whether this can be achieved or not depends upon your particular building. For example, aiming for these lower numbers only makes sense if you can get a windtight barrier on the outside of the insulation & an airtight one on the inside.

    Kingspan & Celotex are more cost effective than aerogel. Are you limited to using internal insulation? Is the thickness of the insulation going to significantly affect room sizes? Perhaps you could approach it in terms of the loss of room size that would be acceptable & then work out what U values the various insulations would offer?

    David
    • CommentAuthormrben
    • CommentTimeApr 13th 2010
     
    Thanks guys - I hear the draft proofing & I will do that - but subjectively I think more is almost certainly required!

    The house is Grade II listed so pretty much no exterior alteration are possible according to local planning control, who are even saying a straight "no" to double glazing in the single sash windows (even if they couldn't visually tell the difference!?), nor external insulation. There is original plaster cornicing in a lot of rooms so I will almost certainly need to, and to be honest would really want to, preserve as well (which is unfortunately because most of the rooms are big enough to loose a fair bit without major bother - except the bay windows...).

    That is why I was interested in Spacetherm - I know it is more expensive - but it is slim. With 30mm the U value of the main (solid) external wall comes to 0.37W/m2K (the R for the 30mm of Spacetherm is 2.308).

    This is not my original question (on the practicalities) but I wonder if anyone has any take on the fundmental legalities... how are the contradictions of listing and the insulation ratings in building reg resolved? Is it the case that I am not actually technically "rennovating"? I have to replace all the electrics (currently circa 1950), boiler (currently coal - CHP hopefully if BG come through in time), and re-roof, plus several structural linel repairs for starters. If by law it is rennovation and I do have to try to aim for the U- values in the regs, and if so how do I do that whilst complying to the listed buildings requirements? Who overrides who?

    I note that in the very recent Planning Policy Statement 5 ofHE1.1 of 23rd March 2010:
    "Local planning authorities should identify opportunities to mitigate, and adapt to, the effects of climate change when devising policies and making decisions relating to heritage assets by seeking the reuse and, where appropriate, the modification of heritage assets so as to reduce carbon emissions and secure sustainable
    development. Opportunities to adapt heritage assets include enhancing energy efficiency, improving resilience to the effects of a changing climate, allowing greater use of renewable energy and allowing for the sustainable use of water. Keeping heritage assets in use avoids the consumption of building materials and energy and
    the generation of waste from the construction of replacement buildings."

    So is the writing on the wall? Can I take them on in an effort to comply to building regs and make the place "sustainable" by central government standards?

    Anyway - in an effort to try an establish the practical state of play and stop myself going round in circles - I'm thinking of getting an independant assessor round to calculate the current SAP/ general state of play and recommend some stuff. Anyone got any thoughts/caveats on that approach? How accurate can/will they be? I had a quote of £90 for a SAP calculation - is that reasonable?
    • CommentAuthortony
    • CommentTimeApr 13th 2010
     
    Yes but we could guess at it for you much cheaper!

    You are about to walk int a minefield full of disappointment! Pretty much at present they (local planning and listed building people) will say no to everything that is a sensible energy saving action to take in direct opposition to what central govt says.

    good luck. They should let you use slimlite window double glazing.
    • CommentAuthorCWatters
    • CommentTimeApr 14th 2010 edited
     
    Posted By: mrben... how are the contradictions of listing and the insulation ratings in building reg resolved?


    I gather you let them fight it out and that Building regs are more likely to compromise on insulation but fight hard for things related to safety (eg fire).
    • CommentAuthorAMc
    • CommentTimeApr 16th 2010 edited
     
    The Listing and the Conservation Officer will usually trump building control.

    Secondary glazing is a more sympathetic alternative to ripping out historic windows and is quite effective - more info here.
    http://www.english-heritage.org.uk/server/show/nav.21479

    Sash windows can be renovated and retrofitted with brush seals which greatly reduce ventilation losses. Ventrolla are one company who offer this as a dedicated service.

    If you look at the payback periods for replacement windows you may find there are better, less contentious places to improve your house's thermal performance.

    Draught proofing, chimney balloons and as much loft insulation as you can manage would be my bet and I wouldn't worry about the SAP assessment unless you're going for a complete renovation as their guesses at construction will be as good as yours as to the thermal efficiency of the materials.

    Be aware that hermetically sealing your house without taking care to ensure vapour permeability (a.k.a. breathability) could result in dampness in an older lime built, non cavity house.
    • CommentAuthorqeipl
    • CommentTimeDec 30th 2010
     
    Follow up Tony's suggestion of Slimlite double glazing -
    http://www.slimliteglass.co.uk/home.html
    It's been accepted on a Grade A listed rebuild in Scotland that I'm involved with, despite an initial flat refusal by Historic Scotland to accept any double or secondary glazing.
    • CommentAuthorJoiner
    • CommentTimeDec 30th 2010
     
    Slimlite is acceptable in certain circumstances, but be aware of the shortcomings and the fact that, until Slimlite choose to answer my query of some months ago to say otherwise, their slim-line units (the ones designed to directly replace s/g) don't conform to Part L either side of the border.

    I also know of two cases where their units have failed 'prematurely' and which, being horrendously expensive to start with, has meant a considerable expense to the poor sod who has to renew them, usually the guy who fitted them in the first place because all you'll get (as is customary with all unit manufacturers) is a replacement unit.

    Slimlite have to get their act together before I'll either use them or recommend them to anyone else without heavy qualification.

    Put 'Slimlite' into the search engine on this forum and see what you get for some kind of perspective.

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