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Fundamentals: Justification of petrochemical based insulants

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      CommentAuthorfostertom
    • CommentTimeJul 24th 2013
     
    Posted By: tonythe widespread use of petrochemical based insulation.

    Presumably when oil runs out we will develop ways of maling them from crops?
    No, we'll use free abundant solar energy to 'reduce' old hydrocarbon rubbish quarried from landfill, back into re-useable virgin feedstock. That's why it's criminal to be burning our future feedstock now - should be stockpiling it.
    •  
      CommentAuthorSteamyTea
    • CommentTimeJul 24th 2013
     
    Would it be better to compare against a single skin brick house, lots of them were built.
    Or compare against whatever is the best PassivHaus standard.
    Or just compare to what you already have.

    Suppose you could compare to a house that needs no excess heating, has a set footprint and perimeter to area ratio, does start to get messy though.

    Price is a bad thing to use as it varies for many reasons and is only valid on the day.

    I know what you are getting at Ed with the 'different' Joules. But is that not why we specify if they are electric or thermal, could add renewable or depleteable to that list to help make a distinction.

    I get a strange 'physics' feeling about entropy and the Second Law coming on, I better go lie down.
  3.  
    Posted By: Seret AIUI petrochemical feedstock is from all the sludge at the bottom of the barrel. The main reason oil is refined is to get at the lighter, more lucrative top fractions. So in a way, petrochemical feedstock is a waste product. We'd be cracking off the lighter stuff for petrol anyway, so we might as well put the heavy stuff to some good use.


    Nope, you've got that backwards. Chemical feedstocks are predominantly the lightest fractions such as methane, ethylene etc. that are (a) easy to transport via pipeline and (b) simple enough molecules that they can be used in synthesis of more complex molecules. The sludge from the bottom of the barrel is either spread on roads (asphalt and bitumen) or used to make steel (petroleum coke).

    As others have pointed out, some PU foams are derived from soy or castor oil, but the isocynate part is still produced from oil.

    Paul in Montreal.
    • CommentAuthorEd Davies
    • CommentTimeJul 24th 2013 edited
     
    Posted By: fostertomWhat you're talking about here? - payback in money terms, or in carbon terms, comparative of PU vs min wool?
    I was using energy both as a direct cost and as an approximate proxy for COâ‚‚ emissions.

    I was comparing quite a lot of PU vs even more PU and finding that even more PU was difficult to justify so considering using incremental amounts of mineral wool instead.
    •  
      CommentAuthorfostertom
    • CommentTimeJul 24th 2013 edited
     
    Oh I see - I misunderstood.
    •  
      CommentAuthorfostertom
    • CommentTimeJul 24th 2013 edited
     
    Posted By: SeretOil isn't likely to actually "run out" any time in the next few centuries, it'll just get increasingly expensive to obtain
    but possibly even more profitable nevertheless, with rising prices - MROMI, Money Return on Money Invested - so expense needn't slow oil production down, even if in the end they're quarrying it on the moon!

    However that hard-to-get oil will come at lower and lower EROEI - Energy Return on Energy Invested, to the point where the more that's produced, the world actually has less to usefully use.
  7.  
    Posted By: Ed Dasvies Mike George's point that we're already way beyond the point of diminishing returns with U-values doesn't fit with my arithmetic. I think Passivhaus is hovering around that point (deliberately, I assume) whereas most building-regs-level houses fall well short..


    Hi Ed, I didn't take my point from your arithmetic; :cool:I took it from my own Conclusions based on Dynamic Simulation which I did for my Dissertation some years ago. My Literature Review Concluded UK Optimum Levels were around Building Regulations 2000 levels I believe (I would say deliberately as well) The software simulations backed up the Literature
    • CommentAuthorEd Davies
    • CommentTimeJul 24th 2013
     
    Posted By: Mike GeorgeHi Ed, I didn't take my point from your arithmetic; …
    Of course not, but my (and lots of other people's) arithmetic points to a significantly different conclusion so it'd be interesting to see an outline of how you get to yours.
    • CommentAuthorMike George
    • CommentTimeJul 24th 2013 edited
     
    Hi Ed, You're welcome to have a copy of the Dissertation if you like? One of the (much slated :bigsmile:) publications with some basic results from it is available here http://www.buildingforafuture.co.uk/winter05/How_much_insulation.pdf
    • CommentAuthorjms452
    • CommentTimeJul 24th 2013
     
    This might be a stupid question but...

    Are we in danger of comparing the literal energy contained within a heating fuel with the embodied energy of insulation? What is the embodied energy of a kWh of heating fuel and what improvement does using this value give to these calculations.

    i.e. taking EROEI of gas of 10, a kwH of gas actually costs 1.1kwH then there's boiler efficiency.
    1kwH of electricity is probably almost double that.

    or is this effect so obvious to be already included?
    • CommentAuthorEd Davies
    • CommentTimeJul 24th 2013
     
    Mike, I seem to have downloaded that before but can't actually read it: all the text is missing. There are pictures of three primates across the top and two graphs but no actual text either as words or in the other tables.
  12.  
    Posted By: Ed Daviesbut can't actually read it: all the text is missing.


    Works OK for me.

    Paul in Montreal.
    • CommentAuthorSeret
    • CommentTimeJul 24th 2013
     
    Posted By: tonyit makes it look like it is not worth doing.


    Well, there will be a point at which it isn't. The question is: where is that point?
    •  
      CommentAuthorfostertom
    • CommentTimeJul 24th 2013
     
    Posted By: Ed DaviesMike George's point that we're already way beyond the point of diminishing returns with U-values doesn't fit with my arithmetic. I think Passivhaus is hovering around that point (deliberately, I assume) whereas most building-regs-level houses fall well short.
    There's no such thing as 'point of diminishing return' - it's just a steepening curve.
    There may be a 'point of zero return', where money-cost or carbon-cost of installation equals or even exceeds money or carbon saved over a lifetime. PH is nowhere near the latter, in fact is much closer to MG's student's "1995 Bldg Regs = optimum" conclusion.
    I can't believe that in that 1980s study anyone envisaged all-fuels' real-price compounding at 20%pa to infinity - it changes all such calcs.
    • CommentAuthorEd Davies
    • CommentTimeJul 24th 2013
     
    Posted By: fostertomThere's no such thing as 'point of diminishing return' - it's just a steepening curve.
    Yes there is, as you say in the following sentence.

    There may be a 'point of zero return', where money-cost or carbon-cost of installation equals or even exceeds money or carbon saved over a lifetime.
    Exactly. If you start with thin insulation then as you add insulation you become better and better off (you save more money/energy/environmental damage in the long run than you expend on the installation of the insulation and heating systems, etc) but as the insulation reaches a certain point this net gain drops to zero. If you increase thickness further your overall cost starts to increase again - i.e., your gains are now diminishing.

    PH is nowhere near the latter, in fact is much closer to MG's student's "1995 Bldg Regs = optimum" conclusion.
    Could you spell that out more slowly, I'm not sure what your pronouns are referring to ('latter' and the elided 'it' in 'in fact is much closer').
    •  
      CommentAuthorfostertom
    • CommentTimeJul 25th 2013
     
    So why not call it 'point of zero return', because AFAIK 'diminishishing returns' in this context customarily means just that the 2nd 100mm of insulation gives diminished benefit compared to the 1st.

    There really isn't a point where returns begin to diminish - they're diminishing all along. But there is a clear point where positive returns fall to zero, then go negative.
    • CommentAuthortony
    • CommentTimeJul 25th 2013
     
    ?? the longer a building is up and used the greater the justification for adding more insulation initially,

    As soon as the cost of energy including price rises is taken into account the previous discussion pales into insignificance.
    • CommentAuthorEd Davies
    • CommentTimeJul 25th 2013
     
    fostertom: Yes, “point of diminishing returns” is used a bit vaguely. There's also the point at which returns diminish such that you're better off spending the resources elsewhere - put in triple glazing rather than more insulation, for example.

    tony: Yes, always worth taking the long view. However, having the returns stretch out into multiple decades is a flag that maybe it's worth having a think if there's a better way of doing it. E.g., mineral wool rather than PIR. Politically it also helps - when somebody says it takes more energy to make a PV panel than it ever produces it's good to be able to say: nope, they pay back the energy in roughly 2 to 6 years depending on type and where they're installed. If it was 8 to 24 years it still might make sense mathematically but it'd be a much weaker come back.
    • CommentAuthorSeret
    • CommentTimeJul 25th 2013
     
    Tony: no one here is advocating anything that will increase the impact of a house over it's lifecycle. Just that when you take a new build's whole lifecycle into account the initial embodied energy can be high enough that it influences the spec.
  20.  
    '' There are pictures of three primates across the top''

    Monkeys or popes?
    • CommentAuthorjms452
    • CommentTimeJul 25th 2013
     
    Posted By: Ed Daviesit's good to be able to say: nope, they pay back the energy in roughly 2 to 6 years depending on type and where they're installed


    have you got a reference for that? - I thought it was a bit longer with mono in this country.

    i.e. lazy wiki mono embodied energy of 4750MJm2 is about 8000kwH/kW which is about 10 years.
    • CommentAuthorEd Davies
    • CommentTimeJul 25th 2013
     
    First source was this or something very like it:

    http://www.nrel.gov/docs/fy04osti/35489.pdf

    That mentions 1 year in some cases which is lower than I remember from when I read it ages ago.

    I think the 6 years came from a Dutch study - maybe one of the ones referenced there. They seem to be assuming a bit more than the 800 kWh/m²·a. Also, as that report explains, the PV industry (used to?) use scrap silicon from semiconductor manufacture so it's a tricky question how much of the embodied energy in that to count as it's otherwise essentially a waste material.
    • CommentAuthorjms452
    • CommentTimeJul 26th 2013
     
    Thanks Ed.

    So the embodied energy is the big question mark (predictably I guess). As these figures are all per m2 the energy payback is presumably improving as the efficiency figures gradually climb.
    •  
      CommentAuthorSteamyTea
    • CommentTimeJul 26th 2013 edited
     
    I think there is a great risk of creating a false correlation between embodied energy and energy expenditure. They do not always have an independent-dependent relationship.
    I also think that the idea of having walls, floors and ceilings at a high U-Value is, in part, to make up for other shortfalls in U-Value caused by windows, doors, bad workmanship etc.

    Not totally sure as only just thought about it, but would a house with high U-Value walls, but leaks air have any more problems with condensation than one with low U-Value walls and better airtightness, assuming that the overall energy losses, heating/cooling loads, usage, floor area to perimeter ratio were the same (basically identical).
    • CommentAuthorEd Davies
    • CommentTimeAug 5th 2013
     
    An additional source on PV payback I just came across: “How much CO2 pollution do solar panels save?”

    https://www.ethex.org.uk/blog/?p=243
  26.  
    Thanks Ed, good reference. I was having a heated debate with a family member recently who had read in the Sun that PV panels use more power to make than will generate, very frustrating debate but I should have known to stop as soon as the Sun was quoted as a reliable source!
    • CommentAuthorjamesingram
    • CommentTimeAug 5th 2013 edited
     
    Phil just tell your family member to buy some REC panels
    "Sandvika, Norway, September 7, 2011: REC today announced an industry leading energy payback time of ONE year and a light carbon footprint for REC modules due to efficient use of clean energy throughout the solar module life cycle."
    "The study is an assessment of the complete environmental impact of a solar module from the extraction of raw materials through the manufacturing to the recycling of a module. The study was completed by ECN for REC during Q1 2011 using the ISO 14040 standard."
    http://www.recgroup.com/en/media/newsroom/REC-produces-first-PV-modules-with-one-year-energy-payback-time-and-leading-low-carbon-footprint/
    And just to let you know they don't cost any more than those with the longer paybacks :wink:
    •  
      CommentAuthorSteamyTea
    • CommentTimeAug 5th 2013
     
    Posted By: jamesingramAnd just to let you know they don't cost any more than those with the longer paybacks
    Interesting point, is most Norwegian energy hydro, was that paid with private money or via government taxes, not that I have a problem with other countries subsidising modules:wink:
    • CommentAuthorjamesingram
    • CommentTimeAug 6th 2013 edited
     
    They have a different manufacturing process ( I believe panel are made in Singapore, silcon grown in the USA)
    "REC’s FBR process, which consumes 90 percent less power than the best competitors, and REC’s world leading energy yields are the two main reasons behind REC’s strong sustainability performance."

    http://www.recgroup.com/en/sustainability/Environment-and-climate/Carbon-footprint-and-Energy-PayBack-time/

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