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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
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    Embodied energy and embodied carbon footprint of building materials
    Download the ICE embodied energy and embodied carbon footprint database free
    • CommentAuthormarkocosic
    • CommentTimeJan 29th 2014
    One shouldn't complain about "free" but I don't trust the head honcho Dr Craig - appears liable to be selective of data to suit his own ends.

    Here for example he chooses odd numbers seemingly just to produce a "shock" answer to drive publicity for his database:



    -Why compare "acoustic" 3G with "energy saving" 2G?

    With argon fill the optimum gap between panes is ~20 mm. 4-20-4 2G units have a U-value of 1.5 W/m^2k centre-pane (hard coat) or 1.2 (soft coat)

    "Acoustic" 3G is where you stuff 3 panes into a 2G mm thick frame; typically 4-12-4-12-4. This is what all the folks that advertise on TV try to sell you, because it fits their cheap and nasty frames.

    "Energy saving" 3G units are 4-16-4-16-4 and 0.8 W/m^2k centre pane (hard coat) or 0.6 (soft coat).

    Disbelieve this? Ask the Pilkington website, rather than relying on the numbers presented by window retailers with vested commercial interests in extracting maximum life from their existing tooling before upgrading to manufacture the deeper profile 3G frames - as the author of this analysis has done.

    Whole window with a relatively cheap 70 mm profile PVC frame you'll get 2G 1.4 W/m^2k or 3G 0.9 W/m^2k (both soft coat). The extra pane of glass in a 70 mm PVC frame adds <£10/m^2 and choosing this is economically a no-brainer unless your retailer is a shark or doesn't own a production line that's 70 mm profile capable. (most of the advertise on TV types)

    They need to re-run the numbers with 1.4 vs 0.9 U-values.

    -Internal temperature is lower with 3G units and they've not taken this into account in their analysis

    A 2G unit is "cold" in winter. You get "cold" air sheeting down the window and into the room: this draught means that for a given comfort level your average room temperature needs to be higher. 3G units elimiate this and allow a lower average internal temperature for a given comfort level. This is why they're specced in passivhaus - they reduce fabric losses elsewhere, not just at the windows.

    Most unqualified people make the same mistake when evaluating the 2G vs 3G decision.

    They need to re-run the numbers with say a 0.25C or greater reduction in internal temperature, depending on window size relative to room size.

    -Lifecycle cost isn't just embodied energy + energy savings.

    Embodied energy is irrelevant where the materials are subsequently recycled, such as with the aluminium frames.

    He has ignored all requests for showing his working via twitter and email. The bloke has to earn a living, but given that he won't show even the most basic working, and chooses unreasonable comparisons to generate headlines, can you trust the rest of the data?
    • CommentAuthorjamesingram
    • CommentTimeJan 29th 2014 edited
    as a quick reply an alternative to the 'ICE' mans 2G to 3G comparison I presume you've seen
    Dutch study http://t.co/0q4YEA7CXT
    Seems to give a much more positive view on ROI for 3G in terms of EE.
    I'll read and digest your post fully when I've got a bit more time.
    whats your twitter acc.?
    • CommentTimeJan 30th 2014
    I'm amazed and disappointed. I have to agree with Marko's assessment of the window comparison; it seems a very amateurish effort. I've been aware that the detail in ICE varies a bit depending on how much some vested interest has spent on providing data in an appropriate form, but hadn't spotted anything as crazy as the window example. But is there anything better than ICE for such assessments?

    Posted By: jamesingramI presume you've seen
    Dutch study http://t.co/0q4YEA7CXT

    Sadly that site seems to be written by a script kiddie and just shows as 404 for me.
    • CommentTimeJan 30th 2014
    What's 'version 2' about it - what has changed? For the better? More sponsored ads maybe.
    • CommentTimeJan 30th 2014
    Note that version 2 was published in 2011. There's nothing new here.
    • CommentAuthormarkocosic
    • CommentTimeJan 31st 2014
    We were brought up on CES - paid product outside the university though:


    Personally I'd adopt the PassivHaus methodology; ignoring these databases and relying on common sense/purely economic analysis in order to select materials. Those which are cheap are usually also low embodied energy.

    Common gotchas:
    -Materials with a high ozone depletion or greenhouse gas effect. Refrigerants, blowing agents, and specialist coatings.
    -Products where the retail cost bears no resemblance to the marginal raw materials cost. Products where you need a large factory and transport is significant.
    -State energy subsidies. Mainly only Chinese made products now.

    The "universal carbon footprints without error bars" products - such as ICE - are intended for public bodies and developers to willy wave. Marketing departments. The number that matters is in-use energy consumption of the finished building.
    • CommentTimeJan 31st 2014
    Entry of 12 Dec 2013 in http://markbrinkley.blogspot.co.uk
    • CommentAuthorEd Davies
    • CommentTimeJan 31st 2014
    More convenient link for the future: http://markbrinkley.blogspot.co.uk/2013/12/does-embodied-energy-really-matter.html

    My impression is that, yes, reducing the in-use energy consumption of the building is the key but it's worth taking any opportunity to do the same thing with a lower embodied energy material and not too painful financial cost. Still, the absolute values of embodied energy in materials are not that interesting - what matters are relative values and then only to about one significant figure.
    • CommentTimeJan 31st 2014
    Ah I see how you did that - good.

    When efforts to reduce embodied energy transform into a priority to increase sequestered unoxidised carbon, it gets interesting, and it then makes less sense to try to weigh against reduced energy-in-use - it becomes a 'different animal'!
    One significant figure - nearest order of magnitude/application of common sense - is ideal.

    [Temporarily} sequestering carbon in the form of lightly processed timber can be done.

    Modelling the effect on carbon emissions of knocking down all existing houses and replacing them with passivhaus grade buildings is an interested exercise. Yes you'd save CO2 in the long run, but the payback period (vs doing nothing or a less effective EnerPhit type retrofit) will surprise you.
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