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The tradeoffs of building green

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    First of all, I'm a geek.
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    I'm an organic food-eating,
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    carbon footprint-minimizing, robotic surgery geek.
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    And I really want to build green,
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    but I'm very suspicious
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    of all of these well-meaning articles,
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    people long on moral authority
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    and short on data,
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    telling me how to do these kinds of things.
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    And so I have to figure this out for myself.
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    For example: Is this evil?
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    I have dropped a blob of organic yogurt
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    from happy self-actualized local cows
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    on my counter top,
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    and I grab a paper towel and I want to wipe it up.
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    But can I use a paper towel? (Laughter)
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    The answer to this can be found in embodied energy.
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    This is the amount of energy that goes into
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    any paper towel or embodied water,
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    and every time I use a paper towel,
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    I am using this much
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    virtual energy and water.
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    Wipe it up, throw it away.
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    Now, if I compare that to a cotton towel
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    that I can use a thousand times,
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    I don't have a whole lot of embodied energy
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    until I wash that yogurty towel.
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    This is now operating energy.
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    So if I throw my towel in the washing machine,
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    I've now put energy and water
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    back into that towel ...
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    unless I use a front-loading, high-efficiency washing machine, (Laughter)
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    and then it looks a little bit better.
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    But what about a recycled paper towel
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    that comes in those little half sheets?
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    Well, now a paper towel looks better.
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    Screw the paper towels. Let's go to a sponge.
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    I wipe it up with a sponge, and I put it under the running water,
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    and I have a lot less energy and a lot more water.
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    Unless you're like me and you leave the handle
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    in the position of hot even when you turn it on,
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    and then you start to use more energy.
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    Or worse, you let it run until it's warm
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    to rinse out your towel.
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    And now all bets are off.
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    (Laughter)
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    So what this says is that
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    sometimes the things that you least expect --
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    the position in which you put the handle --
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    have a bigger effect than any of those other things
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    that you were trying to optimize.
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    Now imagine someone as twisted as me
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    trying to build a house.
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    (Laughter)
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    That's what my husband and I are doing right now.
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    And so, we wanted to know, how green could we be?
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    And there's a thousand and one articles out there
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    telling us how to make all these green trade-offs.
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    And they are just as suspect
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    in telling us to optimize these little things around the edges
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    and missing the elephant in the living room.
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    Now, the average house
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    has about 300 megawatt hours
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    of embodied energy in it;
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    this is the energy it takes to make it --
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    millions and millions of paper towels.
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    We wanted to know how much better we could do.
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    And so, like many people,
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    we start with a house on a lot,
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    and I'm going to show you a typical construction on the top
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    and what we're doing on the bottom.
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    So first, we demolish it.
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    It takes some energy, but if you deconstruct it --
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    you take it all apart, you use the bits --
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    you can get some of that energy back.
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    We then dug a big hole
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    to put in a rainwater catchment tank
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    to take our yard water independent.
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    And then we poured a big foundation
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    for passive solar.
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    Now, you can reduce the embodied energy
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    by about 25 percent
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    by using high fly ash concrete.
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    We then put in framing.
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    And so this is framing -- lumber,
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    composite materials --
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    and it's kind of hard to get the embodied energy out of that,
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    but it can be a sustainable resource
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    if you use FSC-certified lumber.
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    We then go on to
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    the first thing that was very surprising.
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    If we put aluminum windows in this house,
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    we would double the energy use right there.
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    Now, PVC is a little bit better,
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    but still not as good as the wood that we chose.
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    We then put in plumbing,
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    electrical and HVAC,
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    and insulate.
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    Now, spray foam is an excellent insulator -- it fills in all the cracks --
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    but it is pretty high embodied energy,
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    and, sprayed-in cellulose or blue jeans
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    is a much lower energy alternative to that.
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    We also used straw bale
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    infill for our library,
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    which has zero embodied energy.
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    When it comes time to sheetrock,
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    if you use EcoRock it's about a quarter
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    of the embodied energy of standard sheetrock.
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    And then you get to the finishes,
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    the subject of all of those "go green" articles,
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    and on the scale of a house
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    they almost make no difference at all.
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    And yet, all the press is focused on that.
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    Except for flooring.
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    If you put carpeting in your house,
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    it's about a tenth of the embodied energy of the entire house,
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    unless you use concrete or wood
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    for a much lower embodied energy.
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    So now we add in the final construction energy, we add it all up,
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    and we've built a house for less than half
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    of the typical embodied energy for building a house like this.
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    But before we pat ourselves
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    too much on the back,
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    we have poured 151 megawatt hours
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    of energy into constructing this house
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    when there was a house there before.
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    And so the question is:
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    How could we make that back?
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    And so if I run my new energy-efficient house forward,
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    compared with the old, non-energy-efficient house,
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    we make it back in about six years.
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    Now, I probably would have upgraded the old house
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    to be more energy-efficient,
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    and in that case,
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    it would take me more about 20 years to break even.
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    Now, if I hadn't paid attention to embodied energy,
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    it would have taken us
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    over 50 years to break even
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    compared to the upgraded house.
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    So what does this mean?
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    On the scale of my portion of the house,
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    this is equivalent to about
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    as much as I drive in a year,
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    it's about five times as much
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    as if I went entirely vegetarian.
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    But my elephant in the living room flies.
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    Clearly, I need to walk home from TED.
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    But all the calculations
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    for embodied energy are on the blog.
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    And, remember, it's sometimes the things that you are not expecting
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    to be the biggest changes that are.
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    Thank you. (Applause)
Title:
The tradeoffs of building green
Speaker:
Catherine Mohr
Description:

In a short, funny, data-packed talk at TED U, Catherine Mohr walks through all the geeky decisions she made when building a green new house -- looking at real energy numbers, not hype. What choices matter most? Not the ones you think.

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Video Language:
English
Team:
closed TED
Project:
TEDTalks
Duration:
05:52
TED edited English subtitles for The tradeoffs of building green
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