WARNING: this is an extremely long and geeky blog posting. Proceed at your own risk.
We, like so many others, would like to be good global citizens, which means that we would like to minimize the global impact of building our house. So we look for environmentally sound choices. We want to “go green” – Simple! Just pull up a website on a subject like “choosing a green countertop” and read that this choice has “more” embodied energy in it’s manufacture than that choice, and this one has “more” transportation energy than that one… so the choice is clear isn’t it? You choose the one that is “less” than all the others, and you can buy your countertop material with a clean conscience and self-righteous conviction that you are doing right by the earth.
But wait a minute… NO ONE says how much more “more” actually is… these sites just recycle the same meaningless, numberless comparisons – no one ever even thinks to put any of these relative numbers incontext or to make any kind of a statement about how much these differences matter. So yes, ‘this’ is more than ‘that’…. but should I be concerned? or is this a trivial difference?
So what is a geek to do? Calculate the actual numbers, that’s what! (Don’t worry, there is a comparison chart at the end.)
Some useful numbers should you care to try this at home:
(Average US family numbers)
CO2 production per kWh = 1.37 lbs
Water use per day = 720 gallons
shipping: 0.0887 lbs/ton-mile
trucking: 0.3725 lbs/ton-mile
flying (long): 0.4 lbs/passenger mile
flying (short): 0.53 lbs/passenger mile
40 gal gas = 776 lbs CO2
30 hours air conditioner = 411 lbs CO2
Flight SFO-LAX round trip = 345 lbs CO2
Websites with useful info:
So since it was the countertop internet comparison pablum that really set Catherine off, she decided to look at the “usual suspects” in these green counter top comparisons: Concrete, Stone (like soapstone or granite), Engineered Quartz surfaces (like Caesarstone or Silestone), “Paperstone”, and recycled glass counters like ICEStone or Vetrazzo.
For our house, we will need about 124 square feet of finished countertop when you include every bathroom, bar, and kitchen counter top. At an inch thickness, that calculates out to a little over 1500 lbs of material. WIth off-cuts and waste, that sorta rounds up to a nice even ton (short ton, not metric)
So for Concrete, “embodied energy” (or energy of manufacture) is relatively easy to find, and it comes out to about 240 kWh/ton. Although the energy isn’t all electric, we’ll convert it all to CO2 as the common currency, and that comes out to 328 lbs CO2 per ton. Worse if you have to transport it far, but usually you don’t.
Granite and soapstone (and marble and onyx etc) mining in far off Brazil or India is often used as an example of wasteful shipping costs and high transportation energy. So if we ship a ton of granite or soapstone 10,000 miles by sea, we get 887 lbs CO2 per ton plus 200 lbs or so CO2 for truck transportation at either end – certainly worse than concrete. Plus mining is non-renewable.
Go to engineered materials like CaesarStone or SileStone, and (far away mined) quartz (94%) is mixed with binders (6%) to make a nice hard any-color-you-want counter top (such as the now justly famous “tequila sunrise” color). Although some of the content can be recycled, much of the raw material is shipped half way around the world… and it’s mined… so raw material transportation costs start to look a lot like whole stone (although quartz is considerably more abundant than any of the monolithic stones that are quarried for countertops!) But now you need to put more energy in to make it (couldn’t find out how much), and if you make it in Minnesota (SileStone), you need to truck it to California when you are done making it which takes about 560 lbs CO2 per ton more. In the US, Caesarstone is made in Van Nuys California which is only 125 lbs CO2 away by truck. So these start looking like 1447 lbs and 1002 lbs respectively.
So let’s go to paper – nice and renewable. Couldn’t find the actual numbers of how much energy it took to produce, but Paperstone touted on it’s website that it’s super recycled content of it’s best product with extra special resins countertops SAVED 254 lbs CO2 per slab over conventional paper based countertops with phenol resin…. that is 1026 lbs per ton. Since we can assume that at best, it is cutting the energy requirements in half (this is a baseless assumption, but I don’t have a better one), I am assuming that the energy costs of even the best paper based counter tops are around 1026 CO2 per ton and the not so good ones are around 2000 lbs CO2 per ton. Paperstone is in Hoquiam Washington – about 290 lbs of CO2 away
Then you get things like ICE Stone (recycled glass), and Vetrazzo the “original recycled glass countertop”. These both get high marks for recycled content, IceStone has the first cradle to cradle certification because it is made with mostly recycled materials. Couldn’t find an embodied energy number, but even if it is zero, to ship it from New Jersey would take 955 lbs CO2. Vetrazzo which is local (Richmond) got a “green audit” which calculated 193 lbs CO2 per square meter of installed countertop which comes out to 2659 lbs CO2 for our project. This is probably rather unfair to Vetrazzo, as they are accounting for ALL the CO2 which I suspect my calculations are not, but still it is not zero, or even that low, so they don’t seem much different from the other choices.
[Plus – I just have to add – these recycled glass materials currently have a bizarre “emperor’s new clothes” chic about them which is causing so many people to overlook how unbelievably garishly ugly they are. Article after article rhapsodizes about their “gem like” qualities, and they are going into “green” kitchens all over the country. Unfortunately, I don’t think they are going to be very green if in a few years everyone starts ripping out these ticky-tacky, dated looking counter tops and dumping them in landfills once the fad is over. Harvest gold and avocado green appliances anyone? I will grant that there are a few types that are nicer than the others, but most of these just make me cringe!]
So clearly, we could make a difference of about 1000-1500 lbs of CO2 of embodied energy in the one-time choice of countertops, and it looks like concrete might be the way to go (assuming no (somewhat likely) horrible error in my calculations)… or I could drive all over looking for slabs that have been taken out of other kitchens I could re-use which is much better from a landfill perspective, but I might produce a good 400 lbs CO2 doing it if I take more than 2 trips to the East Bay to find these slabs.
…but after all this, does it MATTER compared to the other choices we are making in the house? If you average it out over the life of the countertop, how much of an energy difference is there between these choices?
Not a whole lot as far as I can tell. What DOES make a big difference is how much energy the house uses or saves on a day to day basis.
For example, if we don’t install air conditioning, and therefore don’t run it for 5 hours a day for three months out of the year, then that is 6165 lbs CO2 a year we aren’t producing.
If we do install solar hot water that covers about 60% of our needs, and displace 117 therms a year of natural gas just in our domestic hot water use, that is 4700 lbs of CO2 a year we don’t produce to heat our water.
So the bottom line conclusion we came to is: choose efficient appliances, conserve water, insulate, insulate, and insulate – and then choose whatever damn countertop material makes you happy – even if it IS Vetrazzo.
Hmmm…. but what about the embodied energy in building an entire house…? How long does it take to offset the big energy sink that is all the building materials of a house with the increased efficiency of that house over what was there before…? that will have to be another blog post.