One of the slew of emails that came in over the weekend was from Stacey, a local architect. Stacey asks:
I just read the SF Chronicle article about your Sunset neighborhood house. Thank you very much for your efforts in going sustainable. I think this is a very important thing to be doing.
However, I have a question for you. Since your house’s main energy consumption component is heating, why did you spend $20,000 on a PV system when you could have spent half that on a solar thermal system to heat your hot water instead of using natural gas (a non-renewable, carbon emitting fuel)? You would save much more energy doing that than those PV panels will ever produce. In the total energy/polution equation, this would have greatly reduced your house’s energy consumption and carbon emmisson. The solar thermal would have had a much faster payback as well, despite the incentives being less than PV, particularly considering how you are utilizing hot water to heat the house.
Stacey Stemach
Architect
An outstaning question, my response below. But I ask you, gentel reader,wWhat do you think about PV vs Solar Thermal systems?
I doubt it would surprise you to know that I am something of a wannabe political hack. One of my many daily guilty pleasures is my RSS feed from TPM – a really great blogsite for American Politics. Today’s feed had links us to a who’s who in the Anti Global Warming Camp. Worth a click, just to remind you who is on the other side. We should do a poll for biggest ass clown of the lot.
I had a great email from one of our readers, Bill Roth, who has developed a set of 4 homes out in San Antonio called Arroyo San Antonio. He incorporated a lot of common sense features attentive to both power and water conservation: energy star appliances, dual flush toilets, front load washing machines. I was particularly struck by his approach to greywater harvesting. Obviously being in the desert the good residents of San Antonio are very water conscious, but frankly we all need to think that way. Too much water flows through our homes that can be given a second use, and we all need to think about water consumption more seriously.
Concrete. I mean, I get why cars would be there, and oil, and airplanes, deforestation, unbridled consumption….but concrete? When I bring concrete up people give me a funny look, but most of you at some point or another will have to work with concrete, even if it is just getting your driveway or your foundation redone. So think about this when the time comes. Concrete contributes any wheres from 3%-5% of GLOBAL CO2 production yearly. Were talking millions of tons of carbon. Concrete is far and away the most common man made building material in the world. You have to take it seriously if you are going to build sustainably.
The NY Times has a good piece today that reminded me of the need to talk about concrete. When I remodeled 2139 3th Ave I used close to 30 yards of concrete getting the foundation earthquake strong and pouring a new retaining wall.
30 Yards for a little crappy house in the Sunset – ok not crappy, but you get my drift. Concrete is a major player in building, so how do you do it Sustainable? One option is to use concrete with Fly Ash and/or Slag in it. Bode concrete sells it in the city, and that is what I used here. The problem with concrete is in the Portland Cement used to bind all the stuff toegther. See cement comes from limestone, and you gots to heat it up to over 2,000 degrees to make the limestone into cement – that’s is where the CO2 comes from. Flyash can replace 10% – 20% or more of the cement in your mix. Less cement, less CO2. It is a simple as that.
There are a lot of players trying to make greener concrete, and I give them props. There are pros and cons to all the approaches, but God bless them for working the problem in creative ways – we need more of that and less crying about how bad thigns are getting. One local company that is doing some really interesting stuff is the Calera Corporation. They are mentioned at the end of the times peice and the Chron did a great stort on them in 2008 that is worth reading again…basically they are making cement using sea water similar to how corals form. Don’t ask me for details, I am not smart enough, but I am impressed, it is people like this who are really going to make a difference for our future.
Interesting idea…this seems like it would be a good solution for an NGO working in the third world, not sure about its applications in a developed country like outs, but maybe I am not thinking creatively enough. So here is StrawJet, a funky machine that makes structural, timber type material, out of plants:
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