Monthly Archives: May 2010

CO2 reaches record level: 392 ppm

Article Link. And check out that graphic! 392 ppm. No worries! (Not.) BTW, the recent issue of Solar Today has some very cool photos of gigantic arrays of solar trough collectors as far as the eye can see. But it does lead me to the feeling that it sure would be a lot easier to use less energy, wouldn’t it!

I am as guilty as the next person. The solar array on our soon to be ready energy efficient house will output an average of 690 KWh per month (when it’s new) aging to 80% of that in years 12 through 25, if the warranty has anything to say about that. So let’s see… that’s 23 KWh per panel per month. And 23,000 KWh / (30 days * 24 hrs/day) = 32 watts. In other words, getting rid of a continuous use of 32 watts 24/7 in your house is as good as a 230W solar panel. Oh dear… it has GOT to be way easier to just cut 32W instead! Negawatts Amory Lovins calls it.

To that goal, consider getting a “kill-a-watt” meter (monitors one plug), or a TED 5000 (whole house), or a Powerhouse eMonitor (whole house, but also tracks usage circuit by circuit). And let the electricity saving begin.

Probably the way to do it is to compete with a neighbor or friend to see who can get the lowest. Or maybe go by percentage decrease or something to even the bet. And that’s just electricity of course. You could add oil/natural gas/propane to the list if you heat your house with something other than electricity (which is generally a good idea BTW, because fossil-fuel electric power plants are typically only ~33% efficient) so to do that… insulation.

But that’s not as fun as nagging family members to turn of the bathroom light! And harder to compete with your neighbor on insulation since often there is not a tidy monthly bill to look at as with electricity use. OK, good luck to all of us! Here we go!

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Filed under contrarian, erik-green, passive house

Michael Marquis Finish Carpentry

Review: Mike Marquis is the finish carpenter who did the finish work on our three flights of stairs in our house in Stow, MA. He also installed our kitchen cabinets. He is a meticulous craftsman! I could imagine it might be difficult to find good people who do good work so here is my advice: Highly recommended! Mike works in Massachusetts, the Boston area, and in Southern New Hampshire on a variety of projects and I would highly recommend you consider him for any type of finish carpentry work including custom projects. More at his website: michael marquis finish carpentry His phone: 603-759-1198

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Sudbury Valley School – The place reeks of beauty

A great post from Maria West:

“Today I was at Sudbury Valley, and all around were flowers, a lilac bush so large and loaded with blossoms it seemed unreal, large vases of flowers in the kitchen and in another of the rooms, forsythia bushes loosing their blossoms and growing their leaves. I take back my comment about beautiful materials missing from that environment as opposed to a Reggio inspired space. Beauty is everywhere at Sudbury Valley. The bathroom curtains are handmade of gorgeous prints. The landscape and the buildings are beautifully maintained. The property backs up to acres and acres of wooded conservation land, which by rights the children can explore. Light pours into every room, the art room not least of the sunlit spaces, as well as the office and the kitchen and the sitting rooms. There is art by children as well as famous artists framed and hung all along the walls. The place reeks of beauty. I am not sure if that is highlighted in the many volumes of Sudbury Valley literature. It is clearly evident to any visitor, and must seep into the consciousness of any kid.”

LINK: Flowers on the table and delicious food, take 2

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Filed under alternative education, education, school, Sudbury Schools and Sudbury Valley School

Nissan Leaf / EV calcs

100 miles for full charge of battery (24KWh) commute for one year:
7200 miles/year (10 miles one way x 4 a day)
so that’s 7200 / 100 * 24KWh = 1728 KWh / 12 = 144 KWh per month
$28/month (at $0.20/KWh) vs $66/month for gasoline (at 26MPG and $3/gallon)
And no oil spill guilt (just solar. and/or mountain top removal type guilt)

I doubt we’d buy a LEAF. Probably a plug-in hybrid instead. But who knows.

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Living the grid-connected but non-net metering life

I will have to look into this more on monday, but one very odd *financial* reason to (at the moment) heat our PV grid-intertied house with air-source heat pumps (electricity, but at ~250-300% efficient, counteracting mostly the ~33% efficiency from a fossil fuel usage standpoint for heating) is that since our PVs are connected to the grid, even if we have a 0 KWh use (and this would actually be a miracle since there is no net metering, so it would mean I don’t use the computer and we don’t use lights when it is dark or cloudy)… The “at the moment” part above is that there is always hope that we will some day have some net metering. I assume it will happen eventually.

So anyway, even if we used 0 KWh/month in electricity by only using electricity when our PVs are outputting enough juice, our bill from our municipal electricity company is still going to be ~$20/month for any usage < ~200KWh. Including 0KWh. (I'll know the details on mon). IOW… I bet it will be unlikely, even with no net metering that we will use more than the minimum payment for heat, hot water, and electricity use. We'll see. Vs… if we had a propane hot water heater or Rinnai-style direct vent heater, we would be paying real money for the usage (and on top of that… the price per gallon would be highish since our annual usage would be low and all the propane companies have higher prices for less usage). And by highish I do mean in a KWh of source fossil-fuel-based energy sense since I always multiply electricity use by three because it's ~33% efficient from the mostly kinda dirty power plants around here.

Is this making any sense?

My logic here and always is that you have to think holistically about PVs. They are really just an offset for other usage. IOW, if you are just looking at energy used by the world, it doesn't really matter if YOUR use the electricity pumped out out by your PVs, or your neighbors. So the very best way to heat your house if you are not in a dense area and bugging neighbors, even if you have PVs and/or a net-zero or passivhaus/passive House is still wood. Well, solar heating I should say comes first. But most "traditional" solar heating systems are expensive vs wood stoves. (I should note that I think a re-birth of TAP / "solar siding" / low-mass sunspaces will bring back lower-cost solar heating. Go join the "Solar Heat" discussion list at

Air-Source Heat Pumps are next, especially if you live in an area with lots of hydro electricity, or have a greenup option on your bill, but even then I suppose it is questionable, since this greener electricity could probably be “exported” farther afield if one wasn’t using it. But heat pumps generally are only tied with fossil fuel options like propane or natural gas — IOW, the global fossil fuel usage is probably going to be the same in either case. Break out excel and do the math. I’m pretty sure I’ve got this right, even if assuming the best numbers out there: a 98% efficient Navien hot water heater being used for hot water and radiant heating VS a heat pump with a COP of ~3 like a Fujitsu 9RLS. Since 33% * 300% (heat pump) ~= 100% * 98% (propane)

Hot tip if you are looking at heat pump manuals: COP = HSPF / 3.413
So the Fujitsu is 12 / 3.413 = 3.51. But that’s for a more southerly climate zone (like NC?), so the adjustment I usually use for MA/Massachusetts is the 15% adjustment I think I’ve seen Canada uses for heat pump ratings. So 3.51 / 1.15 = 3.05. Voila.

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