Monthly Archives: April 2010

Bring on the Negawatts: Google Powermeter, TED 5000, and Powerhouse eMonitor

“A negawatt is electricity that’s saved by using it more efficiently or at a smarter time. So, you don’t need to produce it to get the same hot showers, cold beer, or other effect that you want.” — Amory Lovins

OK, so that’s what these devices are for… helping you to identify ways to save on your electricity bill. Usually by identifying phantom loads (computers, TVs, etc. which pull lots of watts even when “off”.) Or inefficient or broken appliances.

In the order of least to most expensive choices: there are ones that you plug in to a single outlet (Kill-A-Watt), and others that monitor your whole house (Powermeter and TED 5000), and now there is one that will monitor every circuit (usually a room or 2) in your house (Powerhouse eMonitor).

Even if you spent the almost $1000 on the eMonitor, I bet most people would break-even on the cost in less than $5, according to MA electricity rates circa 2010 of $.20/KWh. I can easily see people finding easy ways to cut their bill by $15 month, so that’s almost $200/year. So $1000 / $200 = 5 years. And after that… free money thanks to negawatts.

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When two and four year olds have the freedom to talk

“I sit astounded. How is it that when two and four year olds have the freedom to talk as they wish, when they are relaxed in the company of adults who help them to get out the paints and paper and stickers, who don’t tell them what to do, too much, that their talk drifts to flooding and basements? I might as well have been at Dunkin Donuts in Sudbury, where I stopped yesterday for a decaf, envied the table full of older folks drinking coffee and talking with animation to one another, intensity and eye contact at 10 am for the companionship of friends, old and young. Conversation, freedom of expression, a basic human right, a privilege of those who are not alone, is a gift to many of our old folks and to our children, no rule here that says no talking, that says, it is spring and therefore your artwork must look like this.”

This was the main part that caught my brain (since it is all too familiar and fun to experience) but the rest is
HERE at Maria’s blog.

The beauty of this is, I guess is… that at a small family daycare, they are able to have enough staff that they can have age mixing like this. That’s partly what leads to awesome interactions like this. No need for the 3s to be separated from the 4s, or whatever the exact cutoffs are, state to state, that often get followed to maximize the number of kids per staff. Anyway, neat stuff that 2 and 4 year old conversation. The flooding… not so much.

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

Passivhaus comments and observations

We are nearly done with our house construction and basically done with any of the details which will affect the results of our house’s “performance” and results of our analysis using PHPP. (PHPP is the software… a gigantic excel file… used to help design and analyze the expected energy use of a planned or existing house.)

So a few comments about passive house / passivhaus.

There are some people who think the passivhaus requirements are too difficult for new england, the upper midwest, and maybe pheonix I’ve heard (on the heating end of the sprectrum). But I personally disagree. If people want to live in extreme environments, then I see no reason why they should be let off the hook.

What I would say, is that it really is quite reasonable to take an 80% or 90% approach. Well, or 50% is good too! In other words, if one can get to within 90% of a passivhaus, then gosh, that is quite an amazing house you’ve got there. Getting all the way there is trickier in harsh climates. That said, I think it is a valid complaint that there are a number of very low cost things which people can do when building or renovating a house that people just don’t do and also that one can think “I’m going to do some PH things, but not all” and think you are going to get very close (let’s say 80% there) but in reality… you are only 40% there if one ran the numbers in PHPP and monitored the actual usage. So that’s a shame too. Valid point.

And also in the US … it’s harder (more expensive) to get the HRV/ERV and windows one needs. I say that, but perhaps it’s not so bad. Maybe the high VAT (sales tax) in many European countries means that effective prices aren’t THAT much higher here for a fancy window imported from Germany for example.

However, I still wish we could do things more locally.

I guess what I’m saying is… I think there is a place for:

1. People going all out and meeting PH with imported products and maybe some non-typical building products or techniques (this helps informs builders and future custom home or renovators to what is possible) . We need people to push on the edge of what people have done before so we can learn.

2. Sticking to only what is in a typical budget but nailing all the “low hanging fruit” — the cheap stuff. It’s a no brainer and not expensive to build a tight house and one with 2-3 times more insulation (using dense packed cellulose). And there are some quite good and not that expensive triple pane windows out there (like Paradigm in ME).

3. Somewhere in between… using PHPP to analyze, and monitor the house, but don’t go all the way with imported products. This is still great because it helps to validate the PHPP software as a accurate model of “reality”.


4. The usage of a house matters a LOT. If you aren’t careful with electricity usage and hot water usage… it’s been found that people can easily use 2 or 3 times much as another similarly sized family (I’m pretty sure I’ve seen analysis of this with comparably built homes and family sizes at cohousing developments.)

5. I think of PVs (solar electric panels) as an offset. Especially if you have net-metering, it shouldn’t really impact one’s choice of how to heat the house or hot water. IOW, prices being equal… it’s not really any better to use a air-source heat pump that 98% efficient propane hot water heater for heat. That’s based on average utility company mix of using mostly fossil fuels. If you have hydro or a “green up” option on your bill, I think the balance tips to the heat pump approach.

6. Holistic thinking… OK, so nice house. Do you eat meat? What MPG does your car get and how many miles do you drive? These things matter a lot too. Especially relative to a house operating very efficiently. A vegan driving a Prius (or living in the city and walking) maybe has a smaller carbon footprint more than someone living in a small passivhaus. I don’t know! But it’s not too hard to run the numbers. Gary Reysa at does this. See his “half” project. Marc Rosenabaum at does this if you are designing a house or cohousing community or fixing up an office building or dormitory, etc.
If I buy a lot of stuff and fly in airplanes a lot, my passivhaus doesn’t matter so much any more.

7. Related to #5 above… I also think “Zero Energy Homes” are cool too. I mean, zero is better than not zero. A passivhaus can more easily become a zero energy home because there is less usage to offset with PVs. And not everyone has a sunny climate or a sunny lot. And insulation doesn’t break or wear out (if you build it right). Whereas solar electric panels (PVs) do.

8. Burning wood is good. Solar is better obviously, but come on… wood is very good too. So is a greasecar (modification to run any clean TDI diesel using used vegetable oil). Not as cool as a hybrid, but in the end, who is using more fossil fuel? The hybrid!

9. I’ve said this elsewhere, but we are right about at the point that without even factoring in tax credits, etc… a grid-connected solar electric system on a sunny roof is cheaper than paying electricity bills. Prices have come down quite a bit. At least in MA with net metering and high electricity prices.

10. If it’s energy independence that you care about most, improve your car first (or if you have oil heat). Coal etc is not primarily coming from other countries.

If you like math, you can compare all these things! It’s all just BTUs and KWhs and some arithmetic and adding things up! PHPP is really just an incredibly detailed version of this same thing (for just the house).

So let’s all get to 80%! That’s way better than a few going all the way and everyone else feeling put off or excluded because it’s too expensive.

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Filed under erik-green, homesteading, house, passive house, solar, superinsulation

Out of sight out of mind

Ya know how if you have junk food in the house… you eat it? So best to not buy it in the first place? Well, we’re going to try the same thing with our house in two aspects — no exterior venting of our (electric) stove. And no clothes dryer (we’ll see how that works out! We’ll probably have our old one, just not plugged in, and we’ll sell it if all works out…). Health first obviously. Saving energy is a distant second…. so first and foremost this has to make sense from a health stand point. No internal combustion in the kitchen (electric range), so no need to vent out carbon monoxide (CO) from combustion. And clothes drying… no health issues there, except that we obviously need to keep humidity levels in check.

Well so the problem with both of these types of holes/vents in a house in the first place is that there would need to be an equal amount of make-up air coming IN to the house from another source, and since our house is quite tight, that might be kinda tough to get it via leakage as in most houses. (Our house tested at just above Passivhaus tightness levels, and this was the first blower door test before drywall… so we will be even a little tighter probably.) And the basic point that you are venting out conditioned air, and bringing in cold (or hot in summer) air in exchange. So that’s a waste.

On the other hand… it’s also a bit of a waste to be cooking with electricity (vs propane or natural gas) as it takes 3 times the amount of fossil fuels at the power plant. But I believe I’ve done the calculations, and given the fairly low efficiency of gas ranges, the numbers don’t work out to be quite so bad. And some money savings, since no need for “dual fuel” to get an electric oven out of the deal.

Anyway, back to clothes drying. Our clothes already come out of our washer almost dry actually (front loader) so hanging them on a drying rack, even right in the house, should dry them out rather quickly. If need be, a space dehumidifier can help with moisture levels. Or we will stop being lazy and hang clothes outside. Imagine that! See this building science article on latent vs sensible loads. Basically the issue of “how do you dehumidify when you don’t need cooling?” BSI-028: Energy Flow Across Enclosures especially “Photograph 6: Hotel Room Fix—The through-wall unit controls the temperature (the “sensible” system). The dehumidifier controls the humidity (the “latent” system).”

Others will say that this (0.6 ACH) is excessive tightness, and something more like (2.0 ACH) is still plenty tight but would alleviate issues with make-up air. And maybe at that level an “exhaust only” ventilation system would work with no need for a HRV or ERV. Maybe. I think there are smart people on both sides of this issue. Let’s check back in 10 years and see what people think? My current thinking is KISS — keep it simple stupid — so if there is a way to do this with less complicated and more local methods (less complicated HVAC equipment, cellulose-only insulation instead of spray foam) etc, then that’s a more sustainable gameplan ultimately. Better for the environment and the local economy. Another way to put it is I’d rather spend money on people doing work than on expensive equipment. That said, I also prefer negawatts to megawatts. So let’s aim for both of these… local and negawatts!

Good night.

[Update: I should have explained one thing better… There IS a range hood with some fancy grease filters, but it does recirculate. And there IS also an exhaust duct for the HRV in the kitchen. And an operable window right behind the range. We are basically following the approach used in Passivhaus construction to use a recirculating hood and a HRV exhaust duct nearby but not directly connected. We’ll see how it goes. We can always add an outside vented range hood but thought it would be good to at least try this since it apparently works fine for 1000s of passivhauses in Europe.]

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Filed under building science, community, contrarian, erik-green, house, passive house, solar, superinsulation

Visualizing The U.S. Electric Grid

This is awesome! You can see existing transmission line and power plant locations, “sources of power” for each state, proposed wind and solar transmission lines, etc. Wow! LINK

My only question is the accuracy, but I didn’t look closely to see what the source of all of this info is. For instance, the generation mix is quite a bit different than what I received in my National Grid bill each month. See that that here. For instance: 28% nuclear vs a supposed state average of 12% (from the NPR page)

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Observations of a Sudbury school volunteer

This is a nice Sudbury Valley explanation that comes at it from a slightly different angle than I’ve heard before. The author volunteers at a Sudbury school one day a week, and is the parent of a student. But his main job is at a K-5 after-school program. LINK TO ARTICLE

A few quotes:

“Far from being little lord-of-the-flies centers where mere anarchy is loosed, Sudbury schools are communities that are run by the students, for the students. There are plenty of rules, but they are neither arbitrarily imposed from on high, nor artificially “decided on”…

“Not even when one kid stormed off in anger did anyone so much as look at me as anything but another player. ”

“I’m an empiricist too, and I speak from experience. The kids I work with at the after-school program aren’t miserable. They haven’t had their love of life stamped out of them, or their creativity. This isn’t because I’ve imported as many Sudbury-esque features into my class as I can adapt, but because the kids come from families who love them to go to a school run by teachers who care, and because, well, they’re kids. But …. ”

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How many showers can we dish out until the sun shines again?

Until we get real and install some better solar hot-water heating — with a 1500 gallon unpressurized drainback tank (we’ll see!) — we will have a 105 gallon Rheem Marathon electric hot water heater being heated by a Geyser heat pump hot water heater.

My question is how many showers can be had when the sun isn’t shining (due to nighttime or clouds) without having to turn on the heat pump and use non PV electricity. Time for some algebra!

First the assumptions. And let’s make some guess at a usage pattern rather than really doing algebra and solving for n (when n=number of showers)
1. Hot water temp on the hot water heater set to 130F
2. Showers will have H20 Kinetic 1.5 gallon/minute shower heads
3. There will be some mixing with cold water since 130F is too hot for a shower. But let’s just be conservative and say we use a full 1.5 gallons per minute.
4. Pretend like we know the incoming well-water temp (let’s say it’s 50F)
5. Pretend there is no heat loss thru the tank walls and no significant temp stratification. (The Marathon is pretty well insulated…)
6. Timer that switches the HW heater off during night-time hours to prevent slipping into non-solar usage.

Ok so, let’s see what the tank temp (assuming no stratification) is after 2 10-minute long showers is (as a guess of what the tank might be able to handle)

So that’s… 1.5 gallon/minute * 2 * 10 = 30 gallons of outgoing 130F water getting replaced by 50F
So in the tank we will now have
30gallons * 50F
75gallons * 130F
which is an average of (30*50+75*130)/105 = 107.14F

And I think that’s still warm enough for a short shower, so given my conservative numbers, we could have several people taking showers before the sun comes up on our PV array without having to pay for a full-priced KWh from our currently non-net-metering electric company.

I think. And we will have to try to run things like dishwashers and washing machines during the day probably/ideally.

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