My thoughts have turned lately to the challenge of heating and powering residential homes in the Pacific Northwest with renewable energy. My goal was not to just find a way to reduce fossil fuel use, but to eliminate it. When I started this exercise I wasn't at all sure it could be done (in an affordable manner). Here in the Seattle area we average a little more than two clear days a month for six months of the year!
Back in January, I mulled over the concept of an affordable, solar-powered, carbon-neutral home designed for this latitude and longitude that would have no gas, electric, or hot water bills. The key to affordability was small size. You traded the status garnered from cavernous space for the status of being the first on your block with solar technology. That article was based on rough back-of-the-envelope estimates. At the time I was considering hydrogen storage and parabolic collectors. I received a lot of feedback on that first article, which I have incorporated into this latest iteration. People wanted south-facing windows. A lot of people were also skeptical about living in a 1,200 square foot home.
I just completed a fairly rigorous analysis (with simulation and testing) and have some good news to report. The latest design has 2,800 square feet of heated living space, the equivalent of fourteen 4' x 4' windows, and is three stories tall. It could be bigger or it could be smaller. All you have to do is keep the panel area, mass storage, heated volume, and insulated envelope ratios about the same. It took weeks and several iterations to come up with a design that worked. Forget hydrogen. Not only would it be complex and expensive, it would have to be stored in gaseous form and would take up a comically large tank farm. Forget parabolic collectors. Also expensive and complex, they require clear cloudless skies and failure prone tracking devices. Their mirror finishes also degrade fairly rapidly.
As part of this analysis I also built a solar panel test rig and used it to test two types of panels (which I also designed and built). The rig was necessary to fill in some blanks and give me a measure of confidence in my calculations. Yes, those are my daughter's chickens in the foreground and no, I didn't water my lawn this summer.
Almost without exception, when you read about a solar-powered home you are reading about a solar-assisted home. Typically these homes will achieve modest to respectable reductions in the cost of space heating, hot water, or electricity, but claim to drastically reduce or eliminate all three. There is usually something like a wood or propane heater not mentioned in the article making up the difference. It just costs too much to try to take it all the way. An analogy would be to try to make a Hummer get the same mileage as a Prius by bolting a hybrid drive onto it and filling the trunk with batteries. As with the Prius, to get the desired results you have to start from scratch. You can't go fossil-fuel-free by retrofitting an existing house, at least not in Seattle.
Regulations allowing, this latest home design could sell energy to its neighbors. Engineering being the art of compromise, there are any number of cost variables that I could have traded off. As designed, this home should cost roughly 10 to 20 percent more than an equal sized, multi-story fossil-fueled home. I'm going to keep how that is possible, along with most other details, under my hat for now.
I wanted this design to have a large margin of error and to be simple enough to be reliable. For example, I didn't assume the owners would turn the thermostat down to 65 degrees at night, or turn off the fresh air heat exchanger when they leave for work, or make any effort at all to reduce electricity or hot water use. It would consume the average amount of hot water. I assumed the electric load would be the same as that of my four-person family (washer, dryer, dishwasher, and all the attendant electronic devices and phantom loads you can imagine, using natural gas for cooking, heating, and hot water).
Just for the hell of it I'm going to put together several floor plans and options for things like decks, double decks, skylights, emergency power storage, and even an option to capture 90 percent of the rain that falls on your house during the long dark winter. You can mirror the house floor plans East to West but not North to South (or upside down or inside out).
This thought exercise yielded some epiphanies:
- Conventional hot water solar panels consume prodigious amounts of copper because it is such a good conductor (and much cheaper than silver). But thanks to China, the price of copper has risen over 400 percent in the past few years. I wanted this solar home design to be scalable. I'm not sure there is enough copper on this planet to build everyone conventional hot water solar panels, which is why I don't use any copper in this design.
- Locally produced solar power cannot be used to power dense housing because the ratio of solar panel area to insulated envelope would be far too low. You could supplement hot water to some degree but that will be the limit of it. Even so, apartments and condos will still be more efficient per person than even a hybrid solar home. Locally produced solar power requires a lot of space and no shadows. But if you want to raise a family in a house, this is the kind you should do it in.
- Even though this house would generate all of its own electricity, it would not reduce CO2 emissions from the local coal-fired power plant by a single pound. That's because the load is too small to detect. They would not throw one less chunk of coal on the fire. The only hope for a home like this to reduce coal use would be for the design to catch on and spread rapidly. A few thousand of these homes in a given grid area would be noticed and the utility would have to find a way to burn less coal or go bankrupt. The tail would be wagging the dog. Utilities will be forced to come up with a way to handle massive amounts of home-generated solar power.
- It struck me as absurd that we go to such extremes to pamper ourselves inside artificial climates. The surface of the planet is covered with a thin film of housing with microclimates inside. Our cars are an extension of that climate. Nobody hangs out and naps in the shade when it gets hot or snuggles by the fire under a blanket with hot tea and a book when it gets cold. Our homes are like flour sieves. If you hold a candle under a sieve and measure the air temperature in the space, it will rise as the wire mesh impedes the loss of heat. That's essentially what our walls and windows do. And everybody wants lots and lots of windows.
- In all seriousness, somebody should bother to create a line of heated clothing using the latest technology of fast charging batteries and microprocessors. We could stay warm and cozy in a 55 degree home if suited up with electrically heated socks, vests and fingerless gloves. When you think about it, this idea of heating the air in an entire house to 70 degrees 365 days a year when you could just put on some heated underclothes is kind of ridiculous.
- Why do people move to places that can get very cold or very hot, or both? I suspect that subtle instincts motivate us to spread out like water on a table. The same thing that causes lemmings to migrate. That's why there were Inuit and Eskimos living in the Arctic. They traded conflict and competition with neighbors for survival in an extreme climate.
In conclusion, the scalable technology to affordably eliminate fossil fuel use in single family residences exists, which begs the question: Where are these homes? I believe this is a case where house designers in this neck of the woods have not realized it can be done, yet. But the cat is out of the bag now. There also hasn't been a demand for this kind of house. Most consumers are still under the mistaken impression that, as with SUVs, bigger is better. That's going to change also.
Like a Prius, the solution isn't one piece of technology but a dozen technologies strung together in the name of efficiency. And if it can be done here, it can be done anywhere for much less, except maybe in Alaska. If you live in Alaska, your best bet is still long underwear.
Seattleites: Come hang with Amanda Little at Elliott Bay Books
U.N. chief will pressure senators on climate bill
Friday music blogging: Here We Go Magic
Comments
View as Flat
stopgreenpath Posted 3:09 pm
14 Aug 2008
please keep us posted...
the greenest energy is that which you needn't ever produce.
Permalink
amazingdrx Posted 3:26 pm
14 Aug 2008
But of course seeing is believing, build one and document it on video like you did with your plugin bike, and maybe the conventional wisdom will shift?
Let's have a revolution!
http://amazngdrx.blogharbor.com/blog John Schneider, Northern Wisconsin
Permalink
spaceshaper Posted 8:55 pm
14 Aug 2008
The true meaning of life is to plant trees, under whose shade you do not expect to sit.
Permalink
Caroline Posted 11:46 pm
14 Aug 2008
Thanks for the article-may it inspire others to work in their own environments to produce something as effective.
Permalink
Neven Posted 12:16 am
15 Aug 2008
Will you be writing more about this some time soon, biodiversivist? I'm very curious as to what your plans are.
I'm sure you know about the passive house concept: http://en.wikipedia.org/wiki/Passive_house. IMHO it's the best possible way to build a house. Up to now only 7500 passive houses have been built in Europe, which I find totally unbelievable. I feel this building concept should be the standard in the whole northern hemisphere.
I'm planning on building a passive house myself in the near future. It'll be about 1200 square ft for a family of three, possibly five in the future (2800 square ft could easily house ten persons, that is if they're not American). With approximately 3500 Wp of solar panels on the roof I expect the house to be completely energy neutral.
Permalink
Laurence Aurbach Posted 12:18 am
15 Aug 2008
Solar heated houses go back farther than the 1970s, of course. In the 1940s, MIT built a demonstration home in the Boston suburbs that had three-quarters of its heat load provided by solar power.
"I suspect that subtle instincts motivate us to spread out like water on a table."
Consider that 68% of the U.S. population is concentrated on just 2% of the U.S. land area. People live by choice in urban areas because of the opportunities and amenities that cities provide.
Of course, there is a contingent of people who want to live in isolated spots, but that is a minority of Americans.
Ped Shed Blog
Permalink
Steven T Posted 12:47 am
15 Aug 2008
That gives me pause. Really? I've been on the planet long enough to have watched how much bigger middle-class houses have grown.
Seems to me that a major aspect of "green" living is to carefully analyze how much space we really need. When you dig into that question you inevitably surface your basic values.
Permalink
Biodiversivist Posted 1:43 am
15 Aug 2008
In due time. Meanwhile, use your imagination. What would the optimal solar angle of inclination be? What is the roof height limitation in Seattle? What kind of roof would maximize exposure to solar? Use a little geometry and you'll have the basic envelope.
Neven,
This just couldn't be done here with passive. The average American family of four uses over two million BTUs of hot water a month! My family uses over 750 kwhs of electricity a month on top of that and none of it is used for heating the house or hot water. Convert that to BTUs. You'd think there might be enough energy right there to almost heat a properly designed house (hint).
There isn't enough solar radiation hitting a house in Seattle in the winter for a passive design. Partly clear days can also be used for solar but there are only 3 or four of those a month also! Around here you get clear skys or overcast ones, with little in betweeen.
http://home.comcast.net/~russ676/photo/cleardays1.gif
Laurence,
Good points. But there are a lot of solar urban legends floating around out there. The back yard of most solar powered homes hosts a big propane tank and you also typically see an efficient wood stove in the living room. The 70's oil embargo kicked off a lot of experimentation. I was an engineering student at the time helping professors test various collectors. The MIT home provided 75% of its heat load. Did that include a couple million BTUs for hot water a year and another couple million for electricity? Boston also gets a different cloud pattern through the winter than Seattle. I wanted to see for myself if this was possible in Seattle. It is but you really have to pull out the stops. It's a no brainer in Tucson. A third of the cost of this design is the solar collection and storage system, of which 4/5 of the cost is in the PV panels.
When I said we spread out like water I was talking about the fact that cities spring up in every kind of barely hospitable climate. I'm not a fan of urban sprawl
I'm with you, Steven
In the end, it all comes down to biodiversity. Poison Darts--Protecting the biodiversity of our world
Permalink
Delay And Deny Posted 2:09 am
15 Aug 2008
You're missing the point.
A solar-hydrogen home can let you live anywhere.
Retrofitting a home in the dying inner urb is dumb.
Sprawling into rural Eastern Washington and buying some cheap off grid land is now possible.
There's plenty of sunshine and nearly by towns all have cappucino.
Set up solar-hydrogen, you power your SUV and home for free. No roads? Well that's why they call it an "off road vehicle".
Water? Power a reverse Osmosis system and capture back the by product H20 from consuming hydrogen.
As long as a Clearwire Wimax tower is nearby for Internet access what else do you need?
The new America is a sprawling super suburb without the urb...and without the traditional grid...let's say in the language of s+s (software plus services) that we will be loosely coupled to the grid where before we were tightly coupled.
Permalink
amazingdrx Posted 2:24 am
15 Aug 2008
I'll guess how it works yet, hehey.
http://amazngdrx.blogharbor.com/blog John Schneider, Northern Wisconsin
Permalink
zumbi Posted 3:18 am
15 Aug 2008
also, when do you plan on posting more details about the house?
Permalink
Biodiversivist Posted 3:52 am
15 Aug 2008
In the end, it all comes down to biodiversity. Poison Darts--Protecting the biodiversity of our world
Permalink
amazingdrx Posted 3:56 am
15 Aug 2008
But how can you heat domestic hot water in winter with virtually no solar? Use a ground source heat pump.
But how do you store enough solar electricity for the winter months? You don't. You can use net metering, selling excess power to the power company, mainly over summer months, to offset the grid electricity you need in winter.
How close is that guess bio-d? I'll take your silence as a confirmation, hehey.
Come on everybody, start guessing.
Lest anyone claim this puts the hurt on the power company, which gets nearly zero revenue, but has to power the winter months peak load. Wind power peaks in winter, so if every home had this design the power company could install utility scale wind, a cheap way to meet the winter peak.
The power company would still get paid for managing the grid. With a fair profit determined by the utility commision.
http://amazngdrx.blogharbor.com/blog John Schneider, Northern Wisconsin
Permalink
Neven Posted 4:12 am
15 Aug 2008
Zumbi also highlights a major point: How much energy is needed to produce the materials for building the house? It's nice that stone and steel are recyclable but a lot more energy is expended on production than for instance on production of wood. And what about the insulation materials? Chemically derived insulation products take huge amounts of energy when compared to hemp or cellulose.
I have an article here somewhere from a passive house magazine with info on exactly this kind of thing. If I can find it I'll post it here.
Permalink
Laurence Aurbach Posted 4:21 am
15 Aug 2008
Citations for the Saunders houses:
Super-Solar Houses: Saunders's Low-Cost 100% Solar Designs by William A. Shurcliff, Norman B. Saunders (1983).
Saunders' houses were 100% solar space heated, domestic hot water was solar preheated to 80-90% of final temp, cost of houses was same as standard construction.
Citations for the MIT solar demonstration house and other solar architecture:
A golden thread: 2500 years of solar architecture and technology by Ken Butti and John Perlin (1980).
Solar energy: The awakening science by Daniel Behrman (1976).
Ped Shed Blog
Permalink
sunflower Posted 4:27 am
15 Aug 2008
I have been asked to make a community of 15,000 carbon free, plus future growth. The solar heat portion, most of the energy, will cost $60MM, and employs seasonal heat storage. This is much easier than making one house carbon free. Off-site solar power may about double the cost. Carbon free must include everybody, including existing buildings or we are all cooked.
Think outside one box.
Permalink
Biodiversivist Posted 6:02 am
15 Aug 2008
Laurence,
I wasn't challenging the credibility of those studies. I believe the MIT house can provide 75% of its heating needs as you stated. I was asking if it could provide 2 million BTU of hot water for an average family of four, heat the house, and supply all of its electricity. If it can be done here, feasibly, which was my question, I'm sure it can be done there.
Solar homes are very location specific. A solar home located in sunny climates where average temperatures are in the 70's and cooling breezes blow wouldn't be as challenging or expensive-- Maui or San Diego.
Sunflower,
You've mentioned the GSPP mirrors in other threads. Sounds interesting, and maybe expensive. I was not referring to glass mirrors but the cheaper polished aluminum ones. Your project sounds real interesting.
More later.
In the end, it all comes down to biodiversity. Poison Darts--Protecting the biodiversity of our world
Permalink
spaceshaper Posted 6:41 am
15 Aug 2008
Despite dire predictions about the lighting conditions inside the building, all of which proved unfounded, it succeeded. At the time there was no detailed explanation published about why it worked, but work it did, completely eradicating any need for heating. However, Morgan's design died with him, and it was many years before anyone else considered it of more than curiosity value. Similar designs are now being examined across the world.
In practice, the large convector ducts which direct the warmed air to the colder north side of the building are a major safety hazard, and fire breaks have had to be inserted to reduce or cut off the air flow. The result is that on sunny days the south, glazed side of the building reaches unbearable temperatures in excess of 40°C while for most of the time the unglazed north side never reaches a comfortable temperature nor receives much natural light.
A secondary, small single-pipe heating system was installed to give additional heating on cold winter days with very few hours of sunlight. The system is fuelled by oil, which was cheap at the time. Today, the secondary heating has to be used very often, and is very expensive."
The true meaning of life is to plant trees, under whose shade you do not expect to sit.
Permalink
Biodiversivist Posted 7:49 am
15 Aug 2008
Retrofitting existing homes is a different problem altogether. There is little status to be garnered from well insulated walls and crawlspaces and there is no hope in Seattle of eliminating all fossil fuel use by bolting solar panels to patches of your roof where the sun hits. It would cost a small fortune to eliminate just my home hot water load, leaving my home heating and electric loads untouched.
For most urban single family home owners, retrofitted solar options are pretty limited. Although, I do know one guy who has the perfect house for a solar retrofit. The roof line has unobstructed southern exposure and the house is longer than it is wide. It wouldn't be cheap but in his case, it would at least be doable.
In the end, it all comes down to biodiversity. Poison Darts--Protecting the biodiversity of our world
Permalink
sunflower Posted 4:16 pm
15 Aug 2008
Solar can be in the image of supplementing fossil fuels or the system can be 100% not fossil fuels. And solar power is not needed to pay for solar district heating. Both can send heat many miles from the source with low loss and positive economics.
I have attended the international conferences on seasonal heat storage, and on annual efficiencies of very large solar heat arrays. I have also designed and now live in a most efficient passive solar home near Seattle, so I know the limitations of both systems. Achieving 80% carbon free isolated new home heat without firewood is doable with cost savings. The last 20% is expensive in Seattle type climate (ignoring hydroelectric power). Achieving 100% community low-carbon heat for existing homes is doable with cost savings. Sweden interconnected nearly all existing homes with a nation-wide hot water district heating system in a 25 year giant retrofit of their society.
And for further digression, solar cogeneration is possible but more complicated. High-intensity photovoltaic power (HIPV - 500 to 1000 suns) is much more cost effective than solar thermal power. However, those HIPV cells like to be cool (60C) for high performance so there is less district waste heat potential unless additional solar hardware is deployed to boost temperatures to 105C. Distributed local systems can still supply hot water showers and lots of power. Once several hundred billion dollars of HIPV saturate daytime grids then nighttime solar thermal power, with more opportunity for waste heat, becomes a big niche market for capital growth.
For an 80% carbon free world, both high performance new passive solar homes and solar seasonal-heat-storage district heating of existing homes can do the job with positive cost savings and excellent job growth.
Permalink
caniscandida Posted 4:16 am
16 Aug 2008
Hurray for Seattle! Shopping bags should be painful! (for customers of a certain income level).
Chickens deserve our true friendship! So do fish! So do other sentient beings! Let us learn to be kind.
Permalink
amazingdrx Posted 4:36 am
16 Aug 2008
http://amazngdrx.blogharbor.com/blog John Schneider, Northern Wisconsin
Permalink
paz Posted 12:12 pm
17 Aug 2008
Permalink
Dodecadude Posted 6:46 pm
21 Sep 2008
I would have rather the homes be built and data be gathered over several years, with a journal about how things performed, what worked, what didn't work, and what wasn't even used.
Do you know of any follow-up writings about these designs that illustrate they stood the test of time?
Do any of the homes still exist?
Last year I tried to get a hold of Mr. Saunders, only to get a reply from his son that both he and Shurcliff died a couple years ago. (2006 I think)
All the patents mentioned in those books are public domain now (patents only last 17 years).
It seems like the only way I will ever find out if those design concepts are sound is to recreate them, which is an expensive proposition to take on if they turn out to be bogus.
Not that I necessarily expect you to have answers to my questions, but maybe someone out there knows more about Saunders' designs?
Permalink
Biodiversivist Posted 2:32 am
22 Sep 2008
The problem with solar home design is that it is specific to a given latitude and longitude. You cannot take a design that worked in Denver and get it to work in Seattle. A design that works in San Diego would be worthless in Miami.
You have to run the numbers. BTU in - BTU out per unit time. Most solar home designs you hear about are urban legends or exagerations. The one in this article is just an untested design. It makes no attmept to reinvent the wheel. It is simply a super energy efficient home that points the max amount of surface area south, covers it in various kinds of solar collectors, stores the energy in two forms in two places. It pencils out but the devil will be in the details.
Until someone builds and tests a home for every possible place, each home will be a custom engineering job. Cost is always the biggest hurdle. You basically build a super insulated home (zero energy or one-watt home) with a high efficiency air heat exchanger, point it south at the appropriate angle, incorporate devices to store, recycle, and use as little energy as possible. The main challenge with solar is storage. Grid metering works for electricity, and thermal mass works for heat. Also plan for most of construction costs to go into the energy system instead of home volume.
It is pretty much an urban legend that you can go off grid using only passive solar for all energy needs (electric power, hot water, heat) unless you live someplace like San Diego or Maui without a radical change in energy consumption (live like a homesteader on the great plains).
Igloo--grass hut--mud hut--sod house--yurt--airsteam trailer--double wide--prefab--and on and on. You cannot get something for nothing, there is no such thing as a free lunch, you cannot have your cake and eat it too.
In the end, it all comes down to biodiversity. Poison Darts--Protecting the biodiversity of our world
Permalink
Pangolin Posted 6:10 am
22 Sep 2008
Straw bale walls, PV panels, a small geothermal hot water system and a wood stove to boost should be more than ample. Real ascetics could use the stove to heat a sauna placed centrally instead of heating all that air. The 2800 sq. foot figure makes the geothermal cost complaint a joke.
If it's cloudy and wet there is plenty of wood and straw bale's thermal mass minimizes stove feeding. Where the sun shines there is more than enough power from that alone. Since the majority of Seattle's power comes from hydropower using some power from the grid tie isn't exactly a disgrace.
750 Kw/hrs of electricity a month is just excessive unless you have eight people living there. I max at 150 Kw/hrs in July when I air-condition every day to keep the house below 85º.
You can build it; but why brag about it? It's not even pretend sustainable.
Put the Carbon Back
Permalink
Biodiversivist Posted 6:22 am
22 Sep 2008
Not a big fan of straw houses, sticks or bricks for that matter. Give me SIPs.
In the end, it all comes down to biodiversity. Poison Darts--Protecting the biodiversity of our world
Permalink
Pangolin Posted 6:35 pm
24 Sep 2008
While you can duplicate the effect with synthetic insulation and house wrap you can't breathe inside those buildings. My brother once returned to his office after lunch only to find all of his co-workers laid out on the lawn; sick building syndrome. They had turned the fans off due to a maintenance glitch.
High mass walls with insulating properties are comfortable and very long lasting when built properly. Plus you don't have to worry about cold spots where water condenses and causes mold.
Just something else to use as an option.
Put the Carbon Back
Permalink