Towards a better tinyhouse

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Archive for April 2011

Toilet solutions for a tinyhouse roundup and roundaround.

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Yes, I just made up that word. It means speculation and stuff around existing solutions, in addition to existing ones.

Anyway, I’ve been following the “alternative toilets” thread on the tinyhouse forum, and a few days ago I read the Humanure Handbook (his term for human piss & crap is “humanure”). Interesting book, for sure, but I don’t agree with everything he says. He mentions a book, Compost Engineering, that sounds interesting, too, and I think I would have to read more about this before attempting homebrew improvements – or rather adaptation to a tinyhouse context – of the composting process.

But I was thinking of more general improvements:

1. Place whatever composter there is outside the habitable area, so if it does malfunction it is easier to clean up, while the receptacle is obviously better inside. To do this without water, you could use a Teflon toilet bowl and tube, to transfer the humanure outside. In a previous post, I posted a link to a site selling teflon sheet that could be used to make this. Teflon’s pretty amazing stuff, I wonder how well this would work. I wonder if you could figure out a “dry flush” mechanism, which prevented any humanure from sticking to any visible area of the toilet bowl automatically, that might be more acceptable to a lot of people, and non-stick materials would certainly help. I tried to find out more about Nasa’s air-flush toilet, but no dice.

2. Decide what you want (see below). If we can complete the nutrient cycle, that’s great, but if you just wanted disposal, an idea that occurs to me is that you could dry the piss and crap by evaporation, as an “air head” or “nature’s head” does (BTW, it is clear from the info in the humanure handbook, mainly because of the temperature and size of the storage chamber, that no meaningful decomposition is actually occurring in these toilets, rather they are just drying the material, i.e. they are, rather, desiccating toilets, and only the crap, not the piss), then pasteurize it, and it would be perfectly safe to put in the municipal garbage. You can get odor proof bags, made with foil-plastic laminate material, though as stated in the marketing material of these toilets, it does not smell when dry.

Or maybe you could find a gardener that would be happy to take it, but that seems like a hurdle. Crap takes up quite a small amount of space when dried – a human outputs about only 60 grams of solids per day in feces, and the rest of the crap is water.

Disposing of the (sterilized) urine on a lawn also seems like a very simple solution. The problem is that it might require a large lawn area for full time use. Would have to check that, If you have a drip or subsurface greywater system anyway, just increase the size, and, it could be perfect.

Bizarrely, the author of the humanure handbook does not mention pasteurization even once in the whole book . Yet from the data he gives about temperature-time treatments required to kill pathogens, it is clear that this would not be hard at all. I suggest the (dedicated) use of a kitchen appliance of some sort. A slow cooker might be good. I noticed you can get temp-resistant plastic slow cooker liners, basically plastic bags, you could line the storage chamber of the Nature’s head (or more practically a homebrew version for a fraction the cost) with a bag, then every month or two, you just tie it shut with a twist tie, and put it in the slow cooker for 10 minutes, and it is microbiologically safe. They are made to reliably reach the necessary temperatures, because they have to for food safety.

In all fairness, doing this on a large scale might not be a good idea, because some units would malfunction, some people would be too lazy to do the pasteurizaton step, etc, but you could certainly make a unit that performed the operations automatically, and refused to release the material until it had been pasteurized. In the Dymaxion house, a futuristic house by Buckminster Fuller, this approach of putting the humanure in the garbage rather than mixing it with water, was used, but I don’t know if they dried or even pasteurized it.

3. A water content sensor. One of the problems with dry composting is that it can only be done within a narrow water content range. You can get inexpensive sensors made to measure the water content of soil, so you might use one of these to measure the water content of the compost pile without user intervention, and water the pile if needed.

There are a lot of different toilet options out there for toilets of all sorts , looking something up on wikipedia, and following the links gives a view of some of the options. I think it’s fair to say we are talking about several different functions these toilets provide:

1. Waste disposal to avoid transmissible diseases.
2. Keeping the smell and mess down, or at least somewhere else from the habitable area.
3. Completing the nutrient cycle.
4. Preventing environmental pollution (undesirable release of nutrients, chemicals, and bacteria in the wrong place).
5. Prevent contraction of non-transmissible diseases like an e-coli infection.

These are not always connected that closely. Obviously it would be great to have all 5, but a compromise on some if you have to isn’t the end of the world. Traditional municipal systems are great at 1,2 and 5, but mostly fail at 3 and 4, and are ridiculously expensive, and social problems may prevent them from being used (regulations and stuff would fall in this category). A desiccating-pasteurizing toilet seems like it would be pretty cheap and safe. Commercial composting toilets actually look a lot less impressive to me now that I know more about them – because, despite what the manufacturer’s claim, they are not so safe after all from a microbiological standpoint. (And, according to reviews they don’t work very well for disposal either.) As far as I can tell they do not (could not) achieve the high temperatures needed to kill all pathogens in the timeframe in which they work (storing material for 3 to 6 months). It does help a fair bit, though.

In a tinyhouse, you also want to do it without:
1. Suffering from misunderstandings from bad neighbors.
2. Costing too much, including power consumption if off grid.
3. Needing a whole lot of maintenance.
4. Taking up much space.

So it seems like a thermophilic composter would be a lot better. But, like I said, I think I would have to read more to really make any decisions or try to design something.

Stepping outside the box for a second, you have to ask yourself why, exactly, people prefer flush toilets over dry. I assume it is because they flush the humanure completely away, and it is covered immediately while the toilet is being used, preventing any smell, and there is no exposed pile of other people’s crap below, which you are granted the privilege of gazing upon, and which kinda seems like it might splash up somehow or something (whether or not it actually could).

In Japan the toilets they have do not cover the crap, and this shows in the odor around the bathrooms, but by sucking air into the toilet bowl, smell could be prevented. It seems like it is just the possibility of stuff sticking to the bowl, really, and the pile of crap exposed below. And then there is the engineering problem of getting dry material from one point to another, which seems to be the only other point in favor of flush toilets, because fluids are easy to move around. Still, society already has municipal disposal, recycling, and in some cities even compost collection, so after you get over any fecophobia, as long as humanure is reliably pasteurized, and the process is semi automated, I think dry toilet collection could indeed catch on, if the right toilet mechanism were developed… I think the sticking point is the dry flush mechanism. A roots blower like mechanism made of non stick stuff, and maybe rinsed with just a very small amount of clean water, maybe? Or maybe 2 telfon bowls, one in use while the other is automatically emptied and cleaned. Edit on 2010/11/01: Maybe it would be better not to have a flush mechanism at all. Just a nonstick tube, twisted so you don’t see the pile of stuff below. Humanure slides away immediately after being deposited. No moving parts. Negative air pressure is used to prevent any escape of smell. If the Tube was flexible and you didn’t want to have the airflow associated with this approach to preventing smell form entering the habitable area, you might add a moving part that squeezes the tube shut. That way there are no hinges, seams or whatever, exposed to the humanure. You still need the urine separation ability, apparently the most common approach is to use a front receptacle, and a rear receptacle. Another approach that occurs to me is to try to use the adhesive properties of the water, the effect which is so annoying when trying to pour a beer, causing the water to run preferentially along the side of the bottle. I.e. You have a single tube, with mixed solids and liquids coming down, then at the output of the tube have a rounded piece of glass (or other hydrophilic material) of the right shape, which gets the water sticking to it, then guides the water away to s separate chamber. One problem with this is that you get fecal contamination of the urine, which in some circumstances could be bad. One pro is that the urine rinses the transfer tube, but if it was a good nonstick material this might be unneeded anyway. It could also be used in tandem with the 2-receptacle approach, attached to the dry-matter output tube, just in case water is inadvertently dumped into the dry-only receptacle, it still separates most of the water, and puts it in the right container.

Anyway, other options, some from the thread, some of which might not be very practical, seem to include

1. Anaerobic digester. While reading up for the greywater MBR, I read some about these. Basically they only make sense if you need the methane for running an internal combustion engine, cooking, or a lot of water is already mixed with the waste material from which you want to recover energy. The amount of methane you get per person of waste will not be near enough to do your cooking anyway. If you only want the heat and there was not too much water mixed in with the waste, it would make more sense to burn the waste directly, you would get more energy out, and it is a much more compact system, and easier to maintain. Anaerobic digesters take quite a bit of space. They also require various types of management sometimes, and the right input of nutrients and other conditions.

2. Nature’s head and Air head, like I said, these seem to be basically desiccating toilets, and they don’t even deal with the piss, except to store it.
3. Sawdust toilet, see the Humanure handbook for details, the problem with this is that it seems to entail a big compost pile, and yet more chores.
4. Biolet, sun-mar, clivus multrum, etc, there are a dozen commercial composting toilet, and they are are ridiculously expensive, and most seem to get bad reviews.
5. Incinerating toilets seem to get bad reviews, and require a lot of energy. Also expensive.
6. http://www.gocleanwaste.com/homepage So-called PETT, but this doesn’t seem practical for a tinyhouse.

Written by gregor

April 27, 2011 at 00:09

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Reading material about history and politics of zoning and stuff

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What I was going to do was search my own browser history to get the documents that I thought were the best I have read, but firefox’s history search thing doesn’t work. Anyway, I found some of the docs again, and some new ones, too.

However, before you start reading, I just wanted to say, that I really think you have to be aware of post hoc (and other types of) rationalizations. There are really a lot of those. Nicholas Taleb says it well in his book The Black Swan, people are extremely prone to coming up with these – ask someone (especially an adult) why world war I started, and they will mumble something about a prince being killed. The truth is the exact info on why has been lost to history, and in fact may not have been recorded by historians proper, or been available to the public anyway. Most likely that was just an excuse, or just sort of assumed to be the cause.

Ask why cities have zoning and people will sigh, wave, and say something about preventing bad things from happening, like someone building and airport next to a residential area. Whatever the original purported reasons, zoning, like the police, is used for anything and everything that people can get away with, the supposed “reason” for it means nothing, and is always changing. It’s a tool, and excuse. Most of the “reasons” given are excuses people came up with once they decided they want something, of course….

For example, there was one document that I wanted to include but couldn’t find, in which it was noted that almost all the rationalizations for banning mobile homes are clearly not based on reality, e.g. that people who live in them move frequently, but the truth is (and I remember the numbers) residents of site built homes live on average for 54 months between moves, and residents of mobile homes, 49 months. And yet that “reason” has been used for ages. Never mind whether or not it would even make sense if it were true i.e. actually do a community any net harm, which most likely no one has even checked, given that no one had even checked to see if it is in fact true, which is pretty easy, just look at the change of addresses in the right government database(s).

Plus even if it did, you can’t just consider the local community, the government is supposed to work for *everyone*….

Anyway:

http://en.wikipedia.org/wiki/Exclusionary_zoning
http://en.wikipedia.org/wiki/Mobile_homes

Of course you won’t care about these, but you can find the equivalent for your own locale:
http://ottawa.ca/residents/bylaw/a_z/zoning/

Example of rationalizing, practically propaganda, in info given out by the government, they conveniently don’t mention any of the downsides, not that I think zoning is inherently bad, but they are being grossly dishonest: http://www.mah.gov.on.ca/Page1758.aspx

http://city.ottawa.on.ca/calendar/ottawa/citycouncil/occ/2002/10-09/minutes41.htm minutes, search it using the google site: operator to see de facto how they do things

From the blogs, I’m sure there are many more, would be nice if these could be rounded up and added to the tinyhousewiki (heck, that could go for a lot of stuff):
http://www.tinyhousedesign.com/2008/08/31/tiny-house-village-design-concept-part-1/
http://rowdykittens.com/2009/06/tiny-house-obstacles/ I disagree with most of what this says, I would not expect, for instance, a single individual cozying up to local politicians to work for beans, but with a group certainly interesting, and it seems like really the only long term, practical solution.

http://www.mapleridge.ca/assets/Default/Planning/pdfs/garden_suites_discussion_paper.pdf Garden suites discussion paper, pretty good. IIRC this is where the $5000 net reduction in surrounding property values was referred to. Would be nice to see the original study. That’s not for the neighboring properties, but for all them put together. In other words a fraction of a percent the total value. And that calculation excluded other factors such as higher density which may easily more than counteract the supposed loss of value.

Vancouver:
http://www.straight.com/article-140102/anxiety-over-ecodensity
http://www.francesbula.com/uncategorized/the-vancouver-neighbourhoods-backlash-continues/

http://thethunderbird.ca/2008/11/13/laneway-housing-pilot-proceeds-despite-opposition/
Says laneway housing seem to increase, not decrease, property values: http://www.traschet.com/pdfs/tc_laneway_handout.pdf

http://www.cj-network.org/cjsouthwood/taking_out_southwoods_trash.doc Some on the history of mobile homes and stigma, also some stuff about how treating mobile homes as real estate tax-wise would be better, leading to a cascade in which banks are more willing to finance them, and they don’t depreciate as fast. Lots of references, I bet lots of good stuff to find by following those trails.

Only portrays rosy side of what other people think while obviously the nasty side is actually far more dominant: http://www.canada.com/theprovince/features/saturdaymagazine/story.html?id=98b5e9b4-09f9-4097-aa1b-f729c610cd5d

Zoning people don’t or at least didn’t really know what they are doing that much anyway: http://www.planetizen.com/node/109

Problems with zoning and how it raises prices (100% directly!) and cause a lot of the financial crisis, also points put how homeowners abuse policy to jack up prices, but I don’t get why you couldn’t do it better, and get the best of both approaches: http://www.chron.com/disp/story.mpl/business/steffy/5804649.html

The “Circumventions” part seems to indicate developers are getting an absolute ton of free money when land is re-zoned, but that would need more looking into, presumably any rational municipality would auction off the rezoned land so they get the money: http://en.wikipedia.org/wiki/Zoning_in_the_United_States also note the use of zoning for racist purposes and the housing affordability section. You know I’m Canadian. but I tell you, most of what is on the web in english is inevitably US-centric.

Redlining even in the 90s tangentially related http://en.wikipedia.org/wiki/Redlining “FHA appraisal manuals instructed banks to steer clear of areas with “inharmonious racial groups” and recommended that municipalities enact racially restrictive zoning ordinances, as well as covenants prohibiting black owners.”

Just a few random examples of how zoning is abused, I can’t believe the no working at home thing, also aesthetic restrictions are far more common than they say here, in fact they are the norm everywhere in residential neighborhoods (and there’s nothing new about it) : http://www.fff.org/freedom/0896d.asp also, the values vs. prices thing again, and the big, flashy, spectacular examples might be good for argumental purposes, but they are not at all the big story, rather there are effects less likely to get in a newspaper which are far more damaging to the actual population and, far more meaningful.

Also, couldn’t really find any further info abut that house being bulldozed situation except http://www.isil.org/resources/fnn/2001june/usa-police-confiscations.html and http://prfamerica.org/speeches/2nd/Leviathan.html and the city seems to be Skaneateles .

Need to get the documentation on all those judicial decisions and stuff for all those court cases.

Written by gregor

April 26, 2011 at 00:09

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Trying to figure out the political/legal issues relating to tinyhouses in your area

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Why, it must have been in June or thereabouts when I first became interested in tinyhouses. I actually searched for the sort of thing that I was looking for, a small dwelling of sorts, having noticed that the cost of construction materials was minuscule compared to the long term cost an apartment.

Then I found out about tinyhouses and saw Jay Shafer’s video, and after some time coming to terms with the idea, decided that I was going to look seriously into doing this. and designing my own. I was merrily making my plans when I found out it’s Not Allowed.

But naturally I want to know WHY not. It’s just amazing how the people at the other end of the phone line seem to have never heard this question before, so it’s clearly something we all need to ask a lot more often (and of course a lot of the time the answer is not a reasonable one, rather just reveals how bad a job the government is doing). Both the specific laws or other documents that say so, and of course the real-world reasons. Most likely the bureaucrats are useless for the second one, as they will just cough up some rationalization they were told, or assume.

Anyway, you can also find a lot of stuff on tinyhouse blogs about minimum square footage (also called minimum floor area) requirements, how you’re supposedly able to get around them with wheels and so on, but unfortunately it is not that straightforward. The government gets in the way at many stages.

Anyway, the specific laws vary substantially between different locales, but trying to generalize so you might have an easier time finding out in your area, it seems to go like this (and there’s some stuff that I still need to find out more about):

1. Building codes

The 120 sq foot figure is thrown around quite a bit, with the factoid that if you build a stationary house smaller than this the building codes no longer apply, which means you’re all clear to build.

Certainly in my area, and most others, this is not quite how it goes. I have not been able to find anything for my province (the building codes are usually province or state wide) that says buildings under a certain size do not fall under the building code. It’s just that if it is under 10 sq meters of footprint (not habitable area), and there are not other sub-10 sq meter buildings within 20 meters you don’t need a building permit before building, which means it does not need to meet code (because your planned building normally has to meet code before you can get a permit). But you might still need something else, before you can hook up water or something. Also, zoning still applies. Also you are not allowed to live in such a structure. See “examples of people living in tinyhouses full time ” post for more info.

If a commercial builder sells a house to you that does not meet code, you can sue them, but the government does not do anything to them for instance (unless maybe what they did was dangerous or something) (although they may inspect the house before allowing it on the market or something). If you build something in your backyard that does not meet code, I gather it doesn’t really matter, the government does not *necessarily* care, the building code is a guideline for builders, plumbers, etc. to follow and which is used for various purposes like deciding whether to issue a building permit for a proposed building, or certificate of habitability after construction (which you in turn need for some other reason, like before you are allowed to hook up water).

Also, even if it doesn’t need a building permit, does it require an electrical wiring permit or something? I don’t know. If so do they charge an absurd amount of money for the permit or something? That would be something else to look into. Do they demand dedicated electrical service lines be installed or something?

Also, it says in the building code that a “dwelling” must have a certain habitable area, like 400 sq ft. (or in some cases 2400) before it meets code. Which means once you go above 10 sq meters you need a permit to build which means your dwelling has to balloon to 400 sq ft, to meet code to get a permit.

2. Zoning
Zoning throws up several barriers. You won’t find the section that says “oh, and no tinyhouses allowed” because instead of banning certain things, these people only *allow* certain things, and ban everything else by default. There’s a list “a)single family detached dwelling b)low rise multi unit dwelling” etc., with definitions elsewhere in the document. Seems at first pretty much like a dead end, unless it can be changed or the tinyhouse shimmied into one of the definitions. Even then it might say no more than one dwelling per lot, for instance.

One thing I was wondering about is this: You leave some pylons in the yard. Is it violating the zoning code? Presumably not. Now you leave a trailer in the yard. Violating? There is a section of the zoning code here that is different form the rest, which is regarding parking and vehicles, and it says you can have 2 trailers at a time on the property.

What about a plywood box just resting on the ground? An insulated one? How big would it have to be before it was violating the zoning code, and which part says it would be? As far as I can tell, there is nothing explicit that says someone could not use this as a place to sleep at night, work in the day, etc., add a microwave and a sink and a composting toilet… But there might be something that says nothing except a dwelling is allowed to be “occupied” or something. Would have to check that.

But let’s face it, that’s getting further and further from the promise tinyhouses have in the first place. Sure it’s cheap, but it’s not as nice a place to live. Also there might be some sort of health code that says if something is occupied it has to have a normal bathroom.

You can sometimes get a zoning “amendment”, to change the zoning in a particular area or something, because you want it (which is what commercial builders do all the time). Then there is another thing which is a bit different, a “variance” which allows you an exception because of unusual circumstances, *which are specific to the property of concern* and needed to make reasonable use of the property (so they are sort of useless for us, I think).

You can read up about the amendment process, I assume it’s different for different jurisdictions, but basically there is the panel of bureaucrats, and people from the community can comment and stuff, and they allow or deny it, I should look into the other requested amendments and go to one of the meetings… you can apply for one before you buy the property, though, I checked that.

Another idea I had was to make more than one separate building, one for the kitchen, one for the bathroom, but this wouldn’t work because you’re not allowed to have more than 2 of the small buildings closer than 20 meters to each other… unless you could get a permit to do so.

Anyway, the zoning law is the main problem, I think, and it pretty much ruins everything for me, as far as I can tell right now, though there seems to be a few avenues still to look down here, they will probably lead to dead ends.

Also, checking the definitions might be fruitful, tinyhouses might be x but ALSO something else which is allowed, or if X is not allowed maybe it could be argued that it is not exactly x….

Anyway, you can usually find the zoning code for a city on a website somewhere under “bylaws”, and the “Ontario/ (insert state/province here) building code”, too. I do not know what documents the permitting requirements stem from.

Written by gregor

April 25, 2011 at 16:42

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Exterior cosmetic veneer

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Just as an idea to improve appearances or mimic an expensive look without as much cost, I went looking for “exterior veneer”. It looks like it is available, both in wood (looks like normal siding though) and stone, and I wonder if there are other materials, too.

Looks like it could hep a bit with the cost/performance ratio for aesthetics… Also, it seems like it could be interesting to use stone veneer, I don’t know how thick it is, but if you could get some thin stuff maybe it wouldn’t be too heavy. Who expects a building that is apparently be made of stone, to be portable? You could have a way to hide the wheels when stationary with a concrete-lookalike material or something.

As mentioned in the note on the right, the zoning barrier to practical tinyhouses is really the doozy. Based on what I have read in some papers including that one about garden suites I think I posted on this blog (I’ll try to get that up again here later, I have a draft post with a bunch of reading material on the zoning issue for ya in the works), people make gut instinct decisions when they see a garden suite, or other tinyhouse-like thing, and will end up objecting to it if they don’t like the appearance of it.

Let me be clear here, too, that when they object, they don’t say “It no look pretty! No like!”, no doubt partly because it is obvious that you shouldn’t really be preventing progress based on such a trivial concern, and so they don’t want to admit it.

But there is more to it. Even people who will are decent enough to agree that appearance shouldn’t be a major issue, that that shouldn’t be top priority in this world, will still have a problem with it. They will likely come up with post-hoc rationalizations about why they don’t like it, like “introduces transience to the community” etc. etc., and good luck trying to tell people that these don’t really make any sense. Even if you do, they might just come up with an endless supply of vague objections, or over-value any legitimate ones. And fat chance telling them they are just being irrational – and if they, at the end of the day, don’t like it, and other people are like that too, and can’t practically be convinced otherwise, let’s face it, it doesn’t really matter that there are not being reasonable. There aren’t anywhere near enough protections in our country – or rather I should say culture, perhaps – against this sort of irrational tendency people have. Plus it could still actually potentially lead to a legitimate concern, namely reduction in property prices “values” (prices, actually) if potential buyers don’t like the appearance. (though tinyhouses can increases property prices (and value too) plenty, sometimes (including due to density increases).

Even when it does decrease it, that is usually a very small amount, like $5000 on a whole house according to some documents I have read regarding accessory dwelling units, which frankly is just part of normal fluctuations anyway that occur as a result of other, productive activity. The thing is, if you can’t handle that, remember tampering with the market to artificially prop up prices is only going to lead to disaster, as it is doing now, as reality must catch up to you eventually. Nevermind the problems with suppressing progressive activity based on short term whims…).

So I think the cosmetic appearance is really quite an important feature for a tinyhouse, until they are fully permitted, as the MedCottages have been in Virginia, for instance. And improving public perception with better cosmetics would help with the political problems a good deal. Frankly the tumbleweeds would never have been featured on yahoo news, or in glamor-mag, or whatever it has been, if they didn’t look so positively charming.

But, to me, the good news is that there are already a lot of people focused on appearance, and great stuff being done there – hell, “design” to most people, means cosmetic design.

Written by gregor

April 22, 2011 at 00:42

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Laminar (displacement) flow ventilation system

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What is a laminar flow ventilation system? What is the point?
Well, to my surprise, I couldn’t find and good documents describing the use in buildings with those terms, it turns out laminar flow is an extreme version of what is is called “displacement flow”.

Anyway, I heard about this in a lecture by Amory Lovins, head honcho of the Rocky Mountain Institute. You can watch it here. It was a while ago, and I’m not sure which one it was, but I assume it would be the building one.

I found a good document that explains things much better than I could, including some data, here: http://www.price-hvac.com/Repnet-www/PDFs/BR409_DisplacementDesignGuide.pdf

In the “Ventilation Effectiveness” section, you can see it implies that you get about the same air quality being inhaled with about half the ventilation, if you are sitting down (I assume the total amount per second of contaminants in the exhaust stream does not change, because there is still just as much contamination being produced indoors). Less than that if you are standing or moving around, but still, that’s pretty sweet.

Remember the “thermal issues in a tinyhouse” post; ventilation requires a fair bit of power in the winter. If you can get the same air quality with less ventilation, that’s good.

I don’t think it looks too complicated to do, either. You just need the diffusers. Maybe get some of that sock diffuser fabric stuff, or some stainless steel mesh would be fine. Also, it leads to less noise indoors from the ventilation system. Could be nice to have it basically silent. Also, no drafts.

About heating, that document says you can heat using radiant floor heating, but as the amount of ventilation goes down, the efficiency of the ventilation heat exchanger (“energy recovery ventilator”) goes up. The numbers seem like a close call, but I think a good way to go would be to use a high efficiency exchanger, then what you are doing all year long, is actually cooling the house.

Think about it : heat is being produced inside the house. 400 watts or something, 120 from a human body, and all the heat form the hot water system, ventilation system fan (maybe only a few tens of watts), appliances that draw some power even when turned off, computer, lights, and solar gain.

As I said in the thermal issues pose, the conduction of heat through the walls would be ~90 watts or so at 25 deg in and -5 out. Double that if it is a cold snap. In other words, without ventilation, heat would actually build up indoors normally. This scenario is actually the same sort of situation you have when you are trying to air-condition the place in summer; you need to remove heat, not add it. That means if the output diffuser is at the floor, the air coming in will be colder than the ambient air, which is when displacement flow systems work best, apparently. So a dilution flow system and a reasonably good heat exchanger could be a good combo.

Of course if you simply turn on a fan inside the house, or take the diffusers off the air duct outlets, it becomes a mixed flow system, if you want. Or it says radiant floor heating works okay, but it seems like that would remove some of the benefits, as heat convects up from the floor. Also, I would wonder if sunlight coming in a window, hitting the floor, would produce a thermal plume that would siphon away a lot of your fresh air from the floor region, leaving less for you. Hm. But maybe this is already included in the ventilation efficiency figures, because presumably (hopefully) they are real-world figures, not theoretical.

Written by gregor

April 21, 2011 at 00:42

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Openfarmtech and open source business

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I have been reading about Open Farm tech recently, which some people here might be interested in.

There is a omnipresent aura surrounding tinyhouses that involves homesteading type stuff, and the whole bits-to-atoms and design problem. As well as an understanding that there are major problems with our current industrial made-for-the dump and made-to-suit-the-needs-of-the-manufacturer-not-you-the-user way of making stuff, whether it be food, tools, housing, what have you.

The bits to atoms problem is how to turn your ideas and designs into a practical affordable reality – something building a tinyhouse is an obvious manifestation of. We often can’t just buy the stuff we want because either manufacturer’s want a fortune for it or simply because no one makes it. And of course design is made that much harder by these facts, because if you want something to not cost a fortune you can only make use of parts that are easy or cheap to obtain. Designing something that works is a lot easier than designing something you can actually build and afford.

Also, this guy seems to have basically taken some welding and other basic equipment, inexpensive commodity parts, some land and some hard work and time, and he’s got a quite profitable business now, which you are perfectly free, and in fact invited, to copy using the designs and such he is putting on the web. Thus taking much less time to set up than he did.

The whole idea of open source business practices has a ton of potential as a way to start a business and earn money outside of the traditional wage slave system: You’re an entrepreneur, but you dodge one of the main problems that entrepreneurs face, which is the cost and time of the development cycle. An intriguing idea.

Written by gregor

April 20, 2011 at 05:08

Posted in Uncategorized

NiFe batteries

with 3 comments

Nickel-iron batteries

They don’t have any toxic heavy metals, they last a lifetime, and they could be cheaper than lead acid. Potentially you could even make your own.

It says they can have charge/discharge efficiencies of 85% there. Where are the batteries that can do that, is what I want to know. Who sells them or how do you make them?

If they can only achieve 60-65% that is not as good, but do not write them off altogether. Lead acid batteries are only something like 80% efficiency. So you lose ~40-35% vs. 20% of the energy that went into the battery, but if only half of the energy from the solar panels goes into the battery, with the other half being used as soon as it is produced, using nife instead of LA will increase the size of the solar collector array by only 15 to 20%, which might be altogether manageable.

If the cost of the solar collector is only 50% they system cost that is only 7.5% to 10% increase in cost. Then, remember, these batteries last much much longer than lead acid, which wear out fast enough that they have a substantial “running cost”, of roughly 8% the cost of the battery, per year, whereas NiFe do not.

So all things considered, the capital cost of the system as a whole might be more expensive, might be cheaper, depends on if you can get the better batteries, but by eyeballing it, I think they have a lot of potential to actually be cheaper over the long run.

Plus, no environmentally harmful lead, which is nice, and yet they are I think probably cheaper than lithium ion.

Also, there are sources like this one that indicate that in photovoltaic systems, lead acid batteries have other issues too, and depending on their usage patterns, they may have even lower effective charge/discharge efficiencies.

Some more links:

http://www.solarpowerforum.net/forumVB/off-grid/4509-nickel-iron-batteries-10.html
http://www.changhongbatteries.com/Ni-Fe_battery_for_Solar_&_wind_appliances_p53_m2.2.1.html says charge efficiency is actually quite high at room temp, but is not the same as round trip efficiency, but maybe the loss during discharge is pretty low and determined mainly by resistance. I wonder how much these batteries cost and if they are actually for sale.

BTW just a bonus, I discovered that if you search ebay for “thundersky lithium” there are some relatively cheap lithium iron phosphate batteries going on there.

Written by gregor

April 19, 2011 at 05:08

Posted in Uncategorized