Passive Annual Heat Storage
Starting on a project where this is the client preference for…what’s the proper term?…genre? methodology? concept? I can’t think of any reason to question that preference. I’m not going to use this thread for specific design questions, but rather for more theoretical or philosophical ones.
Starting out…
I’m reading Hait’s book: Passive Annual Heat Storage–Improving the Design of Earth Shelters.
For those who’ve read it and had experience with his approach, are there any areas where your thoughts differ from his? Any differing opinions on the size of the insulating umbrella, the thickness, the layering, the waterproofing, the amt of glass, the use of earth tubes or anything else? Or does all he writes hold just as well today as it did when he wrote it in 83?
Replies
Guy up the road has a "Trombe" wall? Think that's how you pronounce it. Anyway it's in his chicken coop, and is just a stack of black poly 55 gal drums filled with water. Believe it's a south facing wall. Got some old shashes on that side so the sun comes in, heats the water, and radiates it at night. Keeps it pretty warm. Drains'em during the summer. He also has an "earth sheltered" house.
This method (PAHS) has specific concepts and components that separate it from generic earth sheltered and passive solar applications. If it has one element that most separates it from others (my initial opinion), it's the use of an insulated umbrella to create a large dry section of the earth that acts as an annualized heat source/sink, with the house in the middle. For most people, this is the big leap of faith--not insulating the house, but insulating the earth.
For most people, this is the big leap of faith--not insulating the house, but insulating the earth.
There's an excellent turn of phrase, too. It's as mind-blowing as explaining persist (dagnabit, now I can't remember Ray Moore's new acronym).
It's equal parts exciting and "you can't do that, can you?"
While noodling the other day on what I'd do on my house lot if it were empty, my mind wandered off Usonian-way, and PAHS nosed in a bit, as a strategy that might "fit" such a house better than FLW's mechanical solutions did. Was a tad "scary" to see how more features fit into a PAHS Usonian. Makes me "want to" more than a bit--just need a lottery win to afford it (because of my poverty, not the expense of the system).Occupational hazard of my occupation not being around (sorry Bubba)
Hi,
Here is a book review by Nick Pine on Hait's book:
http://www.builditsolar.com/Projects/SolarHomes/haitbookreview.htm
I'm inclined to think that his design is good. His website
http://www.earthshelters.com/
has some additional publications, which may include some updates.
Personally, it seems to me to be a kind of expensive way to get an energy efficient home, and that it might tend to be a bit dark toward the back. But, I can also see why some people like it.
Gary
Until he answers you on VaTom's website he says that he did not use the earth tubes:
http://paccs.fugadeideas.org/tom/index.shtml
Thanks Amy. That's the kind of thing I'm trying to ferret out--how much people vary from the base concept and how effective those variations are. I've seen people who talk about shading the glazing and those who don't. I've seen references to maintaining 70 degree temps (average annual) and references to 64 and 63 degrees. Trying to find the boundary conditions.
Jim (and everybody), PAHS is simply a heating/cooling (passive) system utilizing annual heat (or coolth) storage. We get a considerably larger annual temp swing (13º) than Hait for a variety of reasons, all major cheating on his design. Still, I could get close to his performance with simple window treatment. We don't bother.
Which brings up a main point, often missed. It's not success or failure, but a continuum of performance. The only way one can "fail" is to not fulfill your own expectations. The house is going to be comfortable with minimal, if any, supplemental heating/cooling no matter what. No boundaries.
You know Nolan Scheid in Oregon. He hosted your thin shell get-together at the only "failed" PAHS I've ever heard of. Not the heating/cooling system that failed. It didn't. But the umbrella and house leaked badly, plus no air system. Major mold. Also, with the house uninhabitable for several years, Nolan found a wide variety of large burrowing critters when he excavated. He's not exactly an underground fan, likes to drop bombs in forums about the subject, while never answering questions. I gather his had no scrap carpet used to protect the umbrella, whatever it was.
We have half the overhead dirt Hait recommends, are over-glazed (our majority heat loss), didn't use any earth tubes, and have several times the exposed wall we should have for maximum performance. I've been asked on alternative architecture forums what part of PAHS we actually have left: the (passive) annual heat storage part. It works.
For best design, one should consider heating/cooling needs, including rate, and insolation by month of actual % hitting the ground. More mass is better. A Denver engineer offered computer modelling, but I've not seen one. An English group is working on building a spreadsheet, but I'm not holding my breath. They get lost in minutae. The law of diminishing returns holds for PAHS also.
Shading... you know I've only built two. But the second had windows considerably larger than mine facing SW which I considered an error but the client insisted. Turned out I was wrong, no overheating (in a house similarly massed and glazed to ours, including lack of window treatment). Neither has any need for overhangs at 38ºN. During the cooling season there's no direct midday gain. Late afternoons, we're shaded by trees, which I erroneously thought important.
If we settled for the target temp for heating degree-days we'd never use any supplemental heat. Was very interesting to compare these two houses' performance after stabilization. The other got an air source heat pump to aid financing. Turns out their ac use is identical to our dehumidification. Supplemental heating, even though they're normally resorting to electric resistance, they have tiny elec bills. Surprised me how well it worked. Those clients are not particularly "green" or interested in conserving. He knew our house, comparing it to his previous SIPs. The zero maintenance exterior was a major factor in his decision, along with the low cost (as we've previously discussed).
One important point: make the insulation umbrella as continuous as possible. Our two umbrellas start out the recommended 20' behind the rear wall, go up the roof, over or through the rooftop retaining wall, down the exposed walls, and out under landscaping or patio however far. Mine's much smaller than 20' in front as I chose to preserve large trees close to the house. That umbrella is the primary difference between PAHS and other earth-contact houses, and the reason for large performance differences.
Another benefit of overhead dirt. When the top 50' of tulip poplar came down on our roof, we had no damage. Had no idea it'd happened until I found it the next morning. Turned into our next winter's supplemental heat. We find a woodstove cozy, when we bother to fire it. Snow on the ground this morning, stove's cold. PAHS Designer/Builder- Bury it!
Thanks for the considered response. Never saw Nolan on other forums be/c they won't let me join. :) Actually, I get the monthly admin notices, but never seem to get the posts. Hmmmm.I've wondered about burrowing animals and strong roots and such compromising the umbrella. Is this covered in the later chapters of the book that I've not yet gotten to...if so, I'll see it when I get there. Else, you have any thoughts on it?>The only way one can "fail" is to not fulfill your own expectations.Life lesson, to be sure. The challenge is to set reasonable expectations. Hait writes of 70 degrees or higher being a target. Mostly what I've read about performance is closer to 64 or so. That's a gap (if in fact it exists) sufficient that it needs to be addressed, in that I don't want a generic client expecting 70 and getting 64. (That applies to both PAHS and non-PAHS.) One requires supplemental heat, the other doesn't. One's comfortable to most people, the other pushes those boundaries for a lot of people. I'm really, really curious about the glazing and shading. What's your opinion about why the second house, with larger and unshaded windows, didn't overheat in moments of clear skies and bright sun? I'm used to mass being a slow absorber of heat, while things like direct sun through a window are quick response systems. I'd expect the indoor temp to spike. If I read it right, you both had similar performance with a notable difference in the size and shading of the glazing. I'm surprised that doesn't make a more notable difference in performance, just because of the greenhouse effect. I've not yet wrapped my head around this one.
Jim, Nolan pops in occasionally on the MalcolmWells YahooGroup. Many there would be very interested in your presence, with regard to the primary subject. Another list I follow but rarely post. One guy there seems bent on resurrecting that old "infinite earth heat sink" hoax, trying to empirically prove that PAHS can't work. He also claims that rock will transmit heat too fast for PAHS. My mountain never got that memo. Disparate list.
I haven't paid any attention to the fc-ers for awhile. They were all above-grade. As you know, I'm the opposite. Occasionally Nolan drops me an email about whatever. Last time was trying to hook me up with an archy to further my commercialism. I declined.
You're about to be more current on Hait's book than I am. Updates I know almost nothing about. Hait originally said burrowing animals like dry dirt which isn't what you get on top of a plastic umbrella in this climate. Or any climate if you grow things there. Under the umbrella is dry, but hasn't been an issue.
What you grow over the umbrella should consider root depth. We had tulip poplars sprout. Our roof is a poor place for an 80' tree.
You know Don Stephens? He presented in Oregon. Clearly, he and I generally disagree, but we come together about umbrellas, or capes as he prefers to call them. Using scrap carpet to protect the umbrella goes far beyond protecting the 6 mil poly (or whatever you're using) from the backfill. It also discourages burrowing animals. Don claims 100% success, and he's certainly got much more experience than I do.
Nolan spoke of large critters that I wouldn't allow living around the house. I've dispatched 2 groundhogs and a family of copperheads in our 13 yrs here. None were anywhere close to the umbrella, but it strikes me as a resident's responsibility to limit the natural neighbors' proximity. His house had no residents for a prolonged period.
Our rooftop raised veggie beds are an obvious attraction. I've been pleasantly surprised at how little trouble we've had. Foxes, coyotes, and even groundhogs have paid no attention to burrowing here. Plenty of other preferable places. Voles, yes. But they don't go deep. We've got a foot of dirt over the umbrella. And zero presence of carpenter ants in non-borated xps. Woods are full of carpenter ants, they aren't interested in our xps.
Don't know where you got that 64º. Hait says 66º-72º on p. 4 of the printed book. We drop to 65º occasionally. Don Stephens web site claims PAHS goes up to 78º-80º. Until corresponding with me he'd never heard of anybody being uncomfortably warm. Where he got any idea beyond 78º I have no idea. Lots of misinformation out there. Don also never considered climatic differences. When I dug out the difference between here and Spokane, our house out-performed his example.
Once I got our summer rh under control we found that our natural 78º high (briefly, in August) is fine. Actually, the same as the client's prefer their thermostat. Dry air is the key, but you already knew that. If we found our winter temps uncomfortable, I'd increase our mass temp during summer. Simple earth tubes, vented outside.
Conversely, the PAHS I've outlined for zero heating degree-day climates relied on cooling the mass as much as possible during the brief winter. Unfortunately, none built to date.
"I'm really, really curious about the glazing and shading... " That's exactly what happened here with the two houses, no shading on one. Seems I'm less surprised than you. I know what our glazing would do for a small-massed house during the 3 seasons we can have large direct gain. 90º wouldn't be unusual. We almost never have more than a 3º diurnal swing, sunny day or snowing.
Tweaking the mass temp allows considerable control. If your client is concerned, include means to tweak. Very inexpensive during construction. I didn't bury temp sensors after reading Hait's experience.
Mass is a slow heat absorber? Not particularly. But we have to consider air volume also. You're accustomed to considerably more than I am with our 20k cu ft here (client house 26k). Best if there's consideration of glazing/mass/air volume.
Perhaps a fitting end to this tome is a brief description of the energy changes I'm making for our next house. Overhead (under-umbrella) dirt will at least double. Triple, if the steel isn't exorbitant. That's it. The other ways I cheated on Hait's ideas stay.
Major glazing will face west, rather than the south here. From heat loss/gain calculations, I expect a small performance improvement. Lots of other house differences, unrelated to PAHS. Yesterday I got 5-6 tons of ceramic tile in the back of my truck for the pool. Gotta find floorspace for it and unload. Hey, less than a quarter/sq ft. Slow steady source if you need any. Don't show up with your Subaru. <G> <!----><!---->
PAHS Designer/Builder- Bury it!
Edited 4/8/2007 12:06 pm ET by VaTom
Six tons of tile?! Oh my gosh. That's twice the weight of my truck.63/64 degrees came from here: http://www.motherearthnews.com/Alternative-Energy/1985-01-01/Passive-Annual-Heat-Storage.aspx "The following summer, shades were used on the most directly solar-exposed windows, and—naturally—the interior and earth temperatures dropped slightly, so that the late-winter floating temperature hit a low of about 63°F." And this is earlier in the article: "the interior temperature will vary only a few degrees throughout the year. And unless a major change is made in the annual heat-flow balance, it will typically float between about 76°F in the summer and about 70°F in the winter . . . without any additional form of heating or cooling required!"I'm still trying to learn the ways they use terms and explain concepts. If the floating temp in late winter is 63, how can 70 be maintained inside with no supplemental heat? If the earth outside the house is 63, then 70 inside...? See my confusion? I may be interpreting the 63/64 wrong.Tulip poplars! Those things grew EVERYWHERE in Asheville. It was full time job to keep up with them. Had to climb all over my rock walls to keep the roots from digging in too far.I don't subscribe to infinite earth heat sink, either. I've met Don, but not crossed paths with him lately. I had less in common with that group than initially expected. Something I'd love to see happen though, is a database of all houses of these related genres. There are more of them than most think, and even though there's a lot of variation amongst them, there is also much in common. But segregated groups seem to be the norm. I'd love to see a map (a Google Maps mash-up, for example) showing where different ones are located. Hey, I'm allowed to dream... :)Glad to hear your experiences with critters. Could be the dryness of the soil that helps with that.I would appreciate a follow-up on the glazing thing. Two similar houses, one with sun coming directly through the glass and one with shaded glazing and similar reaction on a sunny day? Why won't the direct sun cause a temp rise in the one relative to the other? Does the mass react that fast? That's what I meant by mass as a slow absorber--just as a room with RFH in a slab is slower to heat than RFH in a low-mass setup, I'd expect that the sun could toss btus through glazing faster than the mass could absorb all of them, and so the ambient temp would rise in the house with the more open glazing faster than in the one with the shaded glazing. If not, then what happens to all the btus from the sun? That's where I'm stuck at the moment.
Late finishing this, social obligations.
Apparently my truck's a tad larger than yours... I've got a 7'x12' bed. Cold and windy today, so it's still full. When I descended our driveway I discovered 2 boxes of tile that'd gone over the tailgate.
I hadn't seen that article before. It's confusing at best. He talks about summer window shading like it's necessary, which I don't understand, particularly with such small glass. There's also a lot of that article that I'm not quite sure I understand. Calling temp swings a floating temp makes little sense. I've never been a fan of his writing style, just the concept. Those discrepancies are hard to miss, at least 2 sets of performance numbers. My printed book is far less confusing.
Not that I think expecting exact performance realistic. There are too many variables. Our house has been more consistant over the years than I'd expected. But predictions are just that. Not unlike any house or heating system.
"late-winter floating temperature was 66°F" makes little sense. If that was the low for the first winter, he did very well. Takes a couple years for the mass to settle down. Stabilize isn't quite the right word as it's always in flux.
The house will often be slightly warmer than the mass. Depending on house size, occupants can make a distinct difference. Don's do. Unlikely for the size you're dealing with. Obviously direct insolation will warm the house air before warming the mass much.
Anybody who needs tight climate controls probably isn't a good PAHS candidate without an appropriately responsive supplemental heating/cooling system. My clients approached that, well, she did when she came into the half-finished project. I was surprised at how well their air source heat pump did. They knew our performance and had no qualms, but there was never a º promise.
I'm taking their word about no over-heating. They're not bashful, or particularly interested in PAHS. Once the house settled down I was very curious as to how it worked. We'll never know exactly, as the thermostat's set on 78º. I do know what their electric bills have been, which don't show any ac load exceeding my dehumidification here.
Easier to compare my place to low-mass, similarly glazed, during no-ac high insolation. World of difference. There are a lot of low-mass "solar" houses here. Over-heating is common, requiring shading or venting even when it's cold out. We're high-mass and don't over-heat. As I mentioned, 3º diurnal is normal, sun or not.
Don's not an fc-er. He's rabidly anti-concrete. Toned it down slightly when I complained about the "concrete police". Greener-than-thou arguments don't generally have much merit.
Full western summer exposure isn't anything I'd recommend, but it hasn't proven a problem. As you note, those btus went somewhere, apparently absorbed by the mass (in absence of ac load). Absorbed is clearly what happens in our place on high insolation days before the leaves come out. The only difference between the two is slight mass temp. Higher delta T will mean faster movement. Rather than a critical level, it'll be another continuum. I'll try some numbers next time I get into it. Rate of transfer is the question. Pretty sure it's not significant.
If any of those guys do get a program that works I'll be most interested. Several have been promised, none delivered. Currently, all I can do is hand crank the math. Uncomplicated, but tedious. Starting, as always, with numerous assumptions.
Hope that's clear. PAHS Designer/Builder- Bury it!
Thanks. We'll see what else comes up as this moves along. I appreciate you offering your perspective.
Tom, what's the orientation of the windows on your house? And sf of glass as a % of floor space? Here's why I ask. I've asked about shading of glazing and the risk of overheating. Hait addresses this in chapters subsequent to those I read when I asked those questions. Here's what he says: "These are items that are quite CONTROLLABLE, but, unlike the "conventional passive approach", we actually WANT some of this heat to enter the home. Not all at once, by using large directly south facing windows, since that would only raise the air temperature to an uncomfortable level. The earth cannot soak-up the heat that fast, so, it is better to SPREAD IT OUT. Design the home for as EVEN a supply of this free outdoor heat as you can, by using a more moderate amount of glass, not all facing south but with some to the east and west. Position the windows to maintain an indoor temperature 2 OR 3 DEGREES (1-2E C.) ABOVE THE AVERAGE ANNUAL AIR TEMPERATURE you wish to establish. Then, a long wave of heat at just the right temperature will slowly lumber its way into the heat-saving earth." [Emphasis his]So it seems he favors glazing in the full spectrum of orientations, east to west. I imagine he'll also talk about window size, which is why what I'm really asking is how closely did you follow his guides on window orientation and size, and how much do you think those things matter?
Jim, we have 16% of floor space facing due south. 6% facing E. 4% W. Client house similar. Choice had little to do with PAHS. There's a problem with using % of floor space however. It ignores volume. Bear in mind that his experience is a vastly primary heating climate. Ours is less so. He doesn't deal in btus, which is the real measure.
This time of year we get little direct gain. Our windows are the major heat loss and gain. You have to take climate into account if you want a good predictor. Which is not to suggest that failure's the other option. It isn't. The question becomes how much the client wants an accurate prediction. Enough to justify heat loss/gain calculations?
Don't have a program, not that I expect one would be difficult for anybody more adept with computers than I am. I've relied on manual calcs using "Other Homes and Garbage" ISBN 0-87156-141-7. Tedious, but accurate in my experience.
Far as I can tell, Hait's wrong on glazing. Both on overheating, which he also didn't experience, and on required orientation. A better approach is to determine how much heat you need to store and then determine where that heat comes from. In a cooling climate, no direct gain might very well be best. Pretty sure I mentioned outlining a PAHS system for a cooling-only climate.
It's common for interested parties to request a succesful simple formula. One size does not fit all climates. Just like heat pumps.
Our next house faces due west, the view. I'll change the dimensions of almost everything and, I'm reasonably certain, will get better performance.
Whatever you come up with will work. Client will be happy with tiny elec bills. If there's a reason, view or blight, go ahead and cheat with the windows. Our place is so far from Hait's ideal that he'd probably not recognize it. We got a 13º annual swing, far worse than he'd prefer. But good enough for more than a few to admire. I've mentioned that we could cut into that 13º significantly if we bothered with simple window coverings. PAHS is extremely flexible.
Extreme climates, heating or cooling, will require extra care. Not unlike conventional housing.PAHS Designer/Builder- Bury it!
Finished Hait and the prelim design. Think we'll be doing a credible job of representing both the letter and spirit of his guidelines. Until you actually do something, you can't be sure it'll work as suggested, but I read a lot in the book that closely matched things I have experienced, so that gives me greater faith in those things I have not yet experienced.
Here's the direction in which we're headed. The house will be oriented 15 degrees west of south (chosen for pragmatic site-related reasons), and so used the bay window effect and the notched canopy to provide direct sunlight from morning till evening without concentrating too much in any single time slot.
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Change that entrance and you've got .... teletubbyland. LOL
You've obviously dealt with that sort of roof runoff before, but it looks to me interesting controlling erosion for awhile.
I once tried to keep dirt on a 45º slope. Great, until it rained. After 2 tries I finally figured it wasn't gonna happen and substituted crushed stone, which is now starting to grow stuff. Once was enough.
Don't know as Sandy's interested, but Joe Anderson is still willing and (he says) able to do thermal computer modelling. Not that I'd bother.
Hope those trees are behind the house.... That was one issue I didn't anticipate. I've uprooted hundreds. Dirt depth dictates what you want to grow, but seeds'll start anywhere.
It's gonna work. Thanks for the update.
Ooh, question about the jpg. "Copyright" means don't touch it? Or would you like referrals from it? BT isn't exactly public. Sunflower?PAHS Designer/Builder- Bury it!
The hill isn't to scale...just a rendering to show some height. Same for trees. They don't have many trees there, just scrub and brush. I added them to frame the picture (and did make a point to not put them on the umbrella!). The front is accurate, but I didn't spend a lot of time on the hill, other than to show an arbitrary slope, because the landscape parts of Vectorworks are a total PITA (which might mean I just don't get them). I establish the 3D loci accurately, and then the landscaping component connects them in all sorts of crazy ways. After 4 hours of that I give up and create any ol' gently slope and hell with it! <G>The actual slope at the _worst_ spot should be no more than 30 degrees, and we have gentle slope in numerous directions to avoid an aggregation of water in any single area. Normally on our houses out in the open, the runoff is slow and evenly spread, so we don't experience much erosion.Copyright is an automatic label on my drawings that means someone else can't claim it as their own. That's all. For example, I've encountered some unscrupulous "dome" builders who post pictures of existing houses and/or my drawings and deceive the public that they had something to do with them, when all they did was by implication take credit for the work of another. Scoundrels everywhere. Sandy will blog or otherwise document this house from start to finish. So anyone who is interested will get to see it in all its gory detail. If you know people who'd like a look, feel free to show them. Thanks. Sandy will control the broader, public exposure, as is the prerogative of all my clients. "Sunflower" is the name of her house (we name them akin to the way boat owners name their boats). She lives in the Sunflower state, and may ever include a sunflower logo in the floor inside the front door.I'm starting on the prints now...they want start digging...
4 hrs? Yikes. Better you than me.
Copyright is an automatic label on my drawings that means someone else can't claim it as their own...
Right, knew that, and some past problems. I was asking if you wanted the publicity from reposting/forwarding. Which sometimes makes my life a little simpler, when somebody asks about a dome. You know my interest there. <G> An extension of your web site, for my purpose. For me, an appropriate conclusion. OTOH, you might have considered it more trouble than it was worth.
I'm sure they're excited. Been a long time coming, especially with that confusion from Monolithic. I knew no better until you clued me in. Be interesting so see how Sandy presents it. PAHS Designer/Builder- Bury it!
Cloud , Nice looking concept. I would like to here some solutions from both you and Tom concerning bedroom egress/ interior room layout with these homes. I did quite a few bermed houses and having only one side accessible created some real design issues."Poor is not the person who has too little, but the person who craves more."...Seneca
The quick answer is that I don't make the layouts deep, I make them longer and shallower. In this one there was a bedroom on the left and one on the right. Public spaces in the middle. No hallways per se. Every space was a walkthrough to get to another, so we don't block light where we don't need to. For the bedrooms, the sleeping area is in the front, where is has full light, and not coincidentally, egress. The bathroom and closet sets to the rear. In the public spaces, things like pantries and closets and laundry rooms are to the rear, with the kitchen and living rooms to the front. Partial walls, interior glass block, framed wall openings, etc all allow for some distribution of natural light. The result is that in terms of light and space, it feels no different than any other house. It's a misconception that a bermed/buried house is cave-like. If it is, then that's just inappropriate design, because it need not be.
Where it will feel different is in climate. Most of us are used to houses that fluctuate noticeably throughout the course of a day. My neighbor's house would fluctuate > 15 degrees between 11 am and 3 pm just be/c of the sun. These types of houses, however, should have a diurnal fluctuation of only a few degrees. That's a change from typical that you absolutely notice, and come to cherish!
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Empirically, I can explain it another way (not that you asked). I have one of these thermometers. In the entire time I was in the Asheville house, I never saw more than 2 of the globes rise and fall. Here in our conventional house, I've seen them all rise and all fall in the course of a single day--clearly demonstrating the diurnal fluctuations. Now, you might say it just an indication of a poorly configured hvac system. Maybe, except the system here is 30% larger (btu/h capacity) than the one there, for a house 1/3 the size!
Edited 6/16/2007 12:11 pm ET by CloudHidden
I prefer deep houses. For steel bar joists, it's an economy measure. Last house was 40' deep, the longest bar joist I could get delivered on a straight truck. Guy in LA wanted to talk about 60' deep. No problem (assuming semi access, which I've never had).
What we don't do is only 1 face exposed. Closer to conventional housing and allows light and egress farther back. More earth contact is better thermal performance, so it's a matter of compromise. Jim mentioned diurnal temp swings. Very unusual for us to see more than 3º, usually 2º. And that's with an egress window 9' off the rear wall and still 3' from the retaining wall on that side. We're also way over-glazed, but DW's happy.
Thermally, you need enough dirt storage to cool/heat your design. Where that occurs is up to the designer. For instance, I like it on the roof for a variety of reasons, but not everybody agrees. Takes a substantial roof. No problem for domes or bar joists, not so easy with wood.
Don't know what Jim figured, but I've got 240 tons overhead and unlikely I'll ever build another so light weight. A guy I know, whose house weighs about as much as an SUV (1/4" plywood sphere) , opined that "walls are the easy part. Pile up pretty much anything. It's the roof that gets interesting."
His would be a challenge for PAHS. LOL
PAHS Designer/Builder- Bury it!
>What we don't do is only 1 face exposed.I could have been clearer on this. In the two cases where I've designed a buried house, there was only one (client) desire, and that was single face. Offering faces to the east or west would have compromised one factor or another on these particular sites, whether privacy, access, existing landscaping features, or other. It's not by fiat or ideology that they ended up with one face, but because in these cases, it seemed the most pragmatic solution. I liked Hait's reasoning for wanting to gather sunlight somewhat evenly through the day, rather than only in one direction, and will accommodate it when and where possible.Feel free to mention anything you wish about "sunflower" on any relevant building site as suits you. I'll have it on my site soon. Happy to talk about any house. Right now I'm swamped, but that can change in a heartbeat. The more houses that work get built, the smarter we all get and the easier it becomes to build the next one.
Edited 6/16/2007 7:57 pm ET by CloudHidden
You know that guy?
That's an old Buckminister panel design in a sphere.
Always appreciated his creativity.
http://www.sover.net/~triorbtl/index.htmThere is some of the same fitness in a man's building his own house that there is in a bird's building its own nest.-Thoreau's Walden
You know that guy?
About as well as I know you. (Did wonder about you when I was through Cleveland recently.) He had a brother here, local major hospital. Didn't peruse that link. Hope it showed his NC spheres. Wasn't his land, headed N. when the farm was sold IIRC. I figured he got the plan from somewhere, not that he gave credit that I recall.
He diverged into ferrocement. Didn't appear to be a benefit. Quite awhile since we corresponded. Very interesting guy. You read about his insulation?
Your signature line is apt. Got plans? It's a very good feeling. Pile of plywood, pile of doors, and you're set. Once you figure out where.
Very friendly if you drop him a line. Big part of my amusement was his take on housing is the other extreme from mine. Low mass/high mass.PAHS Designer/Builder- Bury it!
VATom, I helped build and lived in a dome set atop a standard 8' wall . 27 of those 8' walls actually.
I sat in on a conversation with a BI who didn't want to accept the design because of the ply thickness (we had appealed his original decision and were sitting in front of a panel of builders). When he was asked where the walls stopped on the dome and the roof began the old builders started smiling .... he was caught totally off guard and admitted that he had no idea. We built what we had designed to build. Domes are great , as long as you don't have a fire in one, the one I lived in burned to the ground in about 25 minutes."Poor is not the person who has too little, but the person who craves more."...Seneca
LOL That's rich.
Cloud and rez are dome fans. I find domes amusing, but that's it. My interest in PAHS, and that web page on our place put up by a guy promoting discussion, leads a surprisingly large number of folks my way.
Those interested in domes I'm very happy to have another direction to point them.
Cloud might suggest that perhaps you built the dome with the wrong material. I'd obviously agree. OTOH, Steve's sphere would be pretty easy to replace, compared with concrete.
That's what makes it an interesting world.PAHS Designer/Builder- Bury it!
>Cloud and rez are dome fans.That's slander! Rez will never let that one go now! <G>In all seriousness, I'm a sculpted concrete fan, not a dome fan. It's the material and methods I like, not the particular base shape. I've been working a lot lately with poured walls, ICF, barrel vaults and other shapes. I conjure up very little that's pure dome. And I avoid the word itself like the plague, because it kills an appraisal and financing before ya even get started. They hear "dome" and they lump it with geodesic and wood structures, even though they have almost nothing in common. Sandy's is only about 1/2 curved, for example, and the front is strengthened by using folded plates. The building code section we fall under is "Thin Shells and Folded Plates"--not a mention of "domes", and couldn't be happier about it!It's all about strength, energy, and cool shapes for me.Happy Father's Day, y'all!
Edited 6/17/2007 12:04 am ET by CloudHidden
ah, Cloud don't do domes, man.
He builds insulated, sculpted concrete residences.
And me, I'm looking for the biggest bang for the materials and labor and that means the balance of size.
be someday the max,maybeThere is some of the same fitness in a man's building his own house that there is in a bird's building its own nest.-Thoreau's Walden
Thanks for having my back! <G>To say I do domes is like saying frame-house designers do cubes. Nah, we work with the materials we got, and for you, that means whatever makes for efficient usage. For me, it's cool shapes of all variety that the materials can create.I'll come back here with a link once the client starts building. Thanks Tom, et al, I learned some good stuff through this.
Tom,Do your vents--kitchen, bathroom, etc--run through the roof and umbrella, or out a side wall? Have you found running anything through the umbrella to be easy to waterproof or tricky, or have you been able to avoid that entirely?
Rooftop penetration sounded problematic so we avoided it. Would require careful detailing and then still have some maintenance issues.
These houses were only 50' wide with a large area available for utilities created by the bar joists. KISS was our mantra. Plays well with PAHS. <G>
My building dept got me out of a problem, when I put a sink on an outside wall under large windows, with:PAHS Designer/Builder- Bury it!
Thanks.I haven't totally decided where I'll run a few of these things. We only have one open face, and I probably don't want to bring everything out the front facade. Still thinking...As regards KISS, this has sure simplified the elevations! Might end up being the smallest drawing set I've yet done. The time consumer has been changing all my detail drawings to remove and change the insulation details.Later...
We used side walls. Lots of penetrations.
Please post through-the-roof detailing if you go that way. Sealing the umbrella is the only real challenge. It's presumably mulitple sheet plastic so shouldn't be too difficult. Not like some wrinkles make any difference.
You've got a rooftop retaining wall across the front. Would through it (vertically) be an interesting possibility? I've not understood exactly what it is or how it gets attached to your shell, but she and I discussed the concept at length. As you know, she doesn't exactly understand the nuts and bolts. One of the several reasons you're on board.
If you could cluster the penetrations, out the front and hidden behind something would work well. Add an architectural detail? Passive ventilation?
PAHS Designer/Builder- Bury it!
Edited 7/22/2007 12:38 pm ET by VaTom
Whether passive or active ventilation will depend on where they wish to spend the money. I'm guessing they'll choose passive through earth tubes. As Sandy knows, I don't have any experience with earth tubes to guide her one way or the other, aside from suggesting locations for them that won't interfere with the umbrella. It wouldn't be hard to add an in-line fan if that's found to be necessary.For vents, my current inclination is to build a notch into the umbrella to the rear--a poured or block wall to about 8'--and use that as the terminus for the vents. It'd keep the front clean and not compromise either the umbrella or the storage.
Sounds good. What I was trying to suggest was a solar chimney in front that could hide the plumbing. Gap in the rear would do about like our side walls, without the glazing.PAHS Designer/Builder- Bury it!
Tom, I want to add my appreciation for your first hand report. I'm just getting back to studying various experimental projects, concepts and structures which I first read about in the 1970's. You work has really grabbed my attention. I truly admire what you've done and I'm grateful that you're willing to share your unique experience with us here.
Gotta get to work right now, but I'm looking forward to learning more from you.
Sincerely, Peter
Peter, you're welcome. If you can wade through all this, I commend you. Extremely simple concept. Hait's book came out in 1983. Very few had the wherewithal to build one. Now, having dealt with problems of home owners' insurance, mortgage appraisers, and building inspectors, I can recommend without reservation.
I spent a lot of time reading before moving to Virginia. Lots of ways to get a comfortable efficient house. This is what appealed to me. And my small budget.PAHS Designer/Builder- Bury it!
I'm not specifically familiar w/ your reference, but am familiar w/ the concept. A lot of materials and effort. May work, but the effort may not be worth it.
Also, it depends on your climate. Many passive solar design strategies were developed and worked well in e.g. the Southwest ... where they often work well. Your climate will affect your design. You can't extrapolate strategies that work well in the Southwest to just anywhere. Heat storage only works if you have excess heat to store. If your wood stove or gas furnace supplies most of the heat to your house, you will pay for every Btu that you 'store' to very little benefit.
If you have solar heat to store, then you may be good to go. Earth shelters are not 'dark caves'. They can be better day lit than many conventional structures. The key word is CAN.
Don't assume annual heat storage is a good strategy. Northern/cloudy climates have little excess heat, so thermal storage buys you next to nothing.
Mark Williams, HR,OR
Mark, perhaps you're unaware where the original PAHS was built? Missoula, with 8125 heating degree days to your 5499 (base 65º). Take a peek at a book excerpt: http://www.axwoodfarm.com/PAHS/UmbrellaHouse.html
Annual heat storage is probably what you're not understanding. Different from standard passive solar. We had an Alaskan engineer here who opined that even his climate was appropriate, with the very long summer days. No high temps, just lots of sun.
Whereas we get the majority of our stored heat from no direct gain, just high temps.
As any heating system, input needs to balance loss. With low temp storage, many possibilities for heat source. Including your summers with 282 cooling degree days (base 65º). I don't have insolation specifically for Hood River, somewhere around 370 btu/ft² in Dec? Portland has 19% availability, you're similar?
Heat's available there. Squander it if you will. Storage works.PAHS Designer/Builder- Bury it!
winters can be pretty gloomy and long term in Portland. HR is decidedly better, but still frequently cloudy. Regardless, you still need excess energy for PAHS to work. Montana has great cold sunny winters from Missoula on east. You can rely on high summer temps to charge mass, but the temp in the house has to be allowed to rise ... not sure to what temp, but storage heat transfer is directly proportional to delta T. If you supplement w/ tubes, it can really help. But, it's still a lot of effort and just direct gain can be easily achieved and controlled for very low energy costs.
Montana and Minnesota can be good candidates for biannual storage because there is roughly equal very warm days and very cold days.
Montana and Minnesota can be good candidates for biannual storage because there is roughly equal very warm days and very cold days.
That's annual, not biannual. Only one cycle/year. You knew that. <G>
Actually, Missoula only has 280 cooling degree days. Not exactly "roughly equal" to its 8125 heating degree days. Considerably worse ratio than you have.
PAHS works like a dream here in Va. I've outlined a system, unbuilt, for a cooling-only part of Texas. No problem there even though the winter's very brief. All the mass is doing is storage. Whether heating or cooling, it doesn't care.
I gather you assume high cost? That's certainly not my experience. Last client house appraised 50% higher than construction cost. Not entirely due to the shell, but it was a significant part. Appraiser, correctly, ignored the energy features.
PAHS Designer/Builder- Bury it!
biannual, I think. charge half the year discharge the other half. Biannual. Store half the year.
Semiannual would be every other year, right?
Biannual v annual. It's an industry standard nomenclature thing, and this industry is not mature enough to have a standard.Personally, I prefer "Annual", other wise we would have to say "Passive Biannual Heat Storage," and that's just not as aliterative. Also, "Passive Annual Heat Storage" gives one the intuitive insight that we're talking about a year long system.Besides, if we use "Biannual," then, we'ld have to say 120 bicycle AC current, 'cuz there's 60 positive half cycles and 60 negative half cyles every second. Everybody would think the US powers their TV's by pedaling their arse all over town.Reminds me of the time in the Navy I was sent to Diego Garcia to finish installing a SatCom station. This transciever was supposed to have its' front end connected to some British comm gear, but nobody could get it to work, not even the high priced EE imported from MIT or somewhere.At the end of 6 weeks this EE had figured out that the problem was in the signal timing, but he just couldn't solve the problem.So anyway I was having a couple of brews with the Brits and we got to talking shop. They told me that the problem was that somehow their 4.8 kilobit signal was interfering with our 2.4 khz timing and no filter they tried seemed to work good enough. Everybody thought my equipment was too sensitive to their 4.8 khz signal.Turns out, they counted both positive and negative sides of the timing signal, so 4.8 = 2.4. Problem solved the next day, and the EE was a bragin' 'bout how goooood he was.SamT
this industry is not mature enough to have a standard.
Don't know about that. It was 24yrs ago the book was first published, the phrase coined: passive annual heat storage. Since then the only sort of reasonable contender is AGS (annualized geo solar).
MrEnergy is the only one to use biannual that I've seen.
Pretty funny about cycle counting.PAHS Designer/Builder- Bury it!
Maturity has nothing to do with age.Look at me and I'm 57.SamT
That's you with the babe? Always thought you were somewhat fictional.PAHS Designer/Builder- Bury it!
I am truely a creation of my own imagination. As are we all.SamT
Also, to be confusing, Biannual can mean either twice a year or every two years..
.
A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
I'll bi that.SamT