Helpful? 4

Passive Annual Heat Storage & Zero-Energy-HVAC

My question is: Why do we not see more building recommendations along this line of thinking? Various experimental aspects of this structural approach (to managing HVAC with zero-energy input) have been proven effective, in recent decades. Some ancient architecture also demonstrates the effectiveness of the approach. Present day oversight might primarily be induced by subconscious avoidance of anything which seems to relate to cavemen. (Some cavemen may have somewhat understood annualized heat). Yet today we have so many aspects which should delight an architect while incorporating elements of like design. While incorporating such features in houses which appear ordinary might increase costs of a project, could one not suppose that "free energy" is incentive enough, to try some features-- I have studied various approaches to this -- My extended blogs with many web links--
http://www.midcoast.com/~bo/CostFreeHVAC/RealyInsulatedLot/SelfSufficien...

Bo Atkinson

Asked by Bo Atkinson
Posted Mon, 02/16/2009 - 08:38

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33 Answers

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my opinion: because it's not good for the economy. A whole lot of people would be out of a job and out of business if this were common knowledge. Heating and Air Conditioning would become obsolete and a whole lot less power would be necessary. Less solar panels would be sold. etc.. Currently the green movement is still a commercial thing (operating in a "capitialist" world where waste is an important part of the economy). These types of buildings are more harmonious with the planet and a lot less commercial with a whole lot less waste!

Answered by harderthanyerhusband
Posted Tue, 11/24/2009 - 13:22

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Enlightened cavemen notwithstanding, there are multiple legitimate reasons to question or avoid underground living - even with the potential for zero energy living.

I can achieve nearly the same result with an above-ground super-insulated, super-tight building with no windows - it can be heated by human and utility heat in winter and passively ventilated with a solar chimney in summer. But no one wants to live in a windowless box, and few choose to live in a light-deprived and view-restricted cave.

Additionally, PAHS requires enormous volumes of concrete (very high embodied energy and environmental life-cycle costs, including massive global warming contribution), large volumes of petrochemical foam insulation and synthetic waterproofing membranes, and must be perfectly engineered since altering the heat storage system is cost-prohibitive.

For those interested in the advantages of the PAHS approach with few of the drawbacks, Annualized Geo-Solar allows similar storage with above-ground houses built with natural materials.
http://www.greenershelter.org/index.php?pg=2

Answered by Robert Riversong
Posted Tue, 11/24/2009 - 14:56

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Agreed! Getting options is the point. Each according to a budget within reach or at least try for the piecemeal approach. Had to find a cheaper web host, moved the pages here--

http://harmoniouspalette.com/CostFreeHVAC/RealyInsulatedLot/SelfSufficie...

Depends on region or it can also depend on how many years of a life a person commits to sweat equity in general.

These options for living above ground-
http://harmoniouspalette.com/CostFreeHVAC/WholeLotInsulation.html
http://harmoniouspalette.com/PAHS-retrofit.html

http://harmoniouspalette.com/45degTiltUp.html

Composite insulation design-
http://harmoniouspalette.com/BuildGreen.html

http://harmoniouspalette.com/PAHSgreenhouse.html#chimney

Idealizing hobbit holes - Basic underground ideas-
http://harmoniouspalette.com/u-tube.html

Donut vault geometry for extra structural efficiency-
http://harmoniouspalette.com/SqDonutVaults.html

Tried the solar attic style first, flower beds prevented retrofit-
http://harmoniouspalette.com/TranslucentDome.html

Ferrocement and concrete can work in unexpected ways, given ample-know-how. Looking ahead of that curve of life would help, but i slipped a little, off the self-sufficient-ish edge. Back on now, as jobs might be harder and harder to find.

Answered by Bo Atkinson
Posted Tue, 11/24/2009 - 18:12

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PAHS is a long-term investment. You could spend half a million on a McMansion or on a Not-So-Big Earth Sheltered PAHS Home. But, as the price of oil and electricity skyrocket, you would continue to spend royally on the McMansion while spending little on the Earth Sheltered Home.

This 2400 square foot, solar heated, Earth Sheltered PAHS Home http://i41.tinypic.com/b67huf.jpg will have nearly 20% glazing and six light tubes. It will have 0.3 ACH and natural air conditioning through a cold chamber, just as described in Hait's PAHS book. It will also have a Temp-Cast masonry stove with a full-house air distribution system as backup to the PAHS heating system.

Clearly the Earth Sheltered Home will have an initial concrete and steel energy footprint, but the home's green footprint will compensate for that over the years.

Answered by Anonymous
Posted Sun, 03/28/2010 - 10:58

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ANONYMOUS,

First, I don't give any credibility to an anonymous comment.

Second, I can build a similarly sized house with less than 5% of the environmental footprint of that concrete monstrosity at a fraction of the cost that will have better energy performance, better ventilation, better views and daylighting and be completely passive.

Answered by Riversong
Posted Sun, 03/28/2010 - 17:15

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Dear Mr. Riversong,

Please elaborate on your response to Anonymous. If you can build a 2400 square foot house with a 26' by 26' garage and a 16' by 16' root cellar with better energy performance, better ventilation, better views and daylighting, and completely passive.for less than $100K, you're hired!

Answered by Roger Wehage
Posted Mon, 03/29/2010 - 09:23

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As I understand it the PAHS system is quite flexible and having researched it considerably (I'm presenting designing a home for the French Alps) I've seen a broad spectrum of applications in various architectural styles other than what one might find in the links provided at the PAHS website. I have also been impressed by: 1) costs 2) 'potential' for reduced maintenance (this is somewhat backed by marine use of laminated ferrocement and ecc solutions in thin shell construction methods) 3) more glazing than most homes (I'm not competing with a glass home here) and 4) avoiding anything that might create a cave like feeling. The elegance of the PAHS system includes the simplistic use of convection to move warmth and coolth in and out of the home depending on the immediate temperature but always with the advantage that the earth is working as the storage system. There are many other details but I'm sold. As it happens, my wife is very committed to an above-ground home so we are creating a hybrid that will integrate the PAHS system into the above-ground chalet (this is discussed in the PAHS handbook) and I am very curious to see how this all works out ... but I having researched this for a few years now I'm confident that we will benefit from the PAHS system both above and below ground (ironically the greatest amount of glazing will be in the semi-subterranean part of the home).
Great discussion and worthy of openmindedness when considering new solutions ... or old solutions with new applications.
Best, Chuck

Answered by Anonymous
Posted Mon, 03/29/2010 - 11:26

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BTW sorry for appearing as 'Anonymous' but I couldn't put my name in ... however I did sign it. Just to point out that the use of anonymous (such as earlier 'anonymous' submission) may be due to restriction on adding name if one is not a member rather than sinister or evasive reasons.
Cheers
Chuck

Answered by Anonymous
Posted Mon, 03/29/2010 - 11:29

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Another note from a neophyte: Regarding concrete's carbon footprint as per 'anonymous' comments of mar 28 10: portland cement usage can be considerably reduced in today's concrete with ecologically sound cementitious additives which (rather than being prescriptive) can be found in varying types and amounts depending on where one lives. Additionally, working with WWR (welded wire) rather than standard rebar offers considerable savings and efficiencies WRT steel usage. And using shapes from older architectural forms (barrel vaults, groined vaults, etc) it seems one can further reduce - by something on the order of 30% - the materials required by rectilinear structures to create square footage. Of course the efficiency of vaulted systems can be applied above or below ground equally ... below ground it does take advantage of the compressive strength of concrete (and other cementitious materials) while reducing amount of tensile reinforcement and allows for even thinner walls = even greater reduction in materials. At least that's what I've read.
Best
Chuck

Answered by Anonymous
Posted Mon, 03/29/2010 - 11:48

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Chuck has made some reasonable points, yet increasingly, locally available reuse of otherwise discarded materials will sneak into the equation. Long term experience with site consteraints, local markets, materials feasibility, thermal valve choices, ground water and very important. Finding knowledgeable, "non-desperate labor" will impact costs. We may well be at a transition point for long distance shipping of special materials like proven fly-ash, or good cements. Even bulk casting with potato sized stones or larger will improve eco profile, given able hands. Regions where all these things are available will become more key as the "green advocacy" turns into "attainable wholeness" for a good life. Consider strife free Maine. The first blogger on this webpage. Able, experienced builder, fit as many 20 year olds, accepting all aspects concerning helping clients, interested in self-heating housing Bo Atkinson
http://harmoniouspalette.com/CostFreeHVAC/RealyInsulatedLot/SelfSufficie....

Answered by Bo Atkinson
Posted Mon, 03/29/2010 - 12:24

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Robert,

Regarding Annualized Geo-Solar - have you seen any energy use data to support the AGS approach compared to a super-insulated slab? It's certainly an interesting concept.

Answered by John Semmelhack
Posted Mon, 03/29/2010 - 20:46

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Chuck:

It would be nice to learn more about the 2,400 s.f. home linked to above. The site mirrors one I have.

I too am enamored with the PAHS concept. While super insulated homes are wonderful, they require more maintenance and offer little in the way of thermal mass. That's fine if you are building production homes on normal lots. The PAHS concept really shines when one has some land to play with, especially if the owner desires to live off-the-grid. PAHS construction can be as simple as any typical commercial concrete building.

Answered by RL Lemke
Posted Wed, 05/19/2010 - 11:23

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RL LEMKE,

There is nothing inherent in a superinsulated house that would require more maintenance, and there is nothing that limits the amount of thermal mass. Superinsulation and passive solar with thermal mass make a wonderful duet. By drastically limiting heat loss, modest passive solar design can contribute as much as 50% of the heat load.

And no commercial concrete building would come even close to PH standards. PH requires a much more sophisticated level of engineering and detailing than any other building system.

Answered by Riversong
Posted Wed, 05/19/2010 - 18:32

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Robert:

I have no issues with Passivehaus or any super insulated homes. It would be wonderful if every production builder would adopt the energy saving concepts. While I may be inclined to go with the PERSIST system over other forms of building an air tight home, all good systems would save homeowners a lot of money which otherwise would be needlessly paid to utility companies.

My passion is for PAHS homes, where the site is large enough to facilitate the design and orientation. Living in the land of tornados, and having lived in forest fire country, I feel safer in an earth sheltered home. Earth sheltered homes are supposed to do well in earthquakes too, but I have never seen anything proving the assertion.

Isn't it great to be able to experience the passion for green building today? In the 1970's those of us that wanted this kind of construction were considered granola nuts. The passive solar homes I built then were difficult to get past plan-check at city hall.

My desire for the PAHS design is the mountainside property I have. South sloping, views, great aquifer below, and more. To build a home that nobody can see from the road would be a delight. Preserving the natural landscape. Surely you can understand that desire.

If I again take-up building homes, it will be affordable and sensible; air tight, energy efficient and durable homes. Simple in operation, and comfortable to live in, for generations.

Answered by RL Lemke
Posted Wed, 05/19/2010 - 21:41

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A gentleman in Virginia has built two PAHS homes. One for himself, and one for a friend. The simple, and very affordable, construction has proven both durable (concrete is tough) and reliably frugal. The heating and cooling costs have averaged less than $1 a month. I consider that quite affordable. He built the homes after reading a library book on how to construct poured in place concrete walls, a Sierra Club publication called "Other Homes and Garbage", and John Hait's book "Passive Annual Heat Storage - Improving The Design Of Earth Shelters". No special classes, no degrees, nothing more than a belief in the concept. Pretty darn good for a furniture maker, isn't it. I have a world of respect for a pioneer with an idea, especially when they succeed.

John Hait has documented the performance of the PAHS concept with the numerous sensors installed during construction. From that data certain modifications have been made to the recommended design. The beauty of the design is the wide latitude the concept affords. Wide variances still offer almost all the benefits that strict adherence to the criteria offers.

PAHS will always be merely a niche. Just like Mac always was in a PC world. Then, as now, I walk around with that knowing smile. PAHS is a solid performer. Simple to build and frugal to own. "Think different."

To answer the original question, the PAHS design takes more land than the typical 40', 50' or 60' residential lot. Heck, a friend is selling 30' lots to a local merchant builder for single family detached homes. Shotgun design I would guess. Earth sheltered homes will remain appealing to a very small market segment. However, Mike Reynolds has proven that niche markets can be grown to gain world-wide acceptance. His EarthShips are all over the planet, and spreading fast.

Answered by RL Lemke
Posted Wed, 05/19/2010 - 22:15

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Think of the thick concrete and stone buildings built decades and even centuries ago. Still here, still durable. Yes, there are quite a number of timber buildings around too. Maybe not so many in termite country though. One key feature green homes need to include is the ability to function for generations of users. Durably built and flexible in design. Is a green home that has a service life of 80 to 100 years really that green? Building materials are energy intensive to make, transport and construct. Why not seek designs that will offer a service life of 200 years, or more?

A PAHS home is a durable concrete shell that can be easily modified for evolving uses. With an insulation and waterproofing umbrella extending 20 feet beyond the perimeter, the dry thermal mass surrounding the building provides continuous comfort, without maintenance. The concrete structure offers the flexibility to relocate interior walls. Rodents, termites and other unwelcome guests aren't interested in chewing through concrete.

The exposed wall area on the south, with some on the east and west, does need to be insulated and made air tight. The PERSIST system would work equally well with the exposed concrete walls. The same waterproofing layer that is applied to the rest of the PAHS structure works on the exposed walls. On top of that foam insulation, furring strips, air gap and rain shield will complete the package.

The energy efficiency of the PAHS system isn't rocket science. It's real simple. Concrete structures are pretty well darn air tight. Control the windows and doors, make sure there are no thermal bridges, and you are there. The huge dry thermal mass provides energy storage throughout the year. Set the mass temperature over the first three years of living, and it will take care of you for decades.

Answered by RL Lemke
Posted Thu, 05/20/2010 - 00:00

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If you insist on reviving a months-old thread in order to offer a screed on concrete, underground PAHS living, then you should be prepared for critical responses (and it would be helpful to know what in your background so strongly inclines you toward this approach).

The most "green" dwellings are the ones that humanity used for milennia before the fossil fool age: they were mostly very small temporary structures built of locally-available annually-renewable materials that would decompose back into the environment, leaving no trace and no impact.

Today, a reasonable definition of a sustainable building technology is one that uses non-toxic, non environmentally-destructive materials and methods that are durable enough to outlive their short-term impacts (such as forest depletion). In other words, a wooden building that outlasts the time it takes for the forest to regenerate the trees consumed is a durable structure.

Given that the average American spends 7 years in a house before moving on and that the typical commercial property has a lifespan of 30 years before it is demolished - not because it's structurally insufficient but because of change of use - it's hard to make an argument for buildings made from highly impactful materials (such as concrete) that last hundreds of years.

Additionally, and contrary to your assertion, a concrete building is much more difficult to remodel or add on to than a wood-frame building. There is much debate about the effectiveness of using massive earth thermal storage, underground homes make daylighting and ventilation much more difficult, are vulnerable to leakage that is extremely difficult and expensive to repair as well as moisture problems, and consume vast quantities of a material (concrete) that is already the most used substance on earth after water and contributes heavily to energy depletion and global warming.

Answered by Riversong
Posted Thu, 05/20/2010 - 07:46

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Robert and Lemke,

I don't think the super-insulation and PHAS confilcts each other. Let's think a house with high R wall and Roof, air-tight (with HRV/ERV), adequate sount solar gain window. Those can be common. The key issue is whether we want to couple or isolate the concrete floor with the earth. Do we do horizontal insulation (up to 20' as PHAS), or do we do under-slab insulation (like Passivehause recommends)? Perhaps some computer simulation would help to answer that question.

Personally speaking, if lot size is not an issue, I would think the ground coupling may help reduce over-heating issues in sumer/fall. The question is if the floor will be too cold in winter and early spring. Typical PHAS house have earth coupling walls and roofs. That dramatically increased the heat transfer between the house (collector) to the earth storage. However, is there enough heat transfer for floor coupling alone? It may depend on the location/climate. But how to quantify is an issue. I would say for a single story house with slab floor, it may be possible to design an above ground house with supper-insulated wall/roof and earth-coupled floor (with horizontal insulation). This house could potentially be zero heating/cooling if carefully designed. This hybrid approach is close to AGS, just AGS typically advocates a heat charging mechanism for the earth storage. So can we do without charging mechanism? I hope someone would have done such an exercise to provide an example.

Harry

Answered by Harry
Posted Fri, 05/21/2010 - 13:40

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John Hait thinks that standard homes could be modified to take advantages of the thermal mass the earth offers. Remember, the constant temperature of the earth is higher than most think. Where I live it is 68 degrees. After charging the dry thermal mass one can establish any comfortable temperature.

Here is what John Hait says:

1. SUPER-INSULATE FIRST. Basement walls and masonry homes should be super-insulated on the outside. Without super-insulation and minimal infiltration, you will probably NOT achieve full annual heat storage. (Remember, I said it wouldn't be easy.)
2. Design a solar collection system to move the summer's heat into the Storage Zone.
Here are some suggestions:
a. Direct Radiation. Make the sun shine in the basement.
b. Earth tubes made to cool the summer's hot air. Cooling the air saves the heat.
Earth tubes hold the key to inexpensive retrofitting of above-ground buildings.
True, it would be harder to get convection powered air through them, but clever application of heat flow principles should overcome these problems, or just use fans.
c. Convection-connection. A well designed convection loop could connect the home to the earth storage using a very deep, insulated "cold sump."
d. All of the above!
3. Put an umbrella ALL THE WAY AROUND the home just as if it were an earth shelter with a large exposed face. It may prove easier to put an extra couple of feet of dirt Figure 73 Convection connection passive annual heat storage retrofit. on the yard, rather than digging the yard up. Moisture control right next to the house would be the most difficult problem to over come, as improper water control would cause rotting. You could berm further up the wall, but the earth would probably have to be made self-supporting, since regular walls won't stand the strain. Remember that the earth berm is, thermally, a part of the home. So, don't just let the wind blow between your house and some retaining wall next to it. If you have a masonry home check with an engineer before you attempt to use it to hold back very much of an earth berm. You may also want to save the sod by rolling it up, and then putting your nice green lawn back on when the berm is in place.
4. Provide ALL OF THE WATER CONTROL methods of chapter 4.
5. The home MUST have a good thermal connection between itself and the earthen Storage Zone, or else it cannot store and retrieve heat properly.

Answered by RL Lemke
Posted Fri, 05/21/2010 - 19:04

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the constant temperature of the earth is higher than most think. Where I live it is 68 degrees.

And, in much of the lower 48, it's far lower than you might think. The deep earth temperature is nearly identical to the average annual air temperature. Here in north central VT, its about 42°F. You have to be down in climate zone 3 to get ground temps like you have.

Answered by Riversong
Posted Fri, 05/21/2010 - 20:18

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The monitored test PAHS home was built in Montana. Below are the initial results:

This unique heat control method was still in its infancy in January of 1981, when a major feature of Passive Annual Heat Storage (an insulation/ watershed umbrella) was incorporated into the design of an earth-sheltered home that was being built in Missoula, Montana USA. This home, called the Geodome because of its shape, has its insulation/watershed umbrella extended into the earth about 10 feet (3 m) beyond the walls of the house, and encloses a two- foot (.6 m) deep portion of earth on the roof. (fig. 4)
The building is monitored by 48 temperature, and 5 moisture sensors. By the autumn of '81, the temperature 10 feet (3 m) under the surface, 12 feet (3.7 m) behind the north wall, and 2 feet (.6 m) beyond the insulation itself, had been heated by excess summer heat from its usual 45E to 64E (7-18E C). The two-foot (0.6 m) deep portion of insulated earth on the roof was warmed up to 77E (25E C), while two feet under the floor it was 68E(20EC).

Throughout the first year, the north wall temperature on the second floor of the home varied only 6 degrees...from a high of 72E (22E C) in September to a low of 66E (19E C) the next February. Thus the home has been snugly wrapped with a nearly 70E (21EC) layer of earth, several feet thick (1 m), which has kept the home comfortable all winter. Even though the insulation umbrella is only half as big as we now know it should be, the earth around the home remains warm and dry!

Answered by RL Lemke
Posted Fri, 05/21/2010 - 22:22

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I think 68F under floor may not be enough. Say we have a PassiveHause insulation level wall/roof to cut the the peak heating load to 10w/m2 (excluding the floor). Assuming 1 story house, so the earth coupled floor would need to provide 10w/m2 heating. A ball-park concrete floor heat transfer coefficient is around 11w/m2-K. So 68F floor would maintain the indoor 66F (delta T=2F or 1C). Not bad, but typically US house would be set 68F for winter, which means 70F for the floor is needed. TI guess that's probably why it still needs certain mechnism to charge up the earth temperature. That is probably Hait's house lowest annual temperature is 66F. Perhaps Hait's Geodome did not have enough south glazing. It is all about heat gain (in this case, solar) vs. heat loss (insulation,window quality etc) balance, isn't it?

But 6F annual swing is very good data. That means if we can raise the earth temp 2F, then 70~76F is a very good range. Even for cooling season, we only need a dehumidifier to take care of the latent load, then shade the glaze to minimize direct gain, the rest cooling load peak should be only ~1/3 of the heating peak load at place like IL or Montana. Even though the floor cooling coefficient is usually smaller than heating, about half. (~ 5.5w/m2-K). That would still only requires 1F delta T to meet the cooling peak needs, meanng can keep the house <77F (with a dehumidifier).
However, how to raise the earth under floor to this range (70~76F) is a big question...It is not an easy computer simulation due to the changing boundary condition. Typical linear finite differential analysis is not accurate enough to the level of a couple of degrees. A transient analysis with changing boundary condition is not an easy job.

Harry

Answered by Harry
Posted Fri, 05/21/2010 - 23:48

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If I were to use a basement, or slab foundation, as thermal mass for an above ground structure, I would add a perimeter of insulation. There is a Minnesota study where they did just this, where they found significant benefits. I have a copy somewhere on my drive, but not the site. The PAHS idea is an extension of the Minnesota work, as their insulation extension was no more than 5 feet. They tried different angles too.

The key is that the soil must remain dry. Wet soil will wick the stored temperature away too fast. Around the edge of the perimeter insulation needs to be a drain, french or otherwise.

Answered by RL Lemke
Posted Sat, 05/22/2010 - 00:09

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"That is probably Hait's house lowest annual temperature is 66F. Perhaps Hait's Geodome did not have enough south glazing. It is all about heat gain (in this case, solar) vs. heat loss (insulation,window quality etc) balance, isn't it?"

Yes, the lessons learned were to have 25% to 30% of the floor area in windows. To have some on the windows on the east and west side of the home. To extend the umbrella insulation and waterproofing to 20'. The massive thermal mass provided by the the dry soil allows far greater solar heat gain in the summer. Light colored floors and white walls spread the light energy to more surfaces for better heat distribution.

Answered by RL Lemke
Posted Sat, 05/22/2010 - 11:25

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"However, how to raise the earth under floor to this range (70~76F) is a big question...It is not an easy computer simulation due to the changing boundary condition. Typical linear finite differential analysis is not accurate enough to the level of a couple of degrees. A transient analysis with changing boundary condition is not an easy job."

Harry, you are exactly right. Soil types, moisture content, windows, etc... make it very difficult to design a home where all the answers are available by a computer model. That is where building a Passivehaus is easier. An Igloo cooler performs pretty much the same everywhere.

In my mind, the benefits of the PAHS design, on my mountain acreage, outweigh any of the minor uncertainties inherent in the concept. Merchant builders need certainty in the product they build. Custom homes afford the luxury of experimentation, where the owner is willing.

Answered by RL Lemke
Posted Sat, 05/22/2010 - 11:44

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This is part of the work which I referred to above: http://www.huduser.org/Publications/PDF/frost.pdf

A Colorado passive home designer discussed the concept here: http://www.thenaturalhome.com/frostwalls.htm

Answered by RL Lemke
Posted Sat, 05/22/2010 - 16:43

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Frost-protected shallow foundations are hardly PAHS, but they can be used with most cold-climate homes and offer geothermal advantages without the expense, complexities and uncertainties of PAHS.

That HUD study is outdated. The current design manual is at http://www.toolbase.org/PDF/DesignGuides/revisedFPSFguide.pdf with NOAA data for the system available at http://www.ncdc.noaa.gov/oa/fpsf/.

FPSFs have been included in the IRC and IBC since 2003 (and by amendment in the IRC since 2000). You will never see PAHS in the international codes.

In the past 40 years, more than a million such foundations have been constructed successfully in Scandinavia (where it's become standard practice), northern Canada and Alaska. Many more are now supporting small and large buildings in the US. They are simple and reliable, unlike the PAHS approach which will never see widespread use no matter how many posts RL LEMKE puts on this thread.

Answered by Riversong
Posted Sat, 05/22/2010 - 18:10

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Thank-you Robert, for the links above. It was indeed this shallow footing insulation that was the genesis of PAHS. We agree with each other that PAHS isn't suited to mass production housing. Just as I have repeatedly said above. Isn't it great that Americans don't all have to live in production homes? Some of us are able to build a home that is different from what most others have. I see PAHS as a great alternative for a buyer that has an acreage which is suitable for a passive solar design.

I will be building a PAHS home on my acreage, regardless of whether or not anyone here thinks it is the perfect home for themselves. It is the form of custom home I am excited to build myself. Simple, durable, energy efficient, out of sight, blends with the natural landscape and comfortable. I have no interest in living in a wooden Igloo cooler with windows.

Answered by RL Lemke
Posted Sun, 05/23/2010 - 11:38

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I have no interest in living in a wooden Igloo cooler with windows.

Nor should anyone with common sense. But don't present PAHS underground concrete homes as the antithesis of the PassiveHaus approach, for it is not.

I would never design nor build an "igloo cooler" and have been perhaps the most vehement opponent of the insanity of living in plastic or foil boxes. But neither would I design an underground bomb shelter and call it a home.

We may have sought our first shelters, as a species, in natural caves, but we have evolved since then as forest and grassland creatures who need shelter from the elements without divorcing ourselves from the natural landscape that gives us sustenance.

For instance, we know today that because we spend such inordinate time indoors, we need a great deal of natural daylight for both physical and mental health as well as a reliable supply of fresh air. Views to the outdoors and cross-ventilation by natural winds are also important in maintaining that sense of connection to the outside world that we have all but lost.

Yes, it's wonderful that we Americans have so many options. But it's also true that we Americans are exceptionally myopic in our biases and rarely (perhaps never) consider all the ramifications of our choices.

I'm not saying that underground living is never appropriate, but it has liabilities that are typically overlooked by its proponents who tend to by somewhat cultish in their preference. I've talked a couple of my clients out of that approach and they've been very grateful.

Answered by Riversong
Posted Sun, 05/23/2010 - 12:19

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Robert,
Do you know of any Passivehause with FPSF? I have not read any. It seems 10+ inch of foam under slab is the norm. You probably know more about it. I'm not in the building business. I am a mechanical engineer in auto industry. I was guessing the typical FPSF with 2-4ft horizontal insulation is not suitable for PH due to still too large heat loss in winter. (I don't see any problem with summer in most of upper 48 states.) What if you extend the FPSF more like 10~20'. Would that be enough? If lot size is an issue, perhaps the insulation can go into ground at an angle like 45deg. Anybody tried that appoach? Just curious. This energy efficient building stuff is purely an hobby for me, I had a civil engineering major roomate in graduate school. We had some interesting discussion that leads to this hobby till today. It's been almost 15 years. Thank you for any elaboration.

I see Mr. Lemke's choice perhaps will serve his situation well, with a large design margin, such as earth contact, insulation/window, etc. it could work well or even be zero heating/cooling. However such PHAS design may still be a nitch at least for now.

Thank you.
Harry.

Answered by Harry
Posted Mon, 05/24/2010 - 23:56

31.
Helpful? -1

Harry,

I'm sure that a SFPF would be antithetical to the PH approach, which is to hyper-insulate the envelope. But I also believe that the PH approach is as unnecessarily extreme as the PAHS system.

If we minimize the size and complexity of our shelters, hyper-efficiency becomes far less important.

Answered by Riversong
Posted Tue, 05/25/2010 - 23:08

32.
Helpful? 3

Robert wrote:

"If you insist on reviving a months-old thread ..."

Do threads have a cut-off date Robert? I thought one of the beauties of internet threads was that people with ideas can always come along and add to them. This thread is a good example of that. Oops, sorry, I'm commenting on a a comment you made a few months ago.

"unlike the PAHS approach which will never see widespread use no matter how many posts RL LEMKE puts on this thread."

Are Lemke's numerous posts a problem for you?

"neither would I design an underground bomb shelter and call it a home"

Most of the underground houses I've seen photos of look very pleasant inside and their occupants seem to be happy. Your idea of "windowless boxes" is outdated, as almost all the modern ones have big south-facing windows. Light tubes can bring daylight into back utility rooms.

"its proponents who tend to be somewhat cultish in their preference"

Come on Robert. Give us a break. The people I've discussed with on the few PAHS-inclusive forums seem to be more or less as normal as you and I. Certainly no more "cultish" than stamp-collectors, train-watchers or long-distance runners. Nobody on here has suggested that PAHS houses should be forced on anyone else, so why all the angst? In my view it is too early to generalize about whether and in what circumstances PAHS can be a useful practical system. There just aren't enough publicly detailed examples out there.

Bruce

Answered by Bruce Lepper
Posted Sun, 12/12/2010 - 17:50

33.
Helpful? -4

Do threads have a cut-off date Robert?

The question of whether they technically do is different from the question of whether they should?

The problem associated with reviving a thread that began almost two years ago and concluded more than six months ago, particularly one this long, is that no one can possibly remember what they or anyone else posted, such that a meaningful response would require rereading all the previous posts. Additionally, like many such long arguments, this one had already been beaten into the dust and there's little point in reviving it (you know the expression about beating a dead horse?)

And there's even less point in reviving it if your motive is to misrepresent my arguments and merely attack the messenger and make absurd claims that have no bearing on the merits (or lack thereof) of this fringe approach.

And don't ever accuse me of being normal.

Answered by Riversong
Posted Sun, 12/12/2010 - 18:43
Edited Sun, 12/12/2010 - 19:04.

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