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Insulating Thermal Mass suggestions

 
C.J. Murray
Posts: 92
Location: 5,500 ft. desert. 13" annual precip.
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Hello All,
I'm new to these forums but have been lurking about for a while reading and absorbing. I first became interested in thermal mass heat storage in late 2006 when I became aware of masonry heaters. I'm not the most widely read person on eco building as of yet. I continue to read and digest all I can both on eco building and permaculture. But what I have read has led me to some conclusions and I'd like to see how they match up with other's thoughts.

It seems to me that having thermal mass available for heat storage is one of the most important items to be design into an eco building. Along the way during the design process (of a dwelling which will use as little non-renewable energy as possible) a decision needs to be made to either insulate the thermal mass or to leave it uninsulated. The insulation is a way to slow the loss of stored heat to the outside air or, in the case of a below ground portion of a dwelling, to slow that heat loss to the below ground thermal mass. It seems to me that the criterion on which this decision to is made (in regards to heat retention/loss only) is whether ones daily average heat income from all sources is great enough to overcome the larger loss from uninsulated thermal mass or if it is not.

Before I make this comment I want you to know I have tried to have my facts straight by reading but I'll admit I may have missed some details. Please feel free to correct me. As I have read these forums mike oehler seems to be in favor or leaving the thermal mass below the frost line uninsulated. In my mind this says that if the temperature below the frost line is 50 degrees then when the temperature in the dwelling is less than 50 then heat is moving from the thermal mass to inside the dwelling. However, as soon as the temperature inside the dwelling increases above 50 degrees then the heat movement reverses and heat is moved to the thermal mass from inside the dwelling, which is precisely what thermal mass does in order to store the heat. It seems to me that since very few people live in houses below 50 degrees that you will always have a drain of heat into the thermal mass some of which will always "escape". This eternal escape is greater if the thermal mass is uninsulated. Therefore, there must be a greater income of heat into the dwelling than would be necessary if the thermal mass is insulated. In other words, a dwelling requires greater heat input if the thermal mass is uninsulated.

If the above is correct it seems to me that the only reason one would not insulate the thermal mass is if the dwelling can be designed so that the sun can always provide the needed heat 100%. Am I missing something? Please give me your thoughts and input.
 
Brian Knight
Posts: 554
Location: Asheville NC
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Its a fascinating and exiting topic CJ, one that generates lots of good discussion and debate. Based on my short time here, I generally feel that people in this forum tend to give Thermal Mass TM more credit than it deserves. Many of the people here heat with wood which complicates the energy efficiency arguments as wood is such a cheap and (usually) plentiful resource. Go to other forums, like greenbuildingtalk and greenbuildingadvisor and you will see the scales dramatically shift in favor of Air-sealing and Insulation. My opinion is that TM is good when inside the building envelope(especially for passive solar, rocket mass, masonry heaters) but air sealing and insulation is MUCH more important.

Oak Ridge national labs has done most of the best scientific research on the subject so anyone interested in scientific theory over personal feelings based on random experiences should begin their research there.
http://www.ornl.gov/sci/roofs+walls/research/detailed_papers/thermal/results.html

Great article from Environmental Building News:
http://www.buildinggreen.com/auth/article.cfm/1998/4/1/Thermal-Mass-and-R-value-Making-Sense-of-a-Confusing-Issue/

Good article by GBA with comments (a little more specific to ICFs):
http://www.greenbuildingadvisor.com/blogs/dept/qa-spotlight/does-r-value-trump-thermal-mass

You suspect that TM is one of the most important strategies for eco-building but most in the field will put Air-sealing first, followed by Insulation for most of the country. As the articles and research above indicate, TM in exterior walls makes the most sense in high desert climates with a wide diurnal temperature swing which is a pretty small part of this countries population.

I think you are on the right track with your thinking on sub ground insulation. The colder the climate, the more important it becomes to insulate down there. The amount of heat loss through the floor is much less than through the walls and roof but when you start to insulate those areas, the floors will become the path of least resistance at some point. Its interesting the amount of insulation that the Passive Haus people recommend under the slab and it looks like designers in this country are starting to use more based on their research and modeling.

 
Jami McBride
gardener
Posts: 1948
Location: PNW Oregon
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Well I'm from around here, originate from this forum, and I feel it's obvious your TM will work just as easily against you and it does for you, it is no respecter of persons.

I feel the issue is people around here (profiling don't you know) do not want to use typical toxic building materials.... so the question becomes how to insulate the TM without to much trouble and achieve the desired results. On this issue people very in opinions on how this can best be achieved. And even I am not satisfied with the options thus far.

I have done lots of reading and research, and was surprise how this topic of 'envelope' was either not covered or covered very lightly in many publications. I even read a book by a husband and wife team who build only rock houses, successfully, and they did not employ the envelope (complete wrapping) concept. I consider insulating the TM to be the most important factor IMHO.
 
Lolly Knowles
Posts: 159
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I would think that insulating the thermal mass or not would depend in varying degrees on the location and type of home built. In my area, some sort of insulation properties are vital to retain the heat created in the envelope. But I live in a place that can be subjected to -0F temps for a couple of weeks at a time.
 
Brian Knight
Posts: 554
Location: Asheville NC
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Yeah I guess toxic building materials and Permaculture dont really go together too well. I see it as ok to use them in such a permanent component of a home or building having the biggest impact on durability and long term energy and environmental costs. I like this forum because it challenges me to think outside the box in this respect.

Its very promising that foam blowing agents are about to be completely changed for the better. Not that it makes plastic foam completely non toxic and green but its certainly a step in the right direction. Other than mineral wool or glass wool, there still is not an easier, cheaper or more effective way to insulate TM in such a small space (R per inch).
 
C.J. Murray
Posts: 92
Location: 5,500 ft. desert. 13" annual precip.
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Springtime,
Thank you for the links. It's fascinating how there are so many paths to be pursued to make sure you arrive at the solution you need.

You are right, of course, to point out that air-sealing is of massive import. Poor air-sealing can easily negate all the gains of TM. So, I'd like to specify that for the purposes of this discusson that the air-sealing properties of the dwelling are above acceptable.

Jami,
You profiled me accurately. hahahaha.

Having said that, I believe, in the interest of current progression in eco building, we can't wait for all the right answers before trying what we believe are some of the right answers. If we don't have an acceptable eco alternative today then let's progress using some of the answers rather than none or doing nothing.

Speaking as to myself, I can't even keep track of all I need to change to get it right but I can keep track of some of them. Once I've put some questions to rest then I can move on to others.

I believe Lolly brings up another good point which I should clarify. If winter lows aren't much below freezing and summer highs are humid F 80s and 90s TM insulation requirements should be somewhat different. I'm focusing my current efforts in an area where -20F to -30F are not uncommon winter lows while summertime highs are high F 80s to high 90s. Summertime lows are F 55-65.

For the moment I'm going to specify that the TM needing insulated is all adjacent to dirt/rock rather than air. In other words, it is underground or earthbermed. Since wet/damp soil creates it's own set of problems I'll also specify that I really like the thought of covering over a large area with plastic or pond liner and covering it with dirt in order to create a mass of dry dirt/rock below it. So let's assume the dirt is dry (whatever that means).

What eco friendly insulating alternatives are there for below the floor and adjacent to, above and below the TM external to the dwelling wall? Let's talk about even the crazy ideas. Jami has said he is not satified with the options thus far. What are those options?
 
Brian Knight
Posts: 554
Location: Asheville NC
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Inside the box options (conventional green building) In order of affordability and inversely-coincidentally relative greeness:

1. plastic foam sheet goods: EPS preferably XPS for moisture resistance. Eco friendly in my opinion due to long term energy savings but...

2. Mineral Wool Board. Good for against basement walls but not so sure under slab.

3. FoamGlas http://www.greenbuildingadvisor.com/blogs/dept/energy-solutions/foamglas-my-new-favorite-insulation-material


My out of the box suggestion of the day is to find some commercial roofing salvage foam. Havent used or tried to get it yet but sounds promising if you can find a decent source nearby.
 
Lolly Knowles
Posts: 159
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C.J. Murray wrote:Springtime,
Thank you for the links. It's fascinating how there are so many paths to be pursued to make sure you arrive at the solution you need.

You are right, of course, to point out that air-sealing is of massive import. Poor air-sealing can easily negate all the gains of TM. So, I'd like to specify that for the purposes of this discusson that the air-sealing properties of the dwelling are above acceptable.

Jami,
You profiled me accurately. hahahaha.

Having said that, I believe, in the interest of current progression in eco building, we can't wait for all the right answers before trying what we believe are some of the right answers. If we don't have an acceptable eco alternative today then let's progress using some of the answers rather than none or doing nothing.

Speaking as to myself, I can't even keep track of all I need to change to get it right but I can keep track of some of them. Once I've put some questions to rest then I can move on to others.

I believe Lolly brings up another good point which I should clarify. If winter lows aren't much below freezing and summer highs are humid F 80s and 90s TM insulation requirements should be somewhat different. I'm focusing my current efforts in an area where -20F to -30F are not uncommon winter lows while summertime highs are high F 80s to high 90s. Summertime lows are F 55-65.

For the moment I'm going to specify that the TM needing insulated is all adjacent to dirt/rock rather than air. In other words, it is underground or earthbermed. Since wet/damp soil creates it's own set of problems I'll also specify that I really like the thought of covering over a large area with plastic or pond liner and covering it with dirt in order to create a mass of dry dirt/rock below it. So let's assume the dirt is dry (whatever that means).

What eco friendly insulating alternatives are there for below the floor and adjacent to, above and below the TM external to the dwelling wall? Let's talk about even the crazy ideas. Jami has said he is not satified with the options thus far. What are those options?


CJ, it sounds like you and I might have similar situations in mind. I'm planning on doing something that will allow me to use a hillside to protect three sides of the house we will build. One of the alternatives we have discussed is earth bag construction using soil cut from the hillside as filler, but all the reading I have done so far indicates that we will still need insulation of some sort between the exterior wall/roof and the soil itself.

I'm hoping to find a supply of expanded foam sheets that are previously used and apply them on the outside of the walls, then wrapping the whole thing in vapor barrier fabric of some sort. The best option would be if I could acquire that material second hand as well. Family members are in an area with lots of small manufacturers who have plenty of packing material to get rid of, so "free" would be good on some of this. Second hand would ease my conscience so what as well, because the material would have had time to do some off-gassing before being used in a dwelling.

This link might come in handy for someone. http://www.climate-zone.com/index.htm I was able to get specific data for two large communities near my location to give me specifics on the sort of weather we need to plan for.
 
Lolly Knowles
Posts: 159
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The new software doesn't warn you that a new post has come in during the time you've been composing your reply! Springtime Homes, foamglass sounds like it might be promising, at least underfoot.
 
Mark Anderson
Posts: 35
Location: North Olympic peninsula, WA state.
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I had basicly the same question as CJ, wondering whether anyone knew if the mass inside an envelope of dirt under a layer of pond liner/plastc would have to be in direct thermal contact, not be insulated away from, the earth sheltered home. Paul Wheaton speaks about a heat cycle, and that when the amount of soil enclosed is a certain size it gains heat through summer, excess heat from the home, and releases the extra heat all winter. His point was that if it was done correctly, the home would never or hardly ever, need to be heated or cooled. I thought that if the home were insulated you would lose this effect. Has anyone had real world experience with this? I live in a moderate climate summer highs rarely above 80's, winter lows rarely below 30's (Pacific Northwest).
 
kent smith
Posts: 211
Location: Pennsylvania
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Before we move here I was planning to build using a combination of TM and straw bale for insulation. What I found was that I could buy the land, 20 acres, with a hundred year old farm house for half the cost of just building a house. The house is very sound and sturdy, it looks like someone re-insulated, re-sided, new window and roof about a decade ago. Dang all the beams and joists are milled local oak. For us it makes more sense to repurpose, and improve this existing home than to use energy and materials to build from scratch. I see so many places around here that are like this place. I would encourage people to look for areas like this where land is cheap and farms can be productive. I think it is an adjustment of scale and returning to a simpler way of life. We are closer in philosophy to our old and new order amish neighbors than most of the town folks.
kent
 
C.J. Murray
Posts: 92
Location: 5,500 ft. desert. 13" annual precip.
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To offer a little detail as to what my personal views and interests are:

We need to learn to live on nothing. I didn’t say our goals should be to live in a cold mud hut. I think we need to use our resourcefulness to create systems whereby the resources of the earth are maintained and grown rather than depleted.

I love Permaculture. Before I had ever heard the word I was searching for people with views and beliefs similar to mine. Sadly, I have been on a mostly solitary path, until now. I believe Permaculture methods, even with 7 billion people on the planet, can open up a bounty never before experienced by man. But only if we use some of the resources we are now depleting to bring that future into reality sooner rather than later. It will be a much slower and harder process on human life to wait until the bounty of the resource bank we now use to power life is depleted.

7 billion people need to be empowered to bring Permaculture principles to bear in their own existence. It appears to me most are sucked into believing a failing system will still be there for them. I believe we are on the downhill slope and they believe incorrectly.

I want to explore, in addition to exploring the bio-abundance of Permaculture, the empowering of people to shelter themselves for as little as possible thus, hopefully, freeing them to use their time resource to implement other Permaculture principles in their lives. 1 person in 100 cannot bring about the bounty of Permaculture for the 100. Essentially all must do something to make it work.

Springtime,
Since I have some time I really would like to explore less industrialized options for insulating the TM underground. To be clear, I am opposed to using the industrialized insulations but I am willing to do so in the interest of illustrating the viability of a design if no other option presents itself. My opposition is not about the use of oil and energy to make the insulation but rather believing that it should be of last resort. Clearly, today, it may be the only viable option.

Lolly,
I’m not entirely settled on what I want to do other than I know I want to create a dwelling which does not “need” a heat source other than solar gain and I see TM as the battery to store that energy. I want to succeed on the first attempt and be more successful each dwelling after that.

In the dwelling I envision I will have a huge amount of TM within the envelope. I think that is the only way to have enough TM to store the amount of heat I envision will be needed. In your case I think you have the same decision to make. How much TM besides the earth bag wall do you need to achieve your goals? It seems to me that insulating that TM becomes more necessary the higher the temperature of the TM rises above the surrounding earth.

At the risk of sounding naïve and uninformed (which I very well may be so the rest of you may need to speak up and save me from myself) I can tell you this much of my current thoughts. So far I haven’t read anything which says compacted dirt tire walls are a significant hazard. I would like to use a tire wall for the support walls. Inside of those outer walls, say 6 inches to a foot I’d like to build cob walls which would be non-load bearing. The space between the tire walls and cob walls would be used to circulate heated air from trombe walls or somesuch so as to give the solar gain access to both walls. As of yet this thought process is way less than fully fleshed out. I view this as a way to get the beauty and versatility of cob in a larger structure. AND it will be easy to recycle and remodel the living area if needs change upon new occupants. Imagine an outer shell which is standard and an inside which can be arranged any way one likes without affecting structural integrity.

Mark,
Unless you have an alternate way to deliver to your dwelling the heat stored in the TM or to deliver heat to the TM for storage you must not insulate between the TM and your dwelling wall. Being in contact is the conduit for the heat to enter your dwelling or to draw heat from your dwelling for cooling.

Here are two sites which illustrate where insulation is utilized:

http://www.norishouse.com/PAHS/UmbrellaHouse.html

This one shows a cross section of an earthship most of the way down the page.

http://www.greenhomebuilding.com/recyclematerials.htm

Kent,
If I may take the liberty of altering your statement a bit:

“I think it is an adjustment of scale and returning to a simpler, most fascinating and wholly more satisfying way of life.
 
Brian Knight
Posts: 554
Location: Asheville NC
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I like your Philosophy Cj and it sounds like rammed tire walls are a great fit for your project.

Iam not an expert in active/solar heating but Ive done enough research to be dangerous. I think you should be cautious with any attempts to actively circulate passive heating to TM storage. There has been MUCH experimentation with all sorts of active and passive circulation systems but rarely do they prove to be measurably more effective than regular interior TM combined with simple but proper passive solar design. Any system using electricity to power ventilation fans should be especially suspect. One of the problems you mention earlier about storing heat of summer throughout the winter is there is just not enough capable BTU storage in usable dirt or even large amounts of water (which has much more capacity). Even if there was enough capacity, controlling the physics of where it wants to go (outside) is the real challenge.

The problem with passive solar heat only is cloudy, cold periods. I dont think its a matter of adding enough TM for storage so much as it is about getting airtight and insulated enough to slow down the heat flow. The more inefficient the envelope the more that most permaculturists rely on wood heating.

I think the Passiv Haus folks are doing the best job of doing what you seem to be attempting other than the more permaculture like materials.

 
C.J. Murray
Posts: 92
Location: 5,500 ft. desert. 13" annual precip.
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Springtime,
One thing is for sure...your input forces me to narrow down and better define what I'm trying to achieve. I absolutely agree and understand how air-sealing and massive insulation slow heat loss so that even what little heat is stored in a low TM dwelling is significant. As things stand today, I cannot see how everyone can afford to upgrade existing homes or build a new home using better industrial methodology and materials. And even if they could I don't think the planet would support it. I think it would all lead to greater resource depletion rather than achieve resource maintainence and growth. Indeed, we don't hear the Passiv Haus people saying that it will.

So, I guess I'm further clarifying (and I'm betting this is not the last time I'll need to do this) by saying that I'd like people to be empowered to build a dwelling with as little interaction as possible with our current economic system. Sure, we all gotta buy something from someone. I'd just rather we have a multitude of choices as to who we get it from and who made it. I'd like to see the power of providing the product in the hands of many who are truly independent. Where possible I'd like people to be able to produce it themselves if they so desire.

Having said the above it brings another thought to my mind. What if the TM in the rammed earth tire walls were basically ignored and between the inner non-load bearing cob wall and the outer load-bearing rammed earth tire wall is placed a home grown insulating material? Milkweed fiber? Cattail down? Now we're talking out of the box. Theoretically the between wall area will be dry so there should be lots of options available. Surely there are many, many options to achieve a high insulating value if that between wall space became 2 feet. After all, it's not like cob is low TM.

Come to think of it, that's not a bad idea. Outer load-bearing rammed earth tire walls with inner non-load bearing cob walls with enough space between to work. The dwelling could be made and moved into, sans insulation, and the insulation added as one could gather the needed insulative materials.
 
Mark Anderson
Posts: 35
Location: North Olympic peninsula, WA state.
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C.J. one summer I worked in an old apple orchard at Stehekin which is in the north Cascade mountains. There was an above ground root cellar built around 1918; it has thick walls filled with sawdust, when I was there in 1980 it still kept our sodas cold on hot summer days. For my little dome home idea I've thought about using volcanic pumic stone to insulate, there is a lot of it in eastern Washington (unfortunately that is over a hundred miles away). I have always liked the idea of using whatever is at hand to build with, to build smart and simple; there is no reason one couldn't have a warm snug and comfortable home made from local sustainable materials. My goal is to build a 900 square foot super efficient natural home mostly from recycled or onsite materials, for less than 20K. One idea was to collect clean styrofoam from packaging etc.. chop it up, put it in forms and add elmer's glue or ? to make it solid enough to use in walls etc.. Six inch thick panels would have a pretty good R value. Until people stop using styrofoam, it just makes sense to me to use it for the R value it provides instead of letting it go to landfills.

I've been thinking about using the ancient Roman hypocaust system to heat my home using a rocket mass heater, or a solar collector system to heat the floor on sunny days. The southern side of the dome will have a large window for passive solar, and the rest of it will be covered with dirt, soil, etc... except for a smaller window or door on the north side. I'm always re-thinking my plans, especially since coming to this site. I'm learning a lot here.

One thing is for sure, conventional housing is a racket; it seems insane to pay 300 to thousand dollars, and be enslaved to a thirty year mortgage on a modern stick built house that starts to rot as soon as it's built. I've been a handyman for a long time and involved with construction even longer, modern houses are toxic, inefficient, and dangerous... well I guess we already know all that here at Permies.
 
Joe Woodall
Posts: 43
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Hi CJ ,

I get that question often and yes, you must Insulate !

I wrote a blog this week on that very subject to ease a need for that question a bit ~ perhaps ?
Its on my web site, if you would care to view it dated Wed 12-08-11 Thermal Mass, Insulation & Ventilation Are A Buildings Best Friend !
Hope some of that helps you out.

Joe
Georgia Adobe Rammed Earth & Renewable Energy
georgiaadobe.com
 
C.J. Murray
Posts: 92
Location: 5,500 ft. desert. 13" annual precip.
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Mark,
After reading your post and doing a lot of reading last evening I can see that if I have a dry space between two walls and that space and adjustable to the width I require for the insulation material my options are many, beginning with bales of straw. Sawdust, as you point out, is another. I even ran onto what is called “clay slip” to increase natural insulation material’s resistance to fire.

Wow, I just did a little reading on Styrofoam and it’s not a pretty picture on the recycling of it. It says that 30% of the plastic disposed of in landfills is Styrofoam. Apparently the manufactured insulating boards made of Styrofoam are coated with something to make them fire resistant. Keep that in mind in your application.

Interestingly, in my reading I came across reference to a citrus peel extract called limonene at this site: http://www.benefits-of-recycling.com/styrofoamrecycling.html. It says that when limonene is sprayed on Styrofoam it creates a gooey substance which can be used as a super glue. This may be what you need for glue. More reference here: http://www.brighthub.com/environment/green-living/articles/20016.aspx. Hmmm, I wonder how cheap this glue ends up being and what it will glue together.

Joe,
Thanks for your input. At this point I’m in complete agreement with you. I reserve the right to change my mind in an instant. Hahaha. In your blog you said “For above ground construction ( non-earth sheltered ) yet built of solid earth mixes, Insulation should be placed within that mass but, in the outer 1/2 section, leaving sufficient protective earth wall outside that insulation, to safeguard your insulation and of course, completely seal the walls exterior surface, so as not to allow a wicking of moisture into your thermal mass. The builder must tie that insulation to the earth on either side of itself and caution should be taken to not allow the ties to cause damage to the earthen mixes when completed.” Are you willing to expound on that a little bit in regards to what type of solid earth mix walls you have seen which contain the insulation contained as a layer within the wall and how it is accomplished? Are you saying there are essentially two earthen walls built with insulation between?
 
Joe Woodall
Posts: 43
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what type of solid earth mixes ?

70% sand & 30 % clay the standard adobe mix and this is also the Rammed Earth mix most often used.

two earthen walls built with insulation between ?


Yes, that's just what you do and Ram them at the same time with your "Foam ONLY" insulation in between. Just be sure & leave at least 2/3 of the Thermal Mass on the inside of your insulated wall so you get the benefit of that Insulated Thermal Mass.

With a "Basalt" tie within the walls and placed through the foam, in proper amounts you will get a good bond, without the danger of steel rebar wobbling about at vastly differing frequencies than your Rammed Earth is static at. This happens for example during an earthquake or some other wild & yet to be experienced vibration event.

Make it an Earth Sheltered building Or a really thick above ground wall system, Add proper ventilation , rain water catchment & a greywater recycling system, a Southern exposure for passive solar & a Winter Garden along the south wall to grow your selected food crops, add a few fish and other animals to the protected animal stalls , make your own fuels on site and add a power system , generator, solar electricity system & solar thermal system & all with as low a voltage set of appliances you can afford and of course all without spending any more money than your required to do because you used 80% recycled materials & you want a completely paid for home & land and your on your way to a properly designed building !

Hope that's of some help !
Joe
 
Mark Anderson
Posts: 35
Location: North Olympic peninsula, WA state.
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C.J. using clay slip for a natural fire retardant is an interesting idea; but... isn't clay a pretty good heat conductor, and wouldn't it reduce the insulation values of your wall? Also, if your insulation is between two earthen walls, it seems that there would be very little danger of ever having a fire in that space. I would also like to mention that straw bales will not burn, the material is so compacted that there is not enough oxygen to keep a flame going. There are straw bale homes in Nebraska that are 100 years old, I read about one that had a fire on the inside but the straw bale walls would not burn, it smoldered a little and that's all. It's kind of like trying to burn a thick book or Sears catalog, sure it will burn if you open it up and burn one page at a time, but just try to burn the whole book at once.

Yeah, styrofoam is nasty stuff, the chemicals that leach out of it in landfills have been linked to breast cancer, and ambiguouse sexual characteristics in babies; that's why I think one way to repurpose it out of landfills is to use it for insulation. Encapsulate it in the walls of a home that's going to last for generations. Seems dumb to buy foam panels at Home Depot, last thing I want is to encourage someone to make foam just for the housing market when so much of it is free for the taking. Thanks for the links, something that will make the outer surface of the foam sticky sounds perfect, that way I could just trowel the foam into my walls, or mold it into panels that can be cut with a hot wire etc...

There was a heated exchange on this site about "green cement" which I'm watching, since I would like to use a ferro cement over my tubular steel geodesic frame and recycled styrofoam insulation. There is also a spray on foam called "soy foam" but I'm not sure how "green" it is, besides the expense... at least recycled foam would be free, there may even be places that would pay to have it hauled off. There is magnesium phosphate cement called Ceramicrete or Grancrete, it looks very promissing since the ingredients are cheap; lime based cements take a huge amount of energy to produce and a very large percentage of green house gasses come from making conventional cement so I'm always interested in something greener and more sustainable that works like cement. The ceramicrete is supposedly 3 times stronger, fire proof, less than 1% water permeable, expands when drying, 30% lighter than portland cement, and a lot less expensive to produce... well, it sure isn't cheaper when I've found it for sale anywhere. The jury is still out on it, but I'm hoping it's as good as they say.

I'm glad I found this forum, most people on here are very helpful and patient. I'm interested in a life of quality, not quantity. My goal is a non-toxic, hand crafted, as natural as possible, home on a couple of acres classified as organic farm so I don't have to pay much in property taxes. It should be illegal and unconstitutional for the government to tax someone's home and property away from them. I knew people in Sequim, WA. who were retired on fixed incomes; when the area became a retirement mecca for the rich... taxes went up so much that long time residents lost their homes. This is one reason I've thought about building my little place on property that belongs to a big corporation, their little tax dodge could be my homestead until the day I'm caught living there. When I'm found out it wont be a big deal, I could just pack up and find another property to improve with permaculture. Gorilla permaculture... )
 
C.J. Murray
Posts: 92
Location: 5,500 ft. desert. 13" annual precip.
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Thank you, Georgia Adobe.

Mark,
Yes, there would be some loss of thermal resistance with the use of the clay slip. But if there is a requirement for fire resistance and the natural material doesn't meet it on it's own then something will have to be done. I found this site today which speaks to the subject of the fire resitance of rice hulls: http://naturalhomes.org/img/ricehullhouse.pdf. However, rice hulls are very distant from me. So, the search goes on for a more local solution. Hopefully there are several.

Identifying a natural insulation material for use below grade is going to be more difficult. Hard to beat the lifespan and hardiness of foam. The dryer the dirt the better, I can see that.

 
Mark Anderson
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Location: North Olympic peninsula, WA state.
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Hey C.J. thanks for the link, wow, rice hulls sound great for a natural insulation material. The only all natural below grade insulation material I can think of is pumice stone, and I think it's probable the pumice could become infiltrated with water over time. Hmm... I'm sure there is something out there which could be used.
 
Len Ovens
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I vote yes insulate. Yes mass. Insulate outside the mass. Sealing it tight? not so sure. I agree that good sealing will keep the heat in better. However, I also feel that health of the occupants suffer in a too tight house. Yes there are standards for air exchanges per hour, but I would suggest that they are still far from healthy (I personally think that if we were to have the air exchanges needed to be healthy, leaks would be insignificant). I would also suggest that the idea that a home should be an even 72F in every corner at all times of the year is wrong as well. I think there is a lot more to home comfort than conventional (contractor/code based) numbers will show. Radiation is ignored both in heating and cooling as well as window placement and how our body radiates heat. It's all numbers with no real base on comfort or health. I can be too hot with an air temp of 50F and short sleeves and too cold with a sweater at 72F.

My first assumption is that we want to be healthy, that I am willing to spend more on heating to have enough fresh air to be healthy. This affectively means a leaky house. How we leak the house may be important if it is earth tube technology or some high tech heat exchange system we want to keep as much heat as we can. We want to spend less. First design decision then might be a small house.... oh but code doesn't want a small house and low taxes. How connected to grid do we want to be? My personal feeling is none... even in an urban setting... as little as possible anyway. This means passive is always to be favoured. Even if we are only able to use passive systems part way, get as much as we can passively. Heat the person not the space... or at least heat only the space used. Central heating of any kind (heat pump included... at least the ones I have seen) fails on this. Remember any heater that burns something (wood, gas, coal) is only 85% efficient at "100% efficient" because the final 15% doesn't have to be included in efficiency ratings as it is required to make the flue work. Remember the burning appliances only work at their rated efficiency in the lab.... and that lab may not be very comfortable while the testing is happening. Remember that the smaller the heat source is, the hotter it has to be to heat the same amount of air. Hot things burn air. That is they burn the dust in the air.... So the fuel fumes are exhausted outside, but we burn dust and breath it....

Ok, what about mass? Mass takes a long time to heat up or cool down. Mass takes space and as such can heat the same area at a lower temperature than a massless system. People do feel radiation.... a big mass makes a person feel warm even when the air temp is low. In the same way there is a difference in how someone feels with curtains covering a window or not. A number of people have built homes that rely on high mass to keep them warm and are happy with them. Some of them have no other heat source but the sun in the summer and live in cold places... so it appears it can be done. High mass heaters have been shown to be more effective (even by the numbers) than low mass heaters both with the same heat input.

My feeling is that most high tech heating is more about making money than keeping people comfortable. It is about keeping manufacturers running and installers/repairmen employed. It is about achieving a "measurable" state to avoid law suit... not about comfort. A central heat setup that heats air in a sealed insulated house works best in that legal climate.... but is it comfortable? Is it healthy?
 
Brian Knight
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Location: Asheville NC
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Yes. Very comfortable and very healthy. The reason we build tight is to have more control. Control over conditioned air (40-80% of most peoples environmental damage) and control over fresh air. Building a leaky house is problematic because you are not controlling when, where and how you are ventilating. With a tight house you can control exactly where the air is coming from, in what quantities and you can use a heat exchanger to capture the energy you spent conditioning it. Leaky houses tend to not provide fresh air when you want it and they tend to leak like crazy when you dont want them to. Leaky houses can be more at risk of mold issues due to humid air flowing through building cavities containing cold surfaces. Leaky = bad.

Outdoor air is almost ALWAYS healthier than indoor air no matter how much trouble you go through to build naturally or use toxic/VOC free finishes.

The best way to utilize outdoor air in most of the US building climates is to use an ERV/HRV in combination with a tight building envelope. If the rate of fresh air introduction is not high enough for you, you turn it up. If you are leaving for awhile and want to save energy you turn it off. This is a much better strategy than allowing the house to leak whenever and wherever it wants. Yes, its another piece of technology that someone will make money on.

Refrigerators keep food cool just as heat pumps keep people warm, cool and dehumidify the air, in other words keep people comfortable. Air Source Heat Pumps are approaching 400% efficiency while ground source are capable of 600%. If central air bugs you, consider the point source systems (PTAC and mini splits). No indoor combustion ensures that Indoor Air Quality is less compromised. They certainly arent right for every situation but its an amazing technology that works very well in most situations.

Anyone that is near "the grid" and producing clean electricity, should consider that grid tied systems reduce the costs of the system and help their neighbors reduce their dirty energy impact. The grid is currently being changed over to renewable energy. There is a long way to go, but in the future the grid will be society's main source of renewable energy.
 
Terry Davenport
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I think you are correct on what you have said about the thernal mass requiring insulation to retain heat. I have a friend who said his garrage never gets below freezing temps and it has no foam under the slab. He is not heating his garrage and this my be a better way to go in the summer ans the ground will naturally cool his garage, but if he were to heat it..... I checked the December temperature of the water in my eight foot down water line. It is 44 F. (Bitterroot Valley) 7400 HDD's
It is interesting that sand is more of an insulator than wet clay soils. I have been putting seven and a half inches of eps foam under my slabs with great results.
 
Terry Davenport
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Lolly K wrote:
C.J. Murray wrote:Springtime,
Thank you for the links. It's fascinating how there are so many paths to be pursued to make sure you arrive at the solution you need.

You are right, of course, to point out that air-sealing is of massive import. Poor air-sealing can easily negate all the gains of TM. So, I'd like to specify that for the purposes of this discusson that the air-sealing properties of the dwelling are above acceptable.

Jami,
You profiled me accurately. hahahaha.

Having said that, I believe, in the interest of current progression in eco building, we can't wait for all the right answers before trying what we believe are some of the right answers. If we don't have an acceptable eco alternative today then let's progress using some of the answers rather than none or doing nothing.

Speaking as to myself, I can't even keep track of all I need to change to get it right but I can keep track of some of them. Once I've put some questions to rest then I can move on to others.

I believe Lolly brings up another good point which I should clarify. If winter lows aren't much below freezing and summer highs are humid F 80s and 90s TM insulation requirements should be somewhat different. I'm focusing my current efforts in an area where -20F to -30F are not uncommon winter lows while summertime highs are high F 80s to high 90s. Summertime lows are F 55-65.

For the moment I'm going to specify that the TM needing insulated is all adjacent to dirt/rock rather than air. In other words, it is underground or earthbermed. Since wet/damp soil creates it's own set of problems I'll also specify that I really like the thought of covering over a large area with plastic or pond liner and covering it with dirt in order to create a mass of dry dirt/rock below it. So let's assume the dirt is dry (whatever that means).

What eco friendly insulating alternatives are there for below the floor and adjacent to, above and below the TM external to the dwelling wall? Let's talk about even the crazy ideas. Jami has said he is not satified with the options thus far. What are those options?


CJ, it sounds like you and I might have similar situations in mind. I'm planning on doing something that will allow me to use a hillside to protect three sides of the house we will build. One of the alternatives we have discussed is earth bag construction using soil cut from the hillside as filler, but all the reading I have done so far indicates that we will still need insulation of some sort between the exterior wall/roof and the soil itself.

I'm hoping to find a supply of expanded foam sheets that are previously used and apply them on the outside of the walls, then wrapping the whole thing in vapor barrier fabric of some sort. The best option would be if I could acquire that material second hand as well. Family members are in an area with lots of small manufacturers who have plenty of packing material to get rid of, so "free" would be good on some of this. Second hand would ease my conscience so what as well, because the material would have had time to do some off-gassing before being used in a dwelling.

This link might come in handy for someone. http://www.climate-zone.com/index.htm I was able to get specific data for two large communities near my location to give me specifics on the sort of weather we need to plan for.



As for sustainable under slab foams... I've used a product called regrind for foundation walls. It is foam from the door and window cutouts at the pannel manufacturer. This may be more green than new EPS foam. I got it at R controll in Bellgrade.
 
C.J. Murray
Posts: 92
Location: 5,500 ft. desert. 13" annual precip.
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Len,
I believe that both you and Springtime are correct. You want more air. Springtime wants control of that air instead of it being random leaks which cannot be controlled. Yes, there are standards of some sort for how tight a house must be but in actual performance it all gets…uh…thrown out the window…so to speak…when you open a window. Being able to control the amount of air incoming and when, is the way to go.

And I agree with you wholeheartedly about comfort. I want it and I want to be in control of it. If I want to sleep in a 40ºF bedroom in the winter then I’ll need control to be able to accomplish that.

It appears to me that it is very easy with south facing windows and a sunny day to bring way more heat into the home than is comfortable. I want the way to capture that as best possible. I recognize that with consecutive sunny days the house, conceivably, could be storing too much heat and become uncomfortable. I want the ability in some manner to convey that heat deeper into the TM so a larger mass of TM is at a lower temperature rather than a smaller amount being at a higher temp. I have not even begun to delve into how to accomplish that passively. I’m not opposed to using a forced air system if the electricity powering it is provided by PV. Much rather figure it out passively so it can’t break down.

Springtime,
I have not delved into the ground sourced heat pumps just yet. You mention they are 600% efficient. I’m assuming that means that for 100% of the electricity used to power the heat pump system there is a 600% return of heat. Is this correct? If it is then I suggest it also need to be factored in that if the power plant efficiency at generating the power is 33% then the 100% electricity is actually 300% BTUs expended and thus it drops the heat pump efficiency to 300%. Still, I am very willing to admit that is impressive. Of course, for all I know, it’s a gas fired power plant and the efficiency is higher.

With my fairly limited knowledge I tend to agree with you. It will be millions of small renewable plants all over the grid which will ultimately get us to clean energy. And if it’s not, if it’s big electricity supplying it all still, we are indeed less than looking out for our own individual interests.

I have been thinking on the feasibility of using thermal mass to store the heat generated by excess PV capacity and excess solar hot water capacity. All in all, if one has a decently sunny climate in the winter it appears to be very attainable to heat the home off grid and live in a warm home. One of the case studies on the Thousand Home Challenge website said the guy had lowered his temp to like 50ºF and I was thinking that was not what I wanted to have to do.

Terry,
Is the regrind mixed into the cement or ?

This site has some detailed info I have been reading: http://www.azsolarcenter.org/tech-science/solar-architecture/passive-solar-design-manual/passive-solar-design-manual-heating.html
 
Terry Davenport
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C.J. Murray wrote:Len,
I believe that both you and Springtime are correct. You want more air. Springtime wants control of that air instead of it being random leaks which cannot be controlled. Yes, there are standards of some sort for how tight a house must be but in actual performance it all gets…uh…thrown out the window…so to speak…when you open a window. Being able to control the amount of air incoming and when, is the way to go.

And I agree with you wholeheartedly about comfort. I want it and I want to be in control of it. If I want to sleep in a 40ºF bedroom in the winter then I’ll need control to be able to accomplish that.

It appears to me that it is very easy with south facing windows and a sunny day to bring way more heat into the home than is comfortable. I want the way to capture that as best possible. I recognize that with consecutive sunny days the house, conceivably, could be storing too much heat and become uncomfortable. I want the ability in some manner to convey that heat deeper into the TM so a larger mass of TM is at a lower temperature rather than a smaller amount being at a higher temp. I have not even begun to delve into how to accomplish that passively. I’m not opposed to using a forced air system if the electricity powering it is provided by PV. Much rather figure it out passively so it can’t break down.

Springtime,
I have not delved into the ground sourced heat pumps just yet. You mention they are 600% efficient. I’m assuming that means that for 100% of the electricity used to power the heat pump system there is a 600% return of heat. Is this correct? If it is then I suggest it also need to be factored in that if the power plant efficiency at generating the power is 33% then the 100% electricity is actually 300% BTUs expended and thus it drops the heat pump efficiency to 300%. Still, I am very willing to admit that is impressive. Of course, for all I know, it’s a gas fired power plant and the efficiency is higher.

With my fairly limited knowledge I tend to agree with you. It will be millions of small renewable plants all over the grid which will ultimately get us to clean energy. And if it’s not, if it’s big electricity supplying it all still, we are indeed less than looking out for our own individual interests.

I have been thinking on the feasibility of using thermal mass to store the heat generated by excess PV capacity and excess solar hot water capacity. All in all, if one has a decently sunny climate in the winter it appears to be very attainable to heat the home off grid and live in a warm home. One of the case studies on the Thousand Home Challenge website said the guy had lowered his temp to like 50ºF and I was thinking that was not what I wanted to have to do.

Terry,
Is the regrind mixed into the cement or ?

The regrind eps foam is re heated into more sheets of eps varrying density foam. It is cheap, but I would not place it under a slab due to the varrying densitys. I use it for protecting my ICF foam foundations from rock while backfilling the foundation.

This site has some detailed info I have been reading: http://www.azsolarcenter.org/tech-science/solar-architecture/passive-solar-design-manual/passive-solar-design-manual-heating.html
 
Brian Knight
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Yes CJ, I think your efficiency calculations are on track. The 33% from the grid is a good nationwide average. If your neighbor had a PV array then your efficiency will be much higher because its coming from nearby. Its these high efficiency rates that makes heating and cooling with electricity just as efficient and sometimes more efficient than other fossil fuel combustion.

Ive never heard of PV being used to charge TM probably because of the conversion losses. Solar water on the other hand is a great fit for TM, but overly expensive for most of the budgets I work with.

You say that you need to control overheating South windows during Sunny days. What climate are you in? This control is best done with properly sized overhangs. The summer sun can be completely shaded out while the winter sun completely hits the window. TM helps but I feel overhangs are more important especially for warmer climates. Generally properly designed Passive Solar designs tend to overheat only during un-seasonably warm fall days. This overheating is easy to address during this time of year by opening windows.
 
C.J. Murray
Posts: 92
Location: 5,500 ft. desert. 13" annual precip.
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Springtime,
I’m at an arid 5,300 feet where we receive around 13 inches of precipitation annually.

I agree with you on the overhangs and spring, summer and fall. The issue here is winter. Unfortunately, during winter we can get socked in by fog or clouds for extended periods. My desire is to be able to maximize heat gathering and storage during the sunny periods so it can be stored and released for as long as possible during cloudy periods. Thus my desire for large quantities of well insulated TM.

Rather than opening windows, if it is at all feasible, I would rather figure out a system whereby excess heat can be teleported (haha) further back into the TM rather than soaking through from the interior wall. If I understand you correctly, in your studies you have not seen a system for doing that passively which works well…or maybe at all. I have barely even begun to consider this aspect of it. All I know for sure is that you can’t have excess heat to store if your collector is too small. Thus my desire to have enough glazing to overheat on a winter day.

My thoughts are that whatever I do I want it to work the first time. Even if extra PV has to be installed in order to circulate warmed water back farther into the TM. It needs to work the first time and then be modified to work more efficiently/passively on the next one. Ultimately the math will need to be done to decide if electricity is better expended on ground source heat pump operation or solar heat gathering/storing.
 
Brian Knight
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Your climate seems unique to me and I wouldnt want to rule out anything that may work for you. Non-vertical glazing, un-conventional ratios of glass to square foot, and excessive TM all might be a good fit for what you are trying to do in your climate. I still think that it would be easy to get overcome in the expense and details of trying to squeeze out those extra BTUs to get through the cloudy times. I think the air-sealing and insulation details will have a much bigger impact and pose quite a bit of challenge themselves to get to a high level of performance. It would be a shame to spend so much time and money on un-proven techniques to later realize they should have been spent in more simple and proven areas. Sounds like youre on a great path though and look forward to seeing what you come up with.
 
C.J. Murray
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Location: 5,500 ft. desert. 13" annual precip.
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I haven't seen the sun in 6 or 7 days now.

The air sealing is almost a non issue. Picture 3 (or more) side by side vaults facing south with three sides covered with insulated earth. There’s only one wall to seal.

Or, alternatively, one long vault with the long side facing south with some non-vertical glazing higher up on the vault as well as some vertical glazing down low. In this instance there is less than 1 wall to seal.

My guess at this point is that the insulation will be foam. I’m simply not going to fail at the first one because “I just wanted to try it and see if it’d work.” I believe that at particular sites straw bale insulation may be entirely appropriate insulation. In dry dirt I think it will last a gazillion years. However, I’d like to see the bales slighty taller than they are standing on edge now. In other words a staw bale 1 1/2 times as thick at about 27 inches wide by 16 inches tall and then placed on edge. I am currently considering altering a conventional 2 string tie baler to make wider 3 string tie bales. Existing 3 string balers are only 22” wide.

Obviously the main goal here is to have a low energy usage home if at all possible. But equally important to me is how to make this accomplishable by every local Jane/Joe who is willing to put the effort in and not have to go into debt to do it. I believe quality of life is better the more involved we are in producing for ourselves rather than hiring someone to do it for us. We’re all running around just a little too fast these days.
 
Brian Knight
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I hate to discourage any type of homemade innovation but I think two-three days worth of passive solar storage would be the best one could do on a normal budget. Better plan on some sort of backup system.

Air sealing cant be a non-issue. Its one of the biggest challenges in building energy efficient homes. I suggest you become familiar with blower door testing and seek out any results you can find on similar construction types. To get to 1-3 days worth of storage, I think you will need to get your ACH50 to under 1, preferably under .6 (Passive Haus standard). This is a huge challenge but one thats served well by educated DIY.

I dont think dirt or underground walls constitute air tight construction. In fact, air leaks in these area could be more dangerous due to moisture and soil gas.
 
C.J. Murray
Posts: 92
Location: 5,500 ft. desert. 13" annual precip.
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Springtime,
You do a good job of making me look at details closely. That is valuable.

I was thinking more like 4 days. It is possible that the math on the specific amount of TM will not add up to that. All I know is that if what I build has the TM in place and it is well insulated it can be used to assess what works and what doesn’t. Absolutely there will be a backup system. I’m so skeptical I’d put a backup heating system in a home in Costa Rica.

I chose my wording poorly. Air-sealing IS always an issue. Even if you lived in a glass dome underwater…one little leak and………. I assume, and maybe unjustifiably so, that if an electrical box leaks air into dirt the resistance to air flow is going to be quite high, especially into compacted dirt.

I operated greenhouses for a number of years and am well familiar with what a blower door does. Mighty interesting when vents don’t open and a 36” fan comes on and tries to suck the plastic greenhouse glazing in. lol. Hard to even open the door to get in and shut off the fan. I have already spent several hours reading up on the Passiv Haus philosophy and standard and watching/reading about blower door tests. Fascinating stuff.

Regarding soil gas: The intent is to install the below ground components for an active mitigation system even if it is never needed. Don’t want to try and fix it later. This very issue occurred to me as I read up on the “Umrella Home” portion of the PAHS concept. Essentially the umbrella becomes a big ole’ passive radon collector/funnel directed at ones home. How to keep the radon out in the situation I’m envisioning is an interesting thought process but not undoable economically. It’s more about planning than much additional cost.
 
Brian Knight
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I like to tie my sub slab drainage system to a vertical stack that exits the envelope below the slab. Its doing double duty as drainage and radon. A well designed layout will vent passively and can always be hooked up to a fan if its found to not be venting enough on its own.
 
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