# Zero Energy Building



## Davarm (Oct 22, 2011)

For some time now, I have been toying with the ideal of a "Zero-Energy" home. I have only basic building and carpentry skills and no formal training in any type of design. I have, though, been to many different climates and countries and have seen how locals build homes to suit hot and desert climates. Here in Texas, heat and storms are the major climate factors to consider when building a home and many of those building techniques would accommodate these issues very well.

The core of the building would be steel reinforced concrete, this would provide strength for storms, defense and a large thermal mass for climate control. On the outside of that, the concrete shell would be insulated with bales of wheat and/or oat straw. If you have ever been in a barn when the temp was near zero and dug into the bales of hay, it is easy to find temperatures of 70 to 80 degrees +, residual heat from the summer. Then as an outside layer, conventional siding with a radiant barrier and a galvanized metal roof.

For cooling, well water(here it runs about 66 degrees) could be run through the slab/foundation using commercially available radiant tubing.

Question: To all of you with any experience in building, does this sound dooable? I am open to and invite any constructive criticism.


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I just saw that this thread should have been in Building and Construction, If it could be moved, would appreciate it. Sorry for the mistake.


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## forluvofsmoke (Jan 27, 2012)

Have you considered an earth sheltered dwelling? Depending on topography and the climate you're up against, a south-facing slope for cooler climates or a north facing slope for hotter climates will provide the added or reduced accumulation of solar thermal energy.

For colder winter climates, a properly angled awning will allow more sunlight to radiate heat when the sun is low in the winter, while shading the exposure in the summer months. One of the major savings with earth sheltering is that you don't need to provide insulation of any type (except for any exposure on the front wall), just back-fill and cover with the dirt you removed from the slope when you excavated the space for construction.

As I recall, a properly constructed earth sheltered home remains a fairly consistent temperature throughout the year, with possible exceptions being in the more severe winter climates where temps may drop to uncomfortable levels without active radiant floor heat, or at least convection heating. In your climate, it should work great. Add a solar/wind/battery system for LED lighting and refrigeration, along with whatever communication devices you prefer for internet/television, etc...oh, and stay away from 120VAC appliances as much as possible when you go off-grid, as power inverters are energy hungry monsters. The 12 volt refrigerators and freezers are a bit spendy, but the money you'll save by not needing a huge inverter, charge controller, battery bank and solar/wind electric generation system will more than make up for the difference.

The main draw-back to this type of sheltering is, of course, the loss of side/rear room windows, which may seem a bit like living in a cave to those not accustomed to idea. This is where part of your efficiencies of earth sheltering come in: windows and doors are heating/cooling energy inefficiencies, unless proper glass type/window construction for certain energy gain applications are utilized with traditional stick-built construction methods for homes. The benefits of energy savings, very low exterior maintenance, and the bulk of the structure being somewhat fortified like a bunker by earth on three sides and the roof, with the front wall partially to fully exposed is another consideration.

If you google for _*earth sheltered home*_ you should find many links to sites offering tips, and a few blogs or articles written by those with experience in constructing and/or living in them. Your design will need to be approved before permits are issued and construction begins, so you need a registered PE to draw it up, or you could buy plans ready to go, but I'd be careful about the latter route, as the varying sub-soil types (type A, B or C) may have an effect on the required load bearing for the structure (lateral forces on the side-walls), as well as the actual amount of depth of over-burden replaced on the structure's roof when complete. I've seen a lot of cinder block basement wall failure due to water saturation of the soil from improper drainage (lack of french drains at the perimeter of the footer) and/or excessive wall length without lateral reinforcement, as examples.

It's been a long time since I was interested in learning the basics on that subject, but some of what I learned years back did stay with me. Thanks for the ride back in time!!!

Keep your chin up and stick to your guns...where there's a will, there's a way! I still wish I had the real-estate to plant a home similar to what I described above...ah, maybe someday.


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## Davarm (Oct 22, 2011)

Thank you for the reply and yes I had considered it and there are several in the area, built back in the 70's during the energy crunch. I kinda gave up on the ideal though, I only have 2 acres and I thought that that would kinda be pushing it space wise. Another big drawback is the fact that my property and for several miles in any direction is completely flat, not hardly a foot difference in elevation anywhere.

I did look into rammed earth construction but I didn't feel real comfortable with that because every 4 or 5 years we have very wet seasons. I could visualize my home melting away into the yard. 

The earth sheltered and rammed earth methods, I am sure, would be the most energy efficient, comfortable and storm(tornado) tolerant homes to live in here but I am not sure they would be suitable to my property and/or the local climate. 

If I had it all to do over again, I would find a property with a north facing hill, dig in and build/have built the earth sheltered home you suggested, but I didn't have the foresight to consider it 10 years ago.


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## Tirediron (Jul 12, 2010)

Your plan sounds good, if the water table permits you can build a portion in ground and use that for temerature moderation, the best thing to do is start by learning all that you can about any type of building method that you consider.
the big issue is durability, things that make a building work with nature are the best answer IMO, bale walls make great insulation, natural ventilation can be a great help. also check out some of the links in the HVAC section.


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## BasecampUSA (Dec 26, 2010)

Been doing something similar to that since 1976...

This house costs me 15 cents a day to heat in winter, nothing to cool in summer.

We use solar, and when the sun don't shine there is a woodstove. There are coils under the cement floor slab that store heat from the sun and the woodstove. In summer we run well water thru the floor slab too, but need to run a dehumidifier 1-2 days a week.










There is a greenhouse along along the southern side of the earth-sheltered house. A window wall seperates it from the interior of the house. Plenty of sunlight comes in all year round. When the greenhouse heats up to 70-80°, a fan comes on and circulates air thru the house all day in winter.

We use the greenhouse to start our garden plants in sping, and for hydroponics (fresh vegetables) in winter (large green tank is hydroponic circulator storage).


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## Davarm (Oct 22, 2011)

BasecampUSA said:


> Been doing something similar to that since 1976...
> 
> This house costs me 15 cents a day to heat in winter, nothing to cool in summer.
> 
> ...


Thats very impressive, have always wanted to do something like that here but down here in Texas, those windows would not last long with all the hail storms and tornados we have.

Did you use regular glass for the windows or plexiglass? How did you waterproof the walls below the dirt line? Do you have a heat problem in the summer or excessive heat loss in winter?

At one time I subscribed to "The Mother Earth News" and your home looks like something straight out of it(thats a good thing in my book). They had alot of good ideas through the years and I am surprised that more of their ideas haven't caught on. Ethanol is the one that did that I wish hadn't.

There are times that I have considered moving north to an area with a more friendly summer climate, but then we have a cold snap and I come to my senses. Warm weather is in my blood and I just cant bring myself to leave Texas.


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## aluminum (Mar 29, 2009)

Davarm said:


> I did look into rammed earth construction but I didn't feel real comfortable with that because every 4 or 5 years we have very wet seasons. I could visualize my home melting away into the yard.
> 
> The earth sheltered and rammed earth methods, I am sure, would be the most energy efficient, comfortable and storm(tornado) tolerant homes to live in here but I am not sure they would be suitable to my property and/or the local climate.


As long as you have a sufficient overhang on the eaves, you should have no problems at all with any erosion of your walls..... Research the adobe ruins of the southwest... they are still mostly there after hundreds of years WITHOUT any kind of roof to protect them... Yes, they dont get rained on very often, but the 100's of years worth more than exceeds the amount you would need to worry about on your own home...


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## Davarm (Oct 22, 2011)

Well, that is interesting, what got me interested the idea(rammed earth) was seeing the old adobe ruins in the Big Bend area when I was a kid. That is only about 400 miles from here, just a hop, skip, and jump by Texas standards.

They get quite a bit less ran than we do here but that is a good point about them being there for several hundred years. Guess I can reconsider that idea.

Thanks.


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## Tex (Oct 31, 2008)

Air conditioning kills RE plans in TX. I'd like to preheat/cool my air using the ground. http://www.earthairtubes.com/ As far as construction, I'm leaning toward a prefab metal building with large overhangs and a stone facade. I'd like to spray in polyeurethane insulation. Not only does it insulate like crazy, it adds great strength to the structure. It's similar to the stuff used to make skateboard wheels. I suggest checking out www.homepower.com . They are tree huggers, but their info is solid gold. I suggest multiple sources of energy. You never know when it will be cloudy or windless for days. I want a wood burning stove for heat. They are very efficient. Don't even think about a fireplace.


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## Davarm (Oct 22, 2011)

Tex said:


> Air conditioning kills RE plans in TX. I'd like to preheat/cool my air using the ground. http://www.earthairtubes.com/ As far as construction, I'm leaning toward a prefab metal building with large overhangs and a stone facade. I'd like to spray in polyeurethane insulation. Not only does it insulate like crazy, it adds great strength to the structure. It's similar to the stuff used to make skateboard wheels. I suggest checking out www.homepower.com . They are tree huggers, but their info is solid gold. I suggest multiple sources of energy. You never know when it will be cloudy or windless for days. I want a wood burning stove for heat. They are very efficient. Don't even think about a fireplace.


I have considered using the ground to heat/cool air, in most places the ambient temperature of the ground about 4 to 5 feet down is about 65 - 70 degrees. When I was considering moving down around the Pandale/Langtree/Del Rio area(before the drugers started acting up on the border), I was mentally trying to come up with a system like that. I dont have any formal education/training in building or HVAC so the process never progressed past just daydreaming stage.

I looked into the polyurethane foam for insulation but about passed out when I checked out the price. Thats when I checked the wheat/oat straw, similar R-Value but a whole lot cheaper and if you have ever hauled hay - you got all the training you need to handle it.

I have been trying to come up with a type of building that would be relatively cheap and use as many local resources as possible. Some call me cheap but I prefer to call it practical.


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## ContinualHarvest (Feb 19, 2012)

Tex said:


> Air conditioning kills RE plans in TX. I'd like to preheat/cool my air using the ground. http://www.earthairtubes.com/ As far as construction, I'm leaning toward a prefab metal building with large overhangs and a stone facade. I'd like to spray in polyeurethane insulation. Not only does it insulate like crazy, it adds great strength to the structure. It's similar to the stuff used to make skateboard wheels. I suggest checking out www.homepower.com . They are tree huggers, but their info is solid gold. I suggest multiple sources of energy. You never know when it will be cloudy or windless for days. I want a wood burning stove for heat. They are very efficient. Don't even think about a fireplace.


Those and other tree huggers saved me a ton of cash on my electric bill. After making some changes we're saving at minimum $70 per month. Insulation and energy efficient bulbs/appliances go a long way. Nice tax credit too.


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## Bobbb (Jan 7, 2012)

You should check out Randy Bachmann's (from Bachman-Turner-Overdrive fame) rammed earth house up on the "Wet Coast" of British Columbia.


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## catsraven (Jan 25, 2010)

You might want to check these out as well.


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## rockwill (Feb 29, 2012)

Hi,
Thinking about building a few zero energy homes, but the market looks terrible right now. Do you know of any pockets of high demand in New England, New York, or New Jersey? (zero energy houses produce as much energy as they use - heat, hot water, and electric bills net out to zero at the end of each year).


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## TopTop (Nov 11, 2011)

Davarm said:


> If you have ever been in a barn when the temp was near zero and dug into the bales of hay, it is easy to find temperatures of 70 to 80 degrees +, residual heat from the summer.


I think the heat you are talking about is mostly generated by the straw breaking down, not really residual heat from summer, so you would need to replace the bales every year. When I was a little kid playing in the snow & our feet & hands got cold & wet we would go over to the mill & dig a hole in the sawdust pile. You did not need to go very deep to find some of the sawdust glowing like the end of a cigarette, complete with white ashes. You could dig a depression on the side of the pile big enough to set in & warm right up. I have seen mobile homes out in the open in Nebraska & the Dakotas that were protected with straw bales. I am sure it worked well, but I don't think I would risk the fire hazard with a trailer. Mother's covered building with straw bales that involved sealing them in concrete to stop the decomposition.


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## Davarm (Oct 22, 2011)

TopTop said:


> I think the heat you are talking about is mostly generated by the straw breaking down, not really residual heat from summer, so you would need to replace the bales every year. When I was a little kid playing in the snow & our feet & hands got cold & wet we would go over to the mill & dig a hole in the sawdust pile. You did not need to go very deep to find some of the sawdust glowing like the end of a cigarette, complete with white ashes. You could dig a depression on the side of the pile big enough to set in & warm right up. I have seen mobile homes out in the open in Nebraska & the Dakotas that were protected with straw bales. I am sure it worked well, but I don't think I would risk the fire hazard with a trailer. Mother's covered building with straw bales that involved sealing them in concrete to stop the decomposition.


If the bales of straw are kept dry, they will not break down and generate any heat, but add enough moisture to bring it above %7-%12 moisture window, then the molds and bacteria will start to activate and grow. When that starts - there go the bales, it is even possible under the right conditions to have spontaneous combustion.

With your sawdust dont know what the story was, in the years prior to refrigeration, the ice houses would cut ice from bodies of water in the winter and pack them into buildings insulated with sawdust and the ice would sometimes last until the fall freezes.

I recently found some sites where people used bales of straw in home construction, one was from a Texas University, dont remember which school it was, but they were using bales of rice straw to build some experimental homes in the Houston area.

I worked for an old farmer when I was a teenager and he would bale soybean stems from his bean fields after harvesting and stack them around the underpinnings of one of his houses. Made a big difference but as you stated, was a fire hazard to consider.


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## TopTop (Nov 11, 2011)

Right you are about the moisture. That is why the Mother's articles about building with straw bales says to enclose them in concrete. The sawdust is the same way. The logs on the mill have a high moisture content while hay or straw must be dry before baling & then the sawdust pile is outside on bare ground so it will act just like the wet hay bales. I am familiar with the ice houses, but I don't know if they spread it out in the sun to dry first, (dry would have better R value) or maybe because it was only a few inches thick & was packed pretty tight effectively cutting off the air. BTW, one time I built a pump house, using some low grade lumber right off the mill. I planked it inside & outside & filled the walls with sawdust. It never froze although the sawdust would settle & I just topped it off each year. The roof just lifted off to gain access to the pump & pressure tank so it was easy to add sawdust each year. The pump house was out of sight behind some bushes, but it did not look bad. Kind of resembled a kid's playhouse.


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