Sustainable building with earth, corrugated galvanised iron and rebars

[Baluncore]

The bags with earth can obviously make the house bullet-proof and inflammable (more or less), but what about the internal temperature?

How long do polymer bags survive in the environment? What happens when poly-bags burn during a grass-fire, or become water-saturated, and burst?

Avoid the word "inflammable" it is confusing and misunderstood.

 

[Vanadium 50]

Avoid the word "inflammable" it is confusing and misunderstood.

Agreed.
Non-inflammable is even more confusing.

 

[Blokle]

How long do polymer bags survive in the environment? What happens when poly-bags burn during a grass-fire, or become water-saturated, and burst?

Avoid the word "inflammable" it is confusing and misunderstood.

If not exposed to direct sun light I think the bags can survive 10 years or more. So planting something in them can be both decorative and protect them from sun. Another way to protect them is with mud. Also from fire. Make holes in the bottom and water will go out... But what does your intuition tells you regarding the inner temperatures and the thermal mass of all this?

 

[Rive]

planting something in them

That's a taboo. For any earth- (mud, clay) based construction water and plants are bad news. It is even a rule of thumb in the business that any aggressive/invasive root-propagated plants: grapevine, ivy, bamboo, japanese knotweed and such) are to be kept several meters away, and on the walls nothing is allowed what might grow roots or grabs into the wall for support.

Another way to protect them is with mud.

That's the traditional way. Requires frequent attention, but really low cost.

Make holes in the bottom and water will go out...

You need to prevent it going in ... Roof and insulation at the base: also the right placement/environment.

Will the thermal mass be enough to keep the temperature within 20-26C without heating/cooling in mediterranean climate?

It is moisture 'management' what makes the trick, and with (plastic?) bags involved that's not trivial. But with the right materials it is possible. You need to connect the inner (mud) plaster to the main mass of the wall somehow, without any moisture barrier. Think about some non-plastic bags

 

[Baluncore]

If not exposed to direct sun light I think the bags can survive 10 years or more.

The use of polymer bags, is not in any way sustainable.
That they will only last about 10 years, makes it doubly so.

The thread title: "Sustainable building with earth, corrugated galvanised iron and rebars" is a contradiction of terms. To be sustainable, you must avoid all plastics and iron.
Mud bricks, made with straw, do not need reinforcing steel, nor galvanised iron.

If you have windows and doors, bulletproof walls will not save you. If you must build fortifications, you are over-investing, or building in the wrong place.

 

[Blokle]

Ok... what do you think about Gabions ( https://en.wikipedia.org/wiki/Gabion ) as external walls. Maybe 3 layers gabions - internal and external - stones and earth between them.

1. How thick such gabions should be so the temperature inside is within 20-26C all the time without heating/cooling?
2. Will this still work if the inner parts of gabions will be covered with drywall (gypsum panels)?

 

[Nik_2213]

I think you need to urgently research the loadings etc for 'Green Roofs' and 'Earth Sheltered' construction.

Also, like the way an unexpected snow-load may seriously threaten roof, a 'green roof' in heavy rain may become very heavy, very rapidly. 'Usual' loading margins simply do not apply.

 

[Baluncore]

Maybe 3 layers gabions - internal and external - stones and earth between them.

A gabion wall is thick because it must not fall. It will require a huge volume of material to build. Once built, a gabion wall is unmaintainable, you are stuck with your investment. The only advantage of a gabion wall, is that it might be bulletproof.

Barriers to the flow of water are close to impossible with gabions. Expect mice to find their way into a gabion wall. Mice will nest within or burrow under the wall. The mice will be followed by snakes, and rats, which will have no hesitation in gnawing their way through a warm drywall on a cold wet night.

Gabions would make a terrible wall for a house, but they would be great for a garden wall, or to stabilise an earth bank.

 

[Tom.G]

Plants can be planted into the bags walls.

green roof' in heavy rain may become very heavy, very rapidly.

Several years ago a nearby city built a new library with a garden on the roof. Around half a dozen years later they removed the garden because they could not keep up with all the water leaks.

About a decade later they built a Brand New library and removed not only the leaky roof from the old one, but tore down the whole building.

Living things change, that is pretty much the definition of life; where we, as Humans, prefer our homes to last at least as long as we do.

Cheers,
Tom
{edit: fixed typo}

 

[jrmichler]

Reviewing some basic principles:

A house with high thermal mass and low insulation will be at a constant temperature that is the average of the high and low temperatures for the last few days. In a desert climate with daily low at 70 deg F and daily high of 110 deg F, the house will stabilize at 90 deg F. I saw exactly these high and low temperatures in the US Air Force barracks at March AFB when the barracks air conditioning failed. The building was concrete block with no insulation. It took some effort to convince the guys that we should shut down the ventilation fans during the day, and run them all night. That kept the barracks temperature down to about 80 deg F, which was reasonably comfortable with the low humidity in that area. The AC failed at the beginning the summer, and was repaired at the end of the summer.

I toured an earth sheltered home in Illinois, a warmer climate than my home state of Wisconsin. It had minimal insulation, only 2" of foam around and over the house. There was no insulation underneath the house. The owner needed to add a second furnace to keep it warm in the winter.

A house with low thermal mass and low insulation is just plain miserable to live in. I lived in such a house for two years. It was impossible to heat or cool all rooms to the same temperature, so the house was never comfortable. There were many days when the furnace ran at night to keep the temperature above 70 deg F, and the air conditioner ran the following afternoon and evening to keep the temperature below 78 deg F.

A house with low thermal mass and high insulation that is thermally connected to the ground will stay cool in hot weather without air conditioning. My workshop in Northern Wisconsin is such a building. It started as a garage built on a concrete slab. The walls are insulated to R35 and the ceiling to R80. The heating thermostat is set to 66 deg F, and the indoor temperature has has never exceeded 70 deg F, even in an extended spell of 90 deg F temperatures. Much of the heat to get it to that temperature came from the dehumidifier.

A house with low thermal mass and high insulation that is thermally isolated from the ground with 4" of foam insulation under the crawlspace, under the foundation, and around the foundation walls needs air conditioning to keep the temperature down to 78 deg F after several days of 90 deg F and hotter temperatures. This describes my current house. It was a significant effort to get a central air conditioner that was small enough. It is a one ton (12,000 BTUH) unit that is actually oversized for this house. This house has even temperatures throughout the house regardless of the temperature outside. The comfortable house is the primary benefit, the ability to ride through a power outage or furnace failure a secondary benefit, and the low heating bills are a bonus.

Earth construction makes sense in moderate temperature, low humidity climates.

 

[Blokle]

Reviewing some basic principles:

A house with high thermal mass and low insulation will be at a constant temperature that is the average of the high and low temperatures for the last few days. In a desert climate with daily low at 70 deg F and daily high of 110 deg F, the house will stabilize at 90 deg F. I saw exactly these high and low temperatures in the US Air Force barracks at March AFB when the barracks air conditioning failed. The building was concrete block with no insulation. It took some effort to convince the guys that we should shut down the ventilation fans during the day, and run them all night. That kept the barracks temperature down to about 80 deg F, which was reasonably comfortable with the low humidity in that area. The AC failed at the beginning the summer, and was repaired at the end of the summer.

I toured an earth sheltered home in Illinois, a warmer climate than my home state of Wisconsin. It had minimal insulation, only 2" of foam around and over the house. There was no insulation underneath the house. The owner needed to add a second furnace to keep it warm in the winter.

A house with low thermal mass and low insulation is just plain miserable to live in. I lived in such a house for two years. It was impossible to heat or cool all rooms to the same temperature, so the house was never comfortable. There were many days when the furnace ran at night to keep the temperature above 70 deg F, and the air conditioner ran the following afternoon and evening to keep the temperature below 78 deg F.

A house with low thermal mass and high insulation that is thermally connected to the ground will stay cool in hot weather without air conditioning. My workshop in Northern Wisconsin is such a building. It started as a garage built on a concrete slab. The walls are insulated to R35 and the ceiling to R80. The heating thermostat is set to 66 deg F, and the indoor temperature has has never exceeded 70 deg F, even in an extended spell of 90 deg F temperatures. Much of the heat to get it to that temperature came from the dehumidifier.

A house with low thermal mass and high insulation that is thermally isolated from the ground with 4" of foam insulation under the crawlspace, under the foundation, and around the foundation walls needs air conditioning to keep the temperature down to 78 deg F after several days of 90 deg F and hotter temperatures. This describes my current house. It was a significant effort to get a central air conditioner that was small enough. It is a one ton (12,000 BTUH) unit that is actually oversized for this house. This house has even temperatures throughout the house regardless of the temperature outside. The comfortable house is the primary benefit, the ability to ride through a power outage or furnace failure a secondary benefit, and the low heating bills are a bonus.

Earth construction makes sense in moderate temperature, low humidity climates.

Thank you very much! This was exactly the explanation I was looking for. Following your input I now consider to build the outer walls of gabions (i.e. high thermal mass), inner walls of light gauge steel covered with drywall (gypsum panels; i.e. high insulation) on a concrete slab (i.e. thermally connected to the ground).

My next questions are:

1. Will putting plaster on the inner side of the gabions serve as insulation good enough to make light gauge steel covered with drywall unnecessary.

2. How stable is a gabion wall that is 3 m high and 0.8 m wide? Is there a danger of it falling inwards / outwards on its own or during an earthquake? In case of a fall - is it expected to fall as a whole or will it disintegrate and fall as separate stones?

3. Does inner light gauge steel construction that bears the roof - contributes to gabions stability or is it too lightweight for such a task?

Thank you!