earth tunnel house

[Medbury Gardens]

After reading about 'earthship'house construction using thermal mass as its sometimes only form of heating/ cooling,i set about building this tunnel house, built on the same principals.I started with 6 railway sleepers for each of the middle hoops and 4 power poles, 2 each end, these were all cemented in to place,large bolts inserted and 6mm wire netting added between for reinforcement.One ton of cement and a hell of a lot rocks from our local river went into the four walls,then soil added to the sides and planted in native grass.
In winter with outside frost temp down to -8 C/-18 F,inside has not gone below 4 C/40 F, some tomatos"black krim" did make it though winter and have just starting to come away again now.In the summer we average day time highs of 30 C/83 F but when it gets hotter the inside/outside temperates tend even up.

This tunnel house gives me about a 9 month growing season and has helped expand the outside gardens season also.My thoughts now are towards building a second larger one with solar and woodburner for heating.
We have had about a years worth of rain in the last two weeks, thats why there water inside its all ground water its just coming up from below

[levad]

looks great!

is there electric power? could you rig up a sump system? maybe a windmill or solar cell with a battery bank....im not sure how fast the water seeps in.

dave

[Barryblushes]

Wow what a great project! Is that lettuce growing in bathtubs?

[dcarch]

Here are a few things worth considering:

1. If you can get 9 months of growing now, with insulated covering, you should get almost year-round growing.

2. If you can install reflective (white) interior surfaces in the summer and absorptive surfaces (black) in the winter, you can gain a huge advantage.

3. The water problem is very good news. That indicats you have relatively high watertable. It makes it worth while to consider a deep-well pump system to have water for your plants as well as geothermal system for heating and cooling.

4. I see that you have some structural understanding in the design use of interior "A" frames to support the roof. If you design it properly, this is where you can incorporate inexpensive removable foam panels for the winter nights. Imagine what 1" thick 4' x 8' foam panels can do for you!.

Very nice work.

dcarch

[Medbury Gardens]

Dave,

We live here on alluval plains where the water table is normally 2 meters at this time of year when we get most of our years rainfall (average 500 ml-30 in),in summer it drops to 5 m, thanks to our local dairy farmers who use vast amounts for irrigation.Having had so much rain the water table up to 20cm,i did bucketed out a lot of water yesterday so i could pot up some plants, an hour later it was back to the same level.
This time next week it should be gone


Barry ?
On the bottom left are Sikkim cucummbers,lettuces in the baths both sides, the pots down the left wall are this coming seasons tomatos seedlings(PBW,Great white,Black krim and two NZ heirlooms,Waimana and Scotland yellow)Behind the bench are two of last seasons surviving tomato cuttings-Black Krim.Also in pots are potatos,Cape Gooseberries, Marrows, Peas and Lettuces for planting out later.

dcarch
1 I ve given a lot of thought about insulation,problem is in May,June and july the sun just high enough to supply sufficiant heat to make insulation worth while,it would need to have additional heating.
2 On the end wall you will see that i painted the stones on one side of the window as a experiment,mid winter they didn`t warm at all, they have only just started to warm in the last few weeks were the other side is still cool to touch.Summers are ok, its not over heating at all, the stones are keeping it cooler in the day time, warm at night
3 When we bought is place it was spring and the water table was about 2m down, i had a digger come in to dig a well but he couldn t get deeper than 3m cause very time the bucket hit in the water the gravel sides would cave in so i threw a 200mm pipe in and made do,it nearly got me through the first summer before going dry.It has been redug twice since ,today its at 6 m and is sufficiant in the dry period for garden irrigation,wouldn t be able to garden here with out it.I dont know a lot about how to use this underground resource as a geothermal heating syetem.
4 The hoops been manufactured out of aluminium and had long proven to be inadequate to handle snow,hence the A frames, great for tying up tomatos, cucummbers etc.
I think it would be to differcult to add foam panels at each end, the cold air would fall between the stones and foam panels,unless i bolt timber to the walls.That and dugging in a power cable over to it for heating could work Food for thought

[dice]

Around here, well drilling amounts to auguring (rotary) or
pounding (cable rig) a hole in the ground, and driving steel
well casing (pipe) down as you go in 10 foot sections that are
welded together as they are added. (No actual digging.)

With really loose soil like you describe, they would probably
need to pound the well casing down every foot that they
drill, so that when the drill bit hits water, it does it inside
of several feet of pipe that is already in the ground. Easily
doable for an experienced well driller with an actual water
well drilling machine, but it requires a lot of tool changing,
switching the pipe hammer in and out, so it might be expensive.

[Medbury Gardens]

We`re very lucky here to have just so much water close to the surface,i don`t need to drill when at a cost of $100 per foot when i can get a fella from down the road with a digger who did the last well for $190.
My pump works at 70 liters per minute, even in the middle of summer when the weathers at its very driest the water doesn`t drop when i start pumping so there is good inflow into the bottom of the well.
The neighbouring dairy farmers with there deep wells, that were drilled are pumping 4300 liters per minute, theres no way the top aquafer that i use would handle that sort of volumn.
Two more days and all the water will be gone from inside the earth tunnel house.

[dice]

I was thinking about the problem with the gravel falling
in when the bucket on the loader or backhoe hits water.
It seems like you could dig a fairly wide hole with gradually
sloping sides to get around that problem. Maybe start 10' out
all around for the outside of circumference of the hole, dig
down a couple of feet in the center, than clear out a gradual
slope out to the sides of the hole. Dig down a couple of
more feet in the center, and then dig out around the sides,
maintaining that gradual slope, so that the lip at the outside
edges drops at the same rate as the center of the hole.

When the center gets down as deep as it needs to be, you
don't have much in the way of sides around it to cave in.
If any of the lip caves in, out at the edges, it is 10' from
the hole, so no damage done. Just increase the slope as
you go from there, not digging the outside lip any deeper.

I remember a kid from high school that was out helping
hand-dig a well in one of the local river valleys decades
ago. The water tables are shallow there, so they did not
estimate that the hole would need to be very deep, 25 feet
maybe, and the soil was clay subsoil and silt with a lot of sand
in it, easy to dig in. They had a hole about 6' around and 20'
deep, and it caved in on him. Not wide enough.

[johno]

Lucky devils! Wells here usually range from 150 feet to 500 feet deep. Estimating the cost, one can figure around $6,000.00 to be on the safe side, but it could be even more.

I love the earth tunnel house! I though of doing something similar here, built into a south-facing slope. Maybe someday...

[dcarch]

Originally Posted by johno

------------from 150 feet to 500 feet deep. ----------...

You will be getting Chinese water at that depth.

dcarch

[Medbury Gardens]

Dice

The one lesson learnt here was, deeper the water the better,as it didn`t start to cave in until the excavator was below the water table

Johno
I have herd of some deep wells here costing over $NZ20000.00-$US16000.OO.
I would hate to think the cost of dilling some of the deep wells in outback Australia some of them can be up to three or four times deeper than what you need to drill down to Johno.

I would stay away from that Chinese water you wouldn`t know whats in it

[robin303]

I like the rock work.

[Medbury Gardens]

Originally Posted by robin303

I like the rock work.

Thanks very much

[LenaBeanNZ]

What a wonderful earth house, very interesting, using the earth and rocks for insulation. And it looks very nice too.
Reminds me a little of some of the Hundertwasser builings I saw when I was younger. My father was a friend of the great artist, he lived in the Bay of Islands too, where I grew up. Dad is in the alternative power systems business, and did some work for him, while we kids explored the surroundings. All the houses on his land were covered in earth, with grass growing on the roof, one was sunk right into the hilside, barely visible. He used logs, boulders, and beverage bottles for walls, and some sort of solar system for hot water. Dad will know more about it.
How is the water problem by now? Probably not a feasible idea, but the Dutch fixed water problems very well with windmills

[Medbury Gardens]

I will have to keep your Dad in mind,as i really would like to get off the grid with in the next few years.

Yep shes dried nicely now.You would have had it rather wet up our way too??,but typical though all that rain in about three weeks,three months later and its hardly rained since, i`m now watering the garden again as of this week.

Richard