Content for id "text" Goes Here
What is an earth tunnel?
Earth Tunnel
The BaileyWick, a solar home in Saratoga, CA
Following is an interesting email I received from Joe describing plans for an earth tunnel he is building.

Earth Tunnel - I have a  coiled 100ft of 30" culvert pipe setting in loose shale with drainage, buried about 8 feet, starting from raw outside air with a screened & capped roof, that opens into my basement at 4 ft depth. Thus, when the basement needs air, the tunnel is where it comes from.   Instead of using outside air temperature for my reference temperature, I use the temperature of the air from the Earth Tunnel - ~ 62 deg. F. (average yearly temperature) in Saratoga CA.  There used to be some info on the web about earth tunnels, but I can no longer find it.

In hot weather, the incoming air contains moisture, and thus, my circulation system has a de-humidifier in front of the opening to the distribution to the various rooms. The circulation system is a "chimney effect", where the hot air leaving the structure sucks in the cool air from the air distribution. Thus, the structure is naturally cooled, using no energy.
Today, the outside temp is about 100 deg F, and the inside temp is 70 deg F.

Plans in Orcas - With the fireplace in the centre (perhaps in the basement) of the new house to be built on Orcas, I will us this as my circulation system, its air intake will be from the basement (60 deg with the earth tunnel), again with a de-humidifier. And, I will use a wooden chase directly behind the fireplace chimney to return air to the basement in the winter where it will add heat to the trombe wall filled with eutectic salt.

These Eutectic salts have a solid-to-liquid temperature of fusion at 80 deg F.  Its heat of fusion is greater than water, esp. at 80 deg, where it is useful to humans.

Back to the current house - In cool weather, I need a fan to bring the warm air from the tip-top (~26 ft up) of the structure back down(thru a well sealed wooden chase) to the Eutectic salt heat store in the basement, exhausting into the basement.  This also creates a chimney effect, now sucking the (relatively) warm basement air into the various rooms of the structure. When it is 32 deg F outside, 65 deg F inside is very nice, and a light sweater is sufficient.  Of course, there is some air loss to the house, and, again, the air brought in is thru the earth tunnel.

The basement garden - This is an earth floor in the centre of the basement about 10 ft by 6 ft. I only have 4 of those 10W to 20W grow light fluorescent tubes, and I grow herbs, lettuce, cherry tomatoes - the liquid excess from the de-humidifier waters these plants.  It seems to add heat to the basement air, as well as oxygenate the air, adding nice aromas to the
circulated air.  It takes care of itself.

The net result is that out utility bills run about U$100 per month, whereas the least of our neighbours is U$500 per month, with all families about the same size.


Return to SHELTER