$300 Underground Greenhouse: Grow Your Own Food, Fruits & Veggies Year Round!
The walipini underground greenhouse is a simple and effective underground greenhouse that allows you to grow your own food year-round.
This ingenious design will even grow tropical fruit in many climates. The positive and practical aspects of being able to grow food year-round are far-reaching.
The greenhouse pictured below was part of a project piloted by the Benson Institute, now a part of LDS Charities. The aim was to help increase food security for people in Bolovia.
The Walipini underground greenhouse works by utilizing the Earth's natural cooling mechanism and thermal mass heat storage ability.
It captures solar energy, heats the interior of the greenhouse, and stores the heat releasing it gradually keeping temperatures conducive to growing fruits and vegetables all year long.
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More Walipini info: Treehugger
How close to the equator would this reasonably work? Living 56° N growing things in winter time is rather challenging.
Good idea though.
In case you have sandy soil conditions (as opposed to clay or soft rock) and near vertical walls of excavation don`t support themselves, one can easily apply DIY slope reinforcement. Just takes a bit more of work.
https://www.google.lv/search?q=soil+reinforcement&safe=off&source=lnms&tbm=isch&sa=X&ei=KTlmU6uMBcrnywPAroDYDQ&sqi=2&ved=0CAYQ_AUoAQ&biw=1600&bih=771