For growers unlucky enough to be living at high elevations or further than arms length from the equator, frost and cold relentless winds are constant enemies. Twenty years ago in the mountainous regions of South America, frustrated growers set out to pull the arrow from the Achille’s heel of productive year-round growing in cold climates and temperate climates. Their solution? A DIY greenhouse that can be built for less than $300.
The walipini was designed to grow food year-round in the colder and more temperate climates for less than $300.
Traditional greenhouses composed of glass walls are typically as expensive as they are fragile. And while “common sense” would lead you to believe that maintaining the heat necessary for optimal growing conditions would be stretching closer to the sun or manufacturing its rays with an expensive lighting system, designers of the walipini decided to make use of an alternative natural source of heat. A walipini is a passive-solar heating structure that burrows closer to the magma that flows beneath the earth’s crust. Actually, walipini is the Aymara Indian word for “place of warmth”.
By digging just six to eight feet below the earth, growers can take advantage of what is called a thermal constant. The design uses a wall of compressed earth at the spine of the building and a shorter wall as its chest. This makes an angle for a plastic sheet roof that is permeated by the sun’s rays to create the ideal temperature for plant growth. The design should incorporate an entrance that is slightly deeper underground than the grow floor to prevent warm air from exiting the environment. This is because cold air sinks downwards.
The DIY walipini is built six to eight feet underground in order to take advantage of the thermal constant to keep the environment warm enough to grow plants.
The in-earth greenhouse should stretch longer on the east and west and be shorter on the north and south to maximize the solar harvest. Eaves troughs can even be incorporated on the roof to harvest rainwater. Additionally, you could take notes from Earth Ships and line the walls with rubber tires to create additional insulation or incorporate ventilation to use the wind as a natural cooling system on unusually hot summer days. Ladybugs and pollinating insects can also be introduced.
The Benson Institute is an organization concerned with using locally-available resources and community efforts to solve food security issues. Using volunteer labour, they built a community-sized walipini that stands at an astounding 74 feet by 20 feet for just $300. The beauty of the walipini is that its simple but effective design can be built by anyone with a small budget and a few free weekends. Not only is locally sourced food better economically and nutritionally, but as shifting climate affects soil-fertility, permaculture initiatives are a regressive solution to the problems permanent agriculture is currently experiencing.