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Directory:Walipini Underground Greenhouses

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Page first featured January 14, 2010

"The Walipini utilizes nature’s resources to provide a warm, stable, well-lit environment for year-round vegetable production. Locating the growing area 6’- 8’ underground and capturing and storing daytime solar radiation are the most important principles in building a successful Walipini." [1]
"The Walipini utilizes nature’s resources to provide a warm, stable, well-lit environment for year-round vegetable production. Locating the growing area 6’- 8’ underground and capturing and storing daytime solar radiation are the most important principles in building a successful Walipini." [1]

A directory of resources pertaining to the Walipini underground greenhouse mothod developed by the Benson Institute in Provo Utah.

One of the main principles involves embedding the greenhouse in the earth to take advantage of the earth's constant temperature, to store the solar energy collected during the day. Water barrels can also be used to store the thermal heat and carry it through the night or cloudy days (which are not as cold). Water is a much better thermal mass storage mechanism than soil.

The solar gain comes through a light-permeable material such as plastic, Visqueen, polycarbinate. The angle of the panels is designed to be 90-degrees to the Winter Soltace sun (Dec. 21 / June 21, depending on hemisphere). The the upper portion of the walls are insulated down past the frost line.

The word "Walipini" comes from the Aymara Indian language and means "place of warmth". They've been able to grow banannas at 14,000 feet elevation in the Andes.

The Walipini was first developed more than 20 years ago; deployed in South and Central America. The success of those projects has spurred the parent organization, the Church of Jesus Christ of Latter-day Saints, to adopt it in 2009 as part of its Welfare program worldwide.

Contents

Official Website

Image:Benson Institute Walipini cover 600.jpg

Videos

The Power Hour, Jan. 15, 2010

On Jan. 15, 2010, Sterling Allan was interviewed by Joyce Riley on her nationally syndicated show, The Power Hour, about the cheap, effective, year-round greenhouse method. Locating the growing area 6’- 8’ underground and capturing and storing daytime solar radiation in the soil and water barrels are the most important principles.

Walipini Underground Greenhouses 1/3: Sterling Allan & Jeffrey Grupp on The Power Hour

  • Broadcast via Joyce Riley's nationally syndicated show, The Power Hour, on Jan. 15, 2010. (YouTube; January 16, 2010)

- - - -

Walipini Underground Greenhouses 2/3: Sterling Allan & Jeffrey Grupp on The Power Hour

  • Broadcast via Joyce Riley's nationally syndicated show, The Power Hour, on Jan. 15, 2010. (YouTube; January 16, 2010)

- - - -

Walipini Underground Greenhouses 3/3: Sterling Allan & Jeffrey Grupp on The Power Hour

  • Broadcast via Joyce Riley's nationally syndicated show, The Power Hour, on Jan. 15, 2010. (YouTube; January 16, 2010)

- - - -

David Allan on Walipini greenhouse method

  • On Nov. 27, 2009, my dad, David Allan, gave an extemporaneous presentation on the Walipini greenhouse methodology. Present at this presentation was John Day, Michele Roberts, and James Torgeson, who are involved in Grow Utah First and Safe Haven Villages of which I'm also a part, which seeks to deploy the Walipinis widely in Utah to help the state become more self-sufficient in its food production. -- Sterling D. Allan (YouTube; Nov. 27, 2009)
  • See David Allan's solar home design at http://AllansTIME.com/SolarHome/
  • http://GrowingSpaces.com - makes growing domes, available as a kit.

Photo Gallery

Here's a large Walipini built at around 40 degrees latitude where the winter soltace is at around 62 degrees off the horizon. The floor is around 20 feet by 40 feet. There is probably more than enough solar gain in this greenhouse, introducing the problem of radiating out the energy at night or on cloudy days. But it is certainly a good attempt and will serve a useful purpose.


Construction

Quoting from http://bensoninstitute.org/Publication/Manuals/Walipini.pdf

The Walipini, in simplest terms, is a rectangular hole in the ground 6 ‛ to 8’ deep covered by plastic sheeting. By using translucent material, plastic instead of glass, plant growth is improved as certain rays of the light spectrum that inhibit plant growth are filtered out. The longest area of the rectangle faces the winter sun -- to the north in the Southern Hemisphere and to the south in the Northern Hemisphere. A thick wall of rammed earth at the back of the building and a much lower wall at the front provide the needed angle for the plastic sheet roof. This roof seals the hole, provides an insulating airspace between the two layers of plastic (a sheet on the top and another on the bottom of the roof/poles) and allows the suns rays to penetrate creating a warm, stable environment for plant growth.

Flywheel Principles

  • The more dense the mass (water is more dense than rock and rock is more dense than soil) the more energy can be stored in a given area.
  • An easy way to increase the mass is to put a few 55 gallon drums filled with water and painted flat black along the back wall of the Walipini.
  • Mass of a darker color such as flat brown, green or black absorbs heat best. Light colors, such as white, reflect heat.
  • In general, nighttime temperatures should not be allowed to drop below 45º, depending on the crops being grown. [2]

Insulation

A double layer of plastic sheeting (glazing) should be used on the roof. This provides a form of insulation and slows down the escaping of heat during the nighttime. This sealed dead-air space between the plastic sheeting should be between 3/4” to 4” thick. Poles used to span the roof that are 3.5” to 4” in diameter provide the indicated thickness of dead air space when plastic sheeting is affixed to the outside and the inside of the roof’s structure. The inside sheeting also keeps the inside humidity from penetrating and rotting the wooden poles spanning the roof.

When nighttime temperatures are continuously well below freezing, insulated shutters made from foam insulation board or canvas sheets filled with straw or grass can be placed over the glazing. [3]

Water Protection

Water penetration of the walls and/or floor of the Walipini is destructive.

  • Dig the Walipini in an area where its bottom is at least 5’ above the water table.
  • When all of the above ground walls are bermed, a layer of water-proof clay, such as bentonite, or plastic sheeting, should be buried approximately 6” to 1’ under the berm surface. It should be slanted so that the water drains away from the Walipini to the drainage ditches.
  • Be sure to dig a shallow drainage ditch around the perimeter of the Walipini which leads run off water well away from the structure.

Interior Drainage System

Keeping moisture from building up to such a degree that it adversely affects plant growth and contributes to plant disease is an important aspect of the interior drainage system.

As the hole for the Walipini is dug, it is excavated to an approximate depth of 1 - 2’ deeper than it will be when in operation. This area (1 - 2’ of depth) is filled with stone, gravel and 8” of top soil. The larger stones are placed at the bottom with the gravel becoming progressively smaller as it meets the layer of top soil. The bottom of the dig will be progressively sloped from the center to the ends with a drop of 1/4” per foot. [4]

Rainwater Capture

It would be good to try to capture the rainwater, into 55-gallon drums, for example, to be used for the plants as needed. You should store these inside the greenhouse for thermal mass heat storage purposes as well.

Location Considerations

  • Make sure that the Walipini is located so that its face (the roof angle facing the sun) has no obstructions such as trees, other buildings, etc. which will obstruct the sun. The only exception to this rule would be a few deciduous trees which lose their leaves in the winter. They can provide limited shading in the hot summer, but little shade in the winter.
  • Walipinis can be dug into a hillside providing the soil is stable and not under downward pressure, lest the wall eventually collapse.
  • If winter conditions frequently produce hazy or cloudy mornings or high mountains in the east make for a late sunrise, it may be best to locate the Walipini 10-15º to the north west of true east in order keep the afternoon sun in the Walipini for a longer period of time. [5]

Calculating Angle of Roof to Sun

The objective is to obtain a 90-degree angle between the afternoon sun and the walipini roof (plastic glazing).

In order to make the simple calculation for the best angle of the roof for maximum sun penetration at the winter solstice (the shortest day of the year), use the following rule of thumb:

  1. Obtain a good map and determine the latitude on the globe.
  2. Add approximately 23º (for the tilt angle of the earth)

At the summer solstice this angle will have the opposite effect and maximize reflection and minimize penetration. [6]

Ventilation

The chimney system provides the highest volume air flow and the best control of ventilation, while retaining mass, but it requires more labor, a little more material in the adobes, 4 short vertical poles and a rain shield.
The chimney system provides the highest volume air flow and the best control of ventilation, while retaining mass, but it requires more labor, a little more material in the adobes, 4 short vertical poles and a rain shield.

Venting can become a crucial factor in controlling overheating and too much humidity in the Walipini. Below are some options. For an illustrated discussion of the strenghts and weaknesses of each, see Walipini manual.

Two Doors 
ventilating by using two doors at opposite ends of the building
Doors and Vent 
a vent of equal size as one of the doors when the vent is fully opened; centered at top of the back wall
Doors and Roof Trap Door 
This vent is located in the roof at the center, back against the rear wall at the highest point.
Doors and Chimney 
Uses the same doors in conjunction with the addition of a chimney located at the bottom center of the rear wall

Size Considerations

  • A minimum of 94 sq. ft. of growing space per person is recommended for a year-round vegetable supply.
  • Generally speaking, the larger the Walipini, the more cost effective per square foot the construction will be.

Building Factors

  • The top soil from the dig is used at the bottom for the planting soil.
  • The rest of the soil from the dig is used for the rammed earth walls, berms and adobes.
  • Used materials are utilized where possible and practical such as used, cleaned 55 gallon oil drums, used doors, etc.
  • The most economical, durable materials found thus far for spanning the roof are 4” eucalyptus poles or PVC pipe.

Instructions

The Benson Institute document (back-up) contains a list of tools and mateirals, as well as instructions of how to build a Walipini.

Projects

Coverage

Interviews

On Jan. 15, 2010, from 8:00 - 9:00 am Mountain, Sterling D. Allan will be interviewed about Walipini gardening in the third hour of The Power Hour, a U.S. nationally syndicated show with host Joyce Riley. You can listen live or wait for the archive to be posted.

In the News

  • Emergency Preparedness > Gardening > Walipini >
    Mesa family grows food in swimming pool - A family in Mesa, Ariz., turned their unused pool into an organic greenhouse in their backyard. The GardenPool holds a tilapia (fish) pond, hydroponic fruits, veggies and herbs and a chicken coop. Treehugger reports that it uses solar power to keep it off the grid, has a natural water filtration system and uses non-toxic natural means to control garden pests. (ABC News; Aug. 27, 2010)
  • Featured: Solar > Applications / Building >
    Walipini Underground Greenhouses - The Walipini utilizes nature’s resources to provide a warm, stable, well-lit environment for year-round vegetable production. Locating the growing area 6’- 8’ underground and capturing and storing daytime solar radiation in the soil and water barrels are the most important principles in building a successful Walipini. (PESWiki; Jan. 14, 2010)

Other Websites

Mentions

  • ATTRA Question of the Week - What information can you give me on Walipini-style greenhouses? (National Sustainable Agriculture Information Service; Nov. 9, 2009)

Forums

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See also

SOLAR GENERAL:

SOLAR MODALITIES:

SOLAR INFRASTRUCTURE

SOLAR APPLICATIONS:

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