Underground pit greenhouses are not new. They date back to the cold climate of early New England. One of the earliest known earth sheltered greenhouses was built on the famous Lyman estate in Waltham Massachusetts in the 1798. It was expanded into the 1800’s to protect rare grape and fruit tree varieties and is thought to be the oldest greenhouse complex in the United States. The Lyman greenhouses were heated with wood stoves.
Pit greenhouses are actually large cold frames that take advantage of the heating and cooling properties of the earth. Ideally built into hillsides, they can be a useful addition to a sustainable permaculture design. These types of greenhouses are not suitable everywhere, specifically in areas with high water tables.
Interest in these types of greenhouses waned with the advent of cheap coal fired, gas and electricity. Now in the 21st century and due to a renewed interest in sustainability and permaculture, people have once again become interested in available passive solar and geothermal energy use. Many people and groups are once again designing year-round growing spaces in harsh climates. The cold-sink “Walipini” according to Wikipedia and other sources is an Aymara Indian word for a “place of warmth. This principal of the cold sink greenhouse was rediscovered by an independent inventor, Mike Oehler. In his 2007 publication The Earth-sheltered Solar Greenhouse Book: How to Build an Energy Free Year-round Greenhouse which describes how to build these structures. Mr. Oehler (who recently died this year at the age of 78) was a huge influence on the Permaculture movement as an expert in sustainable structures.
One of the key elements of the design of a Walipini greenhouse is that it needs air circulation to move cold air down and out in winter and to cool help cool the greenhouse in summer. There are many types of structures that can be fabricated from this design and they can be as inexpensive or expensive as one wants to build. A very practical aspect and where they are really useful is at high altitudes where night time temperatures drop below freezing most of the year. Fresh greens and lemon trees growing at 13,000 feet is a comforting thought.
An internet search will show construction videos and plans for these structures. World-wide the Walipini type greenhouse is providing fresh vegetables, improving diets and contributing to local economies while providing women farmers with much needed income. They are real example of appropriate technology usage.
Caron Wenzel is an Environmental Educator, writer, and owner of Blazing Star Inc. a 26-year-old native plant seed nursery, soil amendment and environmental consulting business. Blazing-Star.com.