Passive Solar Greenhouse with Aquaponic Cultivation
Since 2016, we’ve been working to increase our food autonomy at the ecovillage site. One of our key initiatives is the SPA Greenhouse—short for Passive Solar Aquaponic Greenhouse.
To build a greenhouse with minimal heating costs that can support year-round aquaponic lettuce production, connected to fish tanks.
The project is now fully operational. However, we continue to refine the systems and optimize efficiency.
Fall 2016: The structure was completed, allowing us to begin collecting temperature variation data. Our biennial seed plants spent the winter inside, protected from the cold. Spring 2017: With the return of the sun, we began planting.
July 5, 2017: Our first rainbow trout arrived in the greenhouse.
October 22, 2017: After many adjustments and adventures, we harvested our first lettuce!
🛠️ A Few Words About the Construction
This is no ordinary greenhouse! The biggest challenge with conventional greenhouses in Quebec is heat loss. Our top priority was to reduce heating costs as much as possible to enable year-round cultivation at a reasonable expense.
We drew inspiration from Solution ERA’s passive solar greenhouse design. Since building codes didn’t allow for a tire-based structure, we opted for a conventional greenhouse base, oriented due south, with insulation in the ground, along the north wall, and the northern portions of the east and west sides.
Water-filled barrels and the soil store heat, creating thermal mass that redistributes warmth throughout the cold season. Additionally, an overhead overheating chamber redirects excess heat into the ground. This summer, we saw the benefits of this thermal mass firsthand—and even had to shut down the overheating system due to rising temperatures in the fish tanks!
🌿 Five Cultivation Systems
As you can see in the photos, we use several growing methods:
Seedlings begin life in starter cells where they begin to grow.
Lettuce plants grow with their roots directly in water, supported by clay pellets.
Tomatoes, radishes, peppers, and herbs grow in soil-free beds where water circulates through gravel.
Other plants grow in recycled containers filled with soil in front of the greenhouse’s south-facing wall. Fish compost (from the first water filtration system) provides fertilizer in this section.
And finally, our biennial seed plants spend another winter in pots inside the greenhouse !
Two recorded interviews with our project lead, Etienne, are available. They offer deeper insight into the project and, we hope, will inspire you to build your own system. Conscious contribution requested—email us at info@capecocommunautaire.org for details.
You can follow the adventure in video format on our Facebook page. And don’t miss the wonderful presentation video created by a visiting student team !
Of course, there are still many steps and elements to balance before we reach full equilibrium, but we’re confident in our progress. We invite you to attend a workshop/visit to better understand all aspects of this research. Visit this page for full details.
This project is led by our training center, CAP Éco-Communautaire. Special thanks to Ferme Bio-Maraîchère for lending us part of their land, and to the volunteers who closely support the research.
And a heartfelt thank you to Khéops International, our generous donor who makes this research possible !
