The Passive Solar Roller…
is Cultivate Cochrane’s Mobile Education Greenhouse! We are thrilled to be able to bring the community opportunities for hands-on learning, skill-building and connection through food. Here’s everything you need to know about the Passive Solar Roller!
How it all began…
In the winter of 2021, nearly one year into the Global COVID-19 Pandemic, an opportunity for funding flew across our radar - The Government of Canada’s Canada Healthy Communities Initiative was seeking to fund projects that responded to the needs that had arisen throughout the Pandemic, that helped create safe and vibrant public spaces.
We got brainstorming as a group and the idea of a mobile greenhouse came into view - as we explored this idea further, we started thinking about the many ways a mobile greenhouse would benefit our community, more specifically, who in the community would benefit. Our focus turned to children and youth, who have missed many opportunities for connecting meaningfully and safely with their peers throughout the pandemic. We felt they would greatly benefit from hands-on learning opportunities that taught them valuable skills, like gardening, while engaging with their peers.
As our first foray into the world of grants, we were beyond thrilled when we found out our application was successful in September of 2021! Since then we have been hard at work bringing this greenhouse to life, with the support of stellar community members right here in Cochrane! We quite literally could not have done this without the generosity of our community with their time, talents, resources and enthusiasm.
Why Passive Solar?
Growing food in southern Alberta is challenging due to our very short frost-free window, cold nights, and risk of snow, hail and high wind. We do, however, have abundant sunshine.
Passive solar greenhouse design harvests the sunshine and provides an elegant solution to the challenges, buffering temperature swings in an extremely energy-efficient manner. Passive solar is a way of designing a greenhouse so that its heat regulation is largely done using the free and perpetual energy of the sun.
Passive solar greenhouses offer major advantages over conventional “glasshouse” designs which overheat easily in the summer only to lose all that heat rapidly once the sun goes down. They also require expensive and energy-intensive supplemental heat to maintain growing temperatures in the shoulder and winter seasons.
Because it is achieved simply through smart design and choice of materials, a passive solar building will continue to function no matter the price or availability of conventional energy sources. It allows us to feed ourselves locally and sustainably beyond our very short growing season.
Why Mobile?
During the COVID-19 pandemic, we saw the challenges faced by children and youth in our community, and wanted to use our greenhouse and gardening knowledge and skills to serve them. However, greenhouses typically stay in one location – great for anyone who has reliable and affordable access to transportation, but not for the child and youth population we are aiming to serve.
Our mobile greenhouse concept was created by this desire to go directly to children and youth groups, to serve them where they are at.
Our Design:
Built on a flatbed trailer, the greenhouse can be brought right to the public, thus increasing accessibility. Multiple people can enter at a time, and a heat-activated venting system ensures fresh airflow for both people and plants.
The south side uses polycarbonate glazing, a material ideally suited to greenhouse growing, in combination with glass windows which allow a clear view to the plants inside.
The remainder of the structure, including the floor, is well-insulated to retain heat overnight and on cooler days.
High thermal mass materials such as water or concrete are typically used to moderate heat in a passive solar greenhouse, but for this mobile application, phase change material was chosen as a lightweight substitute that serves a similar function.
A “climate battery” complements passive solar design by transferring hot air from the peak of the greenhouse to the cooler soil and back out again. A small model of this system is included in the mobile greenhouse for demonstration and educational purposes (short video description here). A rainwater capture, storage, and gravity-feed system is also modelled.
Overall, the structure and the chosen materials serve to demonstrate the principles of passive solar greenhouse function while being durable, road-worthy, and conducive to programming.
The builders…
We needed a builder that was local, skilled, and able to work closely with us on a tight budget. We also hoped they’d share some of Cultivate Cochrane’s values and be excited about bringing a mobile education greenhouse to life. OnGrowing Works fit the bill on all accounts.
Matt Ashton, project manager with OnGrowing Works, describes why they were keen to work with us on this mobile greenhouse: “The idea of sustainability, passive solar design, and food generation all resonate with our company goals and vision. We’re excited to play a role in this project by providing construction support and look forward to seeing the impact the Passive Solar Roller will have on our children, youth and family programs in the area.”
Along with their own labour and materials acquisition, OnGrowing Works was able to draw on relationships with suppliers and tradespeople to help keep our project on budget.
Many Thanks!
The Passive Solar Roller would not exist if it weren’t for our amazing partners and sponsors:
funding
Canada Healthy Communities Initiative
Cochrane Environmental Action Committee
builder
transport
other contributions
Mountain View Building Materials
Where to find the Solar Roller:
Keep an eye out for the Passive Solar Roller around town! It’ll be bouncing around between programming locations and public events until we put it “to bed” for the winter.