Passive solar design is an important strategy in designing an undercover growing area, as well as a home. It can help you create an area where you can successfully grow crops all year round.
A greenhouse can dramatically extend the length of your growing season. It can also make it possible for you to grow a wider range of crops. When you have a greenhouse, you can grow things that you would usually struggle to grow in your area. But not all greenhouses were created equal. Some are far better than others for growing food in a range of climates.
A greenhouse that implements passive solar design is one which takes the sun and its movements into account. Passive solar design is all about making the most of the energy that the sun provides in a direct way. It is also about catching and storing that energy.
It is particularly crucial, in colder climates, to think about making the most of the sun’s heat and light during the months with the shortest days. This involves thinking about the placement and orientation of the structure.
It also involves thinking about adding thermal mass. Thermal mass refers to materials that catch and store heat energy during the day, and release it slowly when temperatures fall. Materials that are high in thermal mass include things like earth, stone, clay and ceramics. Stored water can also be excellent for catching and storing thermal energy.
To add thermal mass in a greenhouse we can think about:
- Adding new pathways or bed edging made from materials with good heat-retention.
- Making staging or support structures that retain the heat of the greenhouse during the day.
- Placing large water barrels or rainwater collection butts inside the structure.
- Positioning a ‘wall’ of water-filled bottles around particularly tender plants to protect them from frosts.
If creating a new greenhouse or polytunnel structure, we can also think about passive solar design as we create the structure itself. We can, for example, make an earth-sheltered or partially earth-sheltered greenhouse, sunken or partially sunken into the ground. (On a south facing slope, for example.)
You could also create a lean-to greenhouse against a south facing wall of a home.
If you would like some help or advice in designing an undercover growing area to protect plants in winter, please do get in touch.