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"The Solar greenhouse"

The solar greenhouse

As a kid, I remember going to the Mutart conservatory in Edmonton and being overwhelmed with a sense of contentment. Whether it was the smell, the warmth or the humidity… I always remember never wanting to leave. Those memories grew into a desire to own a greenhouse of my own. Then, in 2010, it became a a necessessity. A hailstorm wiped out eveything we had put so much of our heart into all season…. there was no way I was going to go through that again.

I started looking into styles of greenhouses.There’s the huge tent style greenhouses…. immense¬†warehouses¬†of cultured life. Unfortunately, my meager 9x30m city lot has no room for that sort of project. There is the glass garden house… beautiful in those coastal yards, where it’s always fairly mild, but lots of cloud cover or regular rainy days. That doesn’t sound like my climate…. well not always. There are those cool, spacey looking domes that look like the EPCOT center…. my yard is definately a rectangle… so nope.

Then I came upon the solar greenhouse.

The passive solar greenhouse is orientated so that the glazed side is facing as south as possible. The north side is insulated so that the winds of winter cannot easily rob the bit of heat maintained in the light of day. East and west walls are insulated as well. But can be great areas for a door or a decorative window, as long as they are air tight and a plan is made for how to insulate for winter. I use the high density foam insulation, cut to size, to keep the cold window from affecting temperature in the cold months.

In a solar greenhouse, special consideration is taken when designing the roof. The roof needs to be built in such a way that it allows for 100% sun exposure when the sun is low in the winter and create a few hours of shade or indirect light during the hot midsummer days. An easy way to decide the slope of the roof is to add 20 degrees to your latitude. In Calgary, 55 degrees is close enough to do the trick.

Since the design of the solar greenhouse is so effective, you don’t need to sweat about the finer details. Any structure that you build that follows these few guidlines will work. However, in any permaculture design, expect to analyse the feedback (too hot, too cold, no air flow… etc) to create something that suits your specific needs.

In future posts, we will visit my greenhouse and I will walk you through the evolution of my design.