The Living Roof- One Year Later

I like to imagine the view of my house from all the places in which any living thing may be gazing.  Before the population explosion of humans and the development of the shelters we build for ourselves, the view from the sky would have been quite a different scene.  With uninterrupted tracts of habitats absorbing the sun and the rain and providing possibilities of nesting places and food, birds and insects had much more to choose from.  Roofs, of course, aren’t the only dead spots in bird and plant habitat, but they are thankfully gaining recognition as an important factor in green building design for homes as well as for commercial and industrial scale buildings for many reasons.  Despite their centuries old history in Scandanavian countries, green roofs are just coming into modern construction as cutting edge eco-design around the world.  In 2008, the Vancouver Convention Centre installed a six-acre living roof of indigenous plants and grasses on its West building, making it the largest green roof in Canada.  Combating the urban heat island effect is one reason for creating a green roof –  traditional building materials soak up the sun’s radiation and re-emit it as heat, making cities at least 4 degrees Celsius (7 °F) hotter than surrounding areas. On Chicago’s City Hall, which features a green roof, roof temperatures on a hot day are typically 1.4–4.4 degrees Celsius (2.5–8.0 °F) cooler than they are on traditionally roofed buildings nearby.  As well as adding insulation value, green roofs decrease the total amount of runoff and slow the rate of runoff from the roof, retaining up to 75% of rainwater and gradually releasing it back into the atmosphere via condensation and transpiration. 

Our little 900 square feet of living roof is certainly small scale compared to the big picture of global sprawl, but it falls into our value of every little drop creates the ocean.  We still have two more roof sections when the rest of the house is built, and we plan on planting those up as well.  For a description of how we constructed our green roof, please see the older post in the Natural Building category called The Living Roof.  We planted the plants one year ago and I have been pleased with the growth of the many varieties, which have spread considerably and seem to be greatly enjoying the view as they take turns flowering.  We used many clumps of stonecrop which were growing on the rocks where the foundation was to be built, as well as hens and chicks, sedums of varying colourations, ice plants, and a few other varieties of winter hardy succulents that I am not sure what they are.  All the plants were propagated from friends’ gardens, given as gifts, or collected from the property.  I haven’t done any watering and I figure that whatever doesn’t survive in the natural climate just won’t have a place on the roof.   Along the center spine of the roof, I set the stonecrop in a large infinity symbol, with the hens and chicks filling in the circles.  Most of the stonecrop flowered, creating a lovely yellow outline, and I hope that in the next few years this symbol will become more defined as an offering to the element of the ethers, and to the winged creatures that I hope will stop for a rest during their journeys across the skies.      


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