Green Roof Research in North America By Jörg Breuning
I am always amazed how much funds, intellectual energy and resources are put into research of extensive green roofs without the consideration of feasibility and without considering the demands of the plants. Especially in research common sense should be the starting point of any qualified discussion. This raises also the questions, why are extensive green roofs in Europe –in particular Germany – are so successful?
It is solely successful because extensive green roofs according modern green roof technology are a cost efficient (and beautiful) tool to manage stromwater issues. Period. All other highly market benefits or positive “side effects” are generated by the system for free because these are only consequences of successful implemented nature. Focusing on the side effects and improving them will compromise and eventually reduce the main purpose of an extensive green roof by increasing costs for designing, engineering, implementing and maintenance.
In the academic world Liebig’s law of the Minimum should be applied in any step of the discussion and research. However understanding the limiting factors – including limiting economic factors – requires a tremendous amount of experience, historical data and common sense. The lack of these factors and the lack of time seem the limiting elements but justified by many unique human properties like vanity, self-promotion and economic restrains. On the other side (consumer side) the humans are also part of nature and it is natural that any of their decisions are made accordingly. If an idea doesn’t fit into this process (controlled by the scarcest or limiting resource) we walk away from it, like plants will “walk away” if their minimum requirements are not met. With the disappearance of plants on an extensive green roof we lose the purpose and the investment.
It is common sense that plants cannot walk away as fast as humans so their disappearance might take 2 decades or more which is still much less than the lifespan of extensive green roofs – the lifespan we promote.
For example measuring and promoting building insulation properties of a thermal mass or heat sinks like extensive green roofs was developed as a selling instrument of the industry (like reflective roofs). Trying to improve that will consequently compromise the main purpose to the negative. The end of this research will find out that it is most efficient and probably 10 times cheaper just to increase the buildings insulation on any surface of the building. It will also perfectly benefit when energy prices will continue to super-proportional increase or when we like to build our settlements that they last longer than just two decades – or when we want that the building has the same lifespan as an extensive green roof.
As I brought modern green roof technology to North America from Europe I expected a higher understanding of common sense and of Liebig’s law since it seemed to work in the social and financial world. Investing the research funds in actual extensive green roofs according proven modern green roof technology (e.g. not pre-planted boxes) would benefit the environment, industry and building owner much more and would help to start an entirely new research generation in 10-15 years from now.
When it comes to living technologies going back to the roots sometimes helps or simply is a necessity.