What if your facility’s roof could be usable space, more than just a place to set roof top units? What if you could use this area as an outdoor classroom, a small garden for a science class or even grow herbs or vegetables for the kitchen? Green roofs, or vegetated roofs, help capture stormwater runoff, reduce heat gain into the building and lessen the urban heat island effect outside of the building. Green roofs are roof systems that are capable of growing grasses, herbs, plants, flowers and even trees of various species, textures, and heights.
There are two different categories of green roofs. Extensive roofs can be placed on slopes up to 30 degrees. They are more lightweight (12-35 psf) with a growth medium of 1-6 inches. These are for low growing plants that typically require minimal maintenance and have little water requirements. Intensive roofs have a growth medium of 6 or more inches and can be designed to grow trees, shrubs, or gardens. These often are higher maintenance and will likely require irrigation. This design can only be used on low sloped roofs. Paver systems can also be integrated into these roof systems.
Our firm recently completed a football stadium for a school district that placed their locker rooms and offices below the bleachers and main concourse where fans entered the stadium and could access concessions. The roof for the locker rooms became a paver system that was supported by small pedestals at each corner. All joints between pavers allowed water to seep through to the sloped roof system below, where it was then drained to internal roof drains like a typical low slope roof system. This allowed the project to maintain a tight footprint on the existing site and maximize usable space, capitalizing on opportunities for fans to maintain a good view to the field from the concession lines.
When considering if these roof systems are a viable option for your project, here are a few things to think about. One, the added installation cost of the roof system and increased load on the roof structure will add to the construction cost. These roof systems may cost 20-50% more than single-ply or multi-ply roof systems. On the other hand, these roofs have longer life spans due to moderated temperature swings and can have lower maintenance (depending on plant species). These also provide a quality space from which students can learn more about their environment.
I love the ideas behind greenroofs: green, low impact, sustainable- whatever you want to call it. It always seems like a no-brainer, putting a garden or a green space on a bare, underutilized rooftop to improve air local air quality, insulation, heat island, ecosystem quality, and educational opportunities, but it still meets much resistance. You are definitely correct in mentioning an additional cost to green roof implementation; it would seem to be the most unattractive factor in determining viability of these kinds of projects. It is the age old debate of short term costs vs. long term benefits…
ReplyDeleteAs educational institutions, I feel we must be the first in implementing these new, be it “risky” ideas. We have to begin thinking of our universities as places of research as well as education. Why can’t our experiments and theories be extended and implemented into the facilities of our campuses if we are the ones claiming them to work?
At Kansas State University, we have been lucky enough to actually host a couple, experimental greenroofs on our College of Architecture, Planning, and Design. However, they are still very small scale. I do feel that it is a step in the right direction and it would be really neat to see these further implemented on campus in support of a system that we have been preaching about in academics for years.
-B. Chmiel, Kansas State University
I agree with the comment above about greenroofs, some say they are unattractive but most I would say think they are aesthetically pleasing to the eye, they encourage people on campuses to look after them and to be proud of them. Here are some benefits that I found to these greenroofs.
ReplyDelete-Green roofs can improve the thermal resistance of the roof
assembly throughout the year, especially in summer months by helping to reduce cooling costs.
-Converting or designing normally unused roof areas into green roofs, simply makes sense. Increase your property value by reclaiming the fifth elevation of a building and make it an amenity to be used by the buildings occupants.
-More and more municipalities and other government agencies are providing incentives that can help off-set the cost of a green roof.
-Natural Habitat for Animals and Plants:
Green roofs create biodiversity, encouraging wildlife, such as birds, butterflies and insects, to remain within urban areas.
-J. Lennan, Kansas State University