Desert Garden in Atlanta's Sky
Over the past 10 years, one of the most important trends in Facility Management has been the increased focus on “green” – both in constructing new buildings and in maintaining those facilities once they have been built. As the public becomes more aware of the way humans affect the environment and are affected by it, it has become imperative that a facility manager respond to these concerns in innovative and pro-active ways.
New, eco-friendly ideas range from making changes as small as eliminating bottled water from vending machines (asking employees to drink filtered water instead) to retro-commissioning aging buildings for improved energy efficiency and significantly lower utility bills. One of the most interesting and innovative has been the creation of green roofs – gardens at the top of our cities’ buildings. These sky gardens help prevent water run-off, reduce heat-island effect and provide a relaxing place for a building’s inhabitants to break-up their workday.
The concept of a green roof is still fairly new. They offer challenges for facility managers both in their construction (how do you make sure your building can stand the weight of all that extra dirt, water and plant-life?) and in all the brand new maintenance issues they bring up – this is definitely not the kind of roof you want to have spring a leak! One of the first facilities in the South East brave enough to jump into the unknown and put a green roof on their building was the Atlanta City Hall, which did so in 2003. Members of the IFMA Sustainability Committee took a tour of this green roof recently — learning much from both its successes and failures.
We were very lucky in the weather we had while on the tour — while we were on the roof the temperature was in the 60s and there was a slight breeze. The first thing I noticed when we walked out was how similar much of the vegetation was to what I had grown up with in the semi-arid region of Southern California. There were cacti, junipers and sedum. The reasoning behind the use of non-native (to Georgia) species of plants is that the windswept conditions at the top of city hall are not “natural” and native plants may not survive them. The 3000 square foot roof area is exposed to constant wind, is mostly unshaded, and there is no irrigation system installed. In a lot of ways, city hall’s roof actually is a very similar to the type of environment that you might find in Southern California, hence the choice in plants.
Even on the roof, though, there are actually several micro-climates. There are a few areas that get a lot of shade, and in those many of the plants that are dried-out or dying in the main sections seem to be thriving. Other areas are occasionally shaded by tall skyscrapers, and in these areas certain species like Rosemary thrive (it does not do so well in the completely unshaded areas). North Georgia’s drought has taken its toll on the green roof in general, killing off many of the plants that had once taken over most of the available soil.
It would be interesting to hear how much more or less maintenance is involved in maintaining the green roof when compared to city hall’s more conventional roof tops. According to Bill Brigham, the project’s landscape architect, maintenance of the plant-life on the roof only requires an average of about one hour per month. Since the roof is Xeriscaped – meaning it uses drought-resistant plants – no watering is required outside extreme circumstances (I believe they have watered the area a few times over the course of the drought in order to keep all of the vegetation from dying). Other janitorial tasks are also required – including a constant vigilance against cigarette butts. Even though smoking is not allowed on the roof, the close proximity of city council and the courts don’t seem to stop people from lighting up. The city has installed cigarette disposal bins on the roof, but there are still butts lying all over the ground which need to be picked up regularly.
There are other challenges to maintaining the green roof which were probably not considered when it was first installed. One of these is the way it was affected by the pressure washing the building recently underwent. The individuals doing the pressure washing needed to use scaffolding which required counterweights be placed on the roof. These were thrown in the middle of the roof garden, and ended up killing many plants over the course of the month this work went on – the plants just could not withstand being crushed by the 500+ pound counterweight. Another challenge has been finding the right mix of plants in a constantly changing climate. What works well in a drought might not be the right set of plants in a more normal circumstance and vice versa.
Being able to see a green roof up close and personal was a fantastic experience. One of the best things about this one is that anyone can go see it – it is open to the public and accessible from city hall’s 5th floor cafeteria. This is one case where Atlanta was truly visionary – doing something here first that the rest of the world has been able to learn and improve from. As more facility and property managers start to see the benefits of going green, I believe we will eventually see sky gardens like this one pop up all over Atlanta and the rest of the country. I can hardly wait!