Again, I keep you project on my list and we talk again.
Jorg

Greek Treasury Green Roof saves 5,630 euros in energy bills in one year.

The “green roof” created on the roof the economy and finance ministry building in Syntagma Square has resulted in savings of 5,630 euros a year, the ministry announced on Tuesday. The savings arise from a reduction in power used for cooling, amounting to 3,600 euros a year, and a reduction in fuel used for heating by 2,030 euros a year.

The green roof was created in July 2008 and covers about 650 square metres, or roughly half the surface at the top of the building.

Measurements carried out by the applied thermodynamics laboratory at the National Technical University of Athens (NTUA) mechanical engineering department have shown that the difference in temperature between the areas of the roof with plants and those without are 18C, with the former reaching 37C and the latter 55C, respectively.

The measurements also confirmed that the energy savings from the planting amount to 9.6 percent for cooling and 4.4 percent for heating. For the top floor of the building, especially, the energy costs for cooling can be more than halved.

The finance ministry noted that the project was initiated to help improve the environment in central Athens, save energy and reduce the buildings operating costs, as well as acting as a model that might encourage initiatives by other private and public organisations.

http://www.oikosteges.gr
http://media.causes.com/ribbon/568189

Since the green roof industry started in the North America I realized that many people in this business are just looking for the big and quick bucks. They come from all kind of professions and hardly have any fundamental and long-term practice with hands-on experience in landscaping plus horticulture.
The ignorance of the North American people to well establish green roof guidance from Europe and the decades of green roof experience (more than 30 years) is an additional factor for many failures of American green roof projects.
The problem starts with the designers/architects continues with consultants, suppliers, general contractors, subcontractors, building owners and closes with governments, cities, Unions and associations.
The system in North America makes it very easy that – for example – a butcher, driving instructor, plumber, mechanic, student or just a talker etc. can get a sort of certification in green roofs consulting in less than 3 days. Sometimes it is even enough having some sort of plants related background or green history and you are accepted as a green roof expert. Another big bummer in America is that on each project there are too many people involved and too many want to say something. This drives the costs up and reduces the responsibility of a single person or company at the same time = nice breeding ground for failures.
I am not complaining – I am taking advantages of the system, too.
In this case and don’t listen since I am from Europe: If you do an extensive green roof in Toronto right -from the beginning- see above- you don’t need irrigation and waste your money. I also know from Europe that water is the most valuable resorce on earth and shouldn’t be wasted on green roofs.
jbi

If a client wants something more like a roof garden, it is the responsiblity of the designer to make clear that this will entail more maintenance as well as a more complex system usually including irrigation.

A green roof can be a practical solution in many cases–for stormwater management, for aesthetics/amenity space, for some saving on energy costs. But a green roof is not appropriate for every project, and no roof, including no green roof, is no-maintenance. If the owner will not commit to maintaining the green roof–maintenance on an extensive roof once plants are established should not be terribly difficult or expensive, but it should be done–then a green roof should not be part of the design.

I have now read this entry 3 times. Thanks for your deep insight and research regarding the potential liabilities of green & vegetative roofs. I am working as hard as I can to help the insurance industry stand up and take notice of the issues at hand and the most effective ways to manage these emerging risks. If new building technologies such as vegetative roofs are able to achieve their expected benefits for reducing energy consumption and reducing storm water runoff, than the insurance community should be working to encourage best practices amongst the construction and development community to foster profitable growth and avoid potential claims. Failure to be proactive now will result in situations like the one you describe above hundreds of times over. In cities that are either encouraging or even mandating green roofs, the insurance community has the responsibility to monitor the construction and development teams to protect both their exposure as well as the public health and safety.