A 6,400 square foot eco-roof on the new administration building for the Bend Metro Park and Recreation District in Oregon has been both green and white this month. Literally.
The surprise snow storm on October 4 blanketed the area with 4 inches of snow. But ordinarily, during fall in Central Oregon, landscapes remain green into November. However, the surprise change of seasons didn’t affect the operations of the eco-roof on the BMPRD administration building. The roof is engineered to support the weight of heavy snow and water from weather run-off.
For those that are new to the concept:
“An ecoroof is a vegetated roof system used in place of a conventional roof. Ecoroofs are comprised of several layers that include a root barrier, waterproof membrane, drainage, soil system, and plants. Similar to landscaping your yard, the viability of any ecoroof is dependent on many variables such as climate, exposure, soil and plant type, and initial maintenance. With those variables in mind, there are many design opportunities to transform a conventional roof into a beautiful, functional and beneficial space.”
The eco-roof on the new Administrative Building for the Bend Metro Parks and Recreation District includes hundreds of plants, which create a micro-climate to help provide insulation for the interior of the building from heat and cold. The planting bed is supported by a fiber-reinforced base structure with technology developed at Oregon State University.
There are several reasons an eco-roof for all seasons is a good idea.
First, as mentioned, a living garden on the rooftop can reduce the “heat-island” effect of regular roofing materials. Second, storm water runoff is minimized, because precipitation can be absorbed by the plants on the roof and funneled through small channels (vegetated swales) which are designed to mimic natural runoff in small creeks.
In some ways, its like having the benefits of an underground home, without having to construct the building into the side of a hill!
Executive Director of the Bend Metro Parks and Recreation District, Don Horton said:
“The direction from the outset was for a very green building, and one of our goals was to attempt to lead by example in utilizing the best sustainable practices.”
Fast facts about the eco-roof in Bend:
- Cost: $21 per square foot
- Plantings: drought-resistant perennials
- A sprinkler system will water plants during dry, summer months
- During winter months, the soil and plants will filter run-off which reduces erosion effects and the amount of sediment in wastewater
- The roof is engineered to withstand the weight of moisture, holding up to 20 pounds per square foot
- Waterproofing layers will protect the roof from moisture damage
I love this video that shows eco-roof engineering in Hawaii:
There are a number of eco-roofs that have been constructed in Oregon. Another one of my favorite examples of going green here is at the Torii Mor Winery, which has implemented both solar panels and an eco-roof at their facility in Yamhill County.
Have you seen eco-roofs in your community? Considered implementing the technology yourself? We’d love to read your comments below!