In Portland Oregon, the Hayden Meadows WalMart’s 92,000 square foot roof is a green roof experiment. 40,000 square feet of the roof is divided into 3 sections each with different soil depths, the rest of the roof is the standard roofing materials for a flat roof for a control section.
Portland State University’s Green Building Research Laboratory will be comparing rainwater absorption and cooling benefits. WalMart gave the university a $133,000 grant to spend the next two years collecting data from the rooftop weather station and sensors in 3 different sections of the roof.
Able to do side by side tests
The students will test the temperatures of the soil to determine if the green roofs lower the urban air temperatures, help reduce the cost to cool the interior of the building and reduce rainwater runoff into the city drains.
Other area agencies are taking advantage of the unique situation of the 3 different soil levels and control section for further green roof studies.
- Portland’s Bureau of Environmental Services also are taking part of the Walmart green roof study by comparing the amount of storm water runoff in the 3 different sections allowing a side by side comparison.
- An environmental consulting company, Cadmus group will be testing the green roof’s cooling properties to determine the efficiency of the buildings air conditioning units.
- Portland Audubon Society will be counting the number of birds that visit the vegetative green roof.
Walmart designed the roof with research in mind to determine if they can cut the cost of doing business. The WalMart spokesperson said they are hoping to determine the best climate for the green roofs to save the most money.
