When it was time to replace a 10,000-square-foot area of the roof at the Badger Meter headquarters, the flow measurement and control solutions provider considered its options to find the most effective solution. After several months of research, Brian Rogers, Badger Meter facilities manager, and his team determined a green roof was the best option. A key benefit of a green roof was water retention. During a rainstorm, green rooftops collect and store water that would otherwise run off into the sewer. “We wanted a solution that would be innovative, efficient, and all-around better for the company,” says Rogers. “The green roof not only makes sense from an environmental standpoint, it was a sound economic choice.”
Installation began last July and was completed in November 2012. The new green roof is expected to reduce the annual runoff into the storm water system (an estimated 249,000 gallons) by as much as 90 percent and delay the remaining 10 percent to a time past peak flows. For every 1 inch of rainfall, the green roof collects just under 6,000 gallons of water if it is dry. If it is saturated or frozen, some of the water will run off. By keeping excess water from roofs, parking lots, and impervious surfaces out of the sewer system, the company is helping reduce the risk of basement backups and sewer overflows. Green roofs also help prevent rain from becoming polluted stormwater runoff.
Since 2003, the Milwaukee Metropolitan Sewerage District (MMSD) has been awarding green roof incentive funding to building owners to help reduce the volume and number of sewer overflows to waterways. Badger Meter was awarded $48,135 through MMSD’s Regional Green Roof initiative program to pay for part of its green roof project.
Rogers says the company is using its own metering technology to measure the water absorption. A global leader in the development of flow measurement products, Badger Meter installed two of its 2-inch M-Series® Electromagnetic (mag) Flow Meters and a controller, so it can measure the outflow from each of two roof drains. It also mounted a weather station on the rooftop to measure rainfall.
“With the possibility of rocks, sticks and debris coming down the drains from the roof, our mag meters are perfect for this application because of their open flow tube design and high accuracy,” explains Rogers. “Once the weather stations are fully integrated into our software system, we’ll be able to determine how much rain the roof is absorbing on a per event basis. We’ll also be able to measure how fast it recovers after a rainfall.”
Other sustainability benefits of the green roof include energy efficiency, noise mitigation and air scrubbing. The insulation properties of the soil and plant material generate both heating and cooling system savings estimated at $3,100 per year or $62,000 over 20 years, the typical lifespan of a conventional roof. Plants, soil and the air trapped in the soil provide acoustic insulation, reducing indoor sound by as much as 40 decibels. The green roof buffers acid rain and helps remove nitrate pollution, while at the same time slowing air movement, allowing pollution to settle and detoxify. Plus, the plant material guards the roof membrane from the damaging effects of weather, so the expected lifespan of a green roof is 35 to 40 years; double that of a conventional roof.
The green roof consists of a 3-inch layer of insulating materials, a layer of hard board, a sealing membrane, a leak-detection material and a 4-inch layer of green material. Langer Roofing and Sheet Metal, Inc. handled the design, tear-off of the old roof, and installation of the conventional portions of the new roof. LiveRoof supplied the green material. Green material is custom grown for each green roof project off site in modules for about 12 weeks. Because the LiveRoof plants are mature, there is no costly establishment period, according to Badger Meter.
The vegetation is primarily sedum, which is selected, developed and tested specifically for rooftop cultivation. The plants require minimal maintenance and are resistant to disease, insects and drought. Several varieties that are green and red in color are arranged in a design that mimics the Badger Meter logo and is visible from above.
“We are continually looking for ways to improve our operations, so we are considering converting another section of roof that needs replacing to green roof,” says Rogers. “This is just one of many sustainable building upgrades we are working on, including a significant LED lighting retrofit, a low flow water-saving project, and many others.”