St. Paul’s Penfield green roof. Angie Durham, AD Greenroof LLC, St. Paul, Minnesota, reviewed one of her projects, the 6-story, 254-unit Penfield apartment complex in downtown St. Paul. The city-owned LEED project is the first new downtown construction for a while. Angie’s firm monitored the 12,000 sq. ft. green roof that was installed in late 2013 as an amenity and for stormwater performance. The city’s stormwater rules require that construction of 1 acre or more must retain 1.1 in. of stormwater. The roof was constructed over a heated garage. Media depths vary greatly and can reach 36 in. where trees are planted. The roof construction uses recycled and regional products as much as possible and features drought tolerant and native species. Perennials in no specific order include liatris, rudbeckia, perennial salvia, nepeta, echinacea, solidago, carex, schizachyrium and deschampsia. Trees and shrubs include populus, quercus, salix and physocarpus. Unlike most traditional green roofs, plants went in as 1-gal. or even larger.
Angie’s post-installation monitoring found the roof retains 80% to 90% of rainfall. Compared to the conventional roof at the same site, both the 8- and 16-in. media profiles retained the vast majority of rainfall, greatly exceeding the 1.5-in. retention requirement.
The maintenance crew for the building irrigates the roof on an irregular schedule, perhaps often when it’s not needed. She’s not sure at times how that played into her results. Starting out, she believed that the 16-in. soil profile would retain more water than the 8-in. profile, but her results didn’t show that. She believes irrigation may be the reason. The courtyard is maintained every two weeks. There’s a lot of mulch that’s been added, too.
Angie also monitored the roof temperature. The green roof showed little temperature fluctuation compared to the conventional roof, meaning that it will likely have a longer useful life.
Bird, biodiversity-friendly Toronto. Great resources mentioned: For encouraging urban biodiversity and wildlife-friendly buildings — City of Toronto Guidelines for Biodiverse Green Roofs supplemental to their green roof guidelines and Toronto’s great new publication on Bird Friendly Best Practices Glass.
We are in public health. Gail Vittori, Co-director, Center for Maximum Potential Building Systems, challenged the audience to realize we all are public health practitioners. Since early research by Roger Ulrich (“View through a window may influence recovery from surgery”) showing that gall bladder patients with a view of trees healed faster and used less medication, it’s taken a while to embed living plants and green into design thinking. She closed saying that healthcare facilities guidelines that inform billions of dollars of healthcare construction now include language instructing the design to connect every healthcare project to nature. She cited results from a post-occupancy evaluation of Dell Children’s Medical Center of Central Texas that showed a 5% boost in employee engagement and employee health and wellbeing and a 6.5% decrease in turnover.
Managing stormwater with food production and food security. Michael Sanchez, Assistant Professor, Landscape Architecture, University of Washington (UW), encouraged the audience to look for opportunities to incorporate multiple goals to help underserved communities by incorporating food production and stormwater management into projects. Michael seeks to create a scalable model working with an interdisciplinary team at UW that includes economists and a civil engineer. Urban agriculture can become part of the decentralized stormwater treatment train, he said. In the process, food security in underserved neighborhoods may also be addressed. Rooftop agriculture, he said, is primarily an eastern phenomenon—Brooklyn Grange, Gotham Greens, the Whole Foods in Lynnfield, Massachusetts. On the west coast, it’s restricted more to small, restaurant-scale and community farms. While rooftop agriculture is an opportunity, Michael’s goal is to look at how to incorporate urban agriculture on a larger scale. He asserted that Serenbe in Chattahoochee Hills, Georgia, has elements that could be adapted elsewhere. “The broader movement is finding more authentic ways of placing food sources into development.”
Selecting plants for green facades. Green Screen publishes a great guide to functional plants for creating living screens. The list of vines is indexed by hardiness zone, height and horticultural features. Leaf area determines how well the vine will shade a structure. The company advocates selecting the right plant for the purpose by making sure growth will match the installation. Plants suitable for screening a parking garage in one location may not be good for decorative columns in another. In some areas, controlling plant growth may be the issue where growth is vigorous, like the south. Vines change through the seasons and can offer multi-season interest, but must also be matched to client maintenance expectations. Using multiple species and native plants will increase success. (Guidelines for Green Façade Plant Selection)
Living Architecture Performance Tool. The Living Architecture Performance Tool is currently a series of white papers, so it’s not yet complete. But, hopefully, it can be completed in the next two years, said Sara Loveland, Chair, Green Infrastructure Foundation and a partner at Annette Environmental. The Living Architecture Performance Tool is to help quantify the benefits of vegetated technologies used on the interior and exterior of buildings. It will help to quantify the complex benefits they provide. Green roofs and green facades will be the first vegetated systems to be included.
The Performance Landscape. Barbara Deutsch, Director of the Landscape Architecture Foundation (LAF), talked about their online tools to help position the landscape as a functional part of our sustainable future. LAF works to bridge the gap between research and practice. Landscape performance can be measured, Barbara said. Landscape features can provide a number of functional benefits. LAF’s website includes more than 100 case studies for reference. They’ve also assembled collections of curated content around themes. If you’re looking for a very enjoyable way to spend a couple of hours, check out The Landscape Performance Series site.
U.S. Coast Guard Building roof is cooler. How does the U.S. Coast Guard Building’s 12.5-acre green roof compare temperature-wise to traditional roofs? To find out, temperature readings were taken once an hour for three months by a University of Maryland research team under direction of Dr. Christopher Ellis. What they found: The traditional roof heated up faster and retained heat longer than the green roof. The findings are that in July the sedum green roof reduced surface temperatures by 4F and maximum surface temperatures by 12F. In July, the tall grass green roof reduced surface temperatures by 4F and maximum surface temperatures by 10F. The entire site in July was 1.6F cooler compared to the modeled average for a nearby building complex. The U.S. Coast Guard Building’s green roof retains up to 424,000 gal. of stormwater (1.7 in. rain event). Trees on the roof, 985 of them, intercept 234,000 gal.; at maturity, that number will jump to 766,000 gal. Those same trees will sequester 883,000 lbs. of CO2 annually at maturity (153,000 currently). Rainwater harvested onsite and used to irrigate the landscape saves 520,000 gal. of potable water that would have to be purchased. The andropogon-designed landscape includes a high proportion of native trees and shrubs compared to nearby office complexes. The study has been published as an LAF Landscape Performance Series Case Study.
Biophilic views bring more green. Catie Ryan, Terrapin Bright Green, New York, New York, said that research by Trip Advisor of 100 hotels (50 resort/50 urban) showed that hotel rooms with a biophilic view of water go for higher prices—a 16% premium at resorts vs. views of a garden or “other views.” In urban areas, rooms with a view of water or a famous landmark have a 12% premium over “city” views. Rooms with a view of a garden or park have a 2% premium. The research, she said, did not include how “occupied” these rooms with a view were relative to other rooms. The concept, she said, raises the opportunity of looking at biophilic design elements that can boost revenues by causing people to want to hang out at a bar longer or to buy spa services.
Green roofs in the treatment train. Green roofs can be part of a larger stormwater treatment train, encouraged Dave Yocca, Conservation Design Forum, Lombard, Illinois. His premise: Look at water as a resource throughout the design process. For instance, Advocate Lutheran General Hospital in Park Ridge, Illinois. A 3-acre site that was formerly outdoor garden space and stormwater detention became a LEED-certified hospital addition in 2009. Located in the Des Plaines River Watershed, Dave and the project team began with asking how rainwater can enhance the landscape. The goal: Keep 90% of rainfall onsite by optimizing every surface. Using bioretention and green roofs, the site can handle up to 1 in. of rain with no discharge. Some of the green roof areas flow into planters. Natives and adapted species were a vital part of the design to conserve water. The hospital didn’t want a “wild” look, however. The design called for about 31,000 plants, mainly perennials and grasses, about 2/3 native (almost half of those to Illinois). (The Advocate Lutheran General Hospital case study in the Landscape Performance Series)
Just going for the credits. In D.C., said Brian Seipp, Center for Watershed Protection, using green roofs as part of a treatment train is difficult due to space constrictions. Currently, many green roofs are connected to cisterns. Also, the harvested rainwater doesn’t earn credits if it’s used to irrigate the green roof — it must be used on another landscape. They’re seeing, he pointed out, “super-deep green roofs on super small spaces.” Trees are also being planted for the canopy tree credit. As a result, quite a number of trees are being planted inappropriately. There’s a lot of focus in the city to mobilize private landowners to help the city meet their stormwater permit requirements.
December 1, 2016 NewTerrain.