Student Intern Column: Sustainable Design and Green Roofs

Dejope Residence Hall Green Rooftop, from University Housing

Jackie Olson is a junior majoring in Landscape & Urban Studies/Environmental Studies and a future designer of sustainable architecture. She began her internship for the Office of Sustainability in summer 2018 on the Waste & Recycling Team and since then has found herself collaborating on multiple teams such as Green Greeks, Green Office, and the up-and-coming team Green Allies.

Throughout my studies in Landscape Architecture and my work at the Office of Sustainability, I have come to understand how we can create beautiful facilities through the principles of sustainable design. Sustainable design is centered around the concept of creating spaces that meet the needs of human use, support existing ecosystems, and ensure that all life forms  maintain the ability to thrive.

Typical urban development puts a strain on a variety of natural resources. Heavily industrialized societies create factories, buildings, and other structures that end up releasing dangerous chemicals into our atmosphere, including greenhouse gases and pollutants. These structures also require significant energy extraction. By coupling development with sustainable design, however, we can alleviate many of the negative impacts of urban development.

Let’s take the example of a Green Roof. A Green Roof is composed of a vegetative layer of shrubs, grasses, trees, and other plants that reduces the temperature of the roof surface and the surrounding air, as well as improves stormwater management. Green Roofs are used specifically to combat “urban heat islands,” which arise when roads, buildings, and other infrastructure create large expanses of land where “surfaces that were once permeable and moist [have] become impermeable and dry”. This change causes an accumulation of heat compared to less developed areas. 

An illustration of an urban heat island. Image credit: NASA/JPL-Caltech.

In addition to their heat and water-related benefits, green roofs are often designed so that they can be viewed from the inside of the building. This allows for increased human interaction with nature by introducing green space into the built environment. Studies have shown that such connections to nature “benefit human physical and mental health and productivity, and reduce blood pressure and hospital stays.” In addition, Green Roofs provide comfortable spaces for workers and community members to enjoy, relax, and feel at peace. Keeping our communities happy and livable is imperative if we want to sustain them in the present and the future.

How Green Roofs Work

Green Roofs utilize multiple different materials, living and nonliving, to mitigate higher temperatures, provide cleaner air, hold and reduce stormwater runoff, and provide visual relief. Green Roofs replace the design practice of creating conventional roofs, which are commonly made of materials such as slate, rubber, and fiber cement. Conventional roof materials are often black, dark gray, and dark brown in color, causing the surface to absorb much of the heat radiation from sunlight. Green Roofs, in contrast, regulate a building’s internal temperature and furthermore lower air pollution. The plants engage in their day-to-day biological cycles including evapotranspiration. The physical structure of plants allow them to absorb heat energy from the sunlight that would otherwise be absorbed by the roofing material and surrounding air. Since these plants reduce the temperature of the roof, the building is able to consume less energy in order to cool it internally. The plants used on Green Roofs can also capture airborne pollutants and filter harmful gases. By improving air quality in two ways—reducing the amount of energy needed to cool the building, and growing plants that can filter toxic substances in our air—Green Roofs allow for the ecosystem to thrive and for future generations to come into a life-supporting environment. 

Green Roofs also provide structure for stormwater management. Conventional roofs typically use the same material throughout and do not have any stormwater holding features—meaning the water immediately runs off the roof and down the gutters, which may flood the surrounding areas. Rain falls on whatever exists below it and eventually finds its way into a watershed. During the water’s journey, it collects and picks up  chemicals, particles and other materials. Often these materials are harmful to our ecosystems.

A map of the Yahara River and its watershed
A map of the Yahara River and its watershed in southern Wisconsin. (Wikimedia Commons)

For example, Madison, WI is situated in among four lakes and surrounded by a great deal of agricultural land. When it rains, phosphorus from agricultural chemicals, manure, and so forth trickles back into the watershed and into our lakes. The increased phosphorus in the lakes disrupts the food chain, allowing cyanobacteria (blue-green algae) to multiply in mass quantities. The algal blooms that occur due to pollution in stormwater runoff are harmful to animals living in the lake and to humans  who dare to swim during a bloom. Green Roofs help to alleviate these issues, because they are able to store stormwater in the plants’ root systems as well as act as a filter for the water that does run off. 

Green Roofs on the UW-Madison Campus

Education Building
A great example of a Green Roof implementation exists right here at UW-Madison. This vegetative rooftop was constructed on the surface of a parking lot behind the Education Building. The goal of this project was to redevelop an area of campus to address green infrastructure goals and meet regulatory requirements. Furthermore, UW-Madison wanted to reduce the environmental impact of stormwater runoff by modifying their land use wherever possible. As stated earlier, stormwater runoff contamination is a huge problem in Madison, WI.

Education Building Green Rooftop, from the UW-Madison 2015 Campus Master Plan
Education Building Green Rooftop
UW-Madison (Photo from 2015 Campus Master Plan.)

Before this project, the space was occupied by a paved surface. By planting elements of a Green Roof in this space, the University was able to modify this land to improve the volume, rate, and quality of stormwater runoff. This site is very close to Lake Mendota, making it a perfect spot to target for reduced pollution. In addition, the outdoor space at the Education Building has been used and adored by members of this university, including students, faculty, and members of our Madison community. As students, we spend multiple hours per day in classrooms and libraries. This Green Roof provides a space for students to engage in an outdoor green space, whether for academic or relaxation purposes. From my own perspective, I have appreciated the time I have been able to spend on this roof receiving a little more sunshine and visual relief from the hardscapes I am constantly surrounded by. 

School of Human Ecology
Another very special example of a Green Roof on campus is located on the top of the School of Human Ecology Building, otherwise known as SoHE. This building underwent various renovations and expansions about a decade ago and was officially reopened to students and faculty in the Fall semester of 2012. UW-Madison’s head Landscape Architect, Gary Brown, worked alongside Saiki Design firm to develop a site plan and implement the design. The location of the green roof on SoHE provides a unique view of Henry Mall and West Campus. The goals of this Green Roof are very similar to the goals of the previous one: reduce the effect of urban heat islands, improve stormwater management, and offer visual relief for the UW-Madison community. I find it quite fitting that the roof was fitted for this location, as the entire school is focused on Human Ecology and increased exposure to green space has been scientifically proven to promote human health and well-being. 

School of Human Ecology Green Rooftop UW-Madison (Campus Planning & Landscape Architecture)
School of Human Ecology Green Rooftop
UW-Madison (Photo courtesy Campus Planning & Landscape Architecture.)

As seen in this photo, the roof was constructed of durable materials that will withstand time yet also contribute to the character of the gathering space. “Ipe” decking is seen on the sections of wood-paneled floor, along with granite pavers throughout and patterned squares of sedum plants along the perimeter of the roof. Wooden benches and a pergola provide seating and a slightly covered area to enjoy, while moveable tables and chairs allow for freedom of choice within the space. Native Wisconsin plants offer users and viewers the feeling of truly being outdoors and engaging with nature. As I said, this Green Roof is very special to me and other Office of Sustainability student interns; we frequent this location to get a change of scenery and accomplish work outside, when the weather permits. I personally find this to be one of the best designed Green Roofs on campus in terms of multiplicity of use, layout, orientation and plant choice/diversity. For those on campus who have not visited this site, I strongly encourage you to within the next month so that you can reap the benefits that this Green Roof is so generously providing to us.