Students at the School of Architecture and Planning, along with UNM professor Bill Fleming, are leading by example with their “green roof,” a unique rooftop garden that recycles rainwater and helps reduce energy costs.

The green roof has been atop George Pearl Hall for the last five years, Fleming said. It consists of several layers that collect and store rainwater, which is then used to water the “green layer,” made up of soil and native plants.

“When the new building was pre-planned I suggested that we have a green roof to demonstrate sustainable design and to demonstrate that we can capture water from the rooftop stormwater in cisterns and use that to water the green roof,” he said.

Aside from the benefits the green roof shows in the irrigation of water, the roof is also about 10 degrees cooler in the summer than another roof on the other side of the building that doesn't have soil and plants. In the winter it demonstrates a greater thermal capacity and insulation, and so it saves heating costs in the winter and cooling costs in the summer, Fleming said.

The aesthetic benefits of the greenery on the roof also have the bonus benefits of cleaning the air, he said.

By Nick Fojud

Community and Regional Planning professor Bill Fleming stands outside of the second floor roof garden on Tuesday, April 18, 2017 in George Pearl Hall. Fleming’s roof garden has been a five year ongoing project that is used as an example to what could be applied to other structures around campus.

Plants such as the grasses, shrubs, cactus and the wildflowers on the roof take carbon dioxide and other pollutants created by cars and filter them out, Fleming said.

“We have a problem with climate change and global warming, and so the roof is helping that because it's sequestering carbon — not allowing that carbon to go into the air, which causes the planet to heat up,” he said.

Fleming was able to receive a grant from a foundation for putting in the layers of the roof, putting the soil on the roof, planting the row and helping with long-term maintenance, he said.

There have been two students who work to maintain the roof each year, while learning about the benefits, Fleming said.

“Students have been involved in all of my classes. I've been asked to lead tours of the roof, and so I've led over 30 groups to see the roof and to explain to them about the benefits of it,” he said.

Fleming has had graduate students working on research projects on the roof and has co-written an article with a student titled “Viability of Living Roof Systems in Albuquerque,
New Mexico: Thermal Performance, Water Efficiency, and Carbon Sequestration Potential.”

“We want to demonstrate that we can use rooftop water that would otherwise go off the roof and into the streets and would simply collect pollutants in the street and transport those pollutants to the Rio Grande,” Fleming said.

Conventional roofs are built to last about 20 years and then have to be replaced. A green roof, with soil and plants on top of it, has been documented to last about 40 years, and that in itself pays for the cost of installing it, Fleming said.

Fleming’s hope is that the green roof will be a demonstration of what should be done on other buildings, and invites people to come see the roof themselves, he said.

“I want them to come on over and look at it and see for themselves how beautiful it is and to look at the posters that we have next to the roof that explain all of the environmental benefits,” Fleming said.

The students who are currently in charge of maintaining the roof are Juliet Isabella Smith and Ginaveve Pepin.

“The project itself is a huge step for UNM and sustainability within the fact that it helps keep the building temperature lower in theory,” Pepin said. “I definitely hope that UNM takes the progress of this garden and adds bigger rooftop gardens to buildings in the future.”

All the plants being used on the roof are native to New Mexico, she said.

“It is incredibly aesthetically appealing, which helps with sustainable design. It has been very successful so far, and I hope that it continues to be more successful and for the project to grow in the future,” Pepin said.

Smith has been working on the green roof for almost a year now, she said.

“The green roof is an incredible place that captures the beauty of our native landscape in a nine-by-nine foot plot of land,” Smith said.

Green roofs help insulate the internal temperatures of buildings, they can filter runoff water before it hits the streets, and if enough are built they can reduce the overall temperature of the area, she said. 

“I hope that one day the garden is more easily accessible so that everyone can see and feel the benefits it can bring,” Smith said. “On a stressful day I will hide up there for hours — just being in the presence of those incredible plants always makes me feel better.”

Nichole Harwood is a reporter at the Daily Lobo. She can be reached at or on Twitter @Nolidoli1.