Growing the Campus and Shrinking Emissions at the Same Time
Campus emissions from energy use fell by 42% while campus grew significantly
鈥淲e鈥檝e made very important progress towards carbon reduction through transformative investments in the University鈥檚 energy infrastructure," said Duke Executive Vice President Daniel Ennis. "These investments have been essential in meeting Duke鈥檚 carbon neutrality goal, but the effort is so much larger and has counted on, amongst many actions, the efforts by so many in our community to carefully consider the carbon footprint of their commuting and travel patterns.鈥
If you've ever had to buy a new HVAC system for your home, you know it can be pricey. The biggest portion of Duke's energy savings so far have come from upgrading a third of the campus鈥 heating and cooling systems. Hot water is being installed to replace steam heating, and air conditioning was centralized in three chiller plants, saving 10 percent of electrical demand.
鈥淪o far, just the hot water conversion work has cost about $73 million and it will take less than 10 years to pay for itself,鈥 said Russell Thompson, executive director of utility and engineering services for Duke Facilities Management Department.
From Coal to Gas and Steam to Hot Water
It all started at Coal Pile Drive behind the hospitals, which came by its name honestly; until 2011, there was in fact a pile of coal there. Duke has converted that coal plant to natural gas to make steam for West campus and the medical center.
That was just a first step, however. New investment is now enabling a transition to using hot water in place of steam. The distribution of 350-degree steam heated Duke's buildings and made sterilizing lots of surgical instruments in the hospital a snap. A tiny whiff of it also helped library humidity stay just right, but it's a bit of overkill these days.
鈥淪team distribution was state of the art in the 1920s,鈥 Thompson told Working at Duke. "But it鈥檚 not the best technology today.鈥
About half of the buildings on campus don't require as much heat as steam provides. They can get by with 150-degree water instead. Steam is still being produced for buildings that need the high heat content that steam provides, and where it can be, the steam is now being used to make hot water. The system relies on the two older utility plants and an entirely new hot water system with 4.5 miles of pipes so far.
Conversion to hot water can drop a building's heating bill up to 30 percent, while also freeing up about 500 square feet of space that the steam system required. Maintenance for hot water systems is also vastly cheaper, safer, and easier to manage. The efficiency gains of the hot water conversion are already avoiding 3,100 metric tons of greenhouse gas emissions each year, approximately 2% of Duke鈥檚 overall energy emissions in 2024.
The next gains will come from heat pumps. A heat pump will be installed that can capture the residual warmth from the 100-degree water coming from chilled water plants and use a small amount of electricity to help get the water up to 150 degrees for a warming lap around campus. Thompson said that one system could save up to an additional 15,000 metric tons of greenhouse gas emissions annually (the equivalent of 3,000 U.S. homes' annual electricity usage), and he's eyeing perhaps a couple more.
When every space that can be converted to hot water has been completed by around 2035, "we would expect to reduce our emissions by over 60,000 metric tons of greenhouse gas emissions per year," Thompson said. This is the equivalent of the carbon captured annually by 70,000 acres of forest land (10 times the size of Duke Forest).
The Fuqua School of Business and the Law School are currently undergoing the conversion to hot water.
鈥淓ast Campus is still a bit of an unknown and will likely involve some hot water conversion and some electrification,鈥 Thompson said. The problem being that these really old buildings require more extensive work to remove the original steam radiators.
Chilling and Conserving Water
On the chilling side, chilled water plant #2, which is mostly hidden by trees between Circuit Drive and Erwin Road, was expanded to more than double its cooling capacity to 40,000 tons (a typical home is about 4 tons). The plant attained LEED Gold certification, the second-highest certification available from the U.S. Green Building Council, in part by switching from using drinkable Durham city water to using captured and reclaimed water, some of which rests in the 5.5 acre pond and recreation area south of the chiller plant at Circuit and Towerview. Using pond water in the plant鈥檚 cooling towers has saved about 100 million gallons of Durham drinking water per year.
On Anderson Street across from the Duke Gardens, a 60-foot-tall tank holds 5 million gallons of cold water. The water is chilled to 39 degrees Fahrenheit in the hours of the day when electricity is cheaper, and then piped around Duke's hospitals and other buildings when AC is needed during the day and electricity costs are higher. This one small step of using off-peak energy saves the university up to $500,000 a year.
Efficiency at the Edges
That's the obvious work. Less obvious perhaps has been the steady replacement of campus buses and other vehicles with new hybrids and electrics. Existing buildings are also being retrofit to work even more efficiently.
"It's what I call around-the-edges energy efficiency," said Tavey Capps, the executive director of the Office of Climate and Sustainability, who has been working on the climate neutrality pledge ever since joining the university as an environmental sustainability coordinator nearly 20 years ago.
The less obvious efforts include temperature controls and scheduling with 'smart building' technology, refitting interior lighting with LED fixtures that require much less energy, and employing a sophisticated, computerized utility monitoring system for the whole campus.
"Because we use our buildings in so many different ways, and people move in and out, you can use the smart controls of a building to perform better as functions change," Capps said.
New buildings that came online during the pledge, including the Rubenstein Arts Center, the Blue Devil Tower at Wallace Wade Stadium, Grainger Hall, the Trent Semans Center, and Wilkinson Hall, were built to high efficiency standards. Grainger, the home of the Nicholas School of the Environment, features 45 kw of solar power and a 15kw solar hot water system that helped it earn LEED platinum status.
Making Culture Change
In the early going, the commitment and investment came from the top. Executive vice president Tallman Trask III took a personal interest in efficiency and greening the campus and hired staff to make it happen. Trask understood the need to make significant investments in utility infrastructure and efficient buildings. Duke鈥檚 first sustainability position was created in the EVP office.
As Duke set ambitious carbon goals, the leadership of operational departments like Facilities Management have engaged deeply in Duke鈥檚 sustainability strategic planning and spearheaded this infrastructure work across campus. "I think we've embedded it so much that it has been sustained over time," Capps said. "It's not just coming from one office or a couple of people."
鈥淲e are working toward a culture where concerns about climate change and interest in sustainability and the efficiencies that come from it, are part of our day-to-day operating culture, not just in facilities, but across the entire institution,鈥 said Toddi Steelman, Vice President and Vice Provost for Climate and Sustainability.
"We've reduced many of the things that we can invest in and make real change -- we've cut energy emissions by over 40% since 2007," Capps said. "There's real money and real intent behind that.鈥
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