After 19 years of work, Penn has installed the final piece in an 18,700-foot jigsaw puzzle.
This past weekend, officials completed the last leg of a system of underground pipes that will change the way Penn provides air conditioning.
The $125 million project, started in 1988, will connect all University buildings to a single network of pipes - 40 to 60 inches, and lying as low as 20 feet underground - that carries chilled water.
This water will then be used to circulate cool air through indoor rooms. Three main plants will produce the water, according to the principal planning engineer, Joe Monahan.
"By centralizing the cooling towers, it's easier to perform maintenance on the equipment, [which] leads to reduced capital costs," he said. "Architecturally, it also eliminates a lot of the cooling towers which were clogging up every building's rooftops."
And the 19-year project also ties into the University's broader sustainability plans.
Monahan said that "consolidating all of the individual coolers into central plants helps cut down on energy usage."
"Because we have sensors around campus, we're able to give air conditioning on an as-needed basis."
And the construction of three new chiller plants - with the largest of these, called Mod VII, located near Murphy Field at the south of campus - will also help, Monahan said.
"The chilled water demand was rising because of a research push by the University," he said. "We quickly realized that the growth of the research buildings would tax the older plants."
Newer technology has also allowed the University to produce ice in certain plants at night, when the demand and price for energy is lower, and use that ice for cool water during the day.
And while student environmental groups are pleased with the improvements, some say other changes may be needed.
College senior and Penn Environmental Group member Nishi Shah said Penn needs "to set up a system of accountability for individual buildings' resource consumption so each building has reason to reduce its heating and cooling bills."
And trying to figure out exactly what those cooling bills would be proved a challenging aspect of the project, said William Trefz of Trefz Engineering Inc. He added that planners had to "predict what would be in the best interest of the University 30 years in the future."
To solve that problem, officials made Mod VII easily expandable, allowing for future construction as Penn pursues eastward expansion, said Trefz, who has worked with Facilities on the project since 1989.
"We're planning two additional chillers [in Mod VII] that will bring up the total production to 30,000 tons of cooling, but the plant can produce 50,000 tons," he said.
One ton can cool 500 square feet of living space.
"We can also adapt the plant to different energy types."
And for Trefz, solving that problem and finishing the project after two decades of work "is very fulfilling from an engineering point of view," he said. "You can't really explain it."
