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University Gazette

The University of North Carolina at Chapel Hill

Energy-saving strategies net $10 million savings

From left are building commissioning technician Todd Freeman, data analyst Jessica O’Hara and energy management director Chris Martin in front of the Mary Ellen Jones Building, where energy-saving measures now yield $200,000 a year. They are part of a team that has helped save $10 million across campus.

 

Most people do not like being asked to do the impossible.

But Christopher Martin Jr., the University’s director of energy management, is not like most people. He is a mechanical engineer, a discipline that methodically applies the principles of physics and materials science to analyze how mechanical systems work.

Recently, Martin was asked to figure out how to make the heating and cooling systems in campus buildings operate more efficiently. “We salivate for opportunities like this to find out what we can do,” Martin said.

It was April 2009 when Martin’s boss issued this audacious goal: In the next two weeks, put together a plan to save 15 percent of energy costs; then have that plan in place by the time students return to campus in August.

Martin had only $200,000 to fund the pilot project that, if successful, held the potential to save millions.

By almost any measure, it was mission impossible, and Martin knew he would need an arsenal of secret weapons to pull it off. Martin found just that on the day he met with a group of HVAC experts to enlist eight volunteers who would form four, two-member teams to implement the project.

Todd Freeman was one of the secret weapons. “I did not volunteer, I was volunteered,” he said.

Freeman is now the only one of the original eight still assigned primarily to the project, which has yielded a cumulative savings that inched past $10 million at the end of 2011. A broad team of HVAC experts support the program as part of their normal job duties.

As for the 15 percent goal, the group didn’t hit the mark – they soared past it, Martin said. From July 2009 through October 2011, energy consumption has dropped by an average of 24.7 percent.

“When we first started this, I thought 15 percent was the best we could hope for,” Martin said. “Now, I wouldn’t want to put a limit on what might be possible.”

Optimizing performance

Too often, people think the only way to achieve dramatic savings is to spend money on the latest, best equipment, Martin said.

“We didn’t have the money to do that so we had to optimize the performance of the equipment we already had,” he explained. “It sounds simple, but there are very few people in the country with the range of diagnostic skills and experience who can do that.”

And that’s where Freeman’s skill set was so crucial, Martin said. “He’s one of the few who understands what needs to be done and can do it,” Martin said.

One cost-saving strategy Freeman has implemented is to reset the temperature of supplied air to keep the air as warm as possible without overheating spaces or causing high humidity.

Equipment is also reprogrammed to operate with lower airflow, an adjustment that allowed the system to be turned down further to save energy, Martin said. Another key factor is to activate or optimize economizers – dampers that use pre-cooled air from outside to reduce the cost of cooling air mechanically. Hence the name economizer, he said.

The economizers, however, were not turned on in most buildings because HVAC crews feared exposing chilled water coils (which are like car radiators) to freezing temperatures that could damage them and lead to the need to replace them.

To address that concern, the four teams calibrated all actuators and sensors on each air handler to ensure that freeze protection devices were working properly, Martin said.

Another strategy is to eliminate the practice of heating and cooling buildings on the same day when it is not necessary to do so.

As Martin explained, “In the summer, we were often cooling our buildings down to 55 degrees in order to dehumidify them – even on days when they didn’t need to be dehumidified – and then heating them back up to a comfortable temperature.

“It was kind of like driving a car with one foot on the brake and the other on the gas.”

Martin said the energy plan also took advantage of new building schedules created as part of the Climate Action Plan the University devised to become climate neutral – meaning no greenhouse gas emissions – by 2050.

“The new building schedules set guidelines for allowable temperatures for building spaces when they were in use and not in use – and they have served as a cornerstone for our project,” Martin said.

Huge energy savings are realized simply by turning off the HVAC equipment and allowing space temperatures to float during unoccupied periods, Freeman said.

Data analyst Jessica O’Hara is another key member of the team. Her role is to keep monthly tallies of energy consumption, building by building, to make sure energy savings are maintained over time.

“If there is an uptick in energy consumption, she lets me know it, and I go out to the building to try to figure out why,” Freeman said.

Seeing real results in real time

Thanks to software control systems, Freeman can execute most of the adjustments electronically while gazing at two computer screens from his office in the Giles Horney Building.

One computer screen flashes the execution of his command; the other shows how much energy is being saved as a result of that command – in real time.

Being able to see these dramatic results flash before his eyes, Freeman said, is still a thrill, and it’s what makes his work so personally rewarding.

Take, for instance, the 11-story Mary Ellen Jones Building on Manning Drive, which houses three School of Medicine departments: microbiology and immunology; pharmacology and biochemistry; and biophysics. The huge building is filled with cage racks of research animals that produce contaminated air that cannot be recycled, Freeman said.

“Air handlers in most buildings circulate a mixture of inside and outside air,” Freeman said. “Research buildings, because of the contaminated air inside, do not return any inside air, which means air handlers draw in 100 percent of outside air.”

When it is 30 degrees outside, the outside air has to be mechanically heated by nearly 40 degrees, which is expensive.

“To reduce the amount of energy needed to reheat that air, a water coil is installed in front of the exhaust fan and captures heat from the air before it leaves the building,” Freeman said.

“After the warm air leaving the building heats the water, the heated water is distributed to a water coil hooked to the air handler. The system is known as a heat reclaim system, and when it works properly, it has the capacity to bring the outside air from 30 degrees to 50 degrees.”

That is important in terms of reducing energy consumption, Freeman said, because the mechanical HVAC system only has to heat the air another 20 degrees – instead of 40 degrees – to bring the air up to a comfortable room temperature of 70 degrees.

Mary Ellen Jones has seven or eight air handlers, he said, which multiplied the savings to a level he could not have imagined.

On the day the heat reclaim system was turned on in the building, Freeman watched as the average demand of PPH (pounds per hour of steam) plummeted from more than 8,000 to below 5,000 within a 12-hour period.

Martin said, “In a single day’s work, the team was able to reduce the use of steam by 39 percent within a 12-hour period. The savings from doing that adds up to $200,000 a year.”

It’s an ongoing success story.

“If I had known what we were going to be able to accomplish, I would have volunteered,” Freeman said.