by Leslie Hill in the VUMC Reporter
Vanderbilt University Medical Center spends about $38 million per year on energy.
That breaks down to $26 million on electricity, almost $9 million on steam and $3 million on water.
As such a large consumer, and with Nashville Electric Service rates expected to rise 8 percent in October, Plant Services is constantly searching for ways to improve efficiency and cut energy usage.
Higher-efficiency bulbs
Beginning in 2004, Plant Services switched every fluorescent light at VUMC to electronic ballast and higher-efficiency lamps. This simple change saves $600,000 per year.
Now there is a pilot trial under way for LED lights on the roof the West Garage. LED lamps use approximately 25 percent of the wattage of incandescent bulbs and have the added advantage of a significantly longer lifespan.
“We have maintenance issues with replacing the roof lights on the garages. LEDs have a much longer life — as much as 20 years,” said Mike Hutcherson, manager of the Medical Electric Shop. “If these perform like they’re supposed to, then all the garage roofs will have that lighting and we’ll look for other places to install them.”
Occupancy sensors
One of Plant Service’s most innovative energy savers was done in Medical Research Building III. It uses ceiling-mounted occupancy sensors to adjust the thermostat’s deadband (temperature range). When a lab is occupied, its deadband is plus or minus 1 degree. If there is no movement in a lab for 30 minutes, the deadband changes to plus or minus 5 degrees.
“If you’re trying to keep the lab at 73 degrees when it is occupied, the heat will kick on if the temperature drifts to 72. But if it is not occupied, the temperature is allowed to drift all the way to 68 before the system reacts.
“If someone walks into the lab, it immediately changes the deadband and will warm back up within 6 minutes,” said Mike Gable, mechanical engineer for Space & Facilities Planning.
The project cost $83,000 but saves about $73,000 per year in energy costs.
Occupancy sensors for lighting control have also been installed in the corridors of Medical Center North, and Plant Services expects that within three years all research labs, offices, classrooms, public areas and some outpatient clinics will have occupancy sensors.
Dedicated OR reheating
Most commercial buildings, including those at VUMC, use cold air to cool and hot water to heat, and those systems work constantly to reach equilibrium.
The Monroe Carell Jr. Children’s Hospital at Vanderbilt was designed with an outside air reset schedule, so that when the temperature outside increases, the reheat water temperature can get cooler and use less energy.
But that system didn’t take the operating rooms into consideration, which require the reheat water temperature to fall no lower than 130 degrees, no matter how high the outside air temperature.
“The ORs were controlling the entire building because we had to meet their critical need,” said Billy Roberts, manager of the Heating and Air Shop.
“By installing a dedicated system for the ORs, we can run the OR reheat water at 130-140 degrees year-round while the rest of the hospital and Doctor’s Office Tower can go down to 95-100 degrees in the summertime.”
Condensation recycling
A building’s cooling towers use domestic water that has to be treated to remove chemicals. The colder this water is the more efficiently the building’s air conditioning system can operate.
On a hot, humid day, the cooling system removes a lot of condensation from the air that is typically wasted to the city sewer system. In Medical Research Building III, this water was just going down the drain until Plant Services noticed its potential: it was distilled and very cold. This condensate was a perfect substitute for buying domestic water, so Plant Services invested in a project to redirect the condensed water to the cooling towers.
“This project cost about $60,000 but we save $32,000 and about 2.5 million gallons of water per year,” Gable said.
After the success of this conservation project, this same recycling system was built into Medical Research Building IV when it was constructed, and Plant Services is planning to install it in other buildings as well.
Efficiency testing
For the past five years, Plant Services and Space and Facilities Planning have undergone a process called commissioning at the end of any new construction. This form of efficiency testing ensures that all systems are working as planned.
“As standard on all our projects that have any major equipment, we test all the systems through every sequence they could possibly see to make sure they are working as designed,” Gable said. “To date the commissioning process has saved more than $5 million in first cost and annual operating cost. For every dollar we’ve spent on commissioning, we’ve saved $5, and in a few instances we found safety issues that you can’t really put a dollar amount on.”
LEED certification
Vanderbilt Health One Hundred Oaks is VUMC’s first facility to achieve LEED Certification.
This internationally recognized certification indicates a building or community was designed and built using strategies aimed at improving performance in the areas of energy savings, water efficiency, CO2 emissions reduction, improved indoor environmental quality and stewardship of resources and sensitivity to their impacts.
Condensation rooms such as this, in MRB III, take water from the air and redirect it to the building’s cooling towers. (photo by Anne Rayner)
All new construction at VUMC will pursue LEED certification, including the new VANTAGE (Vanderbilt Technologies for Advanced Genomics) lab currently being designed for Medical Center North.
What you can do
SustainVU is Vanderbilt’s home for sustainability and environmental efforts, and ThinkOne is its campaign to reduce energy consumption. ThinkOne encourages employees to think of one thing they can do every day to conserve energy.
The ThinkOne website has tips for offices and classrooms, patient care areas and research areas.
Examples include turning off lights and electronics when not in use, closing chemical fume hood sashes when not in use, and taking the stairs instead of the elevator.
“Anything we can do to reduce energy consumption is beneficial,” said Nic Holzmer, associate director of Plant Services.
“Our utility company mandated energy curtailment periods during previous summers, which showed that we can significantly reduce our kilowatt hours. Much of that’s done just by turning off lights or setting thermostats differently.”
Plants Services will not charge for any repair that is wasting energy. Common repairs include dripping faucets, running toilets and malfunctioning light switches. Report any such problems immediately by calling 322-2041.