VUMC Energy Efficiency and Conservation Programs

Vanderbilt University Medical Center has been aggressively implementing many energy efficiency and conservation programs over the past several years. These energy initiatives have been spearheaded by Plant Services Director, Ken Browning. Ken and his staff have completed several projects that include reduction of power consumption through the installation of more efficient electrical lighting, reduction of steam usage through improved maintenance procedures and replacement of several mechanical systems for providing Heating, Ventilation and Air Conditioning (HVAC) that reduce both energy and water usage. Most of these changes have been transparent to faculty, staff, students and patients who use VUMC facilities daily and have saved hundred's of thousands of dollars in operating expenses and millions of tons of carbon dioxide (CO2) emissions.

Project #1 - Lighting Retrofit

From February through September, 2005, Plant Services retrofitted over 150,000 light fixtures throughout VUMC. They replaced the existing T-12 fluorescent lighting throughout Medical Center facilities with more efficient T-8 and electronic ballasts. Incandescent bulbs were also replaced where appropriate with compact fluorescent and LED technology. The result, 4.3% or 10 million kilowatt hours (KWH) and approximately $500K in operating expenses saved annually for VUMC.

Investment return is expected in approximately 3.5 years. The projected 35 million kilowatt-hour reduction over this period will eliminate over 72 million pounds of CO2.

Project #2 - Variable Frequency Drives (VFD's)

There are hundreds of electrical motors throughout VUMC facilities used to pump water, and move air. In 2006, we installed over 60 VFD's and replaced select motors with new high efficiency versions. The speed control capability provided by the VFD's allows us to match motor speed to constantly changing load conditions. Any decrease in the motors speed yields an exponential decrease in the power required to drive that motor. We expect to reduce consumption by 2.24 million kilowatt-hours, eliminate 4 million pounds of CO2, and generate more than $112,000 savings.

Project #3 - New Chiller Installations

Chillers are a critical component of the mechanical systems infrastructure and the largest electrical load. Operating around the clock, they provide air conditioning to an entire building or buildings. As facilities age and expand so must the infrastructure. All new construction or replacement chillers are selected for maximum energy efficiency. These new chillers are on average 10% more efficient than existing machines. For example, an older, air cooled chiller, that served the VUMC data center, was replaced with a smaller, more efficient and more reliable machine requiring 50% less energy to deliver the same air conditioning capacity.

Project #4 - Plate and Frame Heat Exchanger

As part of the new chiller installation for the Imaging Science Center "In-Fill" plant, an additional technology called a "plate and frame heat exchanger" was added to further reduce the energy required to condition air. When outside temperatures are 50 degrees or below, we are able to secure the chiller, redirect condenser water into the "plate & frame" and continue to generate cooling water for critical facility functions like MRI machines and data rooms. The plate & frame utilizes only 5% of the energy required to drive a chiller, for pumps and fans. One month of operation can reduce electric energy consumption by 200,000 KWH and eliminate up to 400,000 pounds of CO2.

Project #5 - Steam Trap Inspection and Maintenance Program

Steam traps are mechanical devices, and there are hundreds installed throughout VUMC facilities. Like any mechanical device, steam traps are subject to failure. Trap failure is seldom obvious but the effect is the same as a leak wasting costly steam system energy around the clock until the leak is identified and corrected.

A single failed trap can pass more than 117,000 pounds of steam per month worth more than $1,000.

Plant Services has incorporated an infrared camera that can detect these leaks as a powerful addition to our trap inspection and maintenance program. Technicians can perform quick non-invasive, visual inspection with Infrared technology increasing the likelihood that the failed traps can be identified and corrected in a timely manner.

To date, over 26 failed traps have been identified and repaired, reducing steam consumption by 18.6 million pounds. The fuel burned to generate this much steam would also produce over 8 million pounds of CO2.

Project #6 - Electrical Power Monitoring

In order to effectively manage power consumption, one must be able to efficiently measure electrical power usage. To better understand how electrical power is used throughout VUMC, 18 new sub-meters have been installed. These new meters provide the ability to measure and collect data that will assist in our effort to better realize more energy savings.

Project # 7 - Highland and 25th Avenue Garage Lighting Fixture Replacement

1,865 high intensity discharge (HID) lamp fixtures were previously used to provide lighting in the Highland & 25th Avenue Garage, 24 hours per day. These fixtures were replaced with a specialized fluorescent bulb and reflector combination that produced comparable lighting levels. The HID fixtures consumed 226 watts per fixture per hour while the fluorescent replacements consume only 69 watts, that's 69.5% less energy! The difference is 180,000 kilowatt-hours per month worth more than $9,000 and 360,000 pounds of CO2.

Project #8 - Children's Hospital Water Heating System Upgrade

For the Children's Hospital Surgery Center, heating water must be maintained at maximum temperature year round. Surgery suites are required to transition from very cool to very warm in a matter of minutes. Maintaining the central hot water loop at maximum through the summer months, increases unintended thermal losses adding to the facility cooling load. By installing a hot water booster system specifically for the surgery center, the main building hot water temperature can be lowered, reducing steam consumption and cooling load which reduces the kilowatt-hours consumed. The combined reduction of steam and electrical energy is expected to save the equivalent of 1.2 million KWH, and over 2 million pounds of CO2.

Project #9 - Children's Hospital VFD Installation

Eight new variable frequency drives (VFD) have been installed in the VCH condenser water loop which is a critical sub-component of the system buildings cooling system. One drive for each of three condenser pumps and one each for five cooling tower fans. Together these drives match their respective motors speed to the load that varies throughout the day. Once again minor changes in speed result in an exponential decrease in the energy required to drive the motors. The result is improved chiller plant performance, we expect reduce consumption by 700,000 killowatt-hours and eliminate 1.4 million pounds of CO2.

Ongoing Energy Saving Opportunities

Throughout VUMC facilities, Plant Services personnel are constantly looking at ways to reduce energy consumption by substituting and matching the most energy efficient products to each specific application.

In total, these energy saving projects, programs, opportunities and investment shows VUMC's commitment to the conservation of energy resources and to a more environmentally responsible and sustainable operation.