Retrofitting for Efficiency


Hospitals and health centers pose a unique energy efficiency challenge due to their complexity and operating schedule. Most facilities are open 24 hours a day, seven days a week, with a constant flow of traffic from staff, patients, and visitors. Daily operations are filled with energy-intensive activities, from laundry to equipment sterilization, computer use to cafeteria service. Maintaining optimal building comfort at all times is also vital to patients’ health and well-being—limiting building operators’ ability to adjust lighting and HVAC (heating, ventilation, and air-conditioning) systems to reduce energy consumption.

So how did UW Health’s University Hospital (one of the largest facilities within the integrated health system associated with the University of Wisconsin-Madison) achieve energy savings of 27% and cost savings of $2.25 million between 2013 and 2017? These impressive results are due to a combination of no- and low-cost retro-commissioning measures, bolstered by strong organizational support and corporate leadership.

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Energy savings at UW Health were
achieved through a diverse combination
of energy efficiency strategies

Achieving Energy Milestones
University Hospital is a central component of the UW Health portfolio, which serves more than 600,000 patients every year. We are currently working towards a goal of reducing energy use intensity (EUI) portfolio-wide, targeting a 20% reduction by 2023. Progress towards this goal is supported by our robust internal sustainability program, Building Operator Certification (BOC) training for staff and status as an ENERGY STAR partner—a distinction we first earned in 2010.

We’ve also partnered with the US Department of Energy (DOE) on the agency’s Better Buildings Challenge, which asks leading public- and private-sector organizations to commit to reducing energy use by at least 20% over 10 years. Better Buildings Challenge partners like UW Health also share their successful energy- and water-savings strategies and results online through the Better Buildings Solution Center, a public platform that helps other organizations replicate partners’ success stories. As a part of this program, we hope our energy-efficiency insights empower other healthcare leaders to join in these efforts and learn from our experience.

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In 2018, UW Health reported improving energy performance by 24% from a 2013 baseline, achieving our Better Buildings Challenge goal six years ahead of schedule. These energy savings were achieved through a diverse combination of energy-efficiency strategies, including retro-commissioning projects and system upgrades, a new Energy & Water team, and portfolio-wide benchmarking to identify opportunities. We have now committed a new Better Building Challenge milestone—our EUI reduction goal—taking building efficiency to the next level over the next five years.

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Credit: UW Health
Aligning operating conditions with actual space usage helped UW Health optimize its energy efficiency.

Elevating Efficiency at University Hospital
The energy efficiency investments that enabled UW Health to meet our initial target so far ahead of schedule also drove significant building enhancements across the organization’s portfolio. At University Hospital, the process of reducing energy intensity began with a 2013 retro-commissioning study conducted by Sustainable Engineering Group (SEG), a third-party engineering firm. SEG’s study, which also included UW Health’s American Family Children’s Hospital, identified potential upgrade opportunities yielding nearly $2 million in annual savings—ranging from simple measures to more intensive building renovations.

Equipped with this information, we first prioritized no- and low-cost measures, specifically those with a payback period of less than two years. Early efforts focused on three primary measures:

Equipment scheduling and optimization: While patient comfort was always at the forefront, SEG ensured that University Hospital’s standard operating conditions aligned with actual space usage. In addition to validating that University Hospital’s ventilation and exhaust rates were correct, the firm found opportunities to adjust HVAC equipment in non-critical spaces that weren’t in constant use, such as professional offices and academic labs. With no minimum humidity requirement for these spaces in the ASHRAE Standard 170-Ventilation of Healthcare Facilities, University Hospital has reduced set points to 20% relative humidity without compromising occupant comfort. SEG’s assessment also helped pinpoint HVAC equipment using more energy than necessary to maintain a comfortable building temperature. At the firm’s recommendation, we began cooling the University Hospital building with outside air for longer periods each day—further reducing the energy required to maintain a comfortable temperature.

Daylighting and lighting controls: Daylighting, in which windows and skylights are used to draw in sun for natural lighting and temperature control, was a logical fit for a facility as large as University Hospital. SEG focused on the building’s atrium, with programmable controls set to dim or turn off overhead lights during periods of abundant sunlight.

Fume hood rebalancing: Rebalancing University Hospital’s exhaust system and reducing exhaust fume hood flow was the last step in the retro-commissioning process. In partnership with independent commissioning and test and balance company Professional System Analysis, SEG redesigned the building’s airflow scheduling to maximize efficiency and stabilize supply, exhaust, and air handler flows. Installing a variable frequency drive on the system’s exhaust fan increased motor efficiency, while reducing duct static pressure helped air circulate properly. These combined efforts resulted in a 50% decrease in the energy used by University Hospital’s supply and exhaust fan.

Measuring the Impact
Equipment scheduling and optimization drove the most significant energy savings for University Hospital, reducing annual spend by more than $340,000. Because operational changes like these require minimal upfront cost, the opportunity yielded a strong return on investment for our organization.

From audit to implementation, our retro-commissioning project cost came to a total of $488,075, which was partially offset by financial incentives provided by Wisconsin’s Focus on Energy Retro-commissioning Program. After factoring in annual savings from implemented measures, that means the payback period for this project was less than four months.

To ensure savings persistence, UW Health will oversee maintenance of newly installed measures and continuously audit University Hospital’s building performance.

Cutting energy usage by 27% and reducing annual energy spend from $8.45 million to $6.2 million already demonstrates the significant impact of University Hospital’s retro-commissioning investment. Between 2013 and 2017, University Hospital also improved its ENERGY STAR score by 16 points. The success of this project has led us to begin retro-commissioning several additional buildings in our portfolio—just part of the energy-efficiency work that will help bring the 2023 goal home.

Focus on the Future
The upcoming five years will showcase UW Health’s commitment to energy efficiency. In addition to retro-commissioning, the initial implementation includes comprehensive lighting upgrades to LEDs, HVAC scheduling changes and temperature setbacks, adoption of HVAC occupancy sensors and high-efficiency equipment, and demand-reduction strategies deployed across our portfolio. Saving both energy and money today benefits our bottom-line, but the enhanced occupant comfort, patient health, and staff efficiency which are enabled by these upgrades also help us to execute our vision—delivering remarkable healthcare for years to come. De Bug Web

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