Energy conservation

Retrocommissioning examines heating and cooling systems, lighting and employee behavior and uses low-cost or no-cost measures to improve efficiency and reduce energy demand. At the time the retrocommissioning program started at Gundersen, the system's energy costs were rising by about $350,000 a year. Those costs were being passed on to patients in the form of higher healthcare costs. The Envision® team knew they had to find areas for improvement and conducted an energy audit.

The audit opened the team's eyes to the dozens of energy saving opportunities, and Gundersen began a retrocommissioning process. Within a year, we improved energy efficiency by 25 percent, resulting in more than $1 million in annual savings.

Air handlers

During the audit, it was found that the air handlers that blow warm or cool air through the buildings were often running during times when staff and patients weren’t in a building or room. The solution—schedule the air handlers to run only when needed.

Air handler scheduling is similar to what a person would do to their home when they’re getting ready to leave for vacation and set the thermostat so the temperature gets warmer or cooler than usual to save on cooling or heating costs.

To accomplish this goal, health system staff measured the temperature in each zone of the building, then calculated how long it takes for the zone to cool down or warm up to a set point. That way, the temperature is comfortable as staff begin arriving for their day, while saving as much energy as possible. The air handler is scheduled to shut off or slow down at the end of the day when staff and patients leave the building.

The health system completed zone air handler scheduling in three buildings. In those buildings alone, the zone scheduling led to a more than $78,000 reduction in energy costs and saved more than 1.2 million kW hours a year.

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Exhaust fans

During the energy audit, Gundersen discovered many exhaust fans were unnecessarily running 24 hours a day, seven days a week. Gundersen has several hundred exhaust fans of various uses and sizes ─ some as wide as a single stall garage door ─ so finding a way to run these fans only when needed became a priority.

Gundersen started retrocommissioning eight exhaust fans in one of its outpatient clinics by reprogramming the fans' building controls to turn off overnight and on the weekends when the facility was unoccupied.

The change reduced electricity consumption by more than 71,000 kilowatt (kW) hours a year and saved the health system $4,300 annually. In comparison, running a home exhaust fan 24 hours a day would use about 500 kW hours and cost homeowners about $50 a year. Similar changes made on fans across Gundersen's campuses and have led to additional savings.

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As Gundersen looked for additional low-cost or no-cost ways to reduce energy consumption, one of the areas they considered was the cooling system. A process called chiller/tower optimization led to quick paybacks.

During this retrocommissioning effort, staff reprogrammed the electrical system controls that monitor the temperature in the building. By doing so, the fan in the cooling tower interacts with the chiller. The two components run at the setting that is the most efficient based on outside conditions at the time, such as temperature and humidity.

When Gundersen reprogrammed the chiller/tower in one building, they immediately saw approximately $13,500 in annual savings and reduced their energy use by about 225,000 kilowatt (kW) hours. Once Gundersen determined chiller/tower optimization worked, the system was replicated in all Gundersen campus buildings with chilled water systems. The change reduced electricity consumption for cooling the campus by about 1.1 million kW hours per year, reducing costs by approximately $65,000 annually.

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Infrastructure investment leads to significant energy savings

When Gundersen Health System needed to replace an aging chiller and three cooling towers, the project team saw it as an opportunity to save energy. When the project team researched replacement options, they opted for the energy efficiency of a chiller, cooling towers and chilled water pumps.

While not the original intent of the project, the opportunistic infrastructure investment was one of the health system's biggest energy conservation measures. It led to a reduction of 800,000 kW hours a year - about 2 percent of the organization's total electricity use - saving the organization about $70,000 in electricity charges annually.

In addition, the new chiller and cooling towers have added capacity, which allows for cooling of both hospital buildings and the data center.

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Gundersen also took a close look at how they were using their boilers.

Gundersen found they could use what are called reducing stations on the high-pressure boilers. Instead of being wasted, the steam from the "back-up" boiler is sent through a valve that reduces the steam pressure so it can be used in areas typically serviced by low-pressure boilers. The change allowed Gundersen to turn off two or more of its four low-pressure boilers most of the year.

The economizers on the boilers also enables the heat that's lost in the process to be recaptured and used to preheat water that's coming into the boilers, saving on fuel needed to heat the water. Improved electronic controls placed on the boilers led to additional efficiency gains. The changes led to energy savings of more than 74,000 therms a year. That's a cost savings of nearly $64,000 annually.

When Gundersen moved its data center to a new location, the IT and construction design teams worked together to develop a model that would improve energy usage.

Data centers are notoriously high energy users because IT equipment runs 24/7 and there is a need to keep the equipment cool. Traditional designs use "cold" and "hot" aisles. Cold air is pumped into the cold aisle, drawn into the equipment and exhausted through the back of the equipment into the hot aisle. The hot air is captured, cooled, forced down into the floor and the cycle repeats. This design makes it difficult to keep the hot and cold air from mixing without expensive containment schemes.

Gundersen's data center incorporates a unique design for cooling and recapturing heat that's led to near "best of class" energy efficiency. It incorporates a chimney design that prevents the mixing of hot and cold air. The equipment is in an enclosed cabinet with a chimney exhaust system that attaches to the ceiling. Because the heat is captured so effectively, the air does not have to return as cold as in the traditional models and the fans in the air handlers run at far lower speeds, resulting in energy savings.

Other efficient features include:

• Free cooling: Rather than running a refrigerant cycle in the winter, Gundersen takes advantage of free cooling by using cold air from outside to cool down the fluid coolers used by the chilled water system that supplies the air handlers.
• Heat recovery: Using a heat-recovery chiller, heat that's captured from the data center is used to heat the rest of the building, also also reducing the amount of cooling needed for the air going to the data center.
• Central chilled water: Rather than relying on a separate cooling system, Gundersen taps into the high-efficiency chillers at their power plant to cool the building in the summer months.

Gundersen's old data center ran at a power usage efficiency (PUE) of 2, meaning only half of the energy was used to run the equipment. The majority of the rest was used for cooling. Currently, the data center is running at a PUE of 1.2., with expected annual energy savings of $65,000 to $75,000 a year.

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Automatic computer shutdown

Gundersen has more than 8,500 computers. Many of those computers were left on 24 hours a day, seven days a week, which led to unnessary energy consumption. Gundersen's Information Systems department teamed up with the Envision team to come up with a solution that is saving the organization approximately $40,000 a year in energy costs.

The project involved the installation of NightWatchman® software on all computers. The Computers that were left on and not used were programmed to automatically shut down at a set time each night. Energy savings have reached approximately 645,000 kilowatt hours a year, for an energy cost reduction of $40,000 annually.

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Gundersen found that by simply retrofitting the light fixtures in six buildings they would see an energy cost savings of approximately $265,000 a year.

The retrofitting involved changing light bulbs, ballasts (the component that controls the electrical current powering the fluorescent bulb) and reflectors.

Besides being more energy efficient, the new light technology has several benefits. The light fixtures produce more light per lamp, so the number of lamps per fixture can be reduced from four lamps to two in most circumstances, resulting in a 50 percent energy reduction. Gundersen's energy use dropped by 4.4 million kilowatt hours annually. That's enough energy to power approximately 440 homes.

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