January 17, 2012
Optimizing Energy Use in a Healthcare Setting: A Detailed Case Study
Michael Della Barba
Why Focus on Healthcare?
Healthcare facilities spend over $6.5 billion on energy costs per year.1 In 2008, healthcare expenditures were $2.3 trillion representing approximately 16% of the Gross Domestic Product.2 When compared to other sectors - education, office, public assembly – healthcare facilities are one of the highest energy consumers.
The primary concern is for patient and caregiver safety. System performance is imperative and you must be cautious about not implementing any changes that could negatively impact patient or staff health. Ventilation systems are designed for infection control.
Many hospital spaces are occupied 24/7 which may restrict access to specific areas and present barriers to implementation.
In hospitals, change is constant. What may have once been a patient area could now be research space, and vice versa.
Energy Optimization Process
Energy optimization focuses on measurement and verification to ensure mechanical system performance is matched to demand. It involves tuning the existing system for performance and energy savings is a natural byproduct of optimal performance. Unlike energy audits which focus on capital equipment upgrades, optimization eliminates waste through low-cost adjustments or minor mechanical fixes to existing equipment to make it operate as intended and as needed in the building’s current state of use. These modifications eliminate energy waste and extend the life of the equipment.
The process of optimization involves the systematic collection of information from the building management system and facilities staff, and most importantly, energy data collected from key pieces of equipment. This energy data often illustrates that what you think is happening in the building is, in fact, incorrect. No matter how advanced the building management system is, these direct energy measurements will often uncover inefficiencies (e.g., overridden control sequences, short-cycling of compressors, unintended equipment operation).
Energy optimization is focused on maximizing the return on investment (ROI), which in order to be viable for healthcare facilities is typically 12 months or less. EH&E has typically seen savings of 10% or more in hospitals, varying in size from 150,000 sq. ft. to 600,000 sq. ft.
Hospitals have unique traits that must be taken into consideration when undertaking an energy optimization project.
Case Study: Energy Optimization in a Hospital
EH&E recently performed an energy optimization project for an acute care hospital with laboratory space and adjacent medical office building.
Size: 337,550 square feet
- 9,818,200 kWh – main building
- 1,456,200 kWh – medical office building
- 453,638 Therms – central plant
Energy costs: ~$1,900,000 per year
Energy Optimization Target: 8% Total Energy Savings. Return On Investment less than 1 year.
An initial review of the hospital’s overall energy usage was conducted to identify potential energy savings opportunities. Then each of these opportunities was further investigated by monitoring to determine how the equipment was actually operating. The objective was to determine when equipment is operating, whether it is operating efficiently, and whether the operational sequence is necessary based on the space it is serving.
Peak/Off Peak Energy Usage
The energy bill summary review revealed high unoccupied usage of 60%. Although a hospital typically will have a high unoccupied electric consumption profile due to 24/7 patient occupancy, the actual consumption indicates that there is very little “turn-down” anywhere in the hospital despite non-patient areas that are unoccupied for specific periods both during the week and weekends. Energy consumption during off peak hours presented an opportunity for savings.
24-Hour Demand Profile
A 24-hour demand profile for the hospital was plotted by selecting a specific day of the month (e.g., the 15th) and spanning a 12 month period. Generating a 24-hour demand profile helps identify the maximum and minimum demand; which in this case were 1,500 KW per month and 1,300 KW per month. Given that 65% of the hospital is not patient or indirect patient space, we expected the turndown to be greater than 200 KW. This step allowed us to cue in on lowering the minimum demand to identify what it is, what is necessary, and what is actually operating during the period versus what is required.
Electrical Use / Equipment
A review of the heating, ventilating air-conditioning (HVAC) equipment by electrical use revealed that 77% of the usage was designated for maintaining temperature and circulating air within the hospital. This information tells us that modifications to ventilation systems, even while still meeting infection control needs in the hospital, will have a significant impact on energy savings.
Natural Gas Usage
Based on the hospital’s square footage, a review of natural gas usage revealed that there was over 10,000 therms unaccounted for. Monitoring revealed that systems were heating and cooling at the same time. Upon further inspection, numerous steam leaks were identified at leaking valves. The result of these leaks was that pipes were being heated that did not need to be, and during the summer months the air-conditioning was working harder to compensate for this.
Real-time data was collected from air handling units, chilled water system, steam/hot water system, compressors, patient rooms, and non-patient rooms with the purpose of determining how systems were actually operating. When examining an air handling unit, we review the chilled water and hot water serving it, and simultaneously the condition of the spaces served by the air handler. Pairing systems provides more meaningful data.
The hospital facilities staff and EH&E conducted a walk-through of the hospital to identify patient rooms, direct patient areas (radiology, ER, nurses’ stations), indirect patient areas (patient equipment storage), office areas, cafeterias, and common areas. The space survey determines exactly what spaces are being served by each air handler to help inform decisions regarding what equipment should be on and off at different times of the day. Staff knowledge of hospital use by area is invaluable.
During these equipment and system inspections, the cooling tower for the onsite chiller plant was inspected and the amount of evaporated water from the cooling tower was measured. We found the hospital was paying for the discharge of that evaporated water, which is substantial, because the local sewer department assumed that all the water used by the hospital ultimately went into the sewer system. The amount of evaporated water from the cooling tower was reported to the local water department, and water meters will be added to isolate the cooling tower loss from the sewer bill. We estimate that the hospital will save $32,000 per year on their water bill. While this savings doesn’t apply to the energy optimization process, it is equally valuable to the hospital.
Key Findings / Opportunities for Energy Savings
Three primary opportunities for energy savings were identified that accounted for 8% of the energy savings gained from the energy optimization process:
- Off peak energy usage higher than required
- Simultaneous heating and cooling as a result of the steam leaks
- Hot water pump sequencing
Virtually all air handlers were scheduled to run 24/7; we’ve found this to be a common issue in hospitals. Twelve of twenty four air handlers were taken offline for between 4-8 hours during the night (slightly more on weekends). Adjustments were also made to the setbacks for exhaust fans and fan coils.
The leaking steam valves were replaced, eliminating the leaks and eliminating the additional summer cooling load.
Secondary hot water pumps were found to be not modulating as a result of the way the sequencing was programmed. Additionally, there were equipment maintenance and cleaning issues mainly on the fan coils which resulted in little air flow and low performance.
Total immediate annual savings from the above of $160,000 (approximately 8%) is calculated for the project to-date. Targeted measurements will be made over the next year (seasonally) and systems re-commissioned as operational. We anticipate exceeding the current 8% savings.
The addition of water meters to isolate the cooling tower is estimated to result in $32,000 annual savings on the water bill.
Seasonal opportunities for additional savings are anticipated and include:
- Patient room fan coil unit improvements. Proper cleaning to improve performance, and thereby reduce energy costs.
- Economizer mode optimization.
- Chilled water distribution control.
- Compressor improvements.
- Process equipment scheduling.
- Optimize schedule for operating rooms, radiology, and laboratories.
Michael Della Barba, Director of Commissioning Services, manages EH&E’s commissioning team, frequently serving as project manager on key projects. EH&E has commissioned over twenty million square feet of commercial and institutional construction. For additional information, Mike can be reached at firstname.lastname@example.org.
Accessed January 5, 2012.
2.) Centers for Medicare and Medicaid Services, Office of the Actuary, National Health Statistics Group, National Health Care Expenditures Data, January 2010.