Operating Room HVAC Unoccupied Setback Year 2 Outcomes; Quality and Energy Success

•  Facility Information •  Issues •  HVAC Unoccupied Setback •  Project Considerations •  The Project •  Quality •  Energy

Facility Information

Facility

•  Located in Humble, Texas

•  255 Beds •  396,201 square feet •  Energy Star Labeled

for 5 years

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Central Plant

•  1970’s vintage chillers •  Central Plant

modifications performed in 1995

•  High efficiency condensing hot water boilers use for heating

HVAC

•  Several combinations of HVAC equipment –  Fan coil units –  VAV systems –  CAV systems –  Split systems –  Heat pumps –  DX rooftop units

Problems and Issues

Problems/Issues

•  Surgery HVAC system was no longer maintaining adequate environmental conditions. Problems most likely stemmed from: –  Increased demand on air and chilled water cooling

demand –  Age of equipment –  Cooling coil deterioration –  Deterioration of control valves and piping

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Problems/Issues

•  Some of the problems were: –  Poor temperature performance - OR suites frequently

too hot for surgeons (75 degrees) –  Poor humidity performance – Unable to maintain

consistent humidity levels below 60% –  Frequent complaints from surgeons and staff –  Frequent phone calls to the Engineering Department for

adjustments –  Unacceptable level of SSI’s occurring in the surgery

department

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•  Something needed to be done. Capital had been allocated for engineering and replacement of the two existing air handlers in order to improve the operating room environmental conditions.

•  This was a perfect opportunity to take advantage of some energy cost saving strategies as well as upgrading and improving controls and filtration systems

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HVAC Unoccupied Setback

What is it?

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HVAC Setback

•  Operating room HVAC setback (also referred to as "night setback" or "unoccupied setback") is an energy-saving strategy that reduces the amount of air supplied to an OR when the room is not in use. HVAC setback may also allow temperature or humidity settings (or both) to drift during times the room is not in use.

•  Depending on your facility’s type and pattern of use, one, or more, of your operating rooms is likely not being used a majority of the time. Yet for most facilities, the heating, ventilation, and air-conditioning (HVAC) system operates continuously, providing air exchanges, humidity, and temperature control as if the OR were occupied.

•  In addition to wasting energy, running your OR HVAC system costs money even while the room is unoccupied. In today’s energy-conscious environment, many facilities are implementing operating room HVAC setback as a way of controlling these costs. (Love, 2011)

Project Considerations

Considerations

•  There were several considerations needed to be made before design and implementation of HVAC night setback. Those were: –  Staff usage –  Existing Conditions –  Costs –  Air Exchange rates –  Pressure Relationships –  Temperature Requirements –  Humidity –  Particulate Control –  Building Automation System Controls –  Unoccupied schedule –  Occupancy sensors –  Manual overrides –  The Infection Preventionist

Staff Usage

•  Profile expected OR occupancies to determined before considering unoccupied setback.

•  Occupancy assessments should be used to determine the best solution for facilities.

•  Customize setback schedules

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Existing Conditions

•  If a setback strategy is being considered for a retrofit project, how does the existing HVAC system condition and control airflow to the ORs? How many ORs are served by each air-handling unit (AHU)? Are there terminal boxes for each OR? The configuration of the existing HVAC system will inform both the scope of the upgrade and the decision on which control strategy is optimal (Love, 2011)

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Costs

•  A setback strategy planned for a new health care facility can be incorporated with little or no additional upfront cost. In a retrofit of an existing health care facility, however, upfront costs must be weighed against the expected energy savings from implementing an OR setback strategy. Since most OR setback setups will require at least periodic maintenance, maintenance costs also need to be considered. The total cost of implementing a setback strategy will depend on the specifics of the strategy selected. Generally, a finer level of control means a more complex system and thus a higher cost. (Love, 2011).

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Air Exchange Rates

•  State and federal codes govern the minimum total and outdoor air change rates for ORs. For instance, ANSI/ASHRAE/ASHE Standard 170-2008: Ventilation of Health Care Facilities requires a minimum of 20 ACH total and 4 ACH of outdoor air when the room is in use. However, 20 to 25 total ACH are commonly needed to maintain temperature, ensure particulate removal, and overcome equipment loads, allowing the facility to easily meet or exceed the code requirements for ventilation in occupied mode. In unoccupied mode, the requirements to maintain positive pressure and humidity below 60 percent, along with other user needs govern the practicable ACH.

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•  ANSI/ASHRAE/ ASHE Standard 170-2008 does not prescribe minimum ACH for unoccupied mode; however, consideration will need to be given to the user needs (e.g., for fast start-up of an unoccupied OR), govern the practicable minimum ACH.

•  For mixed air systems, it is also important to recognize that as the setback strategy varies, the supply air rate and the quantity of outside air can also vary. In addition, exhaust air quantities must be coordinated to maintain appropriate building pressurization.

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Pressure Relationships

•  All health care mechanical and ventilation codes require that ORs maintain a positive air pressure relative to surrounding spaces, whether the OR is in occupied or unoccupied mode. It is this requirement that makes OR setback strategies more complicated than setback strategies for non-critical spaces. An OR must retain a positive pressure relative to surrounding spaces at all times, and the room leakage rate determines the CFM (cubic foot/minute) differential between supply and return air that is needed to maintain that pressure.

•  One AHU often serves multiple ORs due to the high cost of providing one unit for each OR. Generally, when this is the case, it is essential to understand the pressure relationships between all the spaces the AHU serves as well as the system implications of reducing the airflow to one or more of those spaces (Love, 2011)

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•  ASHRAE 170 Operating Room Ventilation Requirements The Facility Guidelines Institutes Guidelines for Design and Construction of Health Care Facilities provides comprehensive guidance for hospital design and is the referenced health care facility standard for many state and federal codes. The 2010 edition of the FGI Guidelines incorporates ANSI/ASHRAE/ASHE Standard 170-2008: Ventilation of Health Care Facilities. Section 7.4.1 of this standard requires that: Operating rooms shall be maintained at a positive pressure with respect to all adjoining spaces at all times. A pressure differential shall be +.01 in. wc (2.5 Pa)

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Temperature Requirements

•  Although ASHRAE 170 reflects current best practice, some codes still reference NFPA 99, which sets the minimum humidity at 35% (now 20%). Less energy is needed to maintain room temperature in ORs during unoccupied periods because equipment loads are low to non-existent when the room is not in use and, because ORs are typically located in the building core, they are not affected by temperature gains and losses in the building envelope. On the other hand, the time it takes ORs in unoccupied mode to reach occupied mode temperature can take longer if the unoccupied room temperature is allowed to migrate too far from the desired user set point (Love, 2011)

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Humidity

•  Humidity The humidity control requirements of ORs have considerations similar to those for temperature requirements. Unoccupied mode requires some level of humidity control to mitigate environmental conditions that could promote condensation or other moisture issues. According to Addendum d to ASHRAE Standard 170-2008, relative humidity can range between 20 and 60 percent whether occupied or unoccupied (Love, 2011)

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Particulate Control

•  Particulate control OR setback strategies typically do not monitor and respond to particulate levels. Unless there is a contaminating event, it is assumed the normal HVAC filtration, coupled with positive pressure relative to surrounding areas, will maintain directional airflow to minimize contamination from surrounding spaces (Love, 2011).

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•  Operating rooms should be maintained at positive pressure with respect to corridors and adjacent areas. Positive pressure prevents airflow from less clean areas into more clean areas. All ventilation or air conditioning systems in hospitals, including those in operating rooms, should have two filter beds in series, with the efficiency of the first filter bed being >30% and that of the second filter bed being> 90%. Conventional operating room ventilation systems produce a minimum of about 15 air changes of filtered air per hour, three (20%) of which must be fresh air. Air should be introduced at the ceiling and exhausted near the floor. Detailed ventilation parameters for operating rooms have been published by the American Institute of Architects in collaboration with the U.S. Department of Health and Human Services (CDC, 1999)

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Building Automation System

•  A building automation system (BAS) is essential in providing adequate control of the operating room environment throughout the setback process.

•  The building automation system provides a user interface to monitor and adjust temperature, humidity, and pressure relationships of the space.

•  Time of day schedules, occupancy and pressure sensors all feed information into the BAS, as well as provide outputs for other user interface devices such as indicator lamps and alarms

•  The BAS can provide trending in order to monitor varying conditions of the operating room and provide documentation for regulatory compliance. 27

Unoccupied Schedule

•  A time schedule program can be an effective means of controlling the HVAC settings in ORs that are used regularly throughout a typical day or week. The schedule shows when each OR is scheduled for occupied or unoccupied mode. A time schedule program is easy to understand and modify and does not require interaction from users as it is usually part of the building automation system. Time schedule controls are well-suited for use in ambulatory surgery centers, where surgical teams keep finite hours and no emergency cases are anticipated (Love, 2011)

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Occupancy Sensors

•  Occupancy sensors (audio, infrared, motion detection) are used to switch an OR between unoccupied and occupied modes. The sensor controls often embed delay when changing to unoccupied mode so the system ramps down slowly enough to maintain positive pressure in HVAC systems. Sensors may also embed a switchover delay from unoccupied/occupied mode to correct for brief entries into the room (e.g., users borrowing equipment or passing through). (Love, 2011)

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Manual Overrides

•  OR can be fitted with controls that are manually activated when the room is occupied. Time it takes HVAC system to reach occupied mode settings is typically much shorter than it takes the surgery team to prepare for surgery. When this control method is chosen, staff must be trained to press the button that reactivates the HVAC system when it is needed (Love, 2011).

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The Infection Preventionist

•  Involving the Infection Preventionist (IP’s)in the planning phase is critical to the success of the project.

•  Many of the IP’s may not be familiar with HVAC setback and may be apprehensive to making changes in the operating room environment.

•  IP’s can provide information to assist with the project; however, information is necessary in order to provide evidence of: –  Compliance with regulations –  Proven practices

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DSHS Regulations

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Proven Practice

•  Operating room setback during unoccupied periods is neither a new nor an unproven approach. For example, OR setback has become standard practice in Washington State since it implemented its own health care design standard in 1986 (Love, 2011).

•  Hospitals in the Memorial Hermann System have experienced successful outcomes with implementing HVAC setback in operating rooms.

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Other

•  In addition to code compliance and proven practices, the addition of a few monitoring devices to assure optimal environmental conditions of the operating room will help alleviate any apprehensiveness of the IP’s, surgery staff or administration.

•  Actually, the argument could be made that with the installation of additional monitoring and control devices, the environment will be in better shape than is would be without the project.

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The Project

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Equipment (pre-project)

•  (2) 1995 vintage constant volume multi-zone units serving OR area

•  Serves 7 OR suites •  Also serves sterile core and sub-sterile hallways •  Direct outside air (not preconditioned) •  25% pre-filter and 90% final filter •  Hot water and chilled water •  DDC Johnson Control Building Automation System

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Plan

•  Replace the two air handlers with higher capacity units (larger chilled water coil)

•  Replace air handler cooling coil valves •  Upgrade DDC controls from N1 to BACnet •  Install HEPA filtration on both units •  Install HVAC setback features to be used for unoccupied

time frames •  Install user interface, overrides, pressure indicators and

visual indicators. •  Project Cost $290,000

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Why HEPA?

•  Charnley and Eftaknan studied vertical laminar airflow systems and exhaust-ventilated clothing and found that their use decreased the SSI rate from 9% to 1%. However, other variables (i.e., surgeon experience and surgical technique) changed at the same time as the type of ventilation, which may have confounded the associations. In a multicenter study examining 8,000 total hip and knee replacements, Lidwell et al. compared the effects of ultraclean air alone, antimicrobial prophylaxis alone, and ultraclean air in combination with antimicrobial prophylaxis on the rate of deep SSIs. The SSI rate following operations in which ultraclean air alone was used decreased from 3.4% to 1.6%, whereas the rate for those who received only antimicrobial prophylaxis decreased from 3.4% to 0.8%. When both interventions were used in combination, the SSI rate decreased from 3.4% to 0.7%. These findings suggest that both ultraclean air and antimicrobial prophylaxis can reduce the incidence of SSI following orthopedic implant operations, but antimicrobial prophylaxis is more beneficial than ultraclean air. Intraoperative UV radiation has not been shown to decrease overall SSI risk. (CDC, 1999)

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HEPA Filters

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HEPA Filters

Project Planning

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HVAC Arrangement

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HVAC Setback Schedule

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Occupancy Sensors

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Occupancy Sensors

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Visual Indicators

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Visual Indicators

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Override

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Controls/Sensors

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Quality, Monitoring, &

Measuring

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Building Automation (BAS)

Building Automation (BAS)

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Temperature Monitoring (BAS)

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Humidity Monitoring (BAS)

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Pressure Monitoring (BAS)

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Pressure Monitoring

Reports

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Room Temperature Setpoint Humidity

NE_MEDICAL.OR_1.RM_T 56.1 °F 55.4 °F 58.2 %NE_MEDICAL.OR_2.RM_T 65.8 °F 50.1 °F 57.8 %NE_MEDICAL.OR_3.RM_T 61.4 °F 50.0 °F 58.8 %NE_MEDICAL.OR_4.RM_T 61.1 °F 60.2 °F 57.6 %NE_MEDICAL.OR_5.RM_T 67.7 °F 65.0 °F 57.2 %NE_MEDICAL.OR_6.RM_T 71.4 °F 50.6 °F 44.7 %NE_MEDICAL.OR_7.RM_T 65.0 °F 58.1 °F 57.1 %NE_MEDICAL.OR_8.RM_T 65.8 °F 50.3 °F 57.6 %NE_MEDICAL CATH_LAB1.RM_T 65.1 °F 64.9 °F 56.4 %NE_MEDICAL CATH_LAB2.RM_T 63.7 °F 63.0 °F 55.9 %NE_MEDICAL.OR_SC.RM_T 67.7 °F 68.0 °F 52.9 %NE_MEDICAL.OR_C1.RM_T1 63.1 °F 68.0 °F 57.1 %NE_MEDICAL.OR_C2.RM_T1 67.3 °F 68.2 °F 54.1 %

Energy

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BAS Programming

•  Fan speed reduction during unoccupied time totaling 83 hours per week

•  Room pressure differential below set point during unoccupied mode will place the system into occupied mode (failsafe).

•  Surgery light activation used to place the system into occupied mode

•  Lamps outside of all OR rooms will be green during occupied and red during unoccupied.

•  Manual override at nurses station will be capable of placing into occupied mode in event of problems.

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Supply Fan Output (BAS)

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Air Volume (BAS)

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Motor Speed and CFM

•  AHU 1-2 (30 hp) –  Motor at 88% (53hz) =

10,775 CFM –  Motor at 55% (33hz) =

7,215 CFM

•  AHU 1-3 (20 hp) –  Motor at 90% (54hz) =

8,974 CFM –  Motor at 57% (34hz) =

5,927

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Savings

300 CFM = 1 ton (262 in this case due to amount of outside air) 1 ton = 12,000 btu Average cost per btu = .000017 83 hours per week of reduced CFM at a total of 6607 CFM 6,607 x 83 = 548,381 548,381 / 262 = 2,093 2,093 x 12,000 = 25,116,000 25,116,000 x .000017 = 426.97 426.79 x 52 = 22,202 $22,202. cost reduction per year cooling $6,489 cost reduction in motor operation

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Savings Summary

•  $28,692 per year cost savings •  The approximate cost of HVAC setback features for this

project was $50,000 •  ROI = 1.74 years

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Conclusion

•  The HVAC setback for surgery has proven to be beneficial in several areas. The implementation of the project as provided: –  Higher end controls that what we would normally have

had. –  Provided higher quality surgery room environments that

can be continuously monitored. –  A higher degree of satisfaction with IP’s –  Improved physician comfort (greatly reduced physician

requests) –  Improved safety for our patients. –  Much improved energy utilization.

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•  Operating room setback is a proven energy-saving strategy for hospitals and ambulatory surgery centers in all climates. However, because of the unique constraints governing the design and operation of ORs, several factors must be considered when designing a solution for a particular facility. A successful solution must take into account the local climate, facility type, and user. Each of the many potential setback solutions has corresponding trade-offs between the level of control, complexity, and cost of the strategy chosen An experienced design professional with detailed knowledge of the facility and its users needs can assist facility staff in identifying the optimal solution (Love, 2011)

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References

•  CDC (1999). Guideline for Prevention of Surgical site Infection. Retrieved February 20, 2015 from: http://

www.cdc.gov/hicpac/SSI/005_SSI.html •  Love (2011). HVAC Setback: Saving Energy and Reducing Cost: OR Manager. Retrieved February 25, 2015 from:

http://www.ormanager.com/wp-content/uploads/2012/05/0512_ORM_HVAC.pdf •  Love (2011). Operating Room HVAC Setback Strategies: The American Society of Healthcare Engineering (ASHE).

Retrieved March 2, 2015 from: www.ashe.org/resources/management_monographs/pdfs/mg2011love.pdf

•  Love (2011). Operating Room HVAC Setback Strategies: Follow Science. Retrieved march 10,2015 from http://followscience.com/content/527686/operating-room-hvac-setback-strategies-mazzetti-nash-lipsey#sthash.YxeGPb4d.dpuf

•  Texas Department of State Health Services, Chapter 133, Table 3

Acknowledgments •  Steve M. Burch, PE, LEED® AP, Principal, Mazzetti Nash Lipsey Burch Bob Gulick, PE, LEED AP, Principal, Mazzetti

Nash Lipsey Burch Jon Inman, PE, LEED AP, Principal, Mazzetti Nash Lipsey Burch Richard Moeller, PE, SASHE, LEED AP, HFDP, Principal, CDi Engineers Michael Sheerin, PE, LEED AP, BD+C, Principal, Director of Healthcare Engineering, TLC Engineering for Architecture Ed Tinsley, PE, CEM, LEED AP, HFDP, Executive Managing Principal, TME, Inc.

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