craig ayers - or hvac setbac

8/18/2019 Craig Ayers - Or HVAC Setbac

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Operating Room HVAC UnoccupiedSetback Year 2 Outcomes; Quality and EnergySuccess


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Facility Information

• Issues

• HVAC Unoccupied Setback

• Project Considerations

• The Project

•

Quality• Energy


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Facility Information


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Facility

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Located in Humble,Texas

• 255 Beds

•

396,201 square feet• Energy Star Labeled

for 5 years

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Central Plant

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1970’s vintage chillers

• Central Plant

modifications

performed in 1995• High efficiency

condensing hot water

boilers use for heating


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HVAC

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Several combinations of HVAC equipment

–

Fan coil units

– VAV systems

– CAV systems

– Split systems

– Heat pumps

– DX rooftop units


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Problems and Issues


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Problems/Issues

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Surgery HVAC system was no longer maintainingadequate environmental conditions. Problems most likelystemmed 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

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Some of the problems were: –

Poor temperature performance - OR suites frequentlytoo 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 foradjustments

–

Unacceptable level of SSI’s occurring in the surgerydepartment

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Something needed to be done. Capital had been allocatedfor engineering and replacement of the two existing airhandlers in order to improve the operating roomenvironmental conditions.

•

This was a perfect opportunity to take advantage of someenergy cost saving strategies as well as upgrading andimproving controls and filtration systems

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HVAC Unoccupied Setback

What is it?

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HVAC Setback

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Operating room HVAC setback (also referred to as "nightsetback" 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) todrift 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.


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In addition to wasting energy, running your OR HVACsystem 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)


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Project Considerations


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Considerations

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There were several considerations needed to be made before design andimplementation 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


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Staff Usage

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Profile expected OR occupancies to determined beforeconsidering unoccupied setback.

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

•

Customize setback schedules

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Existing Conditions

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If a setback strategy is being considered for a retrofitproject, how does the existing HVAC system condition andcontrol airflow to the ORs? How many ORs are served byeach air-handling unit (AHU)? Are there terminal boxes for

each OR? The configuration of the existing HVAC systemwill inform both the scope of the upgrade and the decisionon which control strategy is optimal (Love, 2011)

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Costs

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A setback strategy planned for a new health care facilitycan 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 setbackstrategy. Since most OR setback setups will require atleast periodic maintenance, maintenance costs also needto be considered. The total cost of implementing a setbackstrategy will depend on the specifics of the strategyselected. Generally, a finer level of control means a morecomplex system and thus a higher cost. (Love, 2011).

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Air Exchange Rates

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State and federal codes govern the minimum total andoutdoor air change rates for ORs. For instance, ANSI/

ASHRAE/ASHE Standard 170-2008: Ventilation of HealthCare Facilities requires a minimum of 20 ACH total and 4

ACH of outdoor air when the room is in use. However, 20to 25 total ACH are commonly needed to maintaintemperature, ensure particulate removal, and overcomeequipment loads, allowing the facility to easily meet orexceed the code requirements for ventilation in occupiedmode. In unoccupied mode, the requirements to maintainpositive pressure and humidity below 60 percent, alongwith other user needs govern the practicable ACH.

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•

ANSI/ASHRAE/ ASHE Standard 170-2008 does notprescribe 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 andthe quantity of outside air can also vary. In addition,

exhaust air quantities must be coordinated to maintainappropriate building pressurization.

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Pressure Relationships

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All health care mechanical and ventilation codes require that ORsmaintain a positive air pressure relative to surrounding spaces,whether the OR is in occupied or unoccupied mode. It is thisrequirement that makes OR setback strategies more complicated thansetback strategies for non-critical spaces. An OR must retain a

positive pressure relative to surrounding spaces at all times, and theroom leakage rate determines the CFM (cubic foot/minute) differentialbetween supply and return air that is needed to maintain thatpressure.

• 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 essentialto understand the pressure relationships between all the spaces the AHU serves as well as the system implications of reducing the airflowto one or more of those spaces (Love, 2011)

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•

ASHRAE 170 Operating Room Ventilation RequirementsThe Facility Guidelines Institutes Guidelines for Designand Construction of Health Care Facilities providescomprehensive guidance for hospital design and is the

referenced health care facility standard for many state andfederal codes. The 2010 edition of the FGI Guidelinesincorporates ANSI/ASHRAE/ASHE Standard 170-2008:Ventilation of Health Care Facilities. Section 7.4.1 of thisstandard requires that: Operating rooms shall bemaintained at a positive pressure with respect to alladjoining spaces at all times. A pressure differential shallbe +.01 in. wc (2.5 Pa)

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Temperature Requirements

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Although ASHRAE 170 reflects current best practice,some codes still reference NFPA 99, which sets theminimum humidity at 35% (now 20%). Less energy isneeded to maintain room temperature in ORs during

unoccupied periods because equipment loads are low tonon-existent when the room is not in use and, becauseORs are typically located in the building core, they are notaffected by temperature gains and losses in the buildingenvelope. On the other hand, the time it takes ORs inunoccupied mode to reach occupied mode temperaturecan take longer if the unoccupied room temperature isallowed to migrate too far from the desired user set point(Love, 2011)

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Humidity

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Humidity The humidity control requirements of ORs haveconsiderations similar to those for temperaturerequirements. Unoccupied mode requires some level ofhumidity control to mitigate environmental conditions that

could promote condensation or other moisture issues. According to Addendum d to ASHRAE Standard170-2008, relative humidity can range between 20 and 60percent whether occupied or unoccupied (Love, 2011)

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Particulate Control

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Particulate control OR setback strategies typically do notmonitor and respond to particulate levels. Unless there is acontaminating event, it is assumed the normal HVACfiltration, coupled with positive pressure relative to

surrounding areas, will maintain directional airflow tominimize contamination from surrounding spaces (Love,2011).

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Operating rooms should be maintained at positive pressure withrespect to corridors and adjacent areas. Positive pressure preventsairflow from less clean areas into more clean areas. All ventilation orair conditioning systems in hospitals, including those in operatingrooms, 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 aminimum 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 andexhausted near the floor. Detailed ventilation parameters foroperating rooms have been published by the American Institute of

Architects in collaboration with the U.S. Department of Health andHuman Services (CDC, 1999)

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Unoccupied Schedule

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A time schedule program can be an effective means ofcontrolling the HVAC settings in ORs that are usedregularly throughout a typical day or week. The scheduleshows when each OR is scheduled for occupied or

unoccupied mode. A time schedule program is easy tounderstand and modify and does not require interactionfrom users as it is usually part of the building automationsystem. Time schedule controls are well-suited for use inambulatory surgery centers, where surgical teams keep

finite hours and no emergency cases are anticipated(Love, 2011)

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Occupancy Sensors

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Occupancy sensors (audio, infrared, motion detection) areused to switch an OR between unoccupied and occupiedmodes. The sensor controls often embed delay whenchanging to unoccupied mode so the system ramps down

slowly enough to maintain positive pressure in HVACsystems. Sensors may also embed a switchover delayfrom unoccupied/occupied mode to correct for brief entriesinto the room (e.g., users borrowing equipment or passingthrough). (Love, 2011)

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Manual Overrides

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OR can be fitted with controls that are manually activatedwhen the room is occupied. Time it takes HVAC system toreach occupied mode settings is typically much shorterthan it takes the surgery team to prepare for surgery.

When this control method is chosen, staff must be trainedto press the button that reactivates the HVAC systemwhen it is needed (Love, 2011).

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The Infection Preventionist

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

• Many of the IP’s may not be familiar with HVAC setbackand 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 provideevidence of:

–

Compliance with regulations – Proven practices

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DSHS Regulations

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Proven Practice

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Operating room setback during unoccupied periods isneither a new nor an unproven approach. For example,OR setback has become standard practice in WashingtonState since it implemented its own health care design

standard in 1986 (Love, 2011).• Hospitals in the Memorial Hermann System have

experienced successful outcomes with implementingHVAC setback in operating rooms.

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Other

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In addition to code compliance and proven practices, theaddition of a few monitoring devices to assure optimalenvironmental conditions of the operating room will helpalleviate 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 bewithout the project.

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The Project

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Equipment (pre-project)

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(2) 1995 vintage constant volume multi-zone units servingOR 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 unoccupiedtime 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% to1%. However, other variables (i.e., surgeon experience and surgicaltechnique) changed at the same time as the type of ventilation, which mayhave confounded the associations. In a multicenter study examining 8,000total hip and knee replacements, Lidwell et al. compared the effects of

ultraclean air alone, antimicrobial prophylaxis alone, and ultraclean air incombination with antimicrobial prophylaxis on the rate of deep SSIs. The SSIrate following operations in which ultraclean air alone was used decreasedfrom 3.4% to 1.6%, whereas the rate for those who received only antimicrobialprophylaxis decreased from 3.4% to 0.8%. When both interventions wereused in combination, the SSI rate decreased from 3.4% to 0.7%. These

findings suggest that both ultraclean air and antimicrobial prophylaxis canreduce the incidence of SSI following orthopedic implant operations, butantimicrobial prophylaxis is more beneficial than ultraclean air. IntraoperativeUV radiation has not been shown to decrease overall SSI risk. (CDC, 1999)

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HEPAFilters


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HEPAFilters


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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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O


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Override

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C l /S


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Controls/Sensors

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Quality, Monitoring, &Measuring

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B ildi A t ti (BAS)


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Building Automation (BAS)

B ildi A t ti (BAS)


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Building Automation (BAS)

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T t M it i (BAS)


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Temperature Monitoring (BAS)

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H idit M it i (BAS)


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Humidity Monitoring (BAS)

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P M it i (BAS)


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Pressure Monitoring (BAS)

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PressureMonitoring

Reports


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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 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 %


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Energy

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BAS Programming


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BAS Programming

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Fan speed reduction during unoccupied time totaling 83hours per week

• Room pressure differential below set point duringunoccupied mode will place the system into occupied

mode (failsafe).•

Surgery light activation used to place the system intooccupied 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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Supply Fan Output (BAS)

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Air Volume (BAS)


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Air Volume (BAS)

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Motor Speed and CFM


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Motor Speed and CFM

•

AHU 1-2 (30 hp) –

Motor at 88% (53hz) =

10,775 CFM

–


7,215 CFM

•

AHU 1-3 (20 hp) –


8,974 CFM

–

Motor at 57% (34hz) =5,927

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Savings


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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


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Savings Summary

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$28,692 per year cost savings•

The approximate cost of HVAC setback features for thisproject was $50,000

• ROI = 1.74 years

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Conclusion


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Conclusion

•

The HVAC setback for surgery has proven to be beneficialin several areas. The implementation of the project asprovided:

– Higher end controls that what we would normally have

had. –

Provided higher quality surgery room environments thatcan be continuously monitored.

– A higher degree of satisfaction with IP’s

–

Improved physician comfort (greatly reduced physicianrequests)

– Improved safety for our patients.

– Much improved energy utilization.67


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•

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

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References


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References

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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

cknowledgments

•

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

craig ayers - or hvac setbac

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