Operating Room Ventilation Systems Best Practices Guide for Energy Efficiency, Health and Safety

A GREENING HEALTH CARE RESEARCH PROJECT

ORIGINAL RELEASE: APRIL 2017 © GREENING HEALTH CARE 2017 SPONSORED BY: Lead author: Ian Jarvis, P.Eng, President Technical support: Farhang Vahabi, Project Analyst

This Best Practices Guide (Guide) is for use by Facility Directors of acute care hospitals to help evaluate their existing operating room ventilation systems, and direct staff and service providers in making their operating performance and energy efficiency the best they can be. The Guide is provided as a technical resource for Greening Health Care member hospitals. Greening Health Care is a program of the Living City managed by Toronto and Region Conservation.

Ian Jarvis, President, Enerlife Consulting Inc. [email protected] 416-915-1530 x 203 TABLE OF CONTENTS

1. Background 2

2. Introduction 3

3. Best Practices 3 3.1 Unoccupied Setback 3 3.2 Air Change Rates 4 3.3 Recirculation 4 3.4 Airflow Control 4 3.5 Monitoring and Control 5 3.6 Control Set-points 5 3.7 Measurement and Verification 5

4. Code and Regulatory Requirements 6

5. Pilot Hospital Findings 8

6. Energy Use Breakdown: Reference Ventilation System 11

7. System Design Configurations 12 7.1 Reference System (no heat recovery) 12 7.2 Thermal Wheel Heat Recovery System 12 7.3 Glycol Coil Heat Recovery System 13 7.4 Heat Recovery Chiller System 13 7.5 Air Recirculation System 14

8. Energy Cost Comparison for Different System Design Configurations 15 Appendix A: Checklist 18

Operating Room Ventilation Systems Best Practices Guide for Energy Efficiency, Health and Safety | page 1 1. Background Operating Room (OR) ventilation is the most energy intensive service in acute care hospitals, which in turn are one of the most energy intensive commercial/institutional building types in North America. As well, proper ventilation is essential to the health and safety of hospital staff, surgical teams and patients. Different hospitals are designed and retrofitted with different system and control configurations, and system operating practices vary widely. For all these reasons, at the beginning of 2016, Greening Health Care initiated an applied research project aimed at documenting best practices for OR ventilation design, retrofit, operation and control, for use by member hospitals in optimizing the energy performance of their facilities.

Four major acute care hospitals took part in the project (see sidebar), providing technical input and review as well as information on their existing systems and operations. Utility company and industry sponsors also contributed technical knowledge as well as funding for the project. Findings were presented to and reviewed at the Greening Health Care workshop on November 30th 2016, and the webinar on December 14th 2016. (See Section 5 Pilot Hospital Findings). This Best Practices Guide presents the findings, conclusions and recommendations of the project.

About Greening Health Care Founded in 2003, Greening Health Care is the largest program of its kind in North America, helping hospitals work together to lower their energy costs, raise their environmental performance and contribute to the health and well-being of their communities. Members manage data, assess their performance and track savings using a powerful online system. They share knowledge and best practices through workshops, webinars and networking to help plan, implement and verify improvements. This is a program of The Living City managed by Toronto and Region Conservation.

Kingston General Hospital SickKids Hospital North York General Hospital Humber River Hospital • Kingston, Ontario • Downtown Toronto • North Toronto • North Toronto • 1,238,560 ft2 • 2,840,913 ft2 across three sites • 677,691 ft2 (main hospital) • 1,826,205 ft2 • 440 beds • 283.9 average number of beds • 419 acute beds, • 656 beds • Serves 500,000 people occupied daily 192 long-term beds • Serves a catchment area of • Acute care teaching hospital • 301,997 annual ambulatory visits • 137,123 outpatient volume more than 850,000 people • Children’s hospital and • Acute care, ambulatory and • Acute care hospital research facility long-term care services

Operating Room Ventilation Systems Best Practices Guide for Energy Efficiency, Health and Safety | page 2 2. Introduction Depending on local weather conditions and utility prices, a typical 25,000 cubic feet per minute (cfm) OR ventilation system can cost as much as $125,000/year or more in electricity and thermal energy consumption. Proper design/retrofit, operation and control can reduce this cost by as much as 65%, while ensuring healthy and safe environmental conditions for surgical teams and patients.

For new hospital design, this Best Practices Guide documents the energy use and utility cost implications of alternate system configurations, and lays out the operating, control, measurement and verification requirements for optimizing in-service energy use. For existing hospitals, it is generally not economic to modify the system configuration (for example, installing heat recovery or recirculation), so the Guide is intended to provide the optimal operation, control, measurement and verification practices to get the best performance out of whatever system is installed.

3. Best Practices The individual measures for consideration with every OR ventilation system, to be implemented where practicable, are laid out below and provided as a checklist in Appendix A. See Section 4 for required air change rates and space conditions, and Section 8 for the relative utility costs of the different design configurations and operations.

3.1 Unoccupied Setback The universal strategy for all system configurations is to reduce the airflow to each OR and the other areas served by the system when not in use, along with adjustments to supply air and space temperature set-points. Figure 1 illustrates the requirements for implementing setback as follows:

• Volume control devices on the air supply and exhaust to each OR and other rooms/areas • Relative pressure monitoring of the ORs against adjacent areas • Occupancy sensor(s) in each room • Volume control Variable Frequency Drives (VFDs) on supply and exhaust fans • Space temperature reset so that reheat coils are disabled unless high or low limits are reached

Operating Room Ventilation Systems Best Practices Guide for Energy Efficiency, Health and Safety | page 3 Airflow setback during unoccupied periods reduces energy use for preheat, cooling and humidification in proportion to the airflow reduction. Fan power savings are even greater because of the affinity (cube) law, and reheat savings are proportionately greater because of reduced heat loads in the unoccupied rooms. Section 8 of this Guide shows the savings due to setback for the different system design configurations.

Figure 1. Setback implementation requirements

3.2 Air Change Rates Test the overall air volume and the supply to each OR, and rebalance to the required amounts as laid out in this Guide.

3.3 Recirculation • Operationalize air recirculation for systems which have that capability or can be readily retrofitted.

• Ensure proper capture and monitoring of anesthetic gases, and that the required minimum outside air is maintained at all times when any OR is in use.

3.4 Airflow Control • Install reliable and repeatable volume control devices on the air supply to and exhaust from each individual OR. Test and calibrate for required occupied and unoccupied air volumes at least annually.

• Install reliable and repeatable volume control devices on the air supply to and exhaust from each other space where airflow is to be set back during unoccupied periods. Test and calibrate for required occupied and unoccupied air volumes at least annually.

• Install airflow monitoring stations on total and outside air supply and total exhaust volumes for the air handling system. Test and calibrate at least every two years.

Operating Room Ventilation Systems Best Practices Guide for Energy Efficiency, Health and Safety | page 4 3.5 Monitoring and Control • Install temperature and humidity sensors with continuous local and central monitoring for every individual operating room as well as the combined exhaust air.

• Install occupancy and relative pressure sensors with continuous monitoring for every individual OR, and for other spaces where airflow is set back during unoccupied periods.

• Verify proper operation and calibration of sensors monthly.

3.6 Control Set-points • Maintain OR space temperature (other than Burn Unit) between 65°F (18°C) and 73.5°F (23°C) to suit surgical team requirement.

• For Burn Unit OR the range is 75°F (24°C) to 86°F (30°C).

• Maintain OR relative humidity (RH) between 30% and 60% at all times. Provide central alarm if RH exceeds 58% and local alarm if RH exceeds 60%.

• Automatically reset system supply air temperature down to stay within upper RH limit. During humid outdoor conditions the supply air temperature will go down to 50°F (10°C); during normal operating conditions the supply air temperature can rise to 60°F (16°C).

• Automatically reset chilled water supply temperature as required to maintain supply air temperature.

3.7 Measurement and Verification Rigorous commissioning and ongoing monitoring are essential to verify that the system is operating as intended and continues to do so over time. Recommended verification procedures are as follows:

• Test and verify every 12 months occupied and unoccupied supply airflows for every individual controlled zone and the system as a whole.

• Download and analyze trend logs to verify accurate and consistent control:

u OR space temperatures and RH;

u OR differential pressures;

u supply and exhaust air temperatures;

u outside air volumes;

u chilled water supply temperature.

Operating Room Ventilation Systems Best Practices Guide for Energy Efficiency, Health and Safety | page 5 4. Code and Regulatory Requirements In Canada, Canadian Standards Association (CSA) Z 317 governs the requirements for operating room ventilation systems and space conditions. The equivalent regulation for the United States is ASHRAE 170. For supply air, the recommendation of both CSA and ASHRAE is 20 air changes per hour (ACH). For outside air, ASHRAE 170-2008 requires 4 ACH (20% outside air) while CSA Z 317-15 is more restrictive and requires 6 ACH (30% outside air).

CSA Z 317-15 (5.2.1) All rooms and areas within an Health Care Facility (HCF) shall be ventilated to ensure an air exchange adequate to control contaminant levels, temperature, and humidity while minimizing stratification and drafts. Note: Table 1 provides minimum values for temperature, humidity, and air exchanges based on the function of each room or area.

ASHRAE HVAC Design Manual for Hospitals and Clinics – second edition Minimum air exchange rates for the various types of spaces should comply with ANSI/ ASHRAE/ASHE Standard 170-2008 (see Table 3-3). This standard list minimum air exchange rates for both ventilation air (outdoor air) and total supply air. Some state and local codes may have minimum air exchange rates that differ from the ASHRAE standard. In such instances, the designer should design for the higher value.

Table 1. HVAC design criteria for ORs: OCCUPIED MODE

Reference Function Type Minimum Minimum total Relative Temperature Temperature Relative outdoor air air changes pressurization °C °F humidity changes per hour % per hour

CSA Z 317-15 Operating I 6 20 Positive 18-23 64-73 30-60 (Table 1) rooms ASHRAE Operating B&C 4 20 Positive 20-24 68-75 30-60 170-2008 rooms (Table 3-3)

Operating Room Ventilation Systems Best Practices Guide for Energy Efficiency, Health and Safety | page 6 Table 2 shows the setback (minimum) airflows to be met in unoccupied mode.

CSA Z 317-15 (6.5.4.1.1) Air-handling systems for Type I areas may be operated at a reduced level when the space is unoccupied. The air circulation system should maintain at least six air changes per hour unless the space is continuously monitored for temperature, humidity, and (where applicable) relative pressurization and airflow. Where circulation systems maintain less than six air changes per hour, these parameters shall be kept within the design ranges specified in Table 1.

ASHRAE 170-2008 (7.1.C) For spaces that require a positive or negative pressure relationship, the number of air changes can be reduced when the space is unoccupied, provided that the required pressure relationship to adjoining spaces is maintained while the space is unoccupied Table 2. and that the minimum number of air changes indicated is re-established anytime the HVAC design criteria for ORs: space becomes occupied. Air change rates in excess of the minimum values are expected UNOCCUPIED MODE in some cases in order to maintain room temperature and humidity conditions based upon the space cooling or heating load.

Reference Function Type Minimum Minimum total Relative Temperature Temperature Relative outdoor air air changes pressurization °C °F humidity changes per hour % per hour

CSA Z 317-15 Operating I Not 6 Positive 18-23 64-73 30-60 (Table 1) rooms Mentioned ASHRAE Operating B&C Not As low Positive 20-24 68-75 30-60 170-2008 rooms Mentioned as possible (Table 3-3)

Figure 2 shows the acceptable band within which the space conditions for every individual OR must be maintained. In particular, the upper limit of 60% RH must not be exceeded so that the safety of materials and products within the OR is not compromised.

DB Temp = 73.4F RH = 60%

DB Temp = 64.5F RH = 60%

DB Temp = 73.4F Figure 2. DB Temp = 64.5F RH = 30% OR space conditions: RH = 30% acceptable band

Operating Room Ventilation Systems Best Practices Guide for Energy Efficiency, Health and Safety | page 7 5. Pilot Hospital Findings The four hospitals which took part in this project have a combined total of ten OR ventilation systems, of which five are designed with recirculation capability, but none is being used in either occupied or unoccupied mode. The hospital representatives provided detailed information on their systems, along with insights and recommendations on where and how improvements could be made which are incorporated into the Guide. Tables 3-8 summarize the systems and operations for the four hospitals.

Table 3. Pilot hospital system configurations

Thermal Wheel Heat Recovery Chiller No Heat Recovery No Heat Heat Recovery Hospital # — Unoccupied — Unoccupied — Unoccupied Recovery Chiller Setback Setback Setback 1 3

2 3 3

3 3 3

4 3

Operating Room Ventilation Systems Best Practices Guide for Energy Efficiency, Health and Safety | page 8 The proportion of total air handling unit volume supplying the ORs for the four pilot hospitals ranged between 35% and 55%, with the remainder going to corridors, recovery and service areas. The maximum, minimum and average air changes per hour for the four pilot hospitals are presented in Table 4.

Table 4. Pilot hospital total air changes per hour, as reported by hospitals

# of Occupied Hospital # Operating Rooms Maximum Minimum Average Note 1 12 27 20 24 11 ORs are higher than the standard

2 16 27 20 22 9 ORs are higher than the standard

3 15 24 14 21 1 OR is below the standard and 8 ORs are higher

4 20 20 20 20

CSA Requirement N/A 20 N/A

# of Unoccupied Hospital # Operating Rooms Maximum Minimum Average Note 1 12 12 9 11 All ORs are higher than the standard

2 16 23 9 15 All ORs are higher than the standard

3 15 21 10 18 All ORs are higher than the standard

4 20 20 20 20

CSA Requirement N/A 6 N/A

Table 5. Presence of sensors in pilot hospitals

Unoccupied Hospital # Temperature Humidity Pressurization Occupancy Note 1 3 6 3 3

2 3 6 3 3 Only 2 ORs are equipped with humidity sensors

3 3 3 3 3

4 3 3 3 3

CSA Requirement 3 3 3 3* Best Practice 3 3 3 3

* Only for systems that have the capability to go to unoccupied mode CSA-Z317.2-15-6.5.4.1.3

Operating Room Ventilation Systems Best Practices Guide for Energy Efficiency, Health and Safety | page 9 Table 6. Pilot hospital ventilation controls

Variable Air Volume Box Air Flow Hospital # Individual Individual Common Station Supply Exhaust Exhaust 1 3 6 3 6

2 3 3 6 3

3 3 3 6 3

4 3 3 6 6

Best Practice 3 3 3

Table 7. Pilot hospital central system set-points and controls

Trend-logs AHU Chilled Chilled Back-up Running Main Set-up Supply Air Water Supply Water Supply AHU & Backup AHU Hospital # Temperature Temperature (°F) Temperature (°F) Reset by BAS 1 3 55-60 41 ? 6 6

2 3 53-57 42.5 ? 3 3

3 3 46-50 42.5 3 6 6

4 3 57-61 45 6 3 3

Best Practice 3 50-58 41-50 3 3

Table 8. Pilot hospital operating room set-points and controls

OR OR OR OR OR Does The Burn Unit Burn Unit Temperature Minimum Maximum Minimum Maximum Hospital Temperature Relative Hospital # Reset by BAS Temperature Temperature Relative Relative Have a (°F) Humidity (°F) (°F) Humidity Humidity Burn Unit? (%) (%) (%) 1 3 64 69 No Sensor No Sensor 6

2 ? 66 74.8 57.7 71 3 85 No Sensor

3 3 64 72 45 65 6 6 6

4 ? 67 73 42 54 6 6 6

CSA* Recommendation 64.5 73.4 30 60 75-86 30-60

Best Practice 3 64.5 73.4 30 60 75-86 30-60

Operating Room Ventilation Systems Best Practices Guide for Energy Efficiency, Health and Safety | page 10 6. Energy Use Breakdown: Reference Ventilation System The energy use breakdown of a reference OR ventilation system is shown in Figure 3 for weather conditions in Toronto Table 9. ON, Calgary AB and Sacramento CA. The parameters of this Reference OR ventilation system parameters reference system are provided in Table 9.

Supply Air (cfm) Outside Air Schedule of Operation Heat Recovery Unoccupied Setback 25,000 100% 24 / 7 No No

Exhaust Fan Total Supply Air Temperature (F) Average Room Return Air Relative Supply Fan Total Setpoint (in-wc) Setpoint (in-wc) Temperature (F) Humidity (%) 4 1.5 55 72 50%

Figure 3. Energy cost breakdowns of a reference OR ventilation system under Toronto, Calgary and Sacramento weather conditions ($/cfm)

Fan Energy Humidification Humidification 0.98 Humidification Fan Energy 0.52 1.26 0.72 0.73 Fan Energy 0.90 Cooling 0.38 Cooling Reheat 0.12 0.53 Reheat Reheat 0.84 0.41 Preheat Preheat Preheat Cooling 1.14 0.70 0.09 0.67

Energy cost breakdown of a reference or ventilation system TORONTO CALGARY SACRAMENTO Electricity rate: 0.12 C$/kWh Electricity rate: 0.09 C$/kWh Electricity rate: 0.11 US$/kWh Gas rate: 0.25 C$/M3 Gas rate: 0.12 C$/M3 Gas rate: 0.17 US$/M3

Energy Source Components Toronto Total Calgary Total Sacramento Total Electricity Fan Energy 203,727 203,727 203,727 (kWh) Cooling 79,000 32,194 151,358 Natural Preheat 113,632 145,316 12,847 Gas (M3) Reheat 84,090 84,827 77,938 Humidification 125,525 150,254 76,561

Operating Room Ventilation Systems Best Practices Guide for Energy Efficiency, Health and Safety | page 11 7. System Design Configurations The basic, reference system (100% outside air with no heat recovery), and the four other system design configurations considered in this research, are described as follows:

7.1 Reference System (No Heat Recovery) A constant volume system with 100% outside air supply and 100% exhaust is the reference system against which the rest are compared. No heat recovery system

Figure 4. No heat recovery system Exhaust fan configuration

Supply fan

Hea ting Humidifier Cooling Reheat coil coil coil

Thermal wheel – already sent 7.2 Thermal Wheel Heat Recovery System

The heat recovery wheel rotates between incoming outside air and exhaust air. It Glycol coil heat recovery system recovers both heat and humidity from exhaust to incoming air in winter, and also

provides some pre-cooling of outside air on hot summerGlycol days. Additional fan power is coil used overcoming the static pressure loss through the wheel. A pre-heat coil is provided Exhaust fan for the incoming air to prevent frost forming on the exhaust side of the heat recovery wheel in very cold weather.

Supply fan Figure 5. Thermal wheel heat recovery Exhaust fan system configuration Glycol Hea ting Humidifier Cooling Reheat coil coil coil coil

Supply fan

To/from heat exchanger Glycol Thermal Hea ting Humidifier Cooling Reheat coil wheel coil coil coil

Operating Room Ventilation Systems Best Practices Guide for Energy Efficiency, Health and Safety | page 12 No heat recovery system

Exhaust fan

Supply fan

Hea ting Humidifier Cooling Reheat coil coil coil

7.3 Glycol Coil Heat Recovery System Thermal wheel – already sent Multi-row coils transfer heat from exhaust air to incoming supply air by means of a pumped glycol loop. Additional fan power is used overcoming the static pressure loss Glycolthrough coil heat the recovery coils. system

Figure 6. Glycol coil Glycol coil heat recovery Exhaust fan system configuration

Supply fan

Glycol Hea ting Humidifier Cooling Reheat coil coil coil coil

7.4 Heat Recovery Chiller System A heat recovery chiller typically supplies chilled water throughout the hospital in winter

to cool areas such as data centres and refrigeration, and to recover heat from exhaust air leaving the building. The machine serves as a heat pump, generating hot water which

can be used for a variety of purposes including ventilation reheat. Additional energy is used to run the heat recovery chiller and pumps, and by exhaust fans to overcome the static pressure loss through the heat recovery coils. Heat recovery chiller

Figure 7. Cooling coil Heat recovery chiller Exhaust fan system configuration

To/from heat recovery chiller

Supply fan

Hea ting Humidifier Cooling Reheat coil coil coil

Recirculation

Exhaust fan

Supply fan

Hea ting Humidifier Cooling Reheat coil coil coil

Operating Room Ventilation Systems Best Practices Guide for Energy Efficiency, Health and Safety | page 13

Heat recovery chiller

Cooling coil Exhaust fan

To/from heat recovery chiller

Supply fan

Hea ting Humidifier Cooling Reheat 7.5 Air Recirculation System coil coil coil

A proportion of exhaust air from the surgical suite is recirculated back into the supply

stream, mixing with at least the minimum volume of incoming outside air before delivery to the ORs, and thereby recovering heat and humidity in winter and reducing Recirculationlatent cooling loads in summer.

Figure 8. Exhaust fan Air recirculation system configuration

Supply fan

Hea ting Humidifier Cooling Reheat coil coil coil

Table 10 summarizes the relative energy benefits and offsets of each design configuration.

Table 10. Design Configuration Energy Considerations Energy considerations of system design configurations No heat recovery system Reference system

Thermal wheel heat Recovers as much as 80% of sensible heat and humidity from recovery system exhaust air in winter, along with a smaller pre-cooling and dehumidifying effect in summer. Additional fan power due to static pressure loss through the wheel (Note 1).

Glycol coil heat Recovers around 45% of sensible heat from exhaust air in recovery system winter. Additional pump energy and fan power due to static pressure loss through the intake and exhaust coils (Note 1).

Heat recovery Recovers sensible heat throughout the hospital for use in reheat chiller system coils, and to supplement other heating. Additional energy to run the machine, and fan power due to exhaust air heat recovery coils (Note 1).

Air recirculation system Reuses conditioned return air, recovering heat and humidity in winter, and cooled and dehumidified air in summer.

Note 1: bypass dampers can be installed to avoid static pressure losses by diverting air around heat wheels and coils when heat recovery is not required.

Operating Room Ventilation Systems Best Practices Guide for Energy Efficiency, Health and Safety | page 14 4.59 4.43

4 3.84 3.47 4 3.34 3.17 2.87 8. Energy Cost Comparison for Different 2.36

System Design Configurationscfm 2.20 4 Figures 9, 10 and 11 present the relative energy costs per cfm 1.60

(using gas-fired boiler heating and humidification and electric cooling, at 2015 rates) for each of the system design configurations, and for typical weather conditions in Toronto, Calgary 4 4 and Sacramento, respectively. Tables below the bar charts show no unoccupied no unoccupied no unoccupied no unoccupied no unoccupied the relative energy and utility cost savings comparedsetback setbackwith the setback setback setback setback setback setback setback setback 25,000 cfm reference system (no heat recovery). Reference system Thermal wheel Glycol heat recovery Heat recovery chiller Recirculation (no heat recovery)

Figure 9. OR AHU energy cost breakdown for different design configurations – Gas cfm Gas rate 0.25 CkWh Electricity cfm rateElectricity rate 0.12 C3 Toronto weather conditions Gas rate: 0.25 C$/M3 Electricity rate: 0.12 C$/kWh 4.594.59 4.59 4.434.43 4.43

44 4 3.843.84 3.84 3.473.47 3.47 44 4 3.343.34 3.34 3.173.17 3.17 2.872.87 2.87 2.362.36 2.36

cfm cfm cfm 2.202.20 2.20 4.59 4.59 4.43 4.43 44 4 3.13 1.601.60 1.60 4 3.84 2.68 4 3.84 3.47 4 3.47 4 3.34 2.36 3.17 3.34 2.29 3.17 2.87 2.01 2.87 1.90 44 4 44 4 1.70 2.36 cfm

2.36 2.20 cfm 1.40 cfm 2.20 1.35 4 4 4 1.60 1.01 no no unoccupiedunoccupiedno unoccupiedno no unoccupiedunoccupiedno unoccupiedno no unoccupiedunoccupiedno unoccupied1.60no no unoccupiedunoccupiedno unoccupiedno no unoccupiedunoccupiedno unoccupied 4 setbacksetback setbacksetbacksetback setbacksetbacksetback setbacksetbacksetback setbacksetbacksetback setbacksetbacksetback setbacksetbacksetback setbacksetbacksetback setbacksetbacksetback setbacksetbacksetback setback ReferenceReference system systemReference systemThermalThermal wheel wheelThermal wheelGlycolGlycol heat heat recovery recoveryGlycol heat recoveryHeatHeat recovery recovery chillerHeat chiller recovery chillerRecirculationRecirculationRecirculation (no(no heat heat recovery) recovery)(no heat recovery) 4 4 4 4 4 Savings Reference system Thermal wheel Glycol heat recovery Heat recovery chiller Recirculation relative to (no heat recovery) no unoccupied no unoccupied no unoccupied no unoccupied no unoccupied no unoccupied no unoccupied no unoccupied no unoccupied no unoccupied setback setback setback setback setback setback setback setback setback setback setbackreferencesetback GasGas setbackcfm cfmsetbackGas cfm setback setback setback setbackGasGas rate ratesetback Gas 0.25setback rate 0.25 CkWh CkWh 0.25 CkWh systemno unoccupied nono unoccupiedunoccupied no nounoccupied unoccupied no unoccupiedno unoccupiedno unoccupied no unoccupied no unoccupied setbackReference systemsetback ElectricityElectricitysetbackThermal cfm wheel cfmsetbackElectricity Glycolcfmsetback heat recoverysetback Heatsetback recovery chillersetbackrateElectricityrateElectricitysetbackRecirculation raterateElectricity ratesetback 0.12 0.12 C3 rate C3 0.12 C3Reference system Thermal wheel Glycol heat recovery Heat recovery chiller Recirculation (no heat recovery) setback setback setback setback setback setback setback setback setback setback Reference system Thermal wheel Glycol heat recovery Heat recovery chiller Recirculation (no heat recovery) (no heatTotal recovery) $ $0 $27,962 $35,417 $55,849 $18,839 $55,051 $4,112 $31,253 $66,149 $79,634

Gas cfm M3/yr 0 72,731 166,987Gas rate 202,146 0.25 CkWh 98,136 148,786 169,530 204,116 236,659 251,751 Gas rate 0.12 CkWh GasElectricity cfm cfm rateElectricityGas rate rate 0.25 0.12 CkWh C3 Electricity rate 0.09 C3 ElectricityElec kWh/yr cfm 0 81,491 -52,751rateElectricity44,274 rate 0.12 C3-47,457 148,786 -318,923 -164,804 58,200 139,132

2.71 2.67 2.55 2.61 Operating Room Ventilation Systems Best Practices Guide for Energy Efficiency, Health and Safety | page 15 4 2.02 1.98 2.03 1.88 1.94 4 4 1.50 3.133.13 3.13 3.13 cfm 2.68 2.682.68 2.68 3.13 2.68 2.36 2.29 2.362.36 2.36 2.01 2.292.29 2.29 1.90 2.29 2.36 2.012.01 2.01 1.70 2.01 4 4 4 1.901.90 1.90

cfm 1.90 1.40 1.701.701.35 1.70 4 1.70 cfm cfm cfm cfm 1.40 4 1.01 1.401.40 1.40 1.35 1.351.35 1.35 4 no unoccupied no unoccupied no unoccupied no unoccupied no unoccupied 44 4 setback setback setback setback setback setback setback setback setback setback 4 1.01 44 1.011.014 1.01 4 Reference system Thermal wheel Glycol heat recovery Heat recovery chiller Recirculation (no heat recovery) no unoccupied no unoccupied no unoccupied no unoccupied4 no unoccupied setback setback setback setback setback setback setback setback setback setback 44 4 Referenceno unoccupied system Thermalno wheelunoccupied Glycolno heat recoveryunoccupied Heatno recovery unoccupied chiller Recirculationno unoccupied (no heat recovery) setback setback setback setback setback setback setback setback setback setback Reference system no no Thermalunoccupiedunoccupied wheelno unoccupiedGlycolno no heat recoveryunoccupiedunoccupiedno Heatunoccupied recoveryno no chiller unoccupiedunoccupiedno Recirculationunoccupiedno no unoccupiedunoccupiedno unoccupiedno no unoccupiedunoccupiedno unoccupied (no heat recovery) setbacksetback setbacksetback setbacksetbacksetbackGas ratesetback setback 0.12 CkWhsetbacksetbacksetback setbacksetback setbacksetbacksetback setbacksetback setbacksetbacksetback setbacksetback setback ReferenceReference system systemReference systemThermalThermalElectricity wheel wheel rateThermal 0.09 C3 wheelGlycolGlycol heat heat recovery recoveryGlycol heat recoveryHeatHeat recovery recovery chillerHeat chiller recovery chillerRecirculationRecirculationRecirculation (no(no heat heat recovery) recovery)(no heat recovery) Gas rate 0.12 CkWh Electricity rate 0.09 C3 2.71 2.67 2.61 GasGas rate rate Gas 0.12 rate 0.12 CkWh CkWh 0.12 CkWh 2.55 ElectricityElectricity rate rateElectricity 0.09 0.09 C3 C3 rate 0.09 C3 2.71 2.67 4 2.55 2.61 2.02 1.98 2.03 1.88 1.94 4 kWh 4 2.02 4 2.03 Gas rate 0.17 USkWh 1.98 1.94 1.50 1.88 Electricity rate 0.11 US3 cfm 2.712.71 2.71 2.672.674 2.674 2.552.55 2.55 1.502.612.61 2.61

cfm 44 4 4 42.022.02 2.02 4 1.981.98 1.98 2.032.03 2.03 1.881.88 1.88 1.941.94 1.94 no unoccupied4 4no unoccupied no unoccupied no unoccupied4 no unoccupied 44 444 4 setback setback setbacksetback setback setback setbacksetback setback setback 1.501.50 1.50 Reference system Thermal wheel Glycol heat recovery Heat recovery chiller Recirculation (nocfm no heatcfm recovery)unoccupied cfm no unoccupied no unoccupied no unoccupied no unoccupied setback setback setback setback setback setback setback setback setback setback Reference system Thermal wheel Glycol heat recovery Heat recovery chiller Recirculation (no heat recovery)

44 444 4 44 4

no no unoccupiedunoccupiedno unoccupiedno no unoccupiedunoccupiedno unoccupiedno no unoccupiedunoccupiedno unoccupiedno no unoccupiedunoccupiedno unoccupiedno no unoccupiedunoccupiedno unoccupied setbacksetback setbacksetback setbacksetbacksetback setbacksetback setbacksetbacksetback setbacksetback setbacksetbacksetback setbacksetback setbacksetbacksetback setbacksetback setback ReferenceReference system systemReference systemThermalThermal wheel wheelThermal wheelGlycolGlycol heat heat recovery recoveryGlycol heat recoveryHeatHeat recovery recovery chillerHeat chiller recovery chillerRecirculationRecirculationRecirculation (no(no heat heat recovery) recovery)(no heat recovery) kWh Gas rate 0.17 USkWh Electricity rate 0.11 US3 kWh Gas rate 0.17 USkWh Electricity rate 0.11 US3

kWhkWh kWh GasGas rate rate Gas 0.17 rate 0.17 USkWh USkWh 0.17 USkWh ElectricityElectricity rate rateElectricity 0.11 0.11 US3 US3 rate 0.11 US3 4.59 4.59 4.43 4.43

4 4 3.84 3.84 3.47 3.47 4 4 3.34 3.34 3.17 3.17 2.87 2.87 2.36 2.36 cfm cfm 2.20 2.20 4 4 4.59 1.60 1.60 4.43

4 3.84 3.47 4 4 4 4 4 3.34 3.17 2.87 no unoccupiedno unoccupiedno unoccupiedno unoccupiedno unoccupiedno unoccupiedno unoccupiedno unoccupiedno unoccupiedno unoccupied setback setbacksetback setbacksetback setbacksetback setbacksetback setbacksetback setbacksetback setbacksetback setbacksetback setbacksetback setback 2.36 cfm 2.20 Reference systemReference system Thermal wheelThermal wheel Glycol heat recoveryGlycol heat recoveryHeat recoveryHeat chiller recovery chiller Recirculation Recirculation (no heat recovery)(no heat recovery) 4 1.60

Gas cfm Gas cfm Gas rate Gas rate 0.25 CkWh 0.25 CkWh Electricity cfmElectricity cfm rateElectricityrateElectricity rate 0.12 rate C3 0.12 C3 4 4

no unoccupied no unoccupied no unoccupied no unoccupied no unoccupied setback setback setback setback setback setback setback setback setback setback Figure 10. Reference system Thermal wheel Glycol heat recovery Heat recovery chiller Recirculation OR AHU energy cost breakdown for different design configurations – (no heat recovery) Calgary weather conditions

Gas cfm Gas rate 0.25 CkWh Electricity cfm rateElectricity rate 0.12 C3 4.59 4.43 Gas rate: 0.12 C$/M3 Electricity rate: 0.09 C$/kWh 4 3.84 3.13 3.13 2.68 3.472.68 4 3.34 3.17 2.29 2.29 2.36 2.36 2.87 2.01 2.01 4.59 1.90 1.90 4.59 4.43 1.70 1.70 2.36 4.43 cfm cfm cfm 2.20 1.40 1.40 1.35 1.35 4 4 43.84 4 3.84 4 3.47 4 4 41.01 1.01 3.47 4 3.34 1.60 3.17 3.34 3.17 2.87 2.87 4 4 3.13 2.36 cfm 2.36 2.20 cfm 2.20 2.68 44 4 no unoccupiedno unoccupiedno 4unoccupiedno unoccupiedno unoccupiedno unoccupiedno unoccupiedno unoccupiedno unoccupiedno unoccupied setback setbacksetback setbacksetback setbacksetback setbacksetback setbacksetback 1.60setbacksetback setbacksetback setbacksetback setbacksetback setback 2.36 1.60 2.29 Reference systemReference system Thermal wheelThermal wheel Glycol heat recoveryGlycol heat recovery Heat recoveryHeat chiller recovery chiller Recirculation2.01 Recirculation (no heat recovery)(no heat recovery) 1.90 no unoccupied no unoccupied no unoccupied no unoccupied no unoccupied 1.70 setback setback4 setback setback setback setback 4setback setback setback setback 4 4 cfm 1.40 1.35 Reference system Thermal wheel Glycol heat recoveryGas rate Gas rate 0.12Heat CkWh recovery 0.12 chiller CkWh Recirculation Savings (no heatReference recovery) system Thermal wheel Glycol heat recovery Heat recovery chiller Recirculation4 relative to (no heat recovery) Electricity rateElectricity 0.09 C3rate 0.09 C3 1.01 no unoccupied no unoccupied no unoccupied no unoccupied no unoccupied 4 setbackreferencesetback setback setback setback setback setback setback setback setback systemno unoccupied nono unoccupiedunoccupied no nounoccupied unoccupied no unoccupiedno unoccupiedno unoccupied no unoccupied no unoccupied setbackReference systemsetback setbacksetbackThermal wheelsetbacksetback Glycolsetbacksetback heat recoverysetback setbackHeatsetback recoverysetback chillersetback setbackRecirculationsetbacksetback setback setback setback (no heat recovery) Reference system Thermal wheel Glycol heat recovery Heat recovery chiller Recirculation (no heat recovery) Gas cfm Gas rate 0.25 CkWh Total $ $0 $16,657 $19,282 $31,930 $9,741 $37,096 -$11,299 $7,979 $37,987$46,646 4 2.71Electricity cfm2.71 rateElectricity rate 0.12 C3 2.67 2.67 Gas cfm M3/yr 0 85,589 201,5382.55Gas rate 2.55241,781 0.25 CkWh 117,493 176,646 188,4832.61 2.61231,664 284,200 300,478 rateElectricity rate 0.12 C3 no unoccupied no unoccupied no unoccupied no unoccupied no unoccupied GasElectricity cfm cfm Gas rate 0.25 CkWh setback setback setback setback setback setback setback setback setback setback ElectricityElec kWh/yr cfm 0 70,959 -54,475rateElectricity32,407 rate 0.12 C3-48,427 176,646 -376,857 -220,234 43,145 117,654 4 4 Reference system Thermal wheel Glycol heat recovery Heat recovery chiller Recirculation 2.02 2.02 1.98 1.98 (no heat2.03 recovery)2.03 1.88 1.88 1.94 1.94 4 44 4 1.50 1.50 Gas rate 0.12 CkWh

cfm cfm Electricity rate 0.09 C3 4 44 4 4 42.71 2.67 2.55 2.61 3.13 2.68 no unoccupiedno unoccupiedno unoccupiedno unoccupied3.13 no unoccupiedno unoccupiedno unoccupiedno unoccupiedno unoccupiedno unoccupied setback setbacksetback setbacksetback setbacksetback setbacksetback setbacksetback setbacksetback setbacksetback setback4setback 2.02setbacksetback setback 2.03 3.13 1.98 1.94 2.68 2.29 2.36 1.88 Reference systemReference system Thermal wheelThermal wheel Glycol heat recoveryGlycol heat recoveryHeat recoveryHeat chiller recovery chiller RecirculationRecirculation 2.01 2.68(no heat recovery)(no heat recovery) 2.36 4 1.90 2.29 4 1.70 1.50 2.01

cfm 1.90 1.40 2.29 1.35 2.36 cfm 4 1.70 cfm 2.011.40 4 1.01 1.35 4 1.90 1.70 4 1.01 cfm 1.40 4 1.35 4 4 4 4 4 no unoccupied no unoccupied no unoccupied no unoccupied no unoccupied 4 1.01 setback setback setback setback setback setback setback setback setback setback Referenceno unoccupied system Thermalno wheelunoccupied Glycolno heat recoveryunoccupied Heatno recovery unoccupied chiller Recirculationno unoccupied setback(no heat recovery)setback setback setback setback setback setback setback setback setback no unoccupied no unoccupied no unoccupied no unoccupied no unoccupied Reference system Thermal wheel Glycol heat recovery Heat recovery chiller Recirculation setback setback setback setback setback setback setback setback setback setback (no heat recovery) 4 Gas rate 0.12 CkWh Reference system Thermal wheel Glycol heat recovery Heat recovery chiller Recirculation OperatingElectricity Room rateVentilation 0.09 C3 Systems Best Practices Guide for Energy Efficiency,(no Health heat recovery) and Safety | page 16 no unoccupied no Gasunoccupied rate 0.12 CkWhno unoccupiedkWh kWh no unoccupied no unoccupied setback setback setback Electricitysetback rate 0.09 C3setback Gassetback rate Gas rate 0.17setback USkWh 0.17setback USkWh setback setback Reference system Thermal wheel Glycol heat recoveryElectricity rateElectricity 0.11Heat US3rate recovery 0.11 chiller US3 Recirculation 2.71 (no heat recovery) 2.67 2.61 2.55 2.71 2.67 4 2.55 2.61 2.02 1.98 Gas rate2.03 0.12 CkWh 1.88 1.94 Electricity4 rate 0.09 C3 4 2.02 4 2.03 1.98 1.50 1.88 1.94 cfm 4 4 1.50 cfm 2.71 2.67 2.61 4 4 2.55 4 kWh Gas rate 0.17 USkWh no unoccupied44 4no unoccupied no unoccupied no unoccupied4 no unoccupied Electricity rate 0.11 US3 setback setback setback2.02setback setback setback setback setback 1.98setback setback 2.03 1.88 1.94 Reference system Thermal wheel Glycol heat recovery Heat recovery chiller Recirculation (nono heat recovery)unoccupied no unoccupied no unoccupied no unoccupied no unoccupied 4 setback setback setback setback setback setback setback setback setback setback 4 1.50 Reference system Thermal wheel Glycol heat recovery Heat recovery chiller Recirculation (no heat recovery) cfm

4 4 4

no unoccupied no kWhunoccupied no unoccupied no unoccupied no unoccupied setback setback setbackGas ratesetback 0.17 USkWhsetback setback setback setback setback setback Electricity rate 0.11 US3 Reference system Thermal wheel Glycol heat recovery Heat recovery chiller Recirculation (no heat recovery) kWh Gas rate 0.17 USkWh Electricity rate 0.11 US3

kWh Gas rate 0.17 USkWh Electricity rate 0.11 US3 4.59 4.43

4 3.84 3.47 4 3.34 3.17 2.87 2.36 cfm 2.20 4 1.60

4 4

no unoccupied no unoccupied no unoccupied no unoccupied no unoccupied setback setback setback setback setback setback setback setback setback setback Reference system Thermal wheel Glycol heat recovery Heat recovery chiller Recirculation (no heat recovery) 4.59 4.43 Gas cfm Gas rate 0.25 CkWh Electricity cfm rateElectricity rate 0.12 C3 4 3.84 3.47 4 3.34 3.17 2.87 2.36 cfm 2.20 4 4.59 1.60 4.43

4 3.84 3.47 4 4 4 3.34 3.17 3.13 2.87 2.68 no unoccupied no unoccupied no unoccupied no unoccupied no unoccupied setback setback setback setback setback setback setback setback setback setback 2.36 2.36 2.29 cfm 2.20 Reference system Thermal wheel Glycol heat recovery Heat recovery chiller Recirculation (no2.01 heat recovery) 1.90 4 1.70 1.60 cfm 1.40 1.35 4 Gas cfm Gas rate 0.25 CkWh 4 1.01 Electricity cfm rateElectricity rate 0.12 C3 4 4 4 no unoccupied no unoccupied no unoccupied no unoccupied no no unoccupiedunoccupied no unoccupied no unoccupied no unoccupied no unoccupied setback setback setback setback setback setback setback setback setbacksetbacksetbacksetback setback setback setback setback setback setback setback setback Figure 11. Reference system Thermal wheel Glycol heat recovery Heat recovery chiller ReferenceRecirculation system Thermal wheel Glycol heat recovery Heat recovery chiller Recirculation OR AHU energy(no cost heat breakdown recovery) for different design configurations – (no heat recovery) Sacramento weather conditions Gas rate 0.12 CkWh Electricity rate 0.09 C3 Gas cfm Gas rate 0.25 CkWh Electricity cfm rateElectricity rate 0.12 C3 4.59 4.43 Gas rate: 0.17 US$/M3 Electricity rate: 0.11 US$/kWh 4 2.71 3.842.67 3.13 2.55 2.61 3.472.68 4 3.34 3.17 4 2.02 2.362.03 2.291.98 1.94 1.88 2.87 2.01 4 4.59 1.90 4 4.59 1.50 2.36 4.43 1.70 4.43 cfm cfm

cfm 2.20 1.40 1.35 4 43.84 4 3.84 4 3.47 4 4 1.01 3.47 4 3.34 1.60 3.17 3.34 3.17 2.87 2.87 4 4 4 4 3.13 2.36 cfm 2.36 2.20 cfm 4 2.20 2.68 4 no unoccupiedno unoccupiedno 4unoccupiedno unoccupiedno unoccupiedno unoccupiedno unoccupiedno unoccupiedno unoccupiedno unoccupied setback setbacksetback setbacksetback 4setbacksetback setbacksetback setbacksetback 1.60setbacksetback setbacksetback setbacksetback setbacksetback setback 2.36 1.60 2.29 Reference systemReference system Thermal wheelThermal wheel Glycol heat recoveryGlycol heat recovery Heat recoveryHeat chiller recovery chiller Recirculation2.01 Recirculation (no heat recovery)(no heat recovery) 1.90 no unoccupied no unoccupied no unoccupied no unoccupied no unoccupied setback setback setback setback setback setback setback setback setback setback 1.70 4 4 4 4 cfm 1.40 Reference system Thermal wheel Glycol heat recovery Gas rateHeat recovery 0.12 chiller CkWh Recirculation 1.35 Savings (no heatReference recovery) system Thermal wheel Glycol heat recovery Heat recovery chiller Recirculation4 relative to (no heat recovery) Electricity rate 0.09 C3 1.01 no unoccupied no unoccupied no unoccupied no unoccupied no unoccupied 4 setbackreferencesetback setback setback setback setback setback setback setback setback systemno unoccupied nono unoccupiedunoccupied no nounoccupied unoccupied no unoccupiedno unoccupiedno unoccupied no unoccupied no unoccupied setbackReference systemsetback setbacksetbackThermal wheelsetbacksetback Glycolsetbacksetback heat recoverysetback setbackHeatsetback recoverysetback chillersetback setbackRecirculationsetbacksetback setback setback setback (no heat recovery) Reference system Thermal wheel Glycol heat recovery Heat recovery chiller Recirculation Gas cfm Gas rate 0.25 CkWh (no heatTotal recovery) $ $0 $17,200 $3,979 $20,689 $1,004 $17,463 $2,446 $19,192 $21,234 $34,420 4 Electricity cfm2.71 rateElectricity rate 0.12 C3 2.67 2.61 Gas cfm M3/yr 0 37,653 48,852Gas rate 2.5575,513 0.25 CkWh 31,782 62,284 90,645 107,903 98,684 112,423 no unoccupied no unoccupied no unoccupied no unoccupied no unoccupied GasElectricity cfm cfm rateElectricityGas rate rate 0.25 0.12 CkWh C3 setback setback setback setback setback setback setback setback setback setback ElecElectricity kWh/yr cfm 0 97,771 -39,091rateElectricity71,141 rate 0.12 C3-39,773 62,284 -117,215 7,800 40,455 138,665 4 Reference system Thermal wheel Glycol heat recovery Heat recovery chiller Recirculation 2.02 1.98 2.03 1.88 (no1.94 heat recovery) kWh Gas rate 0.17 USkWh 4 4 1.50 Electricity rate 0.11 US3 Gas rate 0.12 CkWh

cfm Electricity rate 0.09 C3 4 4 2.714 2.67 2.55 2.61 3.13 2.68 no unoccupied no unoccupied3.13 no unoccupied no unoccupied no unoccupied setback setback setback setback setback setback3.13 setback setback4 2.02setback setback 2.03 1.98 1.94 2.68 2.36 1.88 Reference system2.29 Thermal wheel Glycol heat recovery Heat recovery chiller Recirculation 2.012.68 (no heat recovery) 4 1.90 2.29 2.36 4 1.70 1.50 2.01 2.36 cfm 1.90 1.40 2.29 1.35 cfm 4 1.70 2.01 cfm 1.40 4 1.01 1.90 1.35 4 1.70 4 1.01 cfm 1.40 4 1.35 4 4 4 4 4 1.01 no unoccupied no unoccupied no unoccupied no unoccupied no unoccupied 4 setback setback setback setback setback setback setback setback setback setback Referenceno unoccupied system Thermalno wheelunoccupied Glycolno heat recoveryunoccupied Heatno recovery unoccupied chiller Recirculationno unoccupied setback(no heat recovery)setback setback setback setback setback setback setback setback setback no unoccupied no unoccupied no unoccupied no unoccupied no unoccupied setback setback setback setback setback setback setback setback setback setback Reference system Thermal wheel Glycol heat recovery Heat recovery chiller Recirculation 4 (no heat recovery) Reference system Thermal wheel Glycol heat recovery Heat recovery chiller Recirculation Gas rate 0.12 CkWh OperatingElectricity Room rateVentilation 0.09 C3 Systems Best Practices Guide for Energy Efficiency,(no heatHealth recovery) and Safety | page 17 no unoccupied no unoccupied no unoccupied kWh no unoccupied no unoccupied setback setback setback Gas ratesetback 0.12 CkWhsetback setback setback setback setback setback Electricity rate 0.09 C3 Gas rate 0.17 USkWh Reference system Thermal wheel Glycol heat recovery Heat recovery chiller Recirculation Electricity rate 0.11 US3 2.71 (no heat recovery) 2.67 2.61 2.55 2.71 2.67 2.61 4 2.02 2.55 Gas rate2.03 0.12 CkWh 1.98 1.94 1.88 Electricity rate 0.09 C3 4 4 2.02 4 2.03 1.98 1.50 1.88 1.94 cfm 4 4 1.50

cfm 2.71 2.67 2.55 2.61 4 4 4 kWh Gas rate 0.17 USkWh no unoccupied44 4no unoccupied no unoccupied no unoccupied4 no unoccupied Electricity rate 0.11 US3 2.02 1.98 2.03 setback setback setback setback setback setback1.88 setback setback setback setback 1.94 Reference system Thermal wheel Glycol heat recovery Heat recovery chiller Recirculation (nono heat recovery)unoccupied no unoccupied no unoccupied no unoccupied no unoccupied 4 4 setback setback setbacksetback setback setback setback setback setback setback 1.50 Reference system Thermal wheel Glycol heat recovery Heat recovery chiller Recirculation

(nocfm heat recovery)

4 4 4

no unoccupied no unoccupied no unoccupied no unoccupied no unoccupied kWh setback setback setback Gas ratesetback 0.17 USkWhsetback setback setback setback setback setback Reference system ThermalElectricity wheel rate 0.11 US3Glycol heat recovery Heat recovery chiller Recirculation (no heat recovery) kWh Gas rate 0.17 USkWh Electricity rate 0.11 US3

kWh Gas rate 0.17 USkWh Electricity rate 0.11 US3 Appendix A: Checklist Hospital: OR Ventilation Assessment Action Checklist Contact Email:

ACTION

DETAILS # NAME Already Implemented Planned Consider / NA Reject

OPERATIONAL CHANGES

1 Test and adjust supply and exhaust airflows for individual spaces to match CSA requirements for both occupied and unoccupied periods

2 Reset supply air temperature to maintain RH in all ORs while minimizing reheat

3 Reset discharge air static pressure to optimize fan power

4 Reset space conditions during unoccupied periods to minimize simultaneous cooling and heating

5 Reset chilled water supply temperature to achieve required supply air temperatures

6 (If standby AHUs installed) operate both AHUs in parallel

ACTION

DETAILS # NAME Already Implemented Planned Consider / NA Reject

RETROFIT MEASURES

1 Install VFDs to enable efficient occupied/unoccupied air volume reset

2 Install or replace volume control boxes on individual air supply and exhaust to each space

3 Install differential pressure monitoring in ORs and other areas

4 Install temperature and RH sensors for individual ORs

5 Install airflow monitoring stations on supply and exhaust fans

6 Implement air recirculation for 100% outside air systems

7 Install low static pressure loss heat recovery on 100% outside air systems

8 Consider anesthetic gas monitoring and system reset controls

9 Consider anesthetic gas scavenging and recycling

Operating Room Ventilation Systems Best Practices Guide for Energy Efficiency, Health and Safety | page 18