Memorial Hospital

Opportunity

Status

Estimated Start:

Total Annual Savings

Project Cost:

Project Payback:  

Description

Connected Commissioning

Not Started

FY 2020

$325,800

$1,440,000

4.4

Connected commissioning optimizes building performance, reduces operating and maintenance costs and extends equipment lifetimes. As a result of the energy audit, high priority lighting, automation/controls and heating, ventilation and air conditioning (HVAC)-related ECMs are recommended for implementation through a connected commissioning project delivery. In most cases, the building automation system will be used to collect and analyze on-going performance data, identify new trends and ensure persistent savings from previously-implemented ECMs.

Recommendation: 

The following measures were identified as specific opportunities to be completed as part of a connected commissioning process. These opportunities may be implemented independently or as part of a coordinated effort:

• Re-Specify Building Automation System (BAS) Upgrade for Stephen Birch Tower - Leverage analytics-based connected commissioning and functional testing to optimize sequences of operation, upgrade and validate required controls. Control specifications and optimized sequences of operation will be provided for all budgeted HVAC unit replacements.

• Prevent Simultaneous Heating/Cooling Control – Eliminate simultaneous heating & cooling by optimizing humidification & dehumidification control sequences and adding appropriate deadbands to achieve zone humidity requirements. Humidifiers shall modulate to maintain minimum supply air dew point setpoint and dehumidification shall modulate cooling valve to maintain minimum and maximum zone humidity, respectively. Applicable units identified during audit:
o Stephen Birch AHU-2
o Central Tower AHU-9,11
o East Tower AHU-5,7

• Program Air Handler/Rooftop Unit (Air Handler/Rooftop Unit (AHU/RTU) Economizer Lockouts - Economizer enable control relies upon unreliable sensors & enthalpy calculations (specific criteria vary by unit) to determine availability for AHU economizer cooling. Optimize control sequence where the economizer shall be enabled when outside air dew point is 1) lower than 56F and 2) when outside air temperature is lower than the return/zone air temperature by 2F. Economizer control should be disabled when outside air dewpoint is greater than 58F or when the outside air temperature is greater than return/zone air temperature. Applicable units identified during audit:
o Rehab AHU-1,2,3
o Mary Birch AHU-1,2,3,4,5,6,7
o OPP AHU-1,2,3,4
o Stephen Birch AHU-1,3,5,6,7,8,9
o South Tower AHU-13,14,15
o East Tower AHU-4

• Program Air Handler/Rooftop Unit (Air Handler/Rooftop Unit (AHU/RTU) Economizer Staging - Economizer temperature control varies by unit, with some operating to maintain mixed air temperature while cooling and heating valves operate to maintain supply air temperature. In the optimized control sequence, economizer damper shall be modulated in series with heating and cooling valves to maintain supply air temperature. Applicable units identified during audit:
o Mary Birch AHU-2,4,5,6,7
o OPP AHU-1,2,3,4
o South Tower AHU-13,14,15
o Central Tower AHU-11
o East Tower AHU-4

• Integrated Exhaust/Return Fan Control - Many of the AHUs with variable speed return/exhaust fans have fan speed control at a constant 100% speed. Optimize return/exhaust fans by tracking supply fan speed with an adjustable deadband that is balanced to maintain acceptable overall air balance. Applicable units identified during audit:
o Stephen Birch AHU-1,3,5,6,7,8,9

• Program Air Handler/Rooftop Unit (AHU/RTU) Supply Air Temperature Reset - Variations of supply air temperature resets are currently programmed, but the majority are not optimally configured to respond to zone cooling demand and/or are overridden. Program air handler unit supply air temperature resets to modulate the supply air temperature setpoint in order to maintain total (critical) zone temperature cooling error at an adjustable setpoint. Applicable units identified during audit:
o Rehab AHU-1,2,3
o Mary Birch AHU-1,2,3,4,5,6,7
o OPP AHU-1,2,3,4
o Stephen Birch AHU-1,2,3,4,5,6,7,8,9,10
o South Tower AHU-1,2,5,6,7,11,12,13,14,15,17,19,20,21,22,23
o Central Tower AHU-7,8,9,11,19,20
o East Tower AHU-1,2,3,4,5,6,7

• Program Air Handler/Rooftop Unit (AHU/RTU) Static Pressure Reset - Static pressure setpoint resets are not configured for variable volume AHU systems. Program AHU supply air static pressure reset to modulate the supply air static pressure setpoint in order to maintain the maximum (critical) zone supply air damper position at an adjustable setpoint. For example, if static pressure setpoint is fixed at 1.5" water column (W.C.), reset between 0.2 - 1.75” W.C. based on VAV zone voting as referenced in ASHRAE Guideline 3. Applicable units identified during audit:
o OPP AHU-1,2,3,4
o Stephen Birch AHU-1,3,4,5,6,7,8,9,10
o South Tower AHU-7,13,14,15,20,21,22
o Central Tower AHU-7,11,19,20

• Chiller Lockout - The AHU-02 air-cooled booster chiller serving the operating room in Stephen Birch is enabled in parallel with the central plant chilled water system based on outside air temperature, without consideration of the central plant's ability to provide the required cooling to the space. As a result, the chiller cycles to operate at a very low, inefficient load compared to the central plant chiller systems. Program the booster chiller to 1) enable based on requirements indicated by the central plant chilled water valve; and 2) disable when the difference between entering and exiting chiller water temperature is less than 2F. Applicable units identified during audit:
o Operating Room AHU-02 Air Cooled Chiller

• Heating Hot Water (HHW) Variable Speed Pumps & Loop Differential Pressure (DP) Reset - Building heating pump skids modulate pump speed to maintain a constant system differential pressure throughout the year. Program the system differential pressure setpoint to modulate pump speed when heating loads are low to maintain total (critical) zone heating temperature error at an adjustable setpoint. Applicable units identified during audit:
o OPP HW System
o Stephen Birch HW System

• Chilled Water (CHW) Variable Speed Pumps & Loop Differential Pressure (DP) Reset - Building chilled water pump skids modulate pump speed to maintain a constant system differential pressure throughout the year. Program the system differential pressure setpoint to modulate pump speed when AHU cooling loads to maintain the maximum (critical) AHU chilled water valve position at an adjustable setpoint. Applicable units identified during audit:
o Mary Birch CHW System
o OPP CHW System
o Central Tower CHW System
o Stephen Birch CHW System

• Optimize Equipment Schedules - BAS occupancy schedules shows only 6 zones at the Rehabilitation Center and 132 zones at the Outpatient Pavilion are connected to any schedule. Determine the actual occupancy requirements by space/area and reduce terminal equipment run times with automatic schedules configured to occupancy requirements. Standardize schedule by space type where possible, e.g. 6am-6pm for offices. Create after-hours capability that can be used as needed to temporarily override normal schedules.

• Heating & Cooling Setbacks - Zones with applied schedules have varied or missing unoccupied heating & cooling setpoints. Establish and program standard unoccupied schedule heating and cooling zone setback setpoints , e.g. 62F heating and 80F cooling.

• Heating & Cooling Setpoints (Major Spaces) - Establish and program consistent occupied schedule heating and cooling zone setpoints, e.g. 68F heating and 74F cooling. Standardize settings by space type as applicable.

• Heating & Cooling Setpoints (Utility Spaces) - Establish and program standard heating and cooling zone setpoints for non-occupied 24/7 spaces such as telecom, utility or data center rooms, e.g. 60F heating and 80F cooling.

• Add AHU Economizer - If the air handling unit does not have an economizer installed, consider retrofit options to install an economizer. Test & balance the unit to ensure minimum ventilation airflow levels and configure economizer programming per the lockout/staging programs described above. Applicable units identified during audit:
o South Tower AHU-11,12,18
o East Tower AHU-1,2

• Replace Broken Air Handler/Rooftop Unit (AHU/RTU) Economizers - Replace damper actuators or other components needed to ensure reliable damper operation. Broken economizers should be confirmed by physically testing the automatic damper operation. Test and balance the unit to ensure minimum ventilation airflow levels and configure economizer programming per the lockout and staging control sequences above. Applicable units identified during audit:
○ Rehab AHU-1,2
○ Stephen Birch AHU-6
○ South Tower AHU-15

• Replace Leaking CHW or HHW Valves at Air Handler/Rooftop Unit (AHU/RTU) - Test proper operation of CHW and HHW valves at Air Handler/Rooftop Unit (AHU/RTU) by fully cycling valves; verify valves are fully closing/not leaking by observing excess in cooling or heating energy. Repair or replace leaking valves or actuators as needed and test operation using BAS control signal. Applicable units identified during audit:
○ South Tower AHU-11
○ Central Tower AHU-1

• Install Supply Fan Variable Frequency Drives (VFDs) – Several AHUs are designed for variable volume operation via inlet guide vanes but operate at constant speed with inlet guide vanes removed. Install VFDs to supply fan motors and implement supply air static pressure control, with a setpoint reset as described above. For single-zone or multi-zone units without terminal air flow controls, modulate fan speed based on heating and cooling demands from a balanced minimum speed.
○ South Tower AHU-1,2

• Seal Air Duct Leaks – Repair visible punctures in the air duct system near the air handler to reduce fan energy waste. Applicable units identified during audit:
○ South Tower AHU-20

• Repair Fan Belts – Repair air handler fans that have a slipped or worn belt. Applicable units identified during audit:
○ South Tower AHU-20

• Replace Broken Air Handler Unit (AHU) Sensors – Replace AHU sensors where faulty temperature, pressure, or humidity sensors are found (i.e. flatlined, no communication, physically damaged, inaccurate). Institute a maintenance program to calibrate and replace important control sensors (i.e. humidity, return air temperature, supply air temperature, outside air temperature). Applicable units identified during audit:
o Stephen Birch AHU-1,3,5,7,8