Chula Vista Cancer Center
Total Annual Savings:
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 packaged 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.
Perform connected commissioning with a focus on optimizing automated control sequences through programming and control device upgrades to achieve the following energy conservation measure outcomes. The connected commissioning process includes follow up investigation, controls upgrade specifications and sequences, coordination with installing contractor(s), and optimized control sequences validations. Control specifications and optimized sequences of operation will also be provided for all budgeted HVAC unit replacements.
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:
• Equipment Schedules for Air Handler Units & Rooftop Units (AHUs & RTUs) - 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 (e.g. 5am-7am for offices) and based on equipment (e.g. chiller and boilers vs AHUs). Create after-hours capability that can be used as needed to temporarily override normal schedules.
• Heating & Cooling Setpoints (Major Spaces) - Establish and program consistent occupied schedule heating and cooling zone setpoints, e.g. 68°F heating and 74°F cooling. Standardize settings by space type as applicable.
• Program Air Handler/Rooftop Unit (AHU/RTU) Economizer Lockouts - AHU economizers currently lock out at 68°F; optimize control sequence where the economizer shall be enabled when outside air temperature is 1) lower than 50°F and 2) when outside air temperature is lower than the return/zone air temperature by 2°F. Economizer control should be disabled when outside air temperature is 1) higher than 70°F or 2) when the outside air temperature is greater than return/zone air temperature.
• Program Air Handler/Rooftop Unit (AHU/RTU) Supply Air Temperature Reset - Program air handler unit supply air temperature resets to modulate the supply air temperature setpoint (e.g. if supply air temperature setpoint is fixed at 55°F, reset between 55-63°F) in order to maintain total zone temperature cooling error at an adjustable setpoint. Use zone feedback to reset supply air temperature for both VAV zone and single zone units.
• 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 36.
• Program Boiler System Heating Hot Water (HHW) Reset - Program outside air temperature reset of boiler supply temperature setpoint. For conventional boilers or boilers with 3-way valves, use 180-140°F when outside air temperature varies from 20-70°F. For condensing boilers, use 180-80°F when outside air temperature varies from 20-70°F. Alternatively, use voting or hot water value (HWV) rollup based trim and respond based resets.
• Heating Hot Water (HHW) Variable Speed Pumps & Loop Differential Pressure (DP) Reset - Pumps operate at different speeds and manual isolation valves are partially closed. Open isolation values and 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.
• Program Chilled Water (CHW) Setpoint Reset - Program reset of chiller supply temperature setpoint, (e.g. from 42 - 48°F) when outside air temperature varies from 70 - 90°F.
• Program Condenser Water (CDW) Reset - Cooling towers currently control to a constant setpoint of 78°F. Program fans to modulate fan speed in order to maintain cooling tower leaving chilled water (CW) temperature setpoint and reset CDW temperature setpoint between 60 - 75°F. For example, if cooling tower fan speed is above 90%, increase CDW setpoint. If cooling tower fan speed is below 60%, reduce CDW setpoint.
• Chilled Water (CHW) Variable Speed Pumps & Loop Differential Pressure (DP) Reset - Program the system differential pressure setpoint to modulate pump speed and reset the CHW setpoint based on valve position of the air handlers.
• Program Dual Maximum Variable Air Volume (VAV) Control - Program dual maximum VAV control for VAV boxes with a single minimum CFM setpoint. Where minimum air flow setpoint requirements for heating are greater than the requirement for ventilation, minimum air flow setpoints can be reduced.
• Demand Response Sequence - Program sequences to allow non-critical loads such as common area lighting, fountains, displays, etc. to remain OFF during peak hours. Use any available load-shifting technology to delay energy use until after the peak period.