Rees-Stealy Downtown

Opportunity

Status

Estimated Start:

Total Annual Savings

Project Cost:

Project Payback:  

Description

Connected Commissioning

Not Started

FY 2022

$49,400

$216,000

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 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.

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:

• 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 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) Economizer Lockouts - Reprogram control sequence for AHUs 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. Units were found with OA dampers fully closed at an outside air temperature of 64°F.

• Heating Hot Water (HHW) Variable Speed Pumps & Loop Differential Pressure (DP) Reset - Install variable frequency drives (VFDs) & differential pressure sensors; program HHW loop differential pressure reset by modulating pump speed based on outside air temperature or difference in temperature between supply and return loop water (delta T) to reduce pumping demand.

• Integrated Exhaust/Return Fan Control - Multiple exhaust fans (EF3-4 and EF3-6) have variable frequency variable frequency drives (VFDs), but no control or VFD drive speed is shown in the BAS. Control fans to maintain building pressure or track supply fans. Interlock fans with AHU for enable control.

• 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.

• Replace Broken Air Handler Unit (AHU) Sensors - Air handler unit outside air flow sensors are not working; repair known failed sensors as part of ongoing maintenance and use analytics-based connected commissioning to identify other faulty equipment.