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:
• Prevent Simultaneous Heating/Cooling Control - Significant simultaneous heating and cooling observed on AHU-2 with cooling coils open to 40% and heating coils open to 15%. AHU-2 does not have dehumidification control so simultaneous heating and cooling should be eliminated. Program interlocks that do not allow the unit to be only in heating or cooling mode, repair/replace all faulty valves, and commission all air handlers & fan coils.
• Chilled Water (CHW) Variable Speed Pumps & Loop Differential Pressure (DP) Reset - Both a differential pressure and a CHW supply temperature setpoint reset are enabled for the CHW system. However, these resets are poorly implemented resulting in operating conditions near maximum setpoints even during low load conditions. Adjust the existing reset logic to allow the pumps to reset first, then reset the CHW supply temperature setpoint, where both using the worst-case AHU valve as the demand variable.
• Heating Hot Water (HHW) Variable Speed Pumps & Loop Differential Pressure (DP) Reset - There is currently no HHW loop differential pressure reset, which is typical of pneumatically controlled buildings. Program HHW loop differential pressure reset by using outside air temperature or difference in temperature between supply and return loop water (delta T) to reduce pumping demand.
• Program Air Handler/Rooftop Unit (AHU/RTU) Supply Air Temperature Reset - Both single zone & multizone air handler units (AHU-5 and AHU-9, respectively) do not have a supply temperature reset enabled despite having feedback from their respective zones. Program supply air temperature resets by identifying zone temperatures & only provide sufficient cooling to satisfy the warmest zone. This will reduce the amount of cooling & re-heat at the zonal level in addition to providing greater occupant comfort.
• Program Condenser Water (CDW) Reset - The CDW system is currently operating with a constant CDW setpoint regardless of the load on the chillers or the outside air conditions. This measure would install an outside wet bulb temperature-based reset to allow the CDW temperature to lower or raise based on achieving a target approach with the outside air wetbulb temperature. This will allow for more efficient operation of the chillers by using lower condenser water temperatures.
• Add Air Handler Unit (AHU) Economizer - AHU-9 was identified as a return air unit with actuated dampers on the return, exhaust, and outside air intakes, however there are currently no actuators installed on the dampers. Install dampers & commission economizer functionality to let the unit utilize outside air when conditions are appropriate. In conjunction with AHU-6 replacement, this will ensure that all AHUs on the building have economizing capabilities, which will allow the chiller to disable during low outside air temperature conditions rather than running at extremely low loads. This will not only save energy but greatly improve the life of the chillers.