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Copyright 2019 - NICHOLAS A. CHAZAPIS

 BAS DEMONSTRATION AND ACCEPTANCE

   1. Prior to acceptance, the control system BAS will undergo a series of performance tests, to verify operation and compliance with this specification.

   2. These tests will occur after the Contractor has completed the installation, started up the system, and performed systems TAB.

   3. The tests described to be performed in addition to the tests that the contractor performs as a necessary part of the installation, start-up, and debugging process and as specified in the “Control System BAS Checkout and Testing”. The engineer will be present to observe and review these tests. The engineer will be notified at least 10 days in advance of the start of the testing procedures.

   4. The approved checklists and forms will be completed for all systems as part of the demonstration.

   5. The contractor will provide at least two persons and will demonstrate actual field operation of each control and point for all modes of operation including day, night, occupied, unoccupied, fire/smoke alarm, seasonal changeover, and power failure modes. The is to demonstrate the calibration, response, and action of every point and system. Any test equipment required to prove the proper operation will be by and operated by the contractor.

   6. As each control input and output is checked, a log will be completed showing the date, Technician’s initials and any corrective action taken or needed.

   7. Demonstrate compliance with sequences of operation through all modes of operation.

   8. Demonstrate complete operation of operator interface and work station client / server PC's.

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 DETAILED PERFORMANCE PRESENTATION

The following items to be demonstrated:

a. DDC / BAS loop response. The contractor will supply trend data output in a graphical form showing the step response of each DDC / BAS loop. The test will show the loop’s response to a change in set point, which represents a change of actuator position of at least 25% of its full range. The sampling rate of the trend will be from 10 seconds to 3 minutes, depending on the speed of the loop. The trend data will show for each sample the set point, actuator position, and controlled variable values. Any loop that yields unreasonably under-damped or over-damped control will require further tuning by the Contractor.

b. Demand limiting. The contractor will supply a trend data output showing the action of the demand limiting algorithm. The data will document the action on a minute-by-minute basis over at least a 30-minute period. Included in the trend will be building kW, demand limiting set point, and the status of sheddable equipment outputs.

c. Optimum start/stop. The contractor will supply a trend data output showing the capability of the algorithm. The change-of-value or change-of-state trends will include the output status of all optimally started and stopped equipment, as well as temperature sensor inputs of affected areas.Interface to the building fire alarm system.

d. Operational logs for each system that indicate all set points, operating points, valve positions, mode, and equipment status will be submitted to the architect/engineer. These logs will cover three 48-hour periods and have a sample frequency of not more than 10minutes. The logs will be provided in both printed and disk formats.

Any tests that fail to demonstrate the operation of the system BAS, will be repeated at a later date.

The contractor will be responsible for any necessary repairs or revisions to the hardware or software to successfully complete all tests.


 Acceptance

 1. All tests described above, will have been performed to the satisfaction of the engineer and owner, prior to the acceptance of the automatic control system (BAS), as meeting the requirements of completion stage. Any tests that cannot be performed due to circumstances beyond the control of the contractor, may be exempt  from the completion requirements if stated as such, in writing by the engineer. Such tests will then be performed as part of the warranty.

2. The BAS system will not be accepted until all forms and checklists are completed as part of the Demonstration and submitted.

 

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 Demand Limiting:

 

a. Most BAS have a demand limiting algorithm, which can help to maintain the maximum power demand for a building below a set target. This feature helps to minimize maximum demand charges paid to utility companies.

b. Typical demand limiting feature, which predicts the future power demand based on the actual rate of increase of building demand and switches off (sheds) loads to ensure that the set demand limit is not exceeded. Similarly, the feature also normally allows the switching on (restoring) of loads when the demand drops.

c. In general, the demand limiting algorithm calculates the amount of load to be shed or restored and then sheds loads up to the cumulative load required to be shed. If there is an option to shed more than one load, the algorithm will shed loads based on set priority, where loads with lower priority will be shed before shedding loads with higher priority.

d. If there are multiple loads with the same priority, the load that has been shed the least amount of time will be shed first. In this feature, other parameters, such as maximum and minimum off-time for each load, can be set based on operational requirements.


 Optimal start-stop:

 

a. The optimal start-stop algorithm available on most building automation systems (BAS) can predict how long a building or space will take to reach the desired temperature based on the variables that affect it, such as outdoor air temperature, indoor space temperature, and building thermal characteristics.

b. This algorithm can be used to start the AHUs (and chillers/boilers) at the latest possible time to achieve the required space conditions before the space is occupied.

c. Similarly, at the end of the day, the algorithm can help to shut down the cooling or heating plant at the earliest possible time.


Operating Trend Logs:

 

a. Trend logging is a feature that allows recording of selected parameters at preset intervals of time. The feature can be used to log the value of parameters such as temperatures, flow rates, electrical power, and cooling demand. The recording interval can be set from one minute to about two hours.

b. The trend data can be used for various functions, ranging from trouble shooting to identifying energy saving opportunities.

c. An example of the usefulness of the trend logging feature in BAS when it shows the trend data for chilled water supply temperature, which indicates that it exceeds the set point temperature after 12:00 noon, while another trend shows that the condenser water supply temperature exceeds the maximum design value after 11 a.m. indicating that the high condenser water temperature may be the cause of the chillers not being able to meet the chilled water temperature set point.

d. The trend logging feature can also be used for trouble shooting by trending multiple parameters. For example, if a chiller frequently trips, trending of related operating parameters, such as condenser water and chilled water flows and temperatures, may help to identify the cause as low flow or high condenser water temperature.


 Connected building Commissioning (CBCx) - Smart Commissioning

 

a. An automated whole building diagnostics tool (CBCx), a software program that takes a top-down approach to diagnostics to detect excess energy consumption of the whole building and its major system.

b. Smart Commissioning describes a specific application of building data analytics, referred to as connected building commis­sioning, that is significantly enhancing the construction-phase commissioning process and showing improved outcomes for the building owner and occupants. Onsite walk-throughs, systems checklists, and equipment-by-equipment testing are being augmented with high-resolu­tion, real-time data monitoring, automated performance testing, and fault detection analytics that programmatically test and characterize equipment and systems failures.

c. These new processes have allowed for rapid, thorough, and repeatable testing of building systems and for more transparent and reliable testing results. Discussed here is the integration of these new processes into the exist­ing new construction commissioning framework with California Institute of Technology. CBCx specifically targets both the pre-functional and functional testing period, where the greatest opportunities for improve­ment and largest payoffs in terms of budget, time, and added quality assurance reside.

d. CBCx tools offer a greatly enhanced pre-functional test period. The alternative to the documentation-heavy approach of traditional pre-functional testing is to inte­grate analytics software to all equipment that is being controlled by the building’s central automation system (or other networked systems when possible, e.g., light­ing, fire and life safety). In this way, every setpoint, sensor and command point for all equipment can be trended, monitored, and analyzed as a system. Having this data available upfront, immediately after equipment startup, allows the commission­ing engineer to validate whether systems are online, and at least nominally operational.

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