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PowerPoint ® Presentation Chapter 13 Building Automation Systems for IAQ Building Automation Systems and Controllers Operator Interface Methods Building.

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Presentation on theme: "PowerPoint ® Presentation Chapter 13 Building Automation Systems for IAQ Building Automation Systems and Controllers Operator Interface Methods Building."— Presentation transcript:

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2 PowerPoint ® Presentation Chapter 13 Building Automation Systems for IAQ Building Automation Systems and Controllers Operator Interface Methods Building Automation System Input and Output Components Direct Digital Control Strategies, Features, and Algorithms IAQ Strategies and Energy Considerations Building Automation Systems and Controllers Operator Interface Methods Building Automation System Input and Output Components Direct Digital Control Strategies, Features, and Algorithms IAQ Strategies and Energy Considerations

3 PowerPoint ® Presentation Chapter 13 Building Automation Systems for IAQ Building Automation Systems and Controllers Operator Interface Methods Building Automation System Input and Output Components Direct Digital Control Strategies, Features, and Algorithms IAQ Strategies and Energy Considerations Building Automation Systems and Controllers Operator Interface Methods Building Automation System Input and Output Components Direct Digital Control Strategies, Features, and Algorithms IAQ Strategies and Energy Considerations

4 Chapter 13–Building Automation Systems for IAQ Distributed direct digital control systems have multiple CPUs at the controller level.

5 Chapter 13–Building Automation Systems for IAQ Application-specific controllers are designed to control only one type or part of an HVAC system.

6 Chapter 13–Building Automation Systems for IAQ Unitary controllers are designed for simple zone control using a standard wall-mounted temperature sensor.

7 Chapter 13–Building Automation Systems for IAQ Air-handling unit controllers are used when the sophisticated control of large central-station air- handling units is required.

8 Chapter 13–Building Automation Systems for IAQ Variable-air-volume (VAV) air terminal unit controllers are similar in appearance to unitary controllers. The difference is in the factory programming of the erasable programmable read- only memory (EPROM) chip.

9 Chapter 13–Building Automation Systems for IAQ Variable-air-volume (VAV) air-handling unit controllers are used to control VAV air-handling units in order to maintain a minimum static pressure in supply ducts.

10 Chapter 13–Building Automation Systems for IAQ Variable-air-volume (VAV) air-handling controllers are used to control building space temperature and air volume in VAV air-handling systems.

11 Chapter 13–Building Automation Systems for IAQ Network communication modules coordinate communication from controller to controller on a network and provide a location for operator interface.

12 Chapter 13–Building Automation Systems for IAQ Desktop personal computers (PCs), alarm printers, notebook PCs, portable operator terminals, keypad displays, and dumb terminals are used in large buildings to access and troubleshoot a buildings automation system.

13 Chapter 13–Building Automation Systems for IAQ A building automation system with web browser software packages allows a stationary engineer to communicate and change settings from anywhere in the world.

14 Chapter 13–Building Automation Systems for IAQ Analog input devices send 4 mA to 20 mA or 0 V to 10 or 20 V signals to a building automation systems controllers, causing a proportional electrical signal change to output components.

15 Chapter 13–Building Automation Systems for IAQ Temperature sensors are available in a variety of packages and mounting configurations including wall-mounted, duct-mounted, immersion (well-mounted), and averaging.

16 Chapter 13–Building Automation Systems for IAQ Humidity sensors contain a hygroscopic element that changes physical characteristics as the humidity changes.

17 Chapter 13–Building Automation Systems for IAQ Piezoelectric elements (pressure- sensitive crystals) are used in duct pressure-sensing applications, while bellows elements are used in many piping applications.

18 Chapter 13–Building Automation Systems for IAQ In IAQ applications, differential pressure sensors or pitot tubes and temperature sensors in a duct can act as airflow measuring stations (AMS).

19 Chapter 13–Building Automation Systems for IAQ A digital input device signal is a binary (ON or OFF) signal.

20 Chapter 13–Building Automation Systems for IAQ Limit thermostats maintain a temperature above or below an adjustable setpoint.

21 Chapter 13–Building Automation Systems for IAQ Humidistats are digital input devices used in ducts and indicate when a humidity setpoint has been reached.

22 Chapter 13–Building Automation Systems for IAQ Differential pressure switches are often used to indicate a difference in pressure across a fan or pump or to indicate the condition of an air- handling unit filter.

23 Chapter 13–Building Automation Systems for IAQ Electric/pneumatic transducers have an analog input signal, such as 4 mA to 20 mA, from the building automation system and an output air pressure signal of 0 psi to 20 psi.

24 Chapter 13–Building Automation Systems for IAQ Triac-switched controller output terminals require an external power supply and are used to switch alternating current (AC).

25 Chapter 13–Building Automation Systems for IAQ Relays are used to allow low-voltage-rated triacs of building automation system controllers to switch line- voltage components ON and OFF.

26 Chapter 13–Building Automation Systems for IAQ In a direct digital control system, a building automation system controller is wired directly to controlled components.

27 Chapter 13–Building Automation Systems for IAQ In closed-loop control, feedback occurs among the controller, sensor, and controlled component(s).

28 Chapter 13–Building Automation Systems for IAQ In open-loop control, no feedback is provided from sensors to a building automation system controller.

29 Chapter 13–Building Automation Systems for IAQ Setpoint is the desired value to be maintained by a system with the desired accuracy to the setpoint being programmed into a BAS controller.

30 Chapter 13–Building Automation Systems for IAQ Setup and setback setpoints are values that are active during the unoccupied mode of a building automation system.

31 Chapter 13–Building Automation Systems for IAQ Low-limit controls stop outside-air dampers from closing 100% and still allow ventilation air into a building when ventilation-air temperatures are excessively low outside.

32 Chapter 13–Building Automation Systems for IAQ Proportional control algorithms position a controlled component in response to the amount of offset experienced in a building automation system.

33 Chapter 13–Building Automation Systems for IAQ Derivative control algorithms determine the instantaneous rate of change of a controlled variable.

34 Chapter 13–Building Automation Systems for IAQ Adaptive control algorithms are self- tuning algorithms that are often used to correct an overcycling control system.

35 Chapter 13–Building Automation Systems for IAQ Acceptable indoor air quality numbers for ventilation are detailed in ANSI/ASHRAE Standard , Ventilation for Acceptable Indoor Air Quality.

36 Chapter 13–Building Automation Systems for IAQ CO 2 levels in building spaces or zones are used as an indicator of occupancy.

37 Chapter 13–Building Automation Systems for IAQ A typical HVAC system increases ventilation when CO 2 levels rise to 600 parts per million (PPM) so that levels do not exceed 1000 PPM.

38 Chapter 13–Building Automation Systems for IAQ Economizers use outdoor air to provide free cooling and are not practical or advisable in hot-humid climates.

39 Chapter 13–Building Automation Systems for IAQ In night precooling, cool outdoor night air is used to cool a building while simultaneously exhausting accumulated pollutants.


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