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Lecture 5
Pr inc ip les of Model ing for Cyber-Phys ica l Systems
Instructor: Madhur Behl
Principles of Modeling for CPS – Fall 2018 Madhur Behl madhur.behl@virginia.edu 1
Building Energy Simulation
Introduction to EnergyPlus
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How to find the values of the parameters ?
Principles of Modeling for CPS – Fall 2018 Madhur Behl madhur.behl@virginia.edu 2
Previously..
Given the disturbances and inputs, the model should predict the zone temperature.
Principles of Modeling for CPS – Fall 2018 Madhur Behl madhur.behl@virginia.edu 4
Parameter estimation is a search
Principles of Modeling for CPS – Fall 2018 Madhur Behl madhur.behl@virginia.edu 5
Need a good starting point to avoid local minima.
Compute nominal values of the parameters.
For our model:EnergyPlus == A real building
Principles of Modeling for CPS – Fall 2018 Madhur Behl madhur.behl@virginia.edu 6
What is EnergyPlus ?
Principles of Modeling for CPS – Fall 2018 Madhur Behl madhur.behl@virginia.edu 7
EnergyPlus is an energy analysis and thermal load simulation program
User Building DescriptionFile
Building energy simulation
Heating/Cooling Load Calculation
Data outputs
https://github.com/NREL/EnergyPlus
Weather data
Principles of Modeling for CPS – Fall 2018 Madhur Behl madhur.behl@virginia.edu 9
• Data include
• temperature,
• humidity,
• solar,
• wind,
• rain, and
• snow flags, etc.
• Hourly data typical, can be sub-hourly • Interpolated for EnergyPlus time steps
TMY: Typical Meteorological Year data
EnergyPlus workflow and building description
Principles of Modeling for CPS – Fall 2018 Madhur Behl madhur.behl@virginia.edu 10
Envelope Constructions, loadsschedules, etc.
HVAC templatesor custom systems
Run, compare, report, QAQC, and parametric
analysis
EnergyPlus –SimulationArchitecture
Principles of Modeling for CPS – Fall 2018 Madhur Behl madhur.behl@virginia.edu 11
More than an engine or a single tool
Principles of Modeling for CPS – Fall 2018 Madhur Behl madhur.behl@virginia.edu 12
• Whole building energy simulation.• Peak load calculation and equipment
design.• Sub-hourly, user-definable time steps.• Advanced fenestration models.• Illuminance and glare calculations.• Component-based HVAC.• Built-in HVAC and lighting control
strategies.• Functional Mockup Interface.• Standard summary and detailed output
reports.
Integrated simulation manager
Principles of Modeling for CPS – Fall 2018 Madhur Behl madhur.behl@virginia.edu 13
Building systems simulation manager
Principles of Modeling for CPS – Fall 2018 Madhur Behl madhur.behl@virginia.edu 14
Authoring tools: Third party interfaces
Principles of Modeling for CPS – Fall 2018 Madhur Behl madhur.behl@virginia.edu 15
Zone and Air System Integration
Principles of Modeling for CPS – Fall 2018 Madhur Behl madhur.behl@virginia.edu 16
Sum of convective
internal loads
Convective heat transfer
from zone surfaces
Infiltration of outside air
Inter zone air mixing
HVAC air system
Building envelope hierarchy
Principles of Modeling for CPS – Fall 2018 Madhur Behl madhur.behl@virginia.edu 17
Site>> Building
>> Zones>> Surfaces
>> Constructions>> Materials
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