Vision of Building Simulation

Transcription

1 Vision of Building Simulation Informatics Michael Wetter Simulation Research Group January 26,

2 We believe that simulation tools should not constrain the user in what systems can be analyzed and optimized. Our approach is rooted in a separation of data, model, and solvers. This allows using state-of-the-art technologies whose development required skills typically not found in the buildings community. It turns out that that this leads to natural model formulations that allow modeling controls, transferring BIM to simulation, deploying code to hardware,... 2

3 Needs Schematically define any building, HVAC & control system to be simulated, optimized, analyzed and operated 3

4 Needs BIM Manufacturer catalog Schematic editor Specialpurpose GUI User-extensible component & system library, in exchangeable standard format Schematically define any building, HVAC & control system to be simulated, optimized, analyzed and operated PDE and ray-tracing parallel code Modern symbolic & numerical routines for hybrid, stiff, sparse systems of differential algebraic equations simulation code optimization code integration with code compliance, visualization,... code generation for HIL and building control systems 4

5 Separation of concern Modeling Specifies the system Computation Solves the equations Code for time-domain simulation a:=2; b:=2*a; C*der(T) = Q_flow; 0 = T - TBoundary; external "C" y=somecfunction(x); Graphical modeling - input/output free - block-diagram - state machines - bond-graphs Algorithmic code Acausal equations C interface Code for real-time operation Limited memory and storage. Constraints on computing time. Code for optimization Differentiation for gradient. Symbolic processing for collocation. Code for co-simulation as FMU Provide API for model discovery and that returns xk+1=f(xk, tk) Code for model exchange as FMU Provide API for model discovery and that expose right-hand-side of dx(t)/dt=f(x(t),t) Related efforts within the building simulation community include ENET (Low and Sowell, 1982), SPANK (Sowell et al., 1986), SPARK (Buhl et al., 1993) and the Neutral Model Format NMF (Sahlin and Powell, 1989). 5

6 Separation of concerns Building Informatics Environment Design Assistance Code Compliance BIM Models Simulation Operational support Optimization Visualization 6

7 Opportunities Collaborate...and integrate Building science Math Modeling language & tool API Domainspecific libraries Controls Computer science Advanced solvers GUIs 7

8 Adopting open standards allows reusing technologies that can be shared across industries Modelica Open modeling language, started in Free Modelica Standard Library: 2190 models and functions. Functional Mockup Interface ITEA project, 30 partners, > 175 person years, > 28 Mill. budget, July June First version published in Supported by 38 tools. 8

9 Modularization and encapsulation leads to transparency connector HeatPort_a "Thermal port for 1-dim. heat transfer" Modelica.SIunits.Temperature T "Port temperature"; flow Modelica.SIunits.HeatFlowRate Q_flow "Heat flow rate (positive if flowing from outside into the component)"; end HeatPort_a; model HeatCapacitor "Lumped thermal element storing heat" parameter Modelica.SIunits.HeatCapacity C "Heat capacity"; Modelica.SIunits.Temperature T "Temperature of element"; Interfaces.HeatPort_a port "Connector for (T, Q_flow)"; equation T = port.t; C*der(T) = port.q_flow; end HeatCapacitor; a b connect(a.port, b.port); a.port.t = b.port.t 0 = a.port.q_flow + b.port.q_flow 9

10 Acausal models allow graphical coupling of controls, algebraic equations, differential equations and state machines in schematic editor spatially discretized PDE block-diagram state events ordinary differential equation algebraic equation algorithmic code for controls state graph acausal schematic diagram (w. flow reversal) 10

11 Acausal models map directly to physical systems. 11

12 Models can be encapsulated and exported for real-time applications Models of process & controls (Rapid prototyping, design of experiments, analysis) FMU C Exchange formats Real-time applications (Control and monitoring, e.g., MPC algorithms, as part of energy information systems) 12

13 LBNL distributes free open-source Modelica Buildings library with 300+ models and functions Air-based HVAC systems. Hydronic heating systems. Chiller plants. Natural ventilation, multizone air exchange, contaminant transport. Room heat transfer, incl. window (TARCOG). Renewables (2013). Embedded Python (2013). District energy systems (2013/2014). 13

14 The Buildings library has been used across a wide range of applications Control development Workforce training through FDD & verification LearnHPB emulator Standards development Hardware-in-the-loop Rapid prototyping Boundary$$ condi1ons$ RayDtracing$ (Radiance)$ For$each$ Blind$ posi1on$ Room$ absorbed,$$ incident$solar$ irradia1on$ Synchronize$ 1me$ t i+1 = t i + Δt Measured$ data$ Physical$test$cell$ Virtual$test$cell$ (Modelica)$ Hea1ng$and$$ cooling$loads$ Save$state$$ variables$ Report$on$ actual$state$ of$room$&$ blind$ Control$signals$ Find$op1mal$ blind$ posi1on$ 14

15 Building Controls Virtual Test Bed allows run-time data exchange among simulators and control systems Building Controls Virtual Test Bed Free open-source middle-ware based on UC Berkeley s Ptolemy II program. implemented in next release building energy EnergyPlus HVAC & controls Modelica controls Simulink controls & data analysis MATLAB building energy ESP-r lighting Radiance building energy TRNSYS BCVTB wireless networks Ptolemy II co-simulation FMU hardware in the loop A/D building automation BACnet real-time data www+xml 15

16 The Functional Mockup Interface allows export and import of simulators for co-simulation and hardware-in-the-loop National EnergyPlus Instruments VeriStand Modelica BCVTB MATLAB/ Simulink (Incomplete list of tools, see for 38 tools that support FMU). 16

17 The Functional Mockup Interface allows export and import of simulators for co-simulation and hardware-in-the-loop Rapid virtual prototyping. Path towards embedded computing. Whole building energy analysis. Reuse of 500,000 lines of code. 17

18 WUFIPlus links to Modelica models of heating systems through the Functional Mockup Unit Source: Pazold et al., 2012, 18

19 Annex 60 New generation computational tools for building and community energy systems based on the Modelica and Functional Mockup Interface standards Duration: Operating agents: Michael Wetter (LBNL) and Christoph van Treeck (RWTH Aachen, Germany). Participation: 30 institutes from Austria, Belgium, China, France, Germany, Ireland, the Netherlands, Sweden and the USA, and possibly Switzerland. 19

20 Annex 60 Multiple scales Standardized language, APIs and data models Multiple disciplines Multiple domains Multiple tools Building and community energy grids Designed & operated as integrated, robust, performance-based system. Dissemination Applications on building design, district design, model-use during operation Energy and control systems modeling library Modelica. Free and open-source. Standardized interfaces. Buildings, districts, controls. Co-simulation & modelexchange tools and interfaces Functional Mockup Interface standard. FMI interfaces in existing simulators. Co-simulation algorithms. BIM translators Standardized model data exchange. Modelica/BIM interfaces. 20

21 In summary, modeling gets closer to the physical and logical systems: Declare model and generate code Increased level of abstraction. Models are expressed in a modeling language, not as simulation code. Inter-disciplinary collaboration. Links These points allow modeling of phenomena and new use cases that are outside the capabilities of today s building simulation programs. simulationresearch.lbl.gov 21