[Bldg-sim] A critical juncture for Modelica/FMI next week

[Chris Jones]

There are a number of examples of coupling 
Modelica with building simulation, also MatLab with building simulation:
http://www.seas.upenn.edu/~cis800/software.html


At 07:15 AM 10/03/2012, Per Sahlin wrote:
>Content-Language: en-US
>Content-Type: multipart/alternative;
> 
>boundary="_000_E7DE1359657DA948A14588A22C4C7D9701A24ED534DAEQSRVSBS01E_"
>
>Hi Pavel,
>
>It is difficult to explain these things in 
>totally concrete terms. It has to do with 
>simulation model scalability, portability, abstraction and ease-of-use.
>
>Both Simulink and Modelica tools offer ways of 
>describing and simulating the behavior of a wide 
>class of dynamical systems. This allows you to 
>tailor exactly the equations you want to use, 
>for example in the way you outline below. This 
>total freedom is often needed in building 
>simulation problems, since the number of 
>different component models needed for various 
>studies is for all practical purposes infinite. 
>No tool with a fixed set of models will ever be sufficient.
>
>Now, a full-fledged building zone model like 
>that of E+, or our tool IDA ICE, will not 
>require 2-3 equations, but rather on the order 
>of a thousand variables per zone. A fair number 
>of these represent things that are meaningful to 
>observe directly, such as the temperature of the 
>third layer of a particular wall and others are 
>just help variables that are needed to compute 
>for example a sliding average. If you then want 
>to model a thousand zone building, you get by 
>all standards a fairly complex and large system 
>of ordinary differential and algebraic equations 
>(DAEs) to solve. This is where the scalability 
>comes in; not all approaches will be able to handle this size of problem.
>
>When you have this many equations to keep track 
>of, no single person or even team will have the 
>required expertise about each type of process 
>that needs modelling. Portability and 
>abstraction becomes needed. If you can 
>specialize in a particular field, such as 
>advanced heat pump modelling, and then package 
>your models in a way  that will plug right into 
>relevant neighboring models and in a variety of 
>tools, many people can use them without knowing 
>each detail. This is the ultimate purpose of Modelica and FMI.
>
>A building simulation model must also be 
>possible to set up and operate by a person that 
>knows absolutely nothing about Modelica, DAEs 
>and variable timestep solvers. Therefore, it 
>must also be possible to package these 
>equation-based models in a way that, on the 
>surface, looks much the same as traditional BEM tools – the ease-of-use.
>
>I hope this was of some help. If you are 
>interested to learn more about these things, 
>browse the conference proceedings available on 
><https://www.modelica.org/publications>https://www.modelica.org/publications 
>, where you can see how Modelica has been applied in many different domains.
>
>Best regards,
>
>Per
>
>
>
>
>From: pdybskiy at gmail.com 
>[mailto:pdybskiy at gmail.com] On Behalf Of Pavel Dybskiy
>Sent: den 9 mars 2012 12:57
>To: Per Sahlin
>Cc: bldg-sim at lists.onebuilding.org
>Subject: Re: [Bldg-sim] A critical juncture for Modelica/FMI next week
>
>Per,
>
>It is impressive ... but it sounds too abstract to me to digest.
>Can you help me to think about FMI in terms of a 
>BEM (building energy modeling) task.
>
>For example:
>1) There is a  system of ODEs (2 o3 equations), 
>which represents a simple (say 3R2C or 3R3C) 
>thermal network (TN), which in turn models a thermal zone.
>
>2) There is another set of equations and 
>inequalities that specifies HVAC system.
>
>3) There is a given weather file (temps, 
>radiation, etc) which provides some set of time 
>series variables (1hour sample time) for those ODEs.
>
>4) There are 2-3-4 schedule files, 
>which  specifies other sets of 
>variables/parameters  ( 1hour - 1day - 1month 
>sample time ) for those thermal zones and HVAC.
>
>Today I am using Matlab/Simulink to simulate this (1-4) problem.
>
>In case if I need more complex building and HVAC 
>models I may think about BCVTB(LBNL) (people 
>already do this) to co-simulate various combinations of E+ and Matlab models.
>
>What role and how can FMI/FMU play in such a game?
>
>Thank you
>
>Pavel
>
>
>On Fri, Mar 9, 2012 at 5:30 AM, Per Sahlin 
><<mailto:per.sahlin at equa.se>per.sahlin at equa.se> wrote:
>Dear all,
>
>There is a meeting of the FMI 
>(<http://www.functional-mockup-interface.org>www.functional-mockup-interface.org) 
>design group Monday and Tuesday next week where 
>most likely the level of ambition of FMI 2.0 
>will be settled. Different application areas 
>have different needs and priorities and I think 
>it would be wise to provide some input from the 
>building simulation community to this meeting. 
>Let me first give some background.
>
>The ultimate purpose of equation based 
>simulation and Modelica 
>(<http://www.modelica.org>www.modelica.org) is 
>to enable model exchange between users and 
>tools. However, the Modelica language is by 
>necessity a very complex and rapidly evolving 
>“beast.” It is essentially impossible to keep 
>tools in good sync with each other in their 
>interpretation of Modelica. In practice, this 
>means that porting complex model libraries, such 
>as the MSL Fluid and Media libraries and 
>derivatives, from one tool to another often 
>involves man years of work, if possible at all. 
>This is where FMI comes in. FMI provides a means 
>to exchange pre-compiled model units and this 
>can be radically simpler than to achieve a 
>common understanding and interpretation of the 
>underlying Modelica code. FMI 1.0 has proven 
>this since a number of years. However, for our 
>application FMI 1.0 is severely limited.
>
>There are three key areas where FMI 2.0 has 
>previously been planned to be enhanced in ways 
>that in my opinion are essential to the building simulation community:
>
>
>-          Introduction of physical connectors 
>(now only direct variable-to-variable connections are supported)
>
>-          Support for arrays, the size of which 
>is determined by parameters that can be changed 
>after compilation (only scalars in FMI 1.0)
>
>-          Support for sparse analytical Jacobians
>
>In the building simulation world of 
>multiple-port tanks and zones, where many 
>components are built around  discretized PDE:s, 
>FMI without these features is unlikely to become 
>very useful. At the same time the FMI design 
>group is facing some seriously conflicting goals:
>
>
>-          FMI must not be too rapidly evolving 
>– otherwise much of the purpose is lost
>
>-          The standard must not be too complex for vendors to support
>
>-          There is an urgent need to upgrade v. 
>1.0 to something more powerful
>
>Therefore, there is a distinct risk that some of 
>the planned enhancements of 2.0 are postponed. 
>For reasons of stability, it could take a very 
>long time before the next major release.
>
>
>
>If you share my concern about these issues, 
>please write a few lines to underline why we 
>need these features to me.  I will compile for the FMI design committee.
>
>
>
>Best regards,
>
>
>
>Per Sahlin
>
>
>
>-----------------------------------------
>Per Sahlin
>EQUA Simulation AB
><mailto:per.sahlin at equa.se>per.sahlin at equa.se
><tel:%2B46%C2%A0%C2%A0%208%20546%2020%20111>+46   8 546 20 111
><tel:%2B46%2070%20422%2003%2002>+46 70 422 03 02   (mobile)
><tel:%2B46%C2%A0%C2%A0%208%20546%2020%20101>+46   8 546 20 101 (fax)
>plurresahlin (skype)
>Råsundavägen 100
>169 57 SOLNA, Sweden
><http://www.equa.se>http://www.equa.se
>-----------------------------------------
>
>
>
>
>
>Subject: Re: teleconference about IEA proposal 
>"Modelica-based next-generation tools for new 
>and existing buildings and communities"
>
>All,
>
>Thanks to those who contributed to today's 
>conference call. Attached please find the 
>meeting minutes. Please let me know any important omissions or corrections.
>
>As discussed, I also added a google doc where 
>each of you can add your interest in 
>participation and in leading a particular 
>subtask. There is also a column in which you can 
>specify your funding situation for the 
>respective work, and a column in which you can 
>add demonstration objects that could be included 
>in the revised proposal. The link to this spreadsheet is
> 
><https://docs.google.com/spreadsheet/ccc?key=0AnSvCGCOHhzXdHBOSDRuLXJOd2tvSlBzUXBHaU93NVE>https://docs.google.com/spreadsheet/ccc?key=0AnSvCGCOHhzXdHBOSDRuLXJOd2tvSlBzUXBHaU93NVE
>Anyone with the link can edit and view the 
>document. So don't add sensitive information or 
>proprietary information. You are free to share 
>this document, as well as the proposal, at
> 
><https://docs.google.com/a/lbl.gov/document/d/1ia1jyXrvf1jUynN_1-3QBx0quYdXlOdYgPTacpE6lLU/edit?hl=en_US&pli=1>https://docs.google.com/a/lbl.gov/document/d/1ia1jyXrvf1jUynN_1-3QBx0quYdXlOdYgPTacpE6lLU/edit?hl=en_US&pli=1
>with your ExCo delegate and/or your potential funding agency.
>
>Depending on how many people work on the 
>respective subtasks, some subtasks might be 
>combined in future revision. For now I kept the 
>structure that resulted from the Sydney meeting.
>
>All the best,
>
>Michael
>On Thu, Feb 2, 2012 at 3:16 PM, Michael Wetter 
><<mailto:mwetter at lbl.gov>mwetter at lbl.gov> wrote:
>All,
>
>We would like to schedule a teleconference with 
>those of you who are interested in participating 
>in the IEA proposal "Modelica-based 
>next-generation tools for new and existing 
>buildings and communities" that was discussed in Sydney last November.
>
>To schedule the call, please respond by 
>Wednesday February 8 to the poll 
>at 
><http://www.doodle.com/c5fvhz5uuzuq7ykr>http://www.doodle.com/c5fvhz5uuzuq7ykr. 
>
>If you like to be removed from future emails, please respond to me.
>
>The proposal is at 
><https://docs.google.com/a/lbl.gov/document/d/1ia1jyXrvf1jUynN_1-3QBx0quYdXlOdYgPTacpE6lLU/edit?hl=en_US&pli=1>https://docs.google.com/a/lbl.gov/document/d/1ia1jyXrvf1jUynN_1-3QBx0quYdXlOdYgPTacpE6lLU/edit?hl=en_US&pli=1 
>and attached to this email. This version 
>addresses the feedback from the Sydney meeting, 
>as well as feedback received from the Fraunhofer Institute in Kassel.
>
>The items to be discussed at the phone call are below.
>
>    * Outline of next steps.
>    * Proposal due April 16, presentation to IEA ExCo meeting on June 14.
>    * If approved, there will be a 1 year 
> planning period (we will check whether this can 
> be accelerated), followed by 3 years of research and 1 year of reporting.
>    * Expression of interest of research groups 
> to work on the proposed research.
>    * Individual research groups should express 
> what tasks they like to contribute to, and are 
> likely to get funded from their respective country.
>    * Indication of subtask leaders.
>    * Note: Subtask leaders need not be 
> finalized by June, but an indication of what 
> country will lead what task is recommended. The 
> subtask leaders can be finalized during the planning period.
>    * Subtask leaders need a minimum commitment of 3 months/year.
>    * Inform your ExCo delegate.
>    * The ExCo delegates will need to verbally 
> confirm at the June meeting that funding will 
> be available in their country and that the 
> proposal is in the interest of their country. 
> For the proposal to be accepted, around five 
> (minimum 3) countries need to commit to 
> participate. It therefore is essential that you 
> discuss the proposal and your interest to 
> participate with your ExCo delegate prior to 
> the June meeting. See 
> <http://www.ecbcs.org/contacts.htm>http://www.ecbcs.org/contacts.htm 
> for a list of ExCo delegates.
>    * Other points of discussion.
>
>Please let me know if there is anything else you 
>would like to add to the agenda.
>
>All the best,
>
>Michael Wetter & Jan Hensen
>
>
>
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>
>
>--
>Best Regards,
>
>Pavel Dybskiy
><http://M.A.Sc>M.A.Sc. Candidate, Department of Architectural Science
>Faculty of Engineering, Architecture and Science, Ryerson University
>E-mail: <mailto:pdybskiy at ryerson.ca>pdybskiy at ryerson.ca;
>telephone: 647-984-4940
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 >>
Christopher Jones, P.Eng.
Suite 1801, 1 Yonge Street
Toronto, ON M5E1W7
Tel. 416-203-7465
Fax. 416-946-1005
email cj at enersave.ca
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