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

[Per Sahlin]

Dear all,

There is a meeting of the FMI (www.functional-mockup-interface.org<http://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 (www.modelica.org<http://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
per.sahlin at equa.se<mailto:per.sahlin at equa.se>
+46   8 546 20 111
+46 70 422 03 02   (mobile)
+46   8 546 20 101 (fax)
plurresahlin (skype)
Råsundavägen 100
169 57 SOLNA, Sweden
http://www.equa.se
-----------------------------------------





From: Michael Wetter [mailto:mwetter at lbl.gov]<mailto:[mailto:mwetter at lbl.gov]>
Sent: den 29 februari 2012 01:59
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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
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
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 <mwetter at lbl.gov<mailto: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.
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 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.


 1.  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.
 2.  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.
 3.  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.
 4.  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 for a list of ExCo delegates.
 5.  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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