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2017 07 tag agenda
Participation at this meeting is by invitation only.
Date: July 19, 2017, 11am-1pm PDT
Slides are posted at https://github.com/lbl-srg/obc/tree/master/meetings/2017-07-tag
See below agenda for dial-in information.
- Status update: Upcoming deadlines, see https://github.com/lbl-srg/obc/wiki/2017-07-tag-next-steps
- CDL: Need review and control vendor input.
- G36 implementation: Need review.
- Case study. Need a team member to identify building and contribute to study. For this case study, need to work on secondary system only. A small system in terms of number of control loops, and a small building would be best suited. The system should be well documented. We like to share results from the case study in the open literature (the building could be made anonymous if needed). (Primary system and facade will come later.)
- Amir (DOE)
- Brent Eubanks
- Gerry Hamilton
- Jianjun Hu
- Jon Schoenfeld
- KPerrin
- Marina Sofos
- Milica Grahovac
- Paul Ehrlich
- Paul Switenski
- Steven Taylor
- Philip Haves
- Jay Santos
- Janie Page
- Michael Wetter
LBNL team obtained feedback from Larry Bacher, ALC, to date. Mark, Paul, Brent, Jon, and Jay offered to reach out to vendors for further feedback. The feedback is welcome in plain text and word format. The goal is to support all known sequences by different vendors, either natively or via composition of basic blocks. The team went back to this issue later in the meeting and discussed options for cases where the vendor control coding language has a) extra blocks, b) lacks our blocks. The team also suggested to discuss the above and the usage of C++ code for the execution with external experts. The concern is that line programming (e.g. C++) vs block code may be significantly different in vendor languages. Phil noted philosophical distinction PPCL (Siemens) vs function block graphical language. Declarative vs imperative camps of coding noted. Workshop in August got set as a target for the meeting.
No comments were received on the topic of basic blocks composed of other basic blocks.
CDL to be exposed as needed to users, not whole code base.
Brent suggested a list of questions presented to the use, which essentially define the value of the boolean parameters that are used to turn certain features of the block on or off. He also suggested to avoid adding separate sequences. Paul agreed. Brent suggested to extend that functionality to include possibility of adding elements, such as humidifier, which are currently not a part of G36. This is related to the scoping issues discussed in the following section.
CLD does not implement it. The team agreed that it is not necessary.
Collect feedback from control vendors on the scope of the CDL basic block library by September 15.
LBNL team intends to post first version of CDL by September 15.
Optimal start-up - most vendors keep their algorithm proprietary. Discussion on how other control vendors retrieve the operation mode signal: Information provided by several external project partners. If building switches from occupied to unoccupied to occupied again, when/how does controller know about occupation again? Vendors use different approaches: ALC starts at zone level which then informs system. Question of how much ahead the warm-up needs to start. Many systems have schedule control points at which operation changes can be implemented. Can also have some influence by recent historical operations (e.g. recursive on outside air temperature). Most systems have learning based implementations. Operationally, optimal start differs from occupancy. Occupancy, for example, will include ventilation. Need hooks in CDL code to attach to vendor specific optimal start blocks. Units should have flags to indicate assumed state (e.g. optimal start, occupied, unoccupied). LBNL team to implement an in-house version that will allow control sequence testing and verification.
The team agreed to using G36 PPR1 as our reference version of the guideline, being cognizant of elements expected to change. Brent emphasized that some of the sequences, e.g. minimal ventilation logic, might undergo significant changes in future instances of G36.
LBNL team demonstrated multi-zone VAV AHU economizer outdoor and return air damper limit sequence from G36 with plotted results.
Tags in CDL – trying not to pick any particular scheme, but be aware of Brick and Haystack as relatively large players in the area.
LBNL team requested validation and review on the level of atomic and composite sequences. The team discussed the best approach. Options for testing:
- Inspect code and building blocks (parse at visual logic level)
- Use test harness to confirm outputs for given input
- Connect sequences to model of air handler and simulate under different seasons – works without Dymola using open source tools
The team agreed to organize a meeting with developers and key partners to obtain guidance on the scope of the G36 CDL library. Brent suggested Integral offices for the meeting and Jianjun offered to make a doodle for the meeting.
Deadlines: Mid September - release a first version of the library
Structure (atomic, composite) useful to sequence implementation? Better form structure for sequences library?
In August. The team agreed to identify suitable experts, ask for feedback, and organize a workshop.
In August. The team agreed to organize a workshop at Integral Group offices.
The team needs to identify a suitable real building for a case study, ideally multizone. Potential sources: Steve mentioned RP 1747 (E+ and Contam). Phil offered to contact Joe Zhou.
Ideally looking for building that can be used as a case study – not closed loop, but look at HVAC performance when controlled using project code: Single zone AHU in Modelica using G36, then add building model to emulate load, compare differences in energy use. Maybe two zone building. Ideally LBNL designers work with other team members to show how to integrate into existing controls. Stanford notes their simplest building has 50 zones, but may have some simple components. Could be AHU with few zones. Looking for VAV with reheat. Steve Taylor not sure he has building in his portfolio that works. Goal is prove CDL implementation against actual sequences. May not need actual building at this stage. Noted a VAV system with about 4-5 AHUs that may be available for consideration. Or use FLEXLAB? Other options identified as well. Simulation study at Iowa Energy Center proposed since well documented, has trend data. RP1747 may also provide insights. Don’t want to have to implement special control sequences just for the test.
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