Chilled Water System

[Dave Waterworth]

Is there an example of a chilled water system, i.e. chillers, cooling tower, condenser water pump, chilled water pump? I had a quick look and they seem to all be focused on the airside?

The main reason I ask is I couldn't see a number of points - i.e. condenser water entering temp,  condenser water leaving temp, condenser water flow, etc. I also couldn't find a Cooling_Tower entity although there seems to be a Cooling_Tower_Fan (scheme version 1.1).

Also is there any guidance anywhere on extending Brick. I'm assuming the "proper" way of doing it isn't to add your own entity in the brick namespace i.e.

brick:Cooling_Tower a owl:Class ;

   rdfs:label "A Cooling Tower" ;

   brick:hasAssociatedTag tag:Electrical

    ...

I would assume that extensions should be in a vendor namespace - and then ideally upstreamed into the brick namespace?

vendor:Cooling_Tower a owl:Class ;

   rdfs:label "A Cooling Tower" ;

   brick:hasAssociatedTag tag:Electrical

    ...

[Erik Paulson]

I'm not a chiller person so maybe these don't work in the chiller context, but there are some entering/leaving temp sensor classes:

https://brickschema.org/ontology/1.1/classes/Entering_Water_Temperature_Sensor

https://brickschema.org/ontology/1.1/classes/Leaving_Water_Temperature_Sensor

https://brickschema.org/ontology/1.1/classes/Water_Flow_Sensor

There is a cooling tower entity in the nightly builds but it's not yet in a stable release (and so it's not in the search page on the webpage) - you can find it in github nightly builds, though.

Better examples are on the roadmap: https://github.com/BrickSchema/Brick/issues/166 - I think contributions would be welcome, including just suggested systems (I think the plan right now is to take some systems from ASHRAE G36 and show how those would work)

You're on the right path for putting extensions into your own namespace and ideally upstream - either pull requests (ideally to the python generator code) or just open an issue with the suggested classes and descriptions - the more detailed description the better, which helps place it in the right subclasses!

-Erik

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[Dave Waterworth]

Thanks Erik

I saw those points, but chillers have two "sides", the condenser and evaporator both of which have a flow and entering/leaving temperature.

The points required are

Chilled Water Entering Temperature

Chilled Water Leaving Temperature   

Chilled Water Flow

Condenser Water Entering Temperature

Condenser Water Temperature

Condenser Water Flow

Brick only has

Chilled Water Temperature  

Water Entering Temperature 

Water Leaving Temperature   

 

In addition you also observer points for the chilled water system (CHWS)

Chilled Water SupplyTemperature

Chilled Water Return Temperature   

These relate to the supply of water to the AHU's - so they're opposite to the chiller (i.e if there was only one chiller CH Chilled Water Entering Temperature = CHWS Chilled Water Return Temperature)

And the same for the condenser water system - i.e. the cooling towers which supply water to the chiller, each cooling tower has an entering / leaving water temp, and the chilled water system has a supply / return temperature and flow.

I've recently done work on chiller modelling and have access to a large number of (Australian) buildings so I'm happy to contribute where I can, i.e. provide a list of chiller points and equipment I've identified or help to put together examples/issues/pull requests

Regards

David

[Gabe Fierro]

Hi David:

Thanks for reaching out about this! We definitely need to flesh out our
chiller point implementation, and having a wide array of chiller systems
to help validate the design would be fantastic.

I've created a Brick issue to track this progress:
https://github.com/BrickSchema/Brick/issues/197 . I seeded it with the
initial point names that you mentioned. I think for the point names that
are relative (e.g. entering/leaving), we can use the Brick `isPointOf`
relationship to specify the context of that point. If you look at the
definitions of the Entering/Leaving temperature sensors that Erik
metnioned below, they both specify that they are relative to the
condenser. We may want to pull that part of the definition out so that
it is explicit in the Brick model (using `isPointOf`) rather than
relying on the textual definition.

Would you be able to add the list of points/equipment you have on the
Brick issue? We can start from there and eventually I can implement the
actual concepts in a future release.

To answer your question about namespaces: I think that these kinds of
common points for chiller systems should be added to the "official"
Brick namespace. Vendor- or product-specific points and equipment would
likely go into their own namespaces, but would link to the Brick
ontology definition so that their definitions are grounded as extensions
to Brick.

For specialized extensions, we are exploring a "Brick plugin" ecosystem
by which users can optionally pull in additional ontologies that help
them address a specific family of applications
(https://github.com/gtfierro/brick-occupancy-extension/ is the current
example)


Best,
Gabe

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