The Noda Ontology Alignment Project is a publicly available website that is introduced in this Help Center article. Further detail on how, why and when to apply the OAP is discussed in this Help Center article. The purpose of the Help Center article you're reading now is to provide specific guidance to integrators and data modellers on how to apply the OAP during the modelling process, with examples of specific use cases included throughout.
Equipment covered in this article:
VRF systems
Chilled and hot water plants
VFDs
Chiller plant
Relationships covered in this article:
Lighting zones
HVAC zones
Metering
Point data modelling best practices
If you don't know, don't guess. Better to leave point untagged
Duplicate points
In general there should be 1 point of each type on a piece of equipment
Always start from the list of points that have been defined for the equipment type in question.
Sensors + setpoint
In general, there should be 1 sensor for each setpoint on a piece of equipment. i.e. if there is a zone air temperature setpoint, there should be a zone air temperature sensor.
Specific Point Guidance:
For min and max air flow setpoints on a VAV, assume it's the Occupied Airflow Min and Max setpoints if the point does not explicitly note occupied or unoccupied
In general device status should be modelled as communication status
Watch out for gotcha's around Occupancy Points:
Occupancy Schedule – this usually corresponds
Occupancy Command – this is typically the occupancy command from the BMS to a piece of equipment. If an occupancy point is writable or setable, it’s usually this point.
Occupancy Sensor – this reflects the value of an actual sensor in a space
Occupancy Status – this is the product of an equipment’s various occupancy indicators (schedule, command, sensor) and describes it’s resultant state
Occupancy schedule vs. cmd vs. sensor vs. status
How to model a single Occupied Zone Temperature Sp?
If the equipment is cooling-only, use “Occupied Zone Temperature Cooling Setpoint”
If it has heating and cooling, and there are also effective occupancy point(s) or there is also a deadband point, “Zone Temperature Base Setpoint” is the best bet
If this is the only temperature setpoint point, choose “Effective Zone Temperature Sp”
Types of points to typically ignore:
Control Logic points
“And”, “or” or “not” points
Reset logic
trim and respond points
Configuration information
Meta data
K-value
Always use the most generic version of a point possible.
For example, most of the time “Run Status” is a perfectly acceptable way to model a status point regardless of the equipment type.
The exception to this rule is where there may be multiple versions of the same point on different components within an equipment. For example, an AHU may have “Discharge Fan Status” and “Return Fan Status” points in which case, the specific point should be used.
Point type is the most likely kind
Heaing Command (HTCMD) is an instance where the point kind can either be a number (typically %) or bool (on/off). The "kind" field in OAP is not strict, but rather it is the most likely kind. Almost all command points also follow this rule.
Equipment Data Modeling Best Practices Conventions
Unlike points which should be modelled as generically as possible, equipment should be modelled as specifically as possible to the best of the data modeler’s knowledge.
For example, when modelling a VAV, it is perfectly acceptable to tag it as a VAV, but if it is definitely a Fan Powered Series VAV, then it should be tagged as such.
On the other hand, if modelling an AHU but not sure what type of AHU it is, then it is best to leave it as simply an AHU and not guess about specific variants or use the wrong variant.
Modeling Conventions
Relationships: when modeling relationships using the OAP, the section "Contains" is a good place to start.
VRF systems
Typical sub-equipment includes Branch Selector Box, FCU and VRF Outdoor unit, as noted on this OAP page.
Chilled and Hot Water Plants
Larger systems like Chilled or Hot water plants Contain many more pieces of equipment. Note the relationships in both directions on the plant system and the sub-equipment.
Lighting zone vs. lighting panel
Differences between these two models shown below:
Relationships on HVAC zones, model reference:
Metering relationships
Meter to equipment relationships
Meter to meter relationships (as with sub-meters, for example)
VFDs and VFD points
VFD points have deviceRef to VFD
equipRef to equip such as AHU, EF, Pump, etc.
vfd has an equipRef to the Equipment such as AHU, EF, Pump
Convention for entering/leaving for a chiller plant
