The Odysseus dEPC Ontology essentials

Michel Böhms (TNO), Theo Rieswijk (Priva), Ed Lijster (Priva)

12. February 2015

1.Introduction

The Odysseus dynamic Energy Profile Card (dEPC) ontology is an advanced information structure covering a variety of information types relevant for improved energy-efficiency in a city’sneighbourhoods covering entities like buildings where people perform functions(executing processes, activities, actions, ...)enabled/supported by the functionalities provided by appliances under the right indoor climate conditions:

  • Energy:roles like producing, consuming, storing, measuring, transporting or controlling energy, played by: …
  • Matter: physical thingson two aggregation levelslike:
  • Entities like buildings, outbound windmillsor street lighting but also
  • Devices like sensors, measuring room conditions;meters, measuring energy flows; convertors connecting energy networks having different energy forms, and actuators like radiatorsthat condition the: …
  • Space:conditional areas like outdoor areas and rooms (optionally grouped in zones), externally influenced by outdoor climate/weather.

These three aspects (energy, matter and space) are detailed in the next sections.

2.Energy

An energy network is a set of energy nodes and energy connections, where each energy connection connects two energy nodeswith a direction via asource and target relationship. An energy nodes comes in fourflavors:

  • Energy prosumer nodes, producing and/or consuming energy, of one specific energy form, not at the same time
  • Energy storage nodes, holding energy at a certain location in time
  • Energy switch nodes, controlling the flows between energy nodes (blocking certain connections and hereby stopping an energy flow or making the energy flow take a specific path in case of multiple choices)
  • Energy transformer nodes, which do not consume or produce energy but just transform the energy for the same energy form

The energy connections indicate how energy nodes are topologically connected and determine how energy can flow from one to the other.

Energy networks (including their energy nodes and energy connections) have a specific energy form. We distinguish:

  • Electrical
  • Radiant
  • Nuclear
  • Chemical (like Gas)
  • Thermal (like Hot water)
  • Mechanical

Another energy form means another energy network.

3.Matter

Like energy nodes we have “material nodes” that have a relevance in energy management. Sometimes they fulfill one or more energy roles, sometimes they measure conditions (sensors) or energy flows (meters).

Material nodes can be seen on multiple levels of aggregation of which we select two:

  • Neighbourhood Level, where the energy node roles are played by the (energy) installations of Entities like buildings,outbound windmills, solar parks etc., and
  • Entity Level, like the Building Level, where the energy nodes roles are on a lower detail level and played by Devices like appliances or installation parts like actuators (i.e. radiators).

The cities and neighbourhoods can also have energy consumption and production etc. as a whole but are not modelled explicitly (they are not considered playing an energy node role in some higher aggregation level). Energy properties for these levels can be obtained by querying the existing levels.

Sometimes, devices (including the total energy installations of entities) play a ‘double E-Node role’ in two different energy networks having a different energy form. We call them ‘convertors’ because they connect separate energy networks playing an energy consumer role in one and at the same time an energy producer role in another network. A good example is a Boiler, playing a consumer energy node role in a gas network and a producer energy node role in a hot water network. The boiler converts one energy type into another.

A building as special kind of entity has one (total) installation (system) covering various energy forms including electricity, gas and hot water that consists of zero or moredevices.The hierarchy of the decompositions of the energy networks having different energy forms is at building level strongly correlated with the energy node interaction of the energy flows in the energy connections. This makes it possible to state that the energy consumption of a certain form by a system is always the summation of the energy consumption of its direct parts (not in a transitive way also including its indirect parts, otherwise you are counting double, triple etc.). The same its true for the production side of the picture and the connection between production and consumption is always on the higher aggregation level of the building’s installationitself.

Energy Converters transform one form of energy to another form of energy. Actuators do in principle the same but now they consume energy and transfer it to a form that directly changes the conditions of rooms. The actuators can be seen as the end nodes from the chain involving one or more energy convertors.

Examples of special kinds of convertors are:

  • GasBoilers (gas > heat)
  • Combined Heat and Power (CHP) systems(gas > heat + electricity)
  • SolarBoilers(radiation > electricity)
  • Windmills(mechanical > electricity)

Examples of special kinds of buffers are:

  • Batteries(electricity > chemical > electricity)
  • IsolatedWaterTanks(heat > heat > heat)

Examples of special kinds of actuators are:

  • Radiators, increasing the temperature of a room,
  • CoolingSystems, decreasing the temperature of a room,
  • Lightings, increasing the luminance of a room,
  • Blinds, decreasing the luminance of a room,
  • Humidifiers increasing the relativeHumidity of a room.
  • AirConditioners, influencing several of the conditions mentioned before depending on its type

Sensors and Meters

Outdoor climate/weather conditions of the neighbourhood where the entity (like a building) is located, or indoor climate conditions of rooms can be measured by sensors. The mentioned actuators of the indoor climate conditions of associated rooms and the convertors but also other devices like appliances and meters/sensors themselves consume and/or produce energy. Thisenergy consumption/productioncan be measured indirectly byenergy meters that are associated toenergyflows as complex properties in energy connections between energy nodes.

A special case of ComplexProperty is a ProfileProperty being a discrete time series of PointProperties (being themselves ComplexProperties and related to “simple” base or derived quantities (having units) with a time stamp) where quantities refer to the above mentioned space conditions and energy node/energy connection energy properties (consumption, production, balance, flow etc.).

For each complex property we can optionally indicate:

  • valueType: Required, Proposed or Realized (==”Measured/Observed”) (default: Realized)
  • ValueKind: Nominal, Minimal, Maximal or Average (default: Nominal)
  • valueOrigin: Asserted or Inferred (default: Asserted)

Complex Devices

Sometimes we have “multi-purpose” devices that combine energy prosumer and other energy roles like energy storage. A good example is an Electric Vehicle (EV)-station that consists of a LoaderDeloader (being a special kind of Converter) and a Battery (being a special kind of Buffer). So EV-Stations has to be teared apart first before we can relate them to the right energy node subclasses (hereenergy prosumer resp. anenergy storage).

4.Space

Spaces are outdoor areasor indoor areas( referred to as rooms) which typically need certain conditions for activities that have to be performed in them.This is why we refer to them in this context collectively as “conditional areas”. Buildings consist of one or more rooms as conditional area. Furthermore, buildings can have zero or more (horizontal, vertical or mixed) zones that group a minimum of two rooms (and/or other zones) into zones. Note that grouping is not the same as (strong) decomposition: when a zone is deleted, the rooms are still there; also the rooms can be “part of” multiple rooms.

A room or outdoor area has a set of optional conditions that together form its indoor/outdoor climate like temperature, relative humidity, CO2 level and luminance. These conditions are (given structural factors like wall types, roof isolation, room/zone topology, glazing types) determined by, external dynamic factors like the outdoor climate/weather conditions for the relevant neighbourhood, internal dynamic factors (occupation, appliances used)and finally the actuatorsand indirectly theconvertors of the installation playing energy conversion roles.

5.Taxonomy(subClassOf hierarchy)

  • Any(Thing): taxonomy-root: the most generic class
  • E-Network
  • E-Node
  • E-Prosumer
  • E-Storage
  • E-Switch
  • E-Transformer
  • E-Connection
  • City
  • Neighbourhood
  • Entity
  • Building
  • OutboundWindmill
  • SolarPark
  • StreetLighting
  • Device
  • Installation (total system, multi-form)
  • Appliance (providing a functionality, link to entity-level)
  • Convertor
  • GasBoiler (gas > heat)
  • Combined Heat Power (CHP) (chemical > heat+ electricity)
  • PV Panels (radiation > electricity)
  • SolarBoiler (radiation > heat)
  • Windmill (kinetic > electricity)
  • LoaderDeloader (?)
  • Actuator(effecting conditions of a Room)
  • Radiator (air temperature +)
  • CoolingSystem (air temperature -)
  • AirConditioner (humidity + and temperature +/-)
  • Humidifier (humidity +)
  • Lighting (luminance +)
  • Blinds (luminance -)
  • Meter (measuring energy flows in energy connections)
  • Sensor (measuring conditions of rooms)
  • Buffer
  • Battery (electrical > chemical > electricity)
  • IsolatedWaterTank (heat > heat > heat)
  • Switcher
  • Transformer
  • HeatPump (heat > heat)
  • ComplexDevice
  • EV-Station
  • ConditionalArea
  • OutdoorArea
  • Room
  • Zone

6.Meronomy(hasPart hierarchy)

  • not taking into accountrestrictions like ‘optionality’
  • All(Thing): meronomy-root: the most global class
  • E-Network
  • E-Node
  • E-Connection
  • City
  • Neighbourhood
  • OutdoorArea
  • Building
  • Room
  • Zone
  • Installation
  • Device
  • Device, etc.
  • OutboundWindmill
  • SolarPark
  • StreetLighting
  • …

7.Key relationships

(beyond decomposition (hasPart) & topology (hasSource/hasTarget))

Between material & energy

  • Device “playsRoleOf” zero or more E-Node
  • ComplexProperty (“eFlow”) “measuredBy” one Meter

Between material & spaces

  • Actuator “effectsConditionsOf” one Room
  • ComplexProperty (“condition”) “measuredBy” one Sensor

Energy

  • E-Node “hasComplexProperty” zero or more ComplexProperty (“energy subproperties”)
  • E-Connection “hasComplexProperty” zero or more ComplexProperty (“eFlows”)

Space

  • Zone “groups” two or more (Zone or Room)
  • ConditionalArea “hasComplexProperty” zero or more ComplexProperty (“conditions”)

EnergyMeter-to-Space path

-eConsumption and eProduction properties are typically attached to the E-Node subclass ”E-Prosumer”. They can be asserted or derived from measurements related to anE-Connection by an (energy) meter. We can also attached eConsumption/eProduction etc. to a neighbourhood or even a city as a whole by querying the underlying level and aggregating ourselves.

-In the current building-example.ttl we assume this property to be known/measured somehow, but in practice we can only measure flows for energy connections. Because we know the source and target energy nodes where the source is producing in case of positive flow (and target consuming in case of positive flow) we also know what material node (appliance, installation part, energy meter, material node group etc.) is playing this consumption role.In case of

  • an appliance: no condition is changed (just a function is performed), in case of
  • an actuator: we know this energy is used for some condition change in the room related via “effectsConditionsOf”. Based on the type of actuator we know what kind of condition the energy is transferred to (radiator increases temperature). In case of
  • a device having some decomposition (like the total installation) we know the energy flows to all its direct parts and next to their parts etc. so i.e. a whole set of actuators related to potentially different rooms. In this case extra assumptions are needed on how energy is distributed.

8.Out of scope

  • No logistical material connections (“M-Connections”). We are only interested in the E-Connections.
  • No spatial topology
  • No structural information like building element (walls, windows, doors, floors, roofs, ceilings)
  • No “inverse actuators”, say where energy is extracted from conditions in conditional areas (and then say exchanged with other areas)
  • No Grids and GridNodes (they ARE however in the domain model)

9.Issues

  • How to define CO2-levels for rooms (what unit? Now: subproperty of cmo:mass with unit kilogram)
  • Issue: what are Appliances “part of”? (fixed versus mobile?)
  • Where does Occupancy fit (not yet in ontology), needed?
  • People are ‘actuators like radiators’ too (can we neglect?)
  • People are the reason we require certain room conditions (can we assume taken into account via room requirements, i.e. treated as black box)
  • LoaderDeloader : what are the energy conversions