=Paper= {{Paper |id=Vol-2050/fomi-paper4 |storemode=property |title=Reusing Domain Ontologies in Linked Building Data: The Case of Building Automation and Control |pdfUrl=https://ceur-ws.org/Vol-2050/FOMI_paper_4.pdf |volume=Vol-2050 |authors=Walter Terkaj,Georg Ferdinand Schneider,Pieter Pauwels |dblpUrl=https://dblp.org/rec/conf/jowo/TerkajSP17 }} ==Reusing Domain Ontologies in Linked Building Data: The Case of Building Automation and Control == https://ceur-ws.org/Vol-2050/FOMI_paper_4.pdf
    Reusing Domain Ontologies in Linked
     Building Data: the Case of Building
          Automation and Control
      Walter TERKAJ a,1 , Georg Ferdinand SCHNEIDER b and Pieter PAUWELS c
     a Institute of Industrial Technologies and Automation (ITIA-CNR), Milan, Italy
          b Fraunhofer Institute for Building Physics IBP, Nuremberg, Germany
                               c Ghent University, Ghent, Belgium



             Abstract. Linked data and semantic web technologies are gaining impact and im-
             portance in the Architecture, Engineering, Construction and Facility Management
             (AEC/FM) industry. Whereas we have seen a strong technological shift with the
             emergence of Building Information Modeling (BIM) tools, this second technolog-
             ical shift to the exchange and management of building data over the web might
             be even stronger than the first one. In order to make this a success, the AEC/FM
             industry will need strong and appropriate ontologies, as they will allow industry
             practitioners to structure their data in a commonly agreed format and exchange the
             data. Herein, we look at the ontologies that are emerging in the area of Building
             Automation and Control Systems (BACS). We propose a BACS ontology in strong
             alignment with existing ontologies and evaluate how it can be used for capturing
             automation and control systems of a building by modeling a use case.
             Keywords. Linked Data, Semantic Web, Building Data, Building Automation
             Systems, Control Logic




1. Introduction

One of the major challenges in the engineering of complex cyber-physical systems is
the interoperability between software applications that are used to engineer and manage
these systems. Buildings constitute one of these systems and their engineering requires
the interaction of a multitude of stakeholders over several stages of the life cycle [8].
Vast amounts of data are generated during this process. These data are typically stored
across various formats and information silos being both in machine-readable formats
(e.g. XML, STEP), or analog formats (e.g. drawings printed on paper). These data may
include the design specification of the actual layout of a building, product data on the
commissioned technical equipment, weather data [27] and sensor data obtained through
the installation and operation of a Building Automation System (BAS) [23].
     The ontology-based modeling approach and its related use of semantic web tech-
nologies seem to be a promising path towards addressing the prevalent heterogeneity of
 1 Corresponding Author: Institute of Industrial Technologies and Automation (ITIA-CNR), Milan, Italy; E-

mail: walter.terkaj@itia.cnr.it
data in the Architecture, Engineering, Construction and Facility Management (AEC/FM)
industry [5,30,15]. This is mostly undertaken by providing a common semantically well
defined layer enabling seamless information exchange and linkage across domains. How-
ever, a plethora of ontologies is defined to provide conceptualizations of this domain (see
Sect. 2). These ontologies can be used to represent data about buildings in a structured
manner and help facilitating the information exchange between different stakeholders.
     However, the existence of a multitude of ontologies that partly overlap in the scope
of AEC/FM inhibits the wide-spread adoption of the technology throughout the indus-
try. Several ontologies without standardization or consensus can only partially support
the AEC/FM industry. Under the umbrella of the World Wide Web Consortium (W3C),
the Linked Building Data Community Group (LBD) was initiated in 2016 to address
this problem. This group aims at becoming a Working Group and thus effectively de-
velop standard ontologies for the AEC/FM sector. When becoming a Working Group,
the following mission will prevail, as listed in the editor draft of the charter [10]:
    • to determine how building information can best be integrated with other data on
      the Web;
    • to determine how machines and people can discover that different facts in differ-
      ent datasets relate to the same building, especially when building is expressed in
      different ways and levels of granularity;
    • to identify and assess existing methods and tools and then create a set of best
      practices for their use;
    • where desirable, to complete the standardization of informal technologies already
      in widespread use.
     The community group aims at achieving this mission through a number of deliver-
ables. This includes a central ontology (not an upper ontology) that allows to express
the building topology of any building (Site - Building - Storey - Space - Element): the
Building Topology Ontology (BOT) [20]. In addition, a PRODUCT ontology, a GEOM
ontology, and a PSET ontology are being defined, allowing to represent product data, ge-
ometric representations, and properties, respectively. The set of four ontologies form the
core of the work that is aligned with W3C recommendations for adjacent domains, e.g.
the geospatial ontologies [25], SAREF [6], DogOnt [1], and the Semantic Sensor Net-
work (SSN [4]). The group also aligns with the W3C Data on the Web Best Practices [9]
for the adoption of Semantic Web Technologies (SWT) in the domain of building data.
     One subgroup of the LBD Community Group focuses on the formal modeling of
Building Automation and Control Systems (BACS). This partially reflects the need to
integrate tools supporting the monitoring and automation of buildings being in the need
of smart systems to automatically control technical equipment and improve building op-
eration in terms of energy efficiency and indoor comfort.
     As a first result of this work we present in this paper a modular ontology where
we integrate information from Building Information Modelling (BIM) and BAS: notably
building elements, sensors and actuators, devices of BAS and control logic. The work
mainly reuses and aligns existing domain ontologies to comprise domain information in
one common knowledge base for the control and automation of buildings.
     In Sect. 2, we provide an overview on existing domain ontologies regarding smart
appliances and BAS. Then in Sect. 3, we present the BACS Ontology. In Sect. 4, we
apply the BACS ontology to model an application scenario of state-based room control
in a fictional BAS. Finally, we draw the conclusions in Sect. 5.
2. Related Works

In this section we review existing ontology modeling approaches with a special focus
on smart appliances and building automation systems. A comprehensive review on the
usage of Semantic Web Technologies in the building domain is presented in [15], also
including a discussion on ontologies in the BAS domain.

2.1. General Systems and Building Information Modelling (BIM)

The Industry Foundation Classes (IFC) standard2 comprises a well accepted, open model
for the information exchange when applying BIM in the AEC/FM-industry. The data
model has already been converted to the Web Ontology Language (OWL) as the ifcOWL
ontology [14]. Another set of ontologies including building information is available in the
knowledge model for Smart Energy Aware Systems (SEAS) [13]. This includes ontology
modules related to building automation and control, such as modules DeviceOntology,
OptimizationOntology, and FailableSystemOntology.
     An approach to align existing ontologies in the AEC domain is represented by the
Building Topology Ontology (BOT) [20] that is part of the work conducted by the LBD
Community Group. This ontology can be aligned with several of the mentioned ontolo-
gies, using some of the ontology alignment approaches proposed in [20]. In this scope,
a BACS ontology is needed as well to model how appliances and devices can be used to
automate and control the building and its components.

2.2. BACS and Energy-Related

Several works focused on the energy management of facilities [12], such as airports [30].
An approach for domotics intelligent devices (DogOnt) was proposed by [1]. The integra-
tion of buildings with grid and energy market information is tackled in the ThinkHome
ontology [21]. An approach to integrate device descriptions on BAS devices, functional
specification with adjacent domains of BIM was developed in the BASont ontology [16].
An approach to formalize semantic tags by means of ontology is described in the
Haystack Tagging Ontology (HTO) [3]. Among the various ontologies related to BACS
and smart appliances, the Smart Appliances REFerence (SAREF) ontology [6] unifies
common accepted conceptualisations into one reference ontology; SAREF4BLDG [17]
is its extension for the building domain.

2.3. Sensor Data and Control Logic

A well established ontology for the formal specification of sensor data is the W3C Se-
mantic Sensor Network (SSN) ontology [4]. The SSN ontology has been recently up-
dated [11] by including also the more general module SOSA (Sensor, Observation, Sam-
ple, and Actuator) making it possible to model key concepts also for the BACS domain,
including sensor, actuator, observations, observable properties and results. The SSN on-
tology is included in the proposed BACS ontology (see Sect. 3). Within the reported ap-
proaches it may be observed that typically taxonomies are used to describe the actual
control behaviour of a certain control logic in a BACS. A modelling effort to specify
  2 http://www.buildingsmart-tech.org/ifc/IFC4/Add1/
UML state machines, a well known modeling approach for state-based control logic, as
an OWL ontology was presented by Dolog [7].

2.4. Summary

The reported ontologies form a comprehensive board of ontologies that can be reused to
cover the BACS domain by spanning the description of building elements and equipment,
sensors and actuators, BAS, and control logic. The ontology reuse, even if often applied
in a limited fashion, represents a key best practice that was followed in this work.


3. The Building Automation and Control System Ontology

The proposed BACS ontology aims at supporting the modeling of the following infor-
mation requirements:
    • control behavior in a BAS (both discrete and continuous), including the sense-
      comprehend-actuate pattern in closed-loop control logic and the comprehend-
      actuate pattern in open-loop control logic [24];
    • physical devices of Building Automation Systems (BAS) and their location in the
      building as well as affiliation to technical equipment;
    • smart appliances;
    • logical topology in a BAS.
     The architecture of the BACS ontology exploits the ontology reuse and modular-
ity principles [26]. The modular architecture consists of the following Terminological
(Tbox) modules, as shown in Figure 1:
    • statistics, defining basic concepts about probability distributions and descrip-
      tive statistics
    • fsm, the ontology for Finite State Machine
    • sosa, the Sensor, Observation, Sample, and Actuator (SOSA) Ontology
    • ssn, the Semantic Sensor Network Ontology
    • expression, a novel ontology formalizing algebraic and logical expressions
    • osph, a novel ontology modeling object states and performance history
    • list, ontology defining the set of entities used to describe the OWL list pattern
    • express, ontology that maps the key concepts of EXPRESS language to OWL
    • ifcmr, fragment of the ifcOWL ontology (version IFC4) generated from the EX-
      PRESS sub-schema IfcMeasureResource
    • bot, the Building Topology Ontology
    • bacs, a novel domain ontology for building automation and control
     All these modules are available on the web (see Table1). Such composition of mod-
ules was selected by carefully reviewing candidate ontologies (see Sect. 2) against the
following criteria: (1) minimum overlap with each other, (2) possibly W3C standards
(e.g. ssn) and (3) meeting the defined information requirements.
     The ontology modules fsm, sosa, ssn, and bot were already mentioned in Sect. 2.
     The group of modules list, express, and ifcmr supports the definition of quantity
values. This ontology is a fragment of the ifcOWL ontology [28] generated from the IFC
sub-schema IfcMeasureResource according to the method presented in [28]. These
modules could be replaced by other similar ontologies, such as the Ontology of Units of
Measure (OM) [22] or the QUDT ontology [19].
     The statistics module is a minimal ontology defining the basic classes and prop-
erties needed to model data related to descriptive statistics and probability distributions.
As an alternative, the larger and more complex STATO ontology [2] could be adopted.
     The three novel modules proposed in this work (i.e. expression, osph, bacs) are
described in Sect. 3.1, whereas the overall integration and alignment is presented in
Sect. 3.2. The prefixes of the namespaces are defined in Table 1.




           Figure 1. Modular architecture of the BACS Ontology. Arrows represent import relations.



                                        Table 1. Namespaces and prefixes

  Prefix       Value                                             Prefix       Value

  bacs         http://www.ontoeng.com/bacs#                      owl          http://www.w3.org/2002/07/owl#
  bot          https://w3id.org/bot#                             rdf          http://www.w3.org/1999/02/22-rdf-syntax-ns#
  expression   http://www.ontoeng.com/expression#                rdfs         http://www.w3.org/2000/01/rdf-schema#
  expr         https://w3id.org/express#                         sosa         http://www.w3.org/ns/sosa/
  fsm          http://www.learninglab.de/∼dolog/fsm/fsm.owl#     ssn          http://www.w3.org/ns/ssn/
  ifcmr        http://www.ontoeng.com/IFC4 IfcMeasureResource#   statistics   http://www.ontoeng.com/statistics#
  list         https://w3id.org/list#                            xsd          http://www.w3.org/2001/XMLSchema#
  osph         http://www.ontoeng.com/osph#




3.1. Novel Ontology Modules

The expression ontology aims at formalizing algebraic and logical expressions. A
generic expression can be decomposed into atomic, unary, and binary expressions. An
atomic expression can be a constant or a variable. This ontology was developed to pro-
vide a simple formal definition of expressions that can be used also as conditions to
be met before a transition is triggered (see Sect. 3.2). The classes and properties of the
expression ontology are sketched in Figure 2.
    The osph ontology is the evolution and generalization of an early proposal that was
based on the ifcOWL ontology [29]. This ontology plays a key role because it models
Object States and Performance History (OSPH), while integrating the fsm, statistics,
ssn, and expression modules. The following classes are defined in the osph ontology:
     • osph:ObjectDefinition is an abstract class whose definition resembles that of
       IfcObjectDefinition in the IFC standard.
     • osph:ObjectHistory defines a history interval in the lifecycle of a generic object
       that is assigned via the object property osph:isHistoryOf. An interval can be de-
Figure 2. Classes and relations in the expression ontology. Dashed lines represent OWL restrictions,
whereas solid lines represent subsumption relations.


       composed into other intervals via the property osph:isDecomposedByHistory. A
       history interval can be characterized by a start and end time as xsd:dateTime via
       the properties osph:hasIntervalStartTime and osph:hasIntervalEndTime, re-
       spectively. A history interval can be related to individuals of osph:StateFrequency
       via the property osph:hasStateFrequencies.
     • osph:StateFrequency describes the stay of an object in a specific state during a
       history interval.
     • osph:UnitOfMeasurement is a class defining a generic unit of measurement.
The relations between these classes are shown in Figure 3, whereas the relations with
classes defined in other modules are described in Sect. 3.2.




   Figure 3. Classes and relations in the osph ontology, where dashed lines represent OWL restrictions.



     The bacs module defines specializations of classes to directly support
the instantiation of the use case (Sect. 4). Classes bacs:LightSensor and
bacs:TemperatureSensor represent light and temperature sensors, respectively. The
class bacs:SpaceProperty and its subclasses bacs:SpaceIlluminanceProperty and
bacs:SpaceTemperatureProperty model specific properties of a space (e.g. a room).
The class bacs:SpaceObs and its subclasses bacs:SpaceIlluminanceObs and
bacs:SpaceTemperatureObs are designed to represent observations made in a space.
In the future, all these classes will be re-assessed to check if they can be replaced by
definitions imported from other dedicated domain ontologies.
3.2. Integration

The integration of the various ontology modules represents one of the main contri-
butions in the proposed ontology architecture. Indeed, the novel modules osph and
bacs mainly play the role of ontology mediator creating links between different do-
mains, as it can be noticed in the diagram of Figure 1. The alignments between
the various ontology modules are reported in Table 2 by specifying which module
is the mediator (i.e. where the alignment is defined), which are the aligned mod-
ules, which are the involved classes and properties, and finally providing a descrip-
tion. A generic object (osph:ObjectDefinition) can be characterized by a state ma-
chine (fsm:StateMachine) and also by one or more histories (osph:ObjectHistory)
that are able to capture the evolution of the object in terms of observations and
state. An expression (expression:Expression) can be composed by constant values
(ifcmr:IfcValue) and variables (expression:Variable) that are related to measur-
able properties (ssn:Property). The result of an observation (sosa:Observation) can
be a descriptive statistics (statistics:DescriptiveStatistics) or a quantity value
(ifcmr:IfcValue). The relevant alignments are also graphically represented in Figure 4.




Figure 4. Excerpt of classes and relations in the BACS Ontology showing the key alignments. Dashed lines
represent OWL restrictions, whereas solid lines represent subsumption relations.




4. Application Scenario

4.1. Description

The applicability of the proposed BACS ontology was tested against an application sce-
nario that includes the instantiation of building elements, sensors and actuators, automa-
tion systems, and control logics. The scenario is motivated by the deployment of auto-
                       Table 2. Alignments between the modules of the BACS ontology.

 Mediator   Modules        Classes and Properties             Description

 osph       sosa,osph      osph:ObjectDefinition,            osph:ObjectDefinition is defined as a subClassOf
                           sosa:FeatureOfInterest            sosa:FeatureOfInterest.
 osph       fsm,osph       osph:ObjectDefinition,            An individual of osph:ObjectDefinition can be
                           fsm:StateMachine,                 linked with an individual of fsm:StateMachine
                           osph:ObjectHistory;               via the property osph:hasStateMachine, and with
                           osph:hasStateMachine,             individuals of osph:ObjectHistory via property
                           osph:hasHistory                   osph:hasHistory.
 osph       fsm,osph       osph:StateFrequency,              An individual of osph:StateFrequency is related
                           fsm:State;                        with an individual of fsm:State via the property
                           osph:hasRelatedState              osph:hasRelatedState.
 osph       sosa,osph      osph:ObjectHistory,               A history interval osph:ObjectHistory can be related
                           sosa:Observation;                 to individuals of sosa:Observation via the property
                           osph:hasHistoryObservations       osph:hasHistoryObservations.
 osph       expression,    fsm:Condition,                    An individual of class fsm:Condition can be related
            fsm,osph       expression:Expression;            to an individual of expression:Expression via the
                           osph:hasConditionExpression       object property osph:hasConditionExpression.
 osph       expression,    expression:Variable,              An individual of class expression:Variable can be
            ssn,osph       ssn:Property;                     related to an individual of ssn:Property via the ob-
                           osph:representsProperty           ject property osph:representsProperty, i.e. a vari-
                                                             able can be used to represent the property of a feature.
 bacs       bot,osph       osph:ObjectDefinition,            bot:Building,          bot:Space,           bot:Element,
                           bot:Building, bot:Space,          bot:Storey        are      defined       as  subClassOf
                           bot:Element, bot:Storey           osph:ObjectDefinition.
 bacs       bot,sosa       bot:Element, sosa:Sensor          sosa:Sensor is subClassOf bot:Element.
 bacs       sosa,bacs      sosa:Sensor,bacs:LightSensor, bacs:LightSensor and bacs:TemperatureSensor
                           bacs:TemperatureSensor            are subClassOf sosa:Sensor.
 bacs       bacs,bot,      osph:ObjectHistory,               bacs:SpaceHistory                  is        subClassOf
            osph           bot:Space, bacs:SpaceObs,         osph:ObjectHistory and further specializes the
                           bacs:SpaceHistory;                restrictions characterizing osph:ObjectHistory by
                           osph:hasHistoryObervations,       means of properties osph:hasHistoryObervations,
                           osph:isDecomposedByHistory,       osph:isDecomposedByHistory, osph:isHistoryOf and
                           osph:isHistoryOf                  classes bacs:SpaceObs, bot:Space, bacs:SpaceHistory.
 bacs       osph,ifcmr     osph:UnitOfMeasurement,           ifcmr:IfcUnit                   is           subClassOf
                           ifcmr:IfcUnit                     osph:UnitOfMeasurement.
 bacs       sosa,bacs      sosa:ObservableProperty,          bacs:SpaceProperty                  is       subClassOf
                           bacs:SpaceProperty                sosa:ObservableProperty.
 bacs       sosa,bacs      sosa:Observation,bacs:SpaceObs bacs:SpaceObs is subClassOf sosa:Observation.
 bacs       statistics,    statistics:DescriptiveStatistics, sosa:Result             is           a       subClassOf
            ifcmr,         ifcmr:IfcValue,                   the       union      of        ifcmr:IfcValue         and
            sosa           sosa:Result                       statistics:DescriptiveStatistics, i.e. the result
                                                             of an observation must be either a value or a statistics.
 bacs       expression,    expression:Constant,              ifcmr:IfcValue              is         a     subClassOf
            ifcmr          ifcmr:IfcValue                    expression:Constant.



matic control in the room of a building. The focus is on control logic because it can
significantly impact on the energy consumption and comfort conditions.
     In the scenario, a room is equipped with a window, a controllable sunblind, a room
air temperature sensor and an outdoor illuminance sensor. A finite state machine is de-
signed to control the sunblind depending on the room air temperature and outdoor illumi-
nance, as presented in [18]. The sunblind can be in one of the following states: noShade,
nightShadeDeployed, dayShadeDeployed (Figure 5). The following observations have
been made in the system:

    • room temperature: 20◦ C at 2017-03-09T08:00:00; 24◦ C at 2017-03-09T10:00:00
    • room illuminance: 90 lx at 2017-03-09T08:00:00; 200 lx at 2017-03-09T10:00:00
    • sunblind state: noShade at 2017-03-09T09:30:00
                          Figure 5. State Machine to control a sunblind in a room [18].


     4.2. Instantiation

     The Abox ontology module named bacs test3 imports the bacs module and instan-
     tiates the application scenario in terms of OWL individuals defined in its namespace.
     For sake of simplicity, the following fragments in turtle format present only a subset of
     definitions included in bacs test.
          Fragment 1 presents the definition of room, temperature sensor and sunblind. The
     room is associated with two properties: room temperature and room illuminance. Other
     definitions include building, building storey, window, and illuminance sensor.
          Fragment 2 shows a part of the definition of the finite state machine modeling the
     control logic of the sunblind. As an example, the details of the transition from state
     dayShadeDeployed to nightShadeDeployed are reported. This transition can be triggered
     only if the guard condition is met, i.e. if the room illuminance is less then 5.0 lx.
          Fragment 3 provides an example of how the history of the room can be characterized
     by observations of its properties thanks to the sensors. In addition, the history of the
     sunblind considers the evolution of the sunblind state.
          Finally, a couple of SPARQL queries are presented to show how the contents of the
     ontology can be extracted to support business processes, while referring to the prefixes
     defined in Table 1.

 1   :room a owl:NamedIndividual , bot:Space ;
 2       bot:containsElement :lightsensor , :sunblind , :tempsensor ;
 3       ssn:hasProperty :room_illuminance_prop , :room_temperature_prop ;
 4       bot:adjacentElement :window ; osph:hasHistory :room_history .
 5   :tempsensor a owl:NamedIndividual , bacs:TemperatureSensor ;
 6       sosa:observes :room_temperature_prop .
 7   :sunblind a owl:NamedIndividual , bot:Element ;
 8       osph:hasHistory :sb_history ; osph:hasStateMachine :sb_StateMachine .
 9   :room_temperature_prop a owl:NamedIndividual , bacs:SpaceTemperatureProperty ;
10       osph:hasPropertyUnit :temperature_unit .
11   :room_illuminance_prop a owl:NamedIndividual , bacs:SpaceIlluminanceProperty ;
12       osph:hasPropertyUnit :illuminance_unit .

                            Fragment 1: Excerpt of space and elements instantiation

       3 http://www.ontoeng.com/bacs_test
 1   :sb_StateMachine a owl:NamedIndividual , fsm:StateMachine ;
 2       fsm:contains :sb_InitialState, :sb_dayShadeDeployed, :sb_nightShadeDeployed,
 3           :sb_noShade, :sb_trDayNight, :sb_trDayNo, :sb_trInitNo, :sb_trNightNo,
 4           :sb_trNoDay, :sb_trNoNight, :sb_trDayNight_guard, :sb_trDayNo_guard,
 5           :sb_trNightNo_guard, :sb_trNoDay_guard, :sb_trNoNight_guard.
 6   :sb_dayShadeDeployed a owl:NamedIndividual , fsm:Simple .
 7   :sb_nightShadeDeployed a owl:NamedIndividual , fsm:Simple .
 8   :sb_trDayNight a owl:NamedIndividual , fsm:Transition ;
 9       fsm:Source :sb_dayShadeDeployed ; fsm:Target :sb_nightShadeDeployed ;
10       fsm:TransitionGuard :sb_trDayNight_guard .
11   :sb_trDayNight_guard a owl:NamedIndividual , fsm:Guard ;
12       fsm:GuardCondition :sb_trDayNight_condition .
13   :sb_trDayNight_condition a owl:NamedIndividual , fsm:Condition ;
14       osph:hasConditionExpression :sb_trDayNight_expr .
15   :sb_trDayNight_expr a owl:NamedIndividual , expression:BinaryExpression ;
16       expression:hasLhsOperand :room_illuminance_var ;
17       expression:hasOperator expression:LESSTHAN ;
18       expression:hasRhsOperand :illumA .
19   :illumA a owl:NamedIndividual , ifcmr:IfcIlluminanceMeasure ;
20       express:hasDouble "5.0"^^xsd:double .

                        Fragment 2: Excerpt of sunblind state machine instantiation


 1   :room_history a owl:NamedIndividual , bacs:SpaceHistory ;
 2       osph:isDecomposedByHistory :room_history_int1 , :room_history_int2 ;
 3       osph:hasIntervalStartTime "2017-03-09T08:00:00"^^xsd:dateTime .
 4   :room_history_int1 a owl:NamedIndividual , bacs:SpaceHistory ;
 5       osph:hasHistoryObservations :room_illum1 , :room_temp1 ;
 6       osph:hasIntervalStartTime "2017-03-09T08:00:00"^^xsd:dateTime .
 7   :room_illum1 a owl:NamedIndividual , bacs:SpaceIlluminanceObs ;
 8       sosa:hasResult :illum1 ; sosa:madeBySensor :lightsensor ;
 9       sosa:observedProperty :room_illuminance_prop .
10   :illum1 a owl:NamedIndividual , ifcmr:IfcIlluminanceMeasure ;
11       express:hasDouble "90.0"^^xsd:double .
12   :sb_history a owl:NamedIndividual , osph:ObjectHistory ;
13       osph:hasStateFrequencies :statefreq1 ;
14       osph:hasIntervalStartTime "2017-03-09T09:30:00"^^xsd:dateTime .
15   :statefreq1 a owl:NamedIndividual , osph:StateFrequency ;
16       osph:hasRelatedState :noShade ; osph:hasStayRatio "1.0"^^xsd:double .

                       Fragment 3: Excerpt of room and sunblind history instantiation

         The query in Fragment 4 gets the elements in the building and the associated state
     machine (if existing). The query in Fragment 5 explores the finite state machine of any
     element in a room and returns the state machine components (e.g. states, transitions,
     guards) and further details about transitions.

 1   SELECT distinct ?building ?storey ?room ?elem ?statemach
 2   WHERE {
 3     ?building rdf:type/rdfs:subClassOf* bot:Building.
 4     ?building bot:hasStorey ?storey. ?storey bot:hasSpace ?room .
 5     ?room bot:adjacentElement|bot:containsElement ?elem .
 6     OPTIONAL{ ?elem osph:hasStateMachine ?statemach .}
 7   }

                       Fragment 4: SPARQL query to get the elements in the building
 1   SELECT distinct ?statemach ?fsmelem ?class ?source ?target ?guard ?condition
 2   WHERE {
 3     ?statemach rdf:type/rdfs:subClassOf* fsm:StateMachine .
 4     ?statemach fsm:contains/fsm:hasStateMachineElement* ?fsmelem .
 5     ?fsmelem rdf:type ?class . FILTER ( ?class != owl:NamedIndividual ) .
 6     OPTIONAL{
 7     ?class rdfs:subClassOf* fsm:Transition .
 8     ?fsmelem fsm:Source ?source . ?fsmelem fsm:Target ?target .
 9     OPTIONAL{
10       ?fsmelem fsm:TransitionGuard ?guard . ?guard fsm:GuardCondition ?condition .}
11   }}

                       Fragment 5: SPARQL query to get the components of a state machine




     5. Conclusions

     This paper presented a modular ontology to model the domain of building control and au-
     tomation, demonstrating its applicability in a test case. Reusing ontologies through inte-
     gration and alignment is promising to tackle the building control and automation domain,
     but best practices and guidelines from ontology engineering will be further investigated.
     The proposed test case focuses on the building automation domain, but, as automation is
     relevant in many industries (process industry, manufacturing industry, etc.), the reuse of
     the ontology in other domains will be studied. Future works will address also:
            • testing more complex cases requiring the interaction between smart objects;
            • preparation of a library of general purpose SPARQL queries and update to support
              the use of the BACS ontology (e.g. extraction of object history, extraction of
              expressions, triggering and execution of a control action);
            • integration with other ontologies specializing elements, sensors and actuators, and
              defining concepts related to geometry (e.g. placement, representation of objects).


     Acknowledgments

     This work has been partially funded by the Italian research project “Efficientamento dei
     processi di produzione e gestione integrata di utenze energivore con fonti rinnovabili e
     sistemi di accumulo mediante periferiche ICT in un contesto Smart District” within the
     “Piano Triennale 2015-17 della Ricerca di Sistema Elettrico Nazionale”.


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