diff --git a/examples/heatingsystem.ttl b/examples/heatingsystem.ttl
index 4b53c36cd1ab29ed84f7a98450d217adc7a2dcc5..d382dae22d3e3de34434401ae00d634149c0c392 100644
--- a/examples/heatingsystem.ttl
+++ b/examples/heatingsystem.ttl
@@ -199,7 +199,7 @@ s4ener:Slot-3-HS0001
 s4ener:StartTimeDurationDescription_1
   rdf:type s4ener:StartTimeDurationDescription ;
   rdfs:label "Start time duration description 1"^^xsd:string ;
-  s4ener:xsdDuration "PT0H5M"^^xsd:duration ;
+  s4ener:xsdDuration "PT0H5M" ;
 .
 s4ener:StartTime_1
   rdf:type s4ener:StartTime ;
diff --git a/ontology/saref4ener.ttl b/ontology/saref4ener.ttl
index ba3498f291e4929cadef750eb96eb7300686c852..5fe40961492f4a5e3428a05f4761baf7501c82a8 100644
--- a/ontology/saref4ener.ttl
+++ b/ontology/saref4ener.ttl
@@ -1524,28 +1524,15 @@ s4ener:vendorName
   rdfs:label "vendor name"@en ;
   rdfs:range xsd:string ;
 .
-xsd:duration a rdfs:Datatype .
 s4ener:xsdDuration
   rdf:type owl:DatatypeProperty ;
   rdfs:comment """This property is added to the  time:DurationDescription class to allow to express time duration also as xsd:duration. This is necessary because in the EEBus/E@h model time is always expressed as xsd:duration. We use this property to express the following time information in the EEBus/E@h model:
+
 - the startTime of the power sequence (in the PowerSequence class). SHALL be present
 - the endTime of the power sequence (in the PowerSequence class). If the value is available, it SHALL be denoted here. Otherwise the element SHALL be omitted.
 - the startTime of measurement as absolute or relative value (in the Measurement class).
-- the endTime of measurement as absolute or relative value (in the Measurement class)."""@en ;
+- the endTime of measurement as absolute or relative value (in the Measurement class).
+
+The duration is expected to be described as in xsd:duration"""@en ;
   rdfs:label "duration in xsd "@en ;
-  rdfs:range xsd:duration ;
-.
-[
-  rdf:type owl:Class ;
-  owl:unionOf (
-      xsd:int
-      xsd:double
-    ) ;
-].
-[
-  rdf:type owl:Class ;
-  owl:unionOf (
-      xsd:int
-      xsd:double
-    ) ;
-].
+.
\ No newline at end of file