diff --git a/settings.gradle b/settings.gradle
index 04043f00..96cab8a8 100644
--- a/settings.gradle
+++ b/settings.gradle
@@ -1,3 +1,11 @@
+pluginManagement {
+    plugins {
+        id 'org.jetbrains.kotlin.jvm' version '1.9.22'
+    }
+}
+plugins {
+    id 'org.gradle.toolchains.foojay-resolver-convention' version '0.5.0'
+}
 rootProject.name = 'unit-api'
 
 include 'unit-api-core'
diff --git a/unit-api-core/build.gradle b/unit-api-core/build.gradle
index f5bdfc5b..94cc1208 100644
--- a/unit-api-core/build.gradle
+++ b/unit-api-core/build.gradle
@@ -1,3 +1,13 @@
+plugins {
+    id 'org.jetbrains.kotlin.jvm'
+}
 dependencies {
     implementation("org.reflections:reflections:0.10.2")
+    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8"
+}
+repositories {
+    mavenCentral()
+}
+kotlin {
+    jvmToolchain(17)
 }
\ No newline at end of file
diff --git a/unit-api-core/src/main/java/com/raynigon/unit/api/core/quantities/Luminance.java b/unit-api-core/src/main/java/com/raynigon/unit/api/core/quantities/Luminance.java
new file mode 100644
index 00000000..2a569edb
--- /dev/null
+++ b/unit-api-core/src/main/java/com/raynigon/unit/api/core/quantities/Luminance.java
@@ -0,0 +1,19 @@
+package com.raynigon.unit.api.core.quantities;
+
+import javax.measure.Quantity;
+import javax.measure.quantity.Area;
+import javax.measure.quantity.LuminousIntensity;
+
+/**
+ * Luminous intensity per unit area of light traveling in a given direction.
+ * The system unit for this quantity is "cd/m²" (candela per square meter).
+ *
+ * @author <a href="mailto:jean-marie@dautelle.com">Jean-Marie Dautelle</a>
+ * @author <a href="mailto:units@catmedia.us">Werner Keil</a>
+ * @version 1.3
+ *
+ * @see LuminousIntensity
+ * @see Area
+ */
+public interface Luminance extends Quantity<Luminance> {
+}
\ No newline at end of file
diff --git a/unit-api-core/src/main/java/com/raynigon/unit/api/core/units/si/angle/Radian.java b/unit-api-core/src/main/java/com/raynigon/unit/api/core/units/si/angle/Radian.java
new file mode 100644
index 00000000..04c0b787
--- /dev/null
+++ b/unit-api-core/src/main/java/com/raynigon/unit/api/core/units/si/angle/Radian.java
@@ -0,0 +1,21 @@
+package com.raynigon.unit.api.core.units.si.angle;
+
+import com.raynigon.unit.api.core.units.general.BaseUnit;
+import com.raynigon.unit.api.core.units.general.UnitDimension;
+import com.raynigon.unit.api.core.units.si.SISystem;
+
+import javax.measure.quantity.Angle;
+import javax.measure.quantity.SolidAngle;
+
+public class Radian extends BaseUnit<Angle> {
+
+    public Radian() {
+        super(
+                SISystem.ID,
+                "rad",
+                "Radian",
+                Angle.class,
+                UnitDimension.NONE
+        );
+    }
+}
\ No newline at end of file
diff --git a/unit-api-core/src/main/java/com/raynigon/unit/api/core/units/si/angle/Steradian.java b/unit-api-core/src/main/java/com/raynigon/unit/api/core/units/si/angle/Steradian.java
new file mode 100644
index 00000000..6c1943fe
--- /dev/null
+++ b/unit-api-core/src/main/java/com/raynigon/unit/api/core/units/si/angle/Steradian.java
@@ -0,0 +1,20 @@
+package com.raynigon.unit.api.core.units.si.angle;
+
+import com.raynigon.unit.api.core.units.general.BaseUnit;
+import com.raynigon.unit.api.core.units.general.UnitDimension;
+import com.raynigon.unit.api.core.units.si.SISystem;
+
+import javax.measure.quantity.SolidAngle;
+
+public class Steradian extends BaseUnit<SolidAngle> {
+
+    public Steradian() {
+        super(
+                SISystem.ID,
+                "sr",
+                "Steradian",
+                SolidAngle.class,
+                UnitDimension.NONE
+        );
+    }
+}
\ No newline at end of file
diff --git a/unit-api-core/src/main/java/com/raynigon/unit/api/core/units/si/luminance/Candela.java b/unit-api-core/src/main/java/com/raynigon/unit/api/core/units/si/luminance/Candela.java
new file mode 100644
index 00000000..bc2ae7b9
--- /dev/null
+++ b/unit-api-core/src/main/java/com/raynigon/unit/api/core/units/si/luminance/Candela.java
@@ -0,0 +1,23 @@
+package com.raynigon.unit.api.core.units.si.luminance;
+
+import com.raynigon.unit.api.core.units.general.AlternateUnit;
+import com.raynigon.unit.api.core.units.general.BaseUnit;
+import com.raynigon.unit.api.core.units.general.UnitDimension;
+import com.raynigon.unit.api.core.units.si.SISystem;
+import com.raynigon.unit.api.core.units.si.area.SquareMetre;
+
+import javax.measure.quantity.Illuminance;
+import javax.measure.quantity.LuminousIntensity;
+
+public class Candela extends BaseUnit<LuminousIntensity> {
+
+    public Candela() {
+        super(
+                SISystem.ID,
+                "cd",
+                "Candela",
+                LuminousIntensity.class,
+                UnitDimension.LUMINOUS_INTENSITY
+        );
+    }
+}
diff --git a/unit-api-core/src/main/java/com/raynigon/unit/api/core/units/si/luminance/CandelaPerSquareMetre.java b/unit-api-core/src/main/java/com/raynigon/unit/api/core/units/si/luminance/CandelaPerSquareMetre.java
new file mode 100644
index 00000000..d18f0d69
--- /dev/null
+++ b/unit-api-core/src/main/java/com/raynigon/unit/api/core/units/si/luminance/CandelaPerSquareMetre.java
@@ -0,0 +1,24 @@
+package com.raynigon.unit.api.core.units.si.luminance;
+
+import com.raynigon.unit.api.core.quantities.Luminance;
+import com.raynigon.unit.api.core.units.general.AlternateUnit;
+import com.raynigon.unit.api.core.units.general.TransformedUnit;
+import com.raynigon.unit.api.core.units.si.SISystem;
+import com.raynigon.unit.api.core.units.si.area.SquareMetre;
+
+import javax.measure.Unit;
+import javax.measure.quantity.Illuminance;
+
+public class CandelaPerSquareMetre extends AlternateUnit<Luminance> {
+
+    @SuppressWarnings("unchecked")
+    public CandelaPerSquareMetre() {
+        super(
+                SISystem.ID,
+                "lx",
+                "Lux",
+                (Unit<Luminance>) (new Candela().divide(new SquareMetre())),
+                Luminance.class
+        );
+    }
+}
diff --git a/unit-api-core/src/main/java/com/raynigon/unit/api/core/units/si/luminance/Lumen.java b/unit-api-core/src/main/java/com/raynigon/unit/api/core/units/si/luminance/Lumen.java
new file mode 100644
index 00000000..67e872b3
--- /dev/null
+++ b/unit-api-core/src/main/java/com/raynigon/unit/api/core/units/si/luminance/Lumen.java
@@ -0,0 +1,25 @@
+package com.raynigon.unit.api.core.units.si.luminance;
+
+import com.raynigon.unit.api.core.units.general.AlternateUnit;
+import com.raynigon.unit.api.core.units.general.BaseUnit;
+import com.raynigon.unit.api.core.units.general.UnitDimension;
+import com.raynigon.unit.api.core.units.si.SISystem;
+import com.raynigon.unit.api.core.units.si.angle.Steradian;
+
+import javax.measure.Unit;
+import javax.measure.quantity.Illuminance;
+import javax.measure.quantity.LuminousFlux;
+
+public class Lumen extends AlternateUnit<LuminousFlux> {
+
+    @SuppressWarnings("unchecked")
+    public Lumen() {
+        super(
+                SISystem.ID,
+                "lm",
+                "Lumen",
+                (Unit<LuminousFlux>) new Candela().multiply(new Steradian()),
+                LuminousFlux.class
+        );
+    }
+}
diff --git a/unit-api-core/src/main/java/com/raynigon/unit/api/core/units/si/luminance/Lux.java b/unit-api-core/src/main/java/com/raynigon/unit/api/core/units/si/luminance/Lux.java
new file mode 100644
index 00000000..832b65f3
--- /dev/null
+++ b/unit-api-core/src/main/java/com/raynigon/unit/api/core/units/si/luminance/Lux.java
@@ -0,0 +1,22 @@
+package com.raynigon.unit.api.core.units.si.luminance;
+
+import com.raynigon.unit.api.core.units.general.AlternateUnit;
+import com.raynigon.unit.api.core.units.si.SISystem;
+import com.raynigon.unit.api.core.units.si.area.SquareMetre;
+
+import javax.measure.Unit;
+import javax.measure.quantity.Illuminance;
+
+public class Lux extends AlternateUnit<Illuminance> {
+
+    @SuppressWarnings("unchecked")
+    public Lux() {
+        super(
+                SISystem.ID,
+                "lx",
+                "Lux",
+                (Unit<Illuminance>) new Lumen().divide(new SquareMetre()),
+                Illuminance.class
+        );
+    }
+}