diff --git a/samples/physicalquantities/main.cpp b/samples/physicalquantities/main.cpp
index 2fb0e2acb..ea472a4f3 100644
--- a/samples/physicalquantities/main.cpp
+++ b/samples/physicalquantities/main.cpp
@@ -54,7 +54,9 @@ int main(int argc, char *argv[])
 
     CTemperature t1;
     CTemperature t2(20, CTemperatureUnit::C());
-    qDebug() << t1 << t2;
+    CTemperature t3(1, CTemperatureUnit::F());
+    qDebug() << t1 << t2 << t2.convertedSiValueRoundedWithUnit();
+    qDebug() << t3 << t3.valueRoundedWithUnit(CTemperatureUnit::C());
 
     // some logging wit CLogMessage
     bDebug << p1;
diff --git a/src/blackcore/blackcore.h b/src/blackcore/blackcore.h
new file mode 100644
index 000000000..5b91d074e
--- /dev/null
+++ b/src/blackcore/blackcore.h
@@ -0,0 +1,9 @@
+#ifndef BLACKCORE_H
+#define BLACKCORE_H
+
+/**
+ * @namespace BlackCore
+ * To be written
+ */
+
+#endif // BLACKCORE_H
diff --git a/src/blackcore/blackcore.pro b/src/blackcore/blackcore.pro
index 55e4802ab..769070a17 100644
--- a/src/blackcore/blackcore.pro
+++ b/src/blackcore/blackcore.pro
@@ -31,7 +31,8 @@ HEADERS += \
     plane.h \
     simulator.h \
     vector_3d.h \
-    vector_geo.h
+    vector_geo.h \
+    blackcore.h
 
 SOURCES += \
     ecef.cpp \
diff --git a/src/blackmisc/pqbase.h b/src/blackmisc/pqbase.h
index fc0806706..794211fa0 100644
--- a/src/blackmisc/pqbase.h
+++ b/src/blackmisc/pqbase.h
@@ -179,7 +179,7 @@ private:
     QString _type; //!< type,such as distance. Somehow redundant, but simplifies unit comparisons
     bool _isSIUnit; //!< is this a SI unit?
     bool _isSIBaseUnit; //!< SI base unit?
-    double _conversionFactorToSIConversionUnit; //!< factor to convert to SI
+    double _conversionFactorToSIConversionUnit; //!< factor to convert to SI, set to 0 if not applicable (rare cases, e.g. temperature)
     double _epsilon; //!< values with differences below epsilon are the equal
     qint32 _displayDigits; //!< standard rounding dor string conversions
     CMeasurementPrefix _multiplier; //!< multiplier
@@ -278,7 +278,7 @@ public:
      * \param to
      * \return
      */
-    virtual double conversionFactor(const CMeasurementUnit &to) const;
+    double conversionFactor(const CMeasurementUnit &to) const;
     /*!
      * \brief Factor to convert between given units
      * \param from
diff --git a/src/blackmisc/pqphysicalquantity.cpp b/src/blackmisc/pqphysicalquantity.cpp
index 60db0518d..c707d6258 100644
--- a/src/blackmisc/pqphysicalquantity.cpp
+++ b/src/blackmisc/pqphysicalquantity.cpp
@@ -244,14 +244,13 @@ bool CPhysicalQuantity::operator <=(const CPhysicalQuantity &otherQuantity) cons
 /**
  * Switch to another unit
  */
-bool CPhysicalQuantity::switchUnit(const CMeasurementUnit &unit)
+bool CPhysicalQuantity::switchUnit(const CMeasurementUnit &newUnit)
 {
-    if (this->_unit == unit) return true;
-    if (this->_unit.getType() != unit.getType()) return false; // not possible
-
-    double cf = this->_unit.conversionFactor(unit);
-    this->_unit =unit;
-    this->setUnitValue(cf * this->_unitValueD);
+    if (this->_unit == newUnit) return true;
+    if (this->_unit.getType() != newUnit.getType()) return false; // not possible
+    double cf = this->calculateValueInOtherUnit(newUnit);
+    this->_unit = newUnit;
+    this->setUnitValue(cf);
     return true;
 }
 
@@ -275,19 +274,23 @@ void CPhysicalQuantity::setUnitValue(double baseValue)
     this->_unitValueI = qRound(baseValue);
     this->_isIntegerBaseValue = false;
     this->setConversionSiUnitValue();
-
 }
 
 /**
- * @brief set SI value
+ * Set SI value
  */
 void CPhysicalQuantity::setConversionSiUnitValue() {
-    if (this->_unit == CMeasurementUnit::None()) {
-        this->_convertedSiUnitValueD=0.0;
-    } else {
-        double f = this->_unit.conversionFactor(this->_conversionSiUnit);
-        this->_convertedSiUnitValueD =f * this->_unitValueD;
-    }
+    this->_convertedSiUnitValueD = this->calculateValueInOtherUnit(this->_conversionSiUnit);
+}
+
+/**
+ * Standard conversion by factor, used in most cases,in some cases overridden (e.g.CTemperature)
+ */
+double CPhysicalQuantity::calculateValueInOtherUnit(const CMeasurementUnit &otherUnit) const {
+    if (this->_unit == CMeasurementUnit::None() || this->_unitValueD == 0.0) return 0.0;
+    if (this->_unit == otherUnit) return this->_unitValueD;
+    double f = this->_unit.conversionFactor(otherUnit);
+    return f * this->_unitValueD;
 }
 
 /**
@@ -368,13 +371,8 @@ double CPhysicalQuantity::valueRounded(const CMeasurementUnit &unit, int digits)
  */
 double CPhysicalQuantity::value(const CMeasurementUnit &unit) const
 {
-    double v;
-    if (unit == this->_unit)
-        v = this->_unitValueD;
-    else if (unit == this->_conversionSiUnit)
-        v = this->_convertedSiUnitValueD;
-    else
-        v = (this->_unit.conversionFactor(unit)) * (this->_unitValueD);
+    if (unit == this->_conversionSiUnit) return this->_convertedSiUnitValueD;
+    double v =  this->calculateValueInOtherUnit(unit);
     return v;
 }
 
diff --git a/src/blackmisc/pqphysicalquantity.h b/src/blackmisc/pqphysicalquantity.h
index cddf65435..823e3a071 100644
--- a/src/blackmisc/pqphysicalquantity.h
+++ b/src/blackmisc/pqphysicalquantity.h
@@ -70,6 +70,14 @@ protected:
      * \brief Set the SI value
      */
     void setConversionSiUnitValue();
+    /*!
+     * Convert value in another unit, normally just by a factor, but in some cases
+     * (e.g. CTemperature)overridden because arbitrary conversion is required
+     * \sa CMeasurementUnit::conversionFactor(CMeasurementUnit)
+     * \param otherUnit
+     * \return
+     */
+    virtual double calculateValueInOtherUnit(const CMeasurementUnit &otherUnit) const;
 
 public:
     /*!
@@ -79,10 +87,10 @@ public:
     CPhysicalQuantity(const CPhysicalQuantity &otherQuantity);
     /*!
      * \brief Switch unit, e.g. feet meter
-     * \param unit
+     * \param newUnit
      * \return
      */
-    bool switchUnit(const CMeasurementUnit &unit);
+    bool switchUnit(const CMeasurementUnit &newUnit);
     /*!
      * \brief Value in SI base unit? Meter is an SI base unit, hertz not!
      * \return
@@ -116,7 +124,7 @@ public:
      * \param digits
      * @return
      */
-    double valueRounded(const CMeasurementUnit &unit, int digits) const;
+    double valueRounded(const CMeasurementUnit &unit, int digits = -1) const;
     /*!
      * \brief Value to QString with unit, e.g. "5.00m"
      * \param unit
@@ -143,7 +151,7 @@ public:
      * \brief SI value to double
      * @return
      */
-    qint32 siBaseUnitValueToDouble() const { return this->_convertedSiUnitValueD;}
+    double siBaseUnitValueToDouble() const { return this->_convertedSiUnitValueD;}
     /*!
      * \brief Rounded value by n digits
      * \param digits
diff --git a/src/blackmisc/pqtemperature.cpp b/src/blackmisc/pqtemperature.cpp
index 1c592166c..d511435d0 100644
--- a/src/blackmisc/pqtemperature.cpp
+++ b/src/blackmisc/pqtemperature.cpp
@@ -7,7 +7,7 @@ namespace BlackMisc {
  */
 CTemperature::CTemperature(): CPhysicalQuantity(0, CTemperatureUnit::K(),CTemperatureUnit::K())
 {
-    //void
+    this->setUnitValue(this->unitValueToDouble()); // I have to recall, since virtual method overriding does not work in constructor
 }
 
 /**
@@ -15,7 +15,7 @@ CTemperature::CTemperature(): CPhysicalQuantity(0, CTemperatureUnit::K(),CTemper
  */
 CTemperature::CTemperature(const CPhysicalQuantity &temperature): CPhysicalQuantity(temperature)
 {
-    //void
+    this->setUnitValue(this->unitValueToDouble()); // I have to recall, since virtual method overriding does not work in constructor
 }
 
 /**
@@ -23,7 +23,7 @@ CTemperature::CTemperature(const CPhysicalQuantity &temperature): CPhysicalQuant
  */
 CTemperature::CTemperature(qint32 value, const CTemperatureUnit &unit) : CPhysicalQuantity(value, unit, CTemperatureUnit::K())
 {
-    // void
+    this->setUnitValue(value); // I have to recall, since virtual method overriding does not work in constructor
 }
 
 /**
@@ -31,7 +31,41 @@ CTemperature::CTemperature(qint32 value, const CTemperatureUnit &unit) : CPhysic
  */
 CTemperature::CTemperature(double value, const CTemperatureUnit &unit) : CPhysicalQuantity(value, unit, CTemperatureUnit::K())
 {
-    // void
+    this->setUnitValue(value); // I have to recall, since virtual method overriding does not work in constructor
+}
+
+/**
+ * Overriden specializedmethodfortemperture
+ */
+double CTemperature::calculateValueInOtherUnit(const CMeasurementUnit &otherUnit) const
+{
+    if (this->getUnit()==otherUnit) return this->siBaseUnitValueToDouble();
+
+    double siValue;
+    // I always convert via SI Unit, other I would need too many conversions
+    if(otherUnit == this->_conversionSiUnit) {
+        // here I expect a conversion to SI is required and not done yet
+        if(this->_unit == CTemperatureUnit::C()) {
+            siValue = this->unitValueToDouble() + 273.15;
+        } else if(this->_unit == CTemperatureUnit::F()) {
+            siValue = (this->unitValueToDouble() + 459.67) *5.0 / 9.0;
+        } else{
+            // TODO: EXCEPTION
+        }
+    } else {
+        // here I expect the SI value is already set
+        siValue = this->siBaseUnitValueToDouble();
+    }
+
+    // from SI
+    if (otherUnit == this->_conversionSiUnit) return siValue;
+    if(otherUnit == CTemperatureUnit::C()) {
+        return siValue - 273.15;
+    } else if(this->_unit == CTemperatureUnit::F()) {
+        return (siValue * 9.0 / 5.0) - 459.67;
+    }
+    // TODO: Exception
+    return 0;
 }
 
 } // namespace BlackCore
diff --git a/src/blackmisc/pqtemperature.h b/src/blackmisc/pqtemperature.h
index f1b144eaf..32530edc1 100644
--- a/src/blackmisc/pqtemperature.h
+++ b/src/blackmisc/pqtemperature.h
@@ -30,15 +30,20 @@ public:
      */
     CTemperatureUnit(const CMeasurementUnit &otherUnit) : CMeasurementUnit(otherUnit) {}
     /*!
-     * \brief Meter m
+     * \brief Kelvin
      * \return
      */
     static CTemperatureUnit& K() { static CTemperatureUnit K("Kelvin", "K", true, true); return K;}
     /*!
-     * \brief Nautical miles NM
+     * \brief Centigrade C
      * \return
      */
     static CTemperatureUnit& C() { static CTemperatureUnit C("centigrade", "°C", false, false);return C;}
+    /*!
+     * \brief Fahrenheit F
+     * \return
+     */
+    static CTemperatureUnit& F() { static CTemperatureUnit F("Fahrenheit", "°F", false, false, 5.0/9.0);return F;}
 };
 
 /*!
@@ -47,6 +52,14 @@ public:
  */
 class CTemperature : public CPhysicalQuantity
 {
+protected:
+    /*!
+     * Specific method for temperature, a normal factor conversion is not sufficient.
+     * \param otherUnit
+     * \return
+     */
+    virtual double calculateValueInOtherUnit(const CMeasurementUnit &otherUnit) const;
+
 public:
     /*!
      * \brief Default constructor
diff --git a/tests/blackmisc/blackmisctest.h b/tests/blackmisc/blackmisctest.h
new file mode 100644
index 000000000..580552dc6
--- /dev/null
+++ b/tests/blackmisc/blackmisctest.h
@@ -0,0 +1,11 @@
+#ifndef BLACKMISCTEST_H
+#define BLACKMISCTEST_H
+
+/**
+ * @namespace BlackMiscTest
+ * Unit test for BlackMisc. Unit test do have their own namespace, so
+ * the regular namespace BlackMiscis completely free of unit tests.
+ * Add any new tests to TestMain::unitMain as shown there in the pattern.
+ */
+
+#endif // BLACKMISCTEST_H
diff --git a/tests/blackmisc/test_blackmisc.pro b/tests/blackmisc/test_blackmisc.pro
index 7a6335fa7..21f3a453a 100644
--- a/tests/blackmisc/test_blackmisc.pro
+++ b/tests/blackmisc/test_blackmisc.pro
@@ -10,7 +10,8 @@ CONFIG   -= app_bundle
 DEPENDPATH += . ../../src
 INCLUDEPATH += . ../../src
 SOURCES += main.cpp testmain.cpp testphysicalquantitiesbase.cpp
-HEADERS += testmain.h testphysicalquantitiesbase.h
+HEADERS += testmain.h testphysicalquantitiesbase.h \
+    blackmisctest.h
 
 win32-msvc* {
     PRE_TARGETDEPS +=  ../../lib/blackmisc.lib
diff --git a/tests/blackmisc/testphysicalquantitiesbase.cpp b/tests/blackmisc/testphysicalquantitiesbase.cpp
index 5d260ce91..debce3356 100644
--- a/tests/blackmisc/testphysicalquantitiesbase.cpp
+++ b/tests/blackmisc/testphysicalquantitiesbase.cpp
@@ -70,8 +70,8 @@ void TestPhysicalQuantitiesBase::speedBasics()
 {
     CSpeed s1(100, CSpeedUnit::km_h());
     CSpeed s2(1000, CSpeedUnit::ft_min());
-    QVERIFY2(s1.valueRounded(CSpeedUnit::NM_h(),0) == 54, "100km/h is 54NM/h");
-    QVERIFY2(s2.valueRounded(CSpeedUnit::m_s(),1) == 5.1, "1000ft/min is 5.1m/s");
+    QVERIFY2(s1.valueRounded(CSpeedUnit::NM_h(),0) == 54, qPrintable(QString("100km/h is not %1 NM/h").arg(s1.valueRounded(CSpeedUnit::NM_h(),0))));
+    QVERIFY2(s2.valueRounded(CSpeedUnit::m_s(),1) == 5.1, qPrintable(QString("1000ft/min is not %1 m/s").arg(s2.valueRounded(CSpeedUnit::m_s(),1))));
 }
 
 /**
@@ -94,8 +94,8 @@ void TestPhysicalQuantitiesBase::angleTests()
     CAngle a1(180, CAngleUnit::deg());
     CAngle a2(1.5 * CAngle::pi());
     a2.switchUnit(CAngleUnit::deg());
-    QVERIFY2(a2.unitValueToInteger() == 270, "1.5Pi should be 270deg");
-    QVERIFY2(a1.piFactor() == 1, "Pi should be 180deg");
+    QVERIFY2(a2.unitValueToInteger() == 270, qPrintable(QString("1.5Pi should be 270deg, not %1 deg").arg(a2.unitValueToInteger())));
+    QVERIFY2(a1.piFactor() == 1, qPrintable(QString("Pi should be 1PI,not %1").arg(a1.piFactor())));
 }
 
 /**
@@ -129,6 +129,20 @@ void TestPhysicalQuantitiesBase::pressureTests()
     QVERIFY2(p1.unitValueToDouble() == p4.unitValueToDouble(), "mbar/hPa test");
 }
 
+/**
+ * Temperature tests
+ */
+void TestPhysicalQuantitiesBase::temperatureTests()
+{
+    CTemperature t1(0, CTemperatureUnit::C()); // 0C
+    CTemperature t2(1, CTemperatureUnit::F()); // 1F
+    CTemperature t3(220.15, CTemperatureUnit::F());
+    QVERIFY2(t1.convertedSiValueToDoubleRounded() == 273.15, qPrintable(QString("0C shall be 273.15K, not %1 K").arg(t1.convertedSiValueToDoubleRounded())));
+    QVERIFY2(t2.valueRounded(CTemperatureUnit::C()) == -17.22, qPrintable(QString("1F shall be -17.22C, not %1 C").arg(t2.valueRounded(CTemperatureUnit::C()))));
+    QVERIFY2(t3.valueRounded(CTemperatureUnit::C()) == 104.53, qPrintable(QString("220.15F shall be 104.53C, not %1 C").arg(t3.valueRounded(CTemperatureUnit::C()))));
+
+}
+
 /**
  * @brief Just tesing obvious memory create / destruct flaws
  */
diff --git a/tests/blackmisc/testphysicalquantitiesbase.h b/tests/blackmisc/testphysicalquantitiesbase.h
index efb8951ec..09e6cbd65 100644
--- a/tests/blackmisc/testphysicalquantitiesbase.h
+++ b/tests/blackmisc/testphysicalquantitiesbase.h
@@ -48,6 +48,10 @@ private slots:
      * \brief Testing pressure
      */
     void pressureTests();
+    /*!
+     * \brief Testing temperature
+     */
+    void temperatureTests();
     /*!
      * \brief testing construction / destruction in memory
      */