diff --git a/ProcessLib/TH2M/PhaseTransitionModels/PhaseTransitionEvaporation.cpp b/ProcessLib/TH2M/PhaseTransitionModels/PhaseTransitionEvaporation.cpp
index 90696e99505f33dcf26c1317b18f3c7001d61de2..a8a36c7c1d9251b5884735c6c6f599f9e2e93af9 100644
--- a/ProcessLib/TH2M/PhaseTransitionModels/PhaseTransitionEvaporation.cpp
+++ b/ProcessLib/TH2M/PhaseTransitionModels/PhaseTransitionEvaporation.cpp
@@ -215,23 +215,11 @@ PhaseTransitionEvaporation::updateConstitutiveVariables(
     cv.muGR = gas_phase.property(MaterialPropertyLib::PropertyType::viscosity)
                   .template value<double>(variables, pos, t, dt);
 
-    // gas phase thermal conductivity
-    cv.lambdaGR =
-        gas_phase
-            .property(MaterialPropertyLib::PropertyType::thermal_conductivity)
-            .template value<double>(variables, pos, t, dt);
-
     // liquid phase viscosity
     cv.muLR =
         liquid_phase.property(MaterialPropertyLib::PropertyType::viscosity)
             .template value<double>(variables, pos, t, dt);
 
-    // liquid phase thermal conductivity
-    cv.lambdaLR =
-        liquid_phase
-            .property(MaterialPropertyLib::PropertyType::thermal_conductivity)
-            .template value<double>(variables, pos, t, dt);
-
     return cv;
 }
 
diff --git a/ProcessLib/TH2M/PhaseTransitionModels/PhaseTransitionModel.h b/ProcessLib/TH2M/PhaseTransitionModels/PhaseTransitionModel.h
index 1425a35dbb646809120f23b4a1c8133aa1a8abaa..a85caabece69456ab6ac53c2e47cea4a65064796 100644
--- a/ProcessLib/TH2M/PhaseTransitionModels/PhaseTransitionModel.h
+++ b/ProcessLib/TH2M/PhaseTransitionModels/PhaseTransitionModel.h
@@ -75,9 +75,6 @@ struct PhaseTransitionModelVariables
     // viscosities
     double muGR = 0.;
     double muLR = 0.;
-    // thermal conductivities
-    double lambdaGR = 0.;
-    double lambdaLR = 0.;
 
     double diffusion_coefficient_vapour = 0.;
     double diffusion_coefficient_solvate = 0.;
@@ -112,11 +109,9 @@ struct PhaseTransitionModel
 
         // check for minimum requirement definitions in media object
         std::array const required_gas_properties = {
-            MaterialPropertyLib::viscosity, MaterialPropertyLib::density,
-            MaterialPropertyLib::thermal_conductivity};
+            MaterialPropertyLib::viscosity, MaterialPropertyLib::density};
         std::array const required_liquid_properties = {
-            MaterialPropertyLib::viscosity, MaterialPropertyLib::density,
-            MaterialPropertyLib::thermal_conductivity};
+            MaterialPropertyLib::viscosity, MaterialPropertyLib::density};
 
         for (auto const& m : media)
         {
diff --git a/ProcessLib/TH2M/PhaseTransitionModels/PhaseTransitionNone.cpp b/ProcessLib/TH2M/PhaseTransitionModels/PhaseTransitionNone.cpp
index 96c34ff3f7e5c65fd4bf6a78c0c718a1ce19315c..0aa6b89effe033b8d1c93c000f70a259d5595ef6 100644
--- a/ProcessLib/TH2M/PhaseTransitionModels/PhaseTransitionNone.cpp
+++ b/ProcessLib/TH2M/PhaseTransitionModels/PhaseTransitionNone.cpp
@@ -69,10 +69,6 @@ PhaseTransitionModelVariables PhaseTransitionNone::updateConstitutiveVariables(
                    .template value<double>(variables, pos, t, dt);
     cv.muGR = gas_phase.property(MaterialPropertyLib::PropertyType::viscosity)
                   .template value<double>(variables, pos, t, dt);
-    cv.lambdaGR =
-        gas_phase
-            .property(MaterialPropertyLib::PropertyType::thermal_conductivity)
-            .template value<double>(variables, pos, t, dt);
 
     cv.rhoCGR = cv.rhoGR;
 
@@ -86,11 +82,6 @@ PhaseTransitionModelVariables PhaseTransitionNone::updateConstitutiveVariables(
         liquid_phase.property(MaterialPropertyLib::PropertyType::viscosity)
             .template value<double>(variables, pos, t, dt);
 
-    cv.lambdaLR =
-        liquid_phase
-            .property(MaterialPropertyLib::PropertyType::thermal_conductivity)
-            .template value<double>(variables, pos, t, dt);
-
     cv.rhoWLR = cv.rhoLR;
 
     // specific heat capacities
diff --git a/ProcessLib/TH2M/TH2MFEM-impl.h b/ProcessLib/TH2M/TH2MFEM-impl.h
index 7b09d00a020d6826cd6c36796003814e6a316f93..820e62c306749113fbc945f306b4cc1ac84e026d 100644
--- a/ProcessLib/TH2M/TH2MFEM-impl.h
+++ b/ProcessLib/TH2M/TH2MFEM-impl.h
@@ -268,10 +268,6 @@ TH2MLocalAssembler<ShapeFunctionDisplacement, ShapeFunctionPressure,
                 .template value<double>(
                     vars, pos, t, std::numeric_limits<double>::quiet_NaN());
 
-        auto const lambdaSR = MPL::formEigenTensor<DisplacementDim>(
-            solid_phase.property(MPL::PropertyType::thermal_conductivity)
-                .value(vars, pos, t, dt));
-
         double const T0 = _process_data.reference_temperature(t, pos)[0];
         double const delta_T(T - T0);
         ip_data.thermal_volume_strain = ip_data.beta_T_SR * delta_T;
@@ -294,6 +290,7 @@ TH2MLocalAssembler<ShapeFunctionDisplacement, ShapeFunctionPressure,
 
         // porosity
         ip_data.phi = 1. - phi_S;
+        vars[static_cast<int>(MPL::Variable::porosity)] = ip_data.phi;
 
         // solid phase density
 #ifdef NON_CONSTANT_SOLID_PHASE_VOLUME_FRACTION
@@ -313,25 +310,12 @@ TH2MLocalAssembler<ShapeFunctionDisplacement, ShapeFunctionPressure,
         auto const phi_L = ip_data.s_L * ip_data.phi;
         auto const phi_G = (1. - ip_data.s_L) * ip_data.phi;
 
-        // TODO (Grunwald): individual volume fractions can be stored in a
-        // container of type MPL::Composition (a.k.a. std::vector<double>) which
-        // can be stored in the variable array for access in MPL properties
-        // ---
-        // MaterialPropertyLib::Composition volume_fraction{phi_G, phi_L,
-        // phi_S};
-        // vars[static_cast<int>(MPL::Variable::volume_fraction)] =
-        //     volume_fraction;
-        // ---
-        // TODO (Grunwald) replace effective thermal conductivity by a more
-        // sophisticated law by allowing the law to be chosen in the project
-        // file as medium property, e.g.
-        // lambda = medium.property(MPL::PropertyType::thermal_conductivity)..
-        // where volume fraction is stored in the variable array
-
-        auto const lambdaGR = MPL::formEigenTensor<DisplacementDim>(c.lambdaGR);
-        auto const lambdaLR = MPL::formEigenTensor<DisplacementDim>(c.lambdaLR);
-
-        ip_data.lambda = phi_G * lambdaGR + phi_L * lambdaLR + phi_S * lambdaSR;
+        // thermal conductivity
+        ip_data.lambda = MaterialPropertyLib::formEigenTensor<DisplacementDim>(
+            medium
+                .property(
+                    MaterialPropertyLib::PropertyType::thermal_conductivity)
+                .value(vars, pos, t, dt));
 
         auto const cpS =
             solid_phase.property(MPL::PropertyType::specific_heat_capacity)
@@ -430,15 +414,50 @@ TH2MLocalAssembler<ShapeFunctionDisplacement, ShapeFunctionPressure,
         // dphi_L_dp_GR = ds_L_dp_GR * ip_data.phi = 0;
         double const dphi_L_dp_cap = ip_cv.ds_L_dp_cap * ip_data.phi;
 
-        auto const dlambda_GR_dT = MPL::formEigenTensor<DisplacementDim>(
-            gas_phase[MPL::PropertyType::thermal_conductivity].dValue(
-                vars, MPL::Variable::temperature, pos, t, dt));
-        auto const dlambda_LR_dT = MPL::formEigenTensor<DisplacementDim>(
-            liquid_phase[MPL::PropertyType::thermal_conductivity].dValue(
-                vars, MPL::Variable::temperature, pos, t, dt));
-        auto const dlambda_SR_dT = MPL::formEigenTensor<DisplacementDim>(
-            solid_phase[MPL::PropertyType::thermal_conductivity].dValue(
-                vars, MPL::Variable::temperature, pos, t, dt));
+        auto const lambdaGR =
+            gas_phase.hasProperty(MPL::PropertyType::thermal_conductivity)
+                ? MPL::formEigenTensor<DisplacementDim>(
+                      gas_phase
+                          .property(MPL::PropertyType::thermal_conductivity)
+                          .value(vars, pos, t, dt))
+                : MPL::formEigenTensor<DisplacementDim>(0.);
+
+        auto const dlambda_GR_dT =
+            gas_phase.hasProperty(MPL::PropertyType::thermal_conductivity)
+                ? MPL::formEigenTensor<DisplacementDim>(
+                      gas_phase[MPL::PropertyType::thermal_conductivity].dValue(
+                          vars, MPL::Variable::temperature, pos, t, dt))
+                : MPL::formEigenTensor<DisplacementDim>(0.);
+
+        auto const lambdaLR =
+            liquid_phase.hasProperty(MPL::PropertyType::thermal_conductivity)
+                ? MPL::formEigenTensor<DisplacementDim>(
+                      liquid_phase
+                          .property(MPL::PropertyType::thermal_conductivity)
+                          .value(vars, pos, t, dt))
+                : MPL::formEigenTensor<DisplacementDim>(0.);
+
+        auto const dlambda_LR_dT =
+            liquid_phase.hasProperty(MPL::PropertyType::thermal_conductivity)
+                ? MPL::formEigenTensor<DisplacementDim>(
+                      liquid_phase[MPL::PropertyType::thermal_conductivity]
+                          .dValue(vars, MPL::Variable::temperature, pos, t, dt))
+                : MPL::formEigenTensor<DisplacementDim>(0.);
+
+        auto const lambdaSR =
+            solid_phase.hasProperty(MPL::PropertyType::thermal_conductivity)
+                ? MPL::formEigenTensor<DisplacementDim>(
+                      solid_phase
+                          .property(MPL::PropertyType::thermal_conductivity)
+                          .value(vars, pos, t, dt))
+                : MPL::formEigenTensor<DisplacementDim>(0.);
+
+        auto const dlambda_SR_dT =
+            solid_phase.hasProperty(MPL::PropertyType::thermal_conductivity)
+                ? MPL::formEigenTensor<DisplacementDim>(
+                      solid_phase[MPL::PropertyType::thermal_conductivity]
+                          .dValue(vars, MPL::Variable::temperature, pos, t, dt))
+                : MPL::formEigenTensor<DisplacementDim>(0.);
 
         ip_cv.dlambda_dp_cap =
             dphi_G_dp_cap * lambdaGR + dphi_L_dp_cap * lambdaLR;
diff --git a/Tests/Data/TH2M/H2/mcWorther/mcWorther_h2.prj b/Tests/Data/TH2M/H2/mcWorther/mcWorther_h2.prj
index 952625ab724c180610680cadc4f448cfd85462af..7475fd37e9f2a70f48a1842bd443df360d14be8c 100644
--- a/Tests/Data/TH2M/H2/mcWorther/mcWorther_h2.prj
+++ b/Tests/Data/TH2M/H2/mcWorther/mcWorther_h2.prj
@@ -186,6 +186,10 @@
                     <type>Constant</type>
                     <value>0.15</value>
                 </property>
+                <property>
+                    <name>thermal_conductivity</name>
+                    <type>EffectiveThermalConductivityPorosityMixing</type>
+                </property>
             </properties>
         </medium>
     </media>
diff --git a/Tests/Data/TH2M/H2M/Liakopoulos/liakopoulos_TH2M.prj b/Tests/Data/TH2M/H2M/Liakopoulos/liakopoulos_TH2M.prj
index 9b53b9bab8eb4b3fa3799991ca0b0503149179c6..73d38a412e5396c8300158e8b6b6edc14b1974f1 100644
--- a/Tests/Data/TH2M/H2M/Liakopoulos/liakopoulos_TH2M.prj
+++ b/Tests/Data/TH2M/H2M/Liakopoulos/liakopoulos_TH2M.prj
@@ -180,6 +180,10 @@
                     <type>Constant</type>
                     <value>0.2975</value>
                 </property>
+                <property>
+                    <name>thermal_conductivity</name>
+                    <type>EffectiveThermalConductivityPorosityMixing</type>
+                </property>
             </properties>
         </medium>
     </media>
diff --git a/Tests/Data/TH2M/HM/Confined_Compression/HM_confined_compression_gas.prj b/Tests/Data/TH2M/HM/Confined_Compression/HM_confined_compression_gas.prj
index 201b048ee2c8ef6e718d3ae7ff909f0cee945d5a..f125f26c2c466cd016991226a4dafd3d27bb33ee 100644
--- a/Tests/Data/TH2M/HM/Confined_Compression/HM_confined_compression_gas.prj
+++ b/Tests/Data/TH2M/HM/Confined_Compression/HM_confined_compression_gas.prj
@@ -192,6 +192,11 @@
                     <value>0.8</value>
                 </property>
 
+                <property>
+                    <name>thermal_conductivity</name>
+                    <type>EffectiveThermalConductivityPorosityMixing</type>
+                </property>
+
             </properties>
         </medium>
     </media>
diff --git a/Tests/Data/TH2M/HM/Confined_Compression/HM_confined_compression_liquid.prj b/Tests/Data/TH2M/HM/Confined_Compression/HM_confined_compression_liquid.prj
index 4ee3208182415882134173140786508161d65125..e136c915d4d11966c9c5d0b990f74ff0aa2739f8 100644
--- a/Tests/Data/TH2M/HM/Confined_Compression/HM_confined_compression_liquid.prj
+++ b/Tests/Data/TH2M/HM/Confined_Compression/HM_confined_compression_liquid.prj
@@ -198,6 +198,11 @@
                     <value>0.8</value>
                 </property>
 
+                <property>
+                    <name>thermal_conductivity</name>
+                    <type>EffectiveThermalConductivityPorosityMixing</type>
+                </property>
+
             </properties>
         </medium>
     </media>
diff --git a/Tests/Data/TH2M/HM/flow_fully_saturated.prj b/Tests/Data/TH2M/HM/flow_fully_saturated.prj
index febbcee5b61f5bc9ebe02d277830032828fdb19b..b27a12398065bee3af760361e0e6ac1489462411 100644
--- a/Tests/Data/TH2M/HM/flow_fully_saturated.prj
+++ b/Tests/Data/TH2M/HM/flow_fully_saturated.prj
@@ -195,6 +195,10 @@
                     <type>Constant</type>
                     <value>1</value>
                 </property>
+                <property>
+                    <name>thermal_conductivity</name>
+                    <type>EffectiveThermalConductivityPorosityMixing</type>
+                </property>
             </properties>
         </medium>
     </media>
diff --git a/Tests/Data/TH2M/HM/flow_fully_saturated_gas.prj b/Tests/Data/TH2M/HM/flow_fully_saturated_gas.prj
index 5a9f15b783e59a8ed8f83eec30c00b9883f00bd7..490a35078d708e7946aca3742b2401a84b70fb50 100644
--- a/Tests/Data/TH2M/HM/flow_fully_saturated_gas.prj
+++ b/Tests/Data/TH2M/HM/flow_fully_saturated_gas.prj
@@ -195,6 +195,10 @@
                     <type>Constant</type>
                     <value>1</value>
                 </property>
+                <property>
+                    <name>thermal_conductivity</name>
+                    <type>EffectiveThermalConductivityPorosityMixing</type>
+                </property>
             </properties>
         </medium>
     </media>
diff --git a/Tests/Data/TH2M/M/M_2d_neumann/M_2d_neumann.prj b/Tests/Data/TH2M/M/M_2d_neumann/M_2d_neumann.prj
index b108243451b557a7809da07639ba87c88a01f8ac..d88f45d41862e8569653a316c7fe1317ffa5f082 100644
--- a/Tests/Data/TH2M/M/M_2d_neumann/M_2d_neumann.prj
+++ b/Tests/Data/TH2M/M/M_2d_neumann/M_2d_neumann.prj
@@ -189,6 +189,11 @@
                     <value>0.3</value>
                 </property>
 
+                <property>
+                    <name>thermal_conductivity</name>
+                    <type>EffectiveThermalConductivityPorosityMixing</type>
+                </property>
+
             </properties>
         </medium>
     </media>
diff --git a/Tests/Data/TH2M/StrainDependentPermeability/Strain_Dependent_Permeability_Test.prj b/Tests/Data/TH2M/StrainDependentPermeability/Strain_Dependent_Permeability_Test.prj
index 15098a4afd1f7a6bd7f33548f2a505653caa67ae..1b3109aaddf530e61bdaf14466db8deaf2fe3776 100644
--- a/Tests/Data/TH2M/StrainDependentPermeability/Strain_Dependent_Permeability_Test.prj
+++ b/Tests/Data/TH2M/StrainDependentPermeability/Strain_Dependent_Permeability_Test.prj
@@ -194,6 +194,10 @@
                     <type>Constant</type>
                     <value>0.2</value>
                 </property>
+                <property>
+                    <name>thermal_conductivity</name>
+                    <type>EffectiveThermalConductivityPorosityMixing</type>
+                </property>
             </properties>
         </medium>
     </media>
diff --git a/Tests/Data/TH2M/T/T_1d_dirichlet/T_1d_dirichlet.prj b/Tests/Data/TH2M/T/T_1d_dirichlet/T_1d_dirichlet.prj
index f81e1ed03299aec4288542f9d6f3b9545513ec8c..769c0d94b3af7b3cce9dc7ad2aa835a444e3c8b0 100644
--- a/Tests/Data/TH2M/T/T_1d_dirichlet/T_1d_dirichlet.prj
+++ b/Tests/Data/TH2M/T/T_1d_dirichlet/T_1d_dirichlet.prj
@@ -178,6 +178,11 @@
                     <value>0.3</value>
                 </property>
 
+                <property>
+                    <name>thermal_conductivity</name>
+                    <type>EffectiveThermalConductivityPorosityMixing</type>
+                </property>
+
             </properties>
         </medium>
     </media>
diff --git a/Tests/Data/TH2M/TH/idealGasLaw/compression_gas.prj b/Tests/Data/TH2M/TH/idealGasLaw/compression_gas.prj
index fdacedca14631f9e8ad9c6c07553e198b134b6b8..44a8e712faab31eff44062746fb18b36904f4d49 100644
--- a/Tests/Data/TH2M/TH/idealGasLaw/compression_gas.prj
+++ b/Tests/Data/TH2M/TH/idealGasLaw/compression_gas.prj
@@ -199,6 +199,10 @@
                     <type>Constant</type>
                     <value>1.0</value>
                 </property>
+                <property>
+                    <name>thermal_conductivity</name>
+                    <type>EffectiveThermalConductivityPorosityMixing</type>
+                </property>
             </properties>
         </medium>
     </media>
diff --git a/Tests/Data/TH2M/TH2/heatpipe_radial/heatpipe_radial.prj b/Tests/Data/TH2M/TH2/heatpipe_radial/heatpipe_radial.prj
index b90f15da1d5bff2920b68b6c59845fecc07b16d8..ef7c506e9fcc23f23fb2be06c9899a85bb9a3a3d 100644
--- a/Tests/Data/TH2M/TH2/heatpipe_radial/heatpipe_radial.prj
+++ b/Tests/Data/TH2M/TH2/heatpipe_radial/heatpipe_radial.prj
@@ -266,6 +266,11 @@
                     <value>0.4</value>
                 </property>
 
+                <property>
+                    <name>thermal_conductivity</name>
+                    <type>EffectiveThermalConductivityPorosityMixing</type>
+                </property>
+
             </properties>
         </medium>
     </media>
diff --git a/Tests/Data/TH2M/TH2/heatpipe_slab/heatpipe_slab.prj b/Tests/Data/TH2M/TH2/heatpipe_slab/heatpipe_slab.prj
index cb50d2660762f3c6d010f14aa1b4c1b5588bfccb..2bbf114ca83bec48f5cbff80a6cec9bc03cb7f94 100644
--- a/Tests/Data/TH2M/TH2/heatpipe_slab/heatpipe_slab.prj
+++ b/Tests/Data/TH2M/TH2/heatpipe_slab/heatpipe_slab.prj
@@ -270,6 +270,11 @@
                     <value>0.4</value>
                 </property>
 
+                <property>
+                    <name>thermal_conductivity</name>
+                    <type>EffectiveThermalConductivityPorosityMixing</type>
+                </property>
+
             </properties>
         </medium>
     </media>
diff --git a/Tests/Data/TH2M/THM/Confined_Compression/THM_confined_compression_gas.prj b/Tests/Data/TH2M/THM/Confined_Compression/THM_confined_compression_gas.prj
index 5f3db9976e51f3b0b33b6c0a4ab1f54f46e2832f..2bf102adfc87c256a900a04d54de6d9a25f905d1 100644
--- a/Tests/Data/TH2M/THM/Confined_Compression/THM_confined_compression_gas.prj
+++ b/Tests/Data/TH2M/THM/Confined_Compression/THM_confined_compression_gas.prj
@@ -192,6 +192,11 @@
                     <value>1</value>
                 </property>
 
+                <property>
+                    <name>thermal_conductivity</name>
+                    <type>EffectiveThermalConductivityPorosityMixing</type>
+                </property>
+
                 <property>
                     <name>porosity</name>
                     <type>Constant</type>
diff --git a/Tests/Data/TH2M/THM/Confined_Compression/THM_confined_compression_liquid.prj b/Tests/Data/TH2M/THM/Confined_Compression/THM_confined_compression_liquid.prj
index 0745ef994f90e2b97428ada82d9bfa787c531f07..507d0d2fac9a0d341030846ee68a846e401cf14b 100644
--- a/Tests/Data/TH2M/THM/Confined_Compression/THM_confined_compression_liquid.prj
+++ b/Tests/Data/TH2M/THM/Confined_Compression/THM_confined_compression_liquid.prj
@@ -198,6 +198,11 @@
                     <value>0.8</value>
                 </property>
 
+                <property>
+                    <name>thermal_conductivity</name>
+                    <type>EffectiveThermalConductivityPorosityMixing</type>
+                </property>
+
             </properties>
         </medium>
     </media>
diff --git a/Tests/Data/TH2M/THM/slab/THM_1d_dirichlet.prj b/Tests/Data/TH2M/THM/slab/THM_1d_dirichlet.prj
index ca3ebf925ae08be12462a8f8dc99fa376be24949..f13fb0fffb91eba367bce00352a4c0f014395806 100644
--- a/Tests/Data/TH2M/THM/slab/THM_1d_dirichlet.prj
+++ b/Tests/Data/TH2M/THM/slab/THM_1d_dirichlet.prj
@@ -184,6 +184,11 @@
                     <value>0.16</value>
                 </property>
 
+                <property>
+                    <name>thermal_conductivity</name>
+                    <type>EffectiveThermalConductivityPorosityMixing</type>
+                </property>
+
             </properties>
         </medium>
     </media>
diff --git a/Tests/Data/TH2M/THM/sphere/point_heatsource.prj b/Tests/Data/TH2M/THM/sphere/point_heatsource.prj
index 0fecdaa9bf1a6ff976420971dc7f0994aaeed6ca..45c938fd7a3edffbb3100fac10bbf77931ed36b4 100644
--- a/Tests/Data/TH2M/THM/sphere/point_heatsource.prj
+++ b/Tests/Data/TH2M/THM/sphere/point_heatsource.prj
@@ -185,6 +185,11 @@
                     <value>0.16</value>
                 </property>
 
+                <property>
+                    <name>thermal_conductivity</name>
+                    <type>EffectiveThermalConductivityPorosityMixing</type>
+                </property>
+
             </properties>
         </medium>
     </media>
diff --git a/Tests/Data/TH2M/TH_unsaturated/heatpipe_radial_static_gas/heatpipe_radial_static_gas.prj b/Tests/Data/TH2M/TH_unsaturated/heatpipe_radial_static_gas/heatpipe_radial_static_gas.prj
index 54f1769f896c4a989687b5872710a4ce179137b3..bf56bb6e756813ba33aee5355d511fa179cadb38 100644
--- a/Tests/Data/TH2M/TH_unsaturated/heatpipe_radial_static_gas/heatpipe_radial_static_gas.prj
+++ b/Tests/Data/TH2M/TH_unsaturated/heatpipe_radial_static_gas/heatpipe_radial_static_gas.prj
@@ -267,6 +267,11 @@
                     <value>0.4</value>
                 </property>
 
+                <property>
+                    <name>thermal_conductivity</name>
+                    <type>EffectiveThermalConductivityPorosityMixing</type>
+                </property>
+
             </properties>
         </medium>
     </media>
diff --git a/Tests/Data/TH2M/TH_unsaturated/heatpipe_slab_static_gas/heatpipe_slab_static_gas.prj b/Tests/Data/TH2M/TH_unsaturated/heatpipe_slab_static_gas/heatpipe_slab_static_gas.prj
index 27fd3a8b96c485351733b8fac404982549168515..d579c6595eb8d6064a5f21b2c526de8798974d6b 100644
--- a/Tests/Data/TH2M/TH_unsaturated/heatpipe_slab_static_gas/heatpipe_slab_static_gas.prj
+++ b/Tests/Data/TH2M/TH_unsaturated/heatpipe_slab_static_gas/heatpipe_slab_static_gas.prj
@@ -270,6 +270,11 @@
                     <value>0.4</value>
                 </property>
 
+                <property>
+                    <name>thermal_conductivity</name>
+                    <type>EffectiveThermalConductivityPorosityMixing</type>
+                </property>
+
             </properties>
         </medium>
     </media>
diff --git a/Tests/ProcessLib/TH2M/TestTH2MPhaseTransitionEvaporation.cpp b/Tests/ProcessLib/TH2M/TestTH2MPhaseTransitionEvaporation.cpp
index caf98f9296746da4d3aac0992b553b3680d91514..6d95e121ea482dedf0050aaa62eeedfb510de299 100644
--- a/Tests/ProcessLib/TH2M/TestTH2MPhaseTransitionEvaporation.cpp
+++ b/Tests/ProcessLib/TH2M/TestTH2MPhaseTransitionEvaporation.cpp
@@ -36,8 +36,6 @@ TEST(ProcessLib, TH2MPhaseTransitionEvaporation)
 
     auto const diffusion_coefficient_vapour = 2.6e-6;
 
-    auto const thermal_conductivity_air = 0.2;
-    auto const thermal_conductivity_water = 0.6;
     auto const viscosity_air = 1.e-5;
     auto const viscosity_water = 1.e-3;
 
@@ -80,8 +78,6 @@ TEST(ProcessLib, TH2MPhaseTransitionEvaporation)
     m << "<properties>\n";
     m << Tests::makeConstantPropertyElement("viscosity", viscosity_air);
     m << Tests::makeConstantPropertyElement("density", density_air);
-    m << Tests::makeConstantPropertyElement("thermal_conductivity",
-                                            thermal_conductivity_air);
     m << "</properties>\n";
     m << "</phase>\n";
 
@@ -93,8 +89,6 @@ TEST(ProcessLib, TH2MPhaseTransitionEvaporation)
     m << "<properties>\n";
     m << Tests::makeConstantPropertyElement("viscosity", viscosity_water);
     m << Tests::makeConstantPropertyElement("density", density_water);
-    m << Tests::makeConstantPropertyElement("thermal_conductivity",
-                                            thermal_conductivity_water);
     m << Tests::makeConstantPropertyElement("specific_heat_capacity",
                                             specific_heat_capacity_water);
     m << "</properties>\n";
@@ -149,9 +143,7 @@ TEST(ProcessLib, TH2MPhaseTransitionEvaporation)
     double const uG = hG - pGR / density_air;
     double const uL = hL;
     double const muGR = viscosity_air;
-    double const lambdaGR = thermal_conductivity_air;
     double const muLR = viscosity_water;
-    double const lambdaLR = thermal_conductivity_water;
 
     ASSERT_NEAR(density_air, cv.rhoGR, 1.0e-10);
     ASSERT_NEAR(density_water, cv.rhoLR, 1.0e-10);
@@ -172,7 +164,5 @@ TEST(ProcessLib, TH2MPhaseTransitionEvaporation)
     ASSERT_NEAR(diffusion_coefficient_vapour, cv.diffusion_coefficient_vapour,
                 1.0e-10);
     ASSERT_NEAR(muGR, cv.muGR, 1.0e-10);
-    ASSERT_NEAR(lambdaGR, cv.lambdaGR, 1.0e-10);
     ASSERT_NEAR(muLR, cv.muLR, 1.0e-10);
-    ASSERT_NEAR(lambdaLR, cv.lambdaLR, 1.0e-10);
 }
diff --git a/Tests/ProcessLib/TH2M/TestTH2MPhaseTransitionNone.cpp b/Tests/ProcessLib/TH2M/TestTH2MPhaseTransitionNone.cpp
index 7320ddeb74b9c50038fce4bd08d838ab8b6b3a66..15e92ba913999384732116be0a69aa92b9c0dc32 100644
--- a/Tests/ProcessLib/TH2M/TestTH2MPhaseTransitionNone.cpp
+++ b/Tests/ProcessLib/TH2M/TestTH2MPhaseTransitionNone.cpp
@@ -32,8 +32,6 @@ TEST(ProcessLib, TH2MPhaseTransitionNone)
 
     auto const diffusion_coefficient_vapour = 0.0;
 
-    auto const thermal_conductivity_air = 0.2;
-    auto const thermal_conductivity_water = 0.6;
     auto const viscosity_air = 1.e-5;
     auto const viscosity_water = 1.e-3;
 
@@ -48,8 +46,6 @@ TEST(ProcessLib, TH2MPhaseTransitionNone)
     m << "<properties>\n";
     m << Tests::makeConstantPropertyElement("viscosity", viscosity_air);
     m << Tests::makeConstantPropertyElement("density", density_air);
-    m << Tests::makeConstantPropertyElement("thermal_conductivity",
-                                            thermal_conductivity_air);
     m << Tests::makeConstantPropertyElement("specific_heat_capacity",
                                             specific_heat_capacity_air);
     m << Tests::makeConstantPropertyElement("molar_mass", molar_mass_air);
@@ -65,8 +61,6 @@ TEST(ProcessLib, TH2MPhaseTransitionNone)
     m << "<properties>\n";
     m << Tests::makeConstantPropertyElement("viscosity", viscosity_water);
     m << Tests::makeConstantPropertyElement("density", density_water);
-    m << Tests::makeConstantPropertyElement("thermal_conductivity",
-                                            thermal_conductivity_water);
     m << Tests::makeConstantPropertyElement("specific_heat_capacity",
                                             specific_heat_capacity_water);
     m << "</properties>\n";
@@ -119,9 +113,7 @@ TEST(ProcessLib, TH2MPhaseTransitionNone)
     double const uG = hG - pGR / density_air;
     double const uL = hL;
     double const muGR = viscosity_air;
-    double const lambdaGR = thermal_conductivity_air;
     double const muLR = viscosity_water;
-    double const lambdaLR = thermal_conductivity_water;
 
     ASSERT_NEAR(density_air, cv.rhoGR, 1.0e-10);
     ASSERT_NEAR(density_water, cv.rhoLR, 1.0e-10);
@@ -144,7 +136,5 @@ TEST(ProcessLib, TH2MPhaseTransitionNone)
     ASSERT_NEAR(diffusion_coefficient_vapour, cv.diffusion_coefficient_vapour,
                 1.0e-10);
     ASSERT_NEAR(muGR, cv.muGR, 1.0e-10);
-    ASSERT_NEAR(lambdaGR, cv.lambdaGR, 1.0e-10);
     ASSERT_NEAR(muLR, cv.muLR, 1.0e-10);
-    ASSERT_NEAR(lambdaLR, cv.lambdaLR, 1.0e-10);
 }