diff --git a/.github/inactive_workflows/fesom2_icepack.yml b/.github/inactive_workflows/fesom2_icepack.yml
index 9057057b1..9e295d101 100644
--- a/.github/inactive_workflows/fesom2_icepack.yml
+++ b/.github/inactive_workflows/fesom2_icepack.yml
@@ -21,14 +21,13 @@ jobs:
 
     - name: prepeare FESOM2_icepack
       run: |
-        sed -i 's/USE_ICEPACK OFF/USE_ICEPACK ON/g' CMakeLists.txt
         cd ./src/icepack_drivers/
         ./download_icepack.sh
         cd ../../
     
     - name: Compile model
       run: |
-        bash -l configure.sh ubuntu
+        bash -l configure.sh ubuntu -DUSE_ICEPACK=ON
     
     - name: Create global test run with ICEPACK
       run: |
diff --git a/.github/workflows/fesom2.1.yml b/.github/workflows/fesom2.1.yml
index 069a5a669..6c766ae43 100644
--- a/.github/workflows/fesom2.1.yml
+++ b/.github/workflows/fesom2.1.yml
@@ -18,18 +18,43 @@ jobs:
     steps:
     # NK: this changes working directory to fesom2
     - uses: actions/checkout@v2
-    
+
+    - name: Git safe directory
+      run: |
+        git config --global --add safe.directory ${PWD}
+
     - name: Compile model (binary)
       run: |
-        bash -l configure.sh ubuntu
+        ./configure.sh ubuntu
+
+    - name: Compile model (ifs_interface)
+      run: |
+        export BUILD_DIR=$PWD/build.ifs_interface
+        ./configure.sh ubuntu -DENABLE_IFS_INTERFACE=ON -DCMAKE_INSTALL_PREFIX=$PWD/install.ifs_interface
+
+    - name: Test downstream from current install-dir
+      run: |
+        rm -rf test_downstream/build
+        export fesom_ROOT=${PWD}
+        cmake -S test_downstream -B test_downstream/build -DASSERT_HAVE_IFS_INTERFACE=OFF -DASSERT_FESOM_DIR=${fesom_ROOT}
+        cmake --build test_downstream/build
+        test_downstream/build/main
 
-    - name: Compile model (library)
+    - name: Test downstream from ifs_interface build-dir
       run: |
-        bash ./test/ifs_interface/configure_lib.sh -l
+        export fesom_ROOT=$PWD/build.ifs_interface
+        rm -rf test_downstream/build
+        cmake -S test_downstream -B test_downstream/build -DASSERT_HAVE_IFS_INTERFACE=ON -DASSERT_FESOM_DIR=${fesom_ROOT}
+        cmake --build test_downstream/build
+        test_downstream/build/main
 
-    - name: Library exists
+    - name: Test downstream from ifs_interface install-dir
       run: |
-        bash ./test/ifs_interface/check_exist.sh
+        export fesom_ROOT=$PWD/install.ifs_interface
+        rm -rf test_downstream/build
+        cmake -S test_downstream -B test_downstream/build -DASSERT_HAVE_IFS_INTERFACE=ON -DASSERT_FESOM_DIR=${fesom_ROOT}
+        cmake --build test_downstream/build
+        test_downstream/build/main
 
     - name: Create global test run
       run: |
diff --git a/.github/workflows/fesom2_openmp.yml b/.github/workflows/fesom2_openmp.yml
index fd1e8cafa..f87229749 100644
--- a/.github/workflows/fesom2_openmp.yml
+++ b/.github/workflows/fesom2_openmp.yml
@@ -19,15 +19,13 @@ jobs:
     # NK: this changes working directory to fesom2
     - uses: actions/checkout@v2
 
-    - name: switch OpenMP ON
+    - name: Git safe directory
       run: |
-        cd ./src/
-        sed -i 's/with OpenMP\" OFF/with OpenMP\" ON/g' CMakeLists.txt
-        cd ../
+        git config --global --add safe.directory ${PWD}
 
     - name: Compile model
       run: |
-        bash -l configure.sh ubuntu
+        bash -l configure.sh ubuntu -DENABLE_OPENMP=ON
     
     - name: Create global test run with 4 OpenMP threads
       run: |
diff --git a/.gitignore b/.gitignore
index 7e9b58fcd..2a3bd44e4 100644
--- a/.gitignore
+++ b/.gitignore
@@ -9,6 +9,7 @@
 src/icepack_drivers/Icepack
 lib/*.a
 lib/*.so
+lib64/*
 /work_*
 Makefile.in
 mesh_part/build
diff --git a/configure.sh b/configure.sh
index 86d7eb02a..482461832 100755
--- a/configure.sh
+++ b/configure.sh
@@ -1,11 +1,16 @@
 #!/usr/bin/env bash
 
 set -e
+HERE=$PWD
+
+SOURCE_DIR="$( cd $( dirname "${BASH_SOURCE[0]}" ) && pwd -P )"
+BUILD_DIR=${BUILD_DIR:-build}
 
 source env.sh # source this from your run script too
-mkdir build || true # make sure not to commit this to svn or git
-cd build
-cmake .. $@ -DCMAKE_BUILD_TYPE=Debug # not required when re-compiling
-                                     # additional cmake arguments can be passed to configure.sh
-				     # this also includes fesom specific options in CMakeLists, can be used as -DFESOM_COUPLED=ON
+mkdir -p ${BUILD_DIR}
+cd ${BUILD_DIR}
+cmake .. -DCMAKE_INSTALL_PREFIX=$HERE -DCMAKE_BUILD_TYPE=Debug ${CMAKE_ARGS} $@
+  # not required when re-compiling
+  # additional cmake arguments can be passed to configure.sh
+  # this also includes fesom specific options in CMakeLists, can be used as -DFESOM_COUPLED=ON
 make install -j`nproc --all`
diff --git a/env.sh b/env.sh
index a073ad208..93ce4294e 100755
--- a/env.sh
+++ b/env.sh
@@ -37,7 +37,11 @@ else
 fi
 
 
-if [[ $LOGINHOST =~ ^m[A-Za-z0-9]+\.hpc\.dkrz\.de$ ]]; then
+if [[ "$LOGINHOST" == "local" ]]; then
+   echo "Using local environment $BEING_EXECUTED"
+   [ $BEING_EXECUTED = true ] && exit
+   return 0 # if we are being sourced, return from this script here
+elif [[ $LOGINHOST =~ ^m[A-Za-z0-9]+\.hpc\.dkrz\.de$ ]]; then
    STRATEGY="mistral.dkrz.de"
 elif [[ $LOGINHOST =~ ^levante ]] || [[ $LOGINHOST =~ ^l[:alnum:]+\.lvt\.dkrz\.de$ ]]; then 
    STRATEGY="levante.dkrz.de"
@@ -85,7 +89,6 @@ else
    return # if we are being sourced, return from this script here
 fi
 
-
 if [ $BEING_EXECUTED = true ]; then
    # file is being executed, why is this here?
    echo $DIR/env/$STRATEGY
diff --git a/env/ubuntu/shell b/env/ubuntu/shell
index 29fc59dbc..c391d6e04 100644
--- a/env/ubuntu/shell
+++ b/env/ubuntu/shell
@@ -1,5 +1,6 @@
 export FC=mpifort CC=mpicc CXX=mpicxx
-export BLAS_LIBRARIES=/usr/lib/x86_64-linux-gnu/blas/
-export UBUNTU_BLAS_LIBRARY="libblas.a"
-
+if [[ -f "/usr/lib/x86_64-linux-gnu/liblapack.so.3" ]]; then
+  export LAPACK_LIBRARIES=/usr/lib/x86_64-linux-gnu/liblapack.so.3
+  export CMAKE_ARGS=-DLAPACK_LIBRARIES=${LAPACK_LIBRARIES}
+fi
 
diff --git a/test/ifs_interface/check_exist.sh b/test/ifs_interface/check_exist.sh
index e89a674e1..7d80ec346 100755
--- a/test/ifs_interface/check_exist.sh
+++ b/test/ifs_interface/check_exist.sh
@@ -2,11 +2,21 @@
 
 set -e
 
-FILE=./lib/libfesom.a
-if [ -f "$FILE" ]; then
+LIB_NAMES=("libfesom.a" "libfesom.so" "libfesom.dylib")
+
+libfesom_exists=false
+for LIB_NAME in ${LIB_NAMES[@]}; do
+  FILE=./lib/${LIB_NAME}
+  if [ -f "$FILE" ]; then
     echo "$FILE compiled and linked."
+    libfesom_exists=true
+  fi
+done
+
+if ${libfesom_exists}; then
     exit 0
 else
-    echo "$FILE does not exist."
+    echo "libfesom not found"
     exit 1
 fi
+
diff --git a/test/ifs_interface/configure.sh b/test/ifs_interface/configure.sh
new file mode 100755
index 000000000..40f268ead
--- /dev/null
+++ b/test/ifs_interface/configure.sh
@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+
+# custom build script in use at ECMWF
+
+set -e
+
+#cd ../../
+source env.sh # source this from your run script too
+
+HERE=$PWD
+echo "+ mkdir -p build"
+mkdir -p build
+echo "+ cd build"
+cd build
+echo + cmake .. -DCMAKE_INSTALL_PREFIX=$HERE -DBUILD_SHARED_LIBS=ON -DENABLE_IFS_INTERFACE=ON ${CMAKE_ARGS} $@ # not required when re-compiling
+cmake .. -DCMAKE_INSTALL_PREFIX=$HERE -DBUILD_SHARED_LIBS=ON -DENABLE_IFS_INTERFACE=ON ${CMAKE_ARGS} $@ # not required when re-compiling
+echo "+ make install -j`nproc --all`"
+make install -j`nproc --all`
+
diff --git a/test/ifs_interface/configure_lib.sh b/test/ifs_interface/configure_lib.sh
deleted file mode 100755
index cf1609bcb..000000000
--- a/test/ifs_interface/configure_lib.sh
+++ /dev/null
@@ -1,28 +0,0 @@
-#!/usr/bin/env bash
-
-# custom build script in use at ECMWF
-
-set -e
-
-LIB=no
-while getopts "l" OPT
-do
-  case "$OPT" in
-    l) LIB=yes;;
-  esac
-done
-shift $((OPTIND-1))
-
-#cd ../../
-source env.sh ubuntu # source this from your run script too
-
-if [[ ${LIB} = yes ]]; then
-  mkdir build.lib || true # build dir for library
-  cd build.lib
-  cmake -DBUILD_FESOM_AS_LIBRARY=ON .. # not required when re-compiling
-else
-  mkdir build || true # build dir for binary
-  cd build
-  cmake .. # not required when re-compiling
-fi
-make install -j`nproc --all`