diff --git a/astromodels/core/units.py b/astromodels/core/units.py
index 4bd5d99b..711f6b81 100644
--- a/astromodels/core/units.py
+++ b/astromodels/core/units.py
@@ -6,17 +6,11 @@
 
 import astropy.units as u
 
+from astromodels.utils.configuration import astromodels_config
 from astromodels.utils.pretty_list import dict_to_list
 
 # This module keeps the configuration of the units used in astromodels
 
-# Pre-defined values
-
-_ENERGY = u.keV
-_TIME = u.s
-_ANGLE = u.deg
-_AREA = u.cm**2
-
 
 class UnknownUnit(Exception):
     pass
@@ -63,13 +57,13 @@ def __init__(
     ):
 
         if energy_unit is None:
-            energy_unit = _ENERGY
+            energy_unit = u.Unit(astromodels_config.units.energy)
         if time_unit is None:
-            time_unit = _TIME
+            time_unit = u.Unit(astromodels_config.units.time)
         if angle_unit is None:
-            angle_unit = _ANGLE
+            angle_unit = u.Unit(astromodels_config.units.angle)
         if area_unit is None:
-            area_unit = _AREA
+            area_unit = u.Unit(astromodels_config.units.area)
 
         self._units = collections.OrderedDict()
 
@@ -189,5 +183,12 @@ def __call__(self, *args, **kwds):
 
 
 # Create the factory to be used in the program
+def set_units(key: str, value: u.Unit):
+    """
+    Update the units used
+    """
+    if getattr(get_units(), key) != value:
+        setattr(get_units(), key, value)
+
 
 get_units = _AstromodelsUnitsFactory()
diff --git a/astromodels/tests/test_units.py b/astromodels/tests/test_units.py
new file mode 100644
index 00000000..9cb10ef2
--- /dev/null
+++ b/astromodels/tests/test_units.py
@@ -0,0 +1,37 @@
+from copy import deepcopy
+import astropy.units as u
+from omegaconf import OmegaConf
+
+from astromodels.core.units import get_units, set_units
+from astromodels.utils.configuration import astromodels_config
+from astromodels.utils.file_utils import get_path_of_user_config
+
+
+def test_config_unit_same():
+    for user_config_file in get_path_of_user_config().glob("*.yml"):
+        user_conf = OmegaConf.load(user_config_file)
+        if "units" in user_conf.keys():
+            for k in user_conf["units"].keys():
+                assert u.Unit(user_conf["units"][k]) == getattr(get_units(), k)
+                assert astromodels_config["units"][k] == user_conf["units"][k]
+    for k, v in astromodels_config["units"].items():
+        assert u.Unit(v) == getattr(get_units(), k)
+
+
+def test_set_units():
+    mapping = {"energy": u.TeV, "area": u.m**2, "time": u.h, "angle": u.rad}
+    ref = deepcopy(get_units())
+    not_changed = []
+    for k, v in mapping.items():
+        if getattr(ref, k) != v:
+            set_units(k, v)
+        else:
+            not_changed.append(k)
+    for k, v in mapping.items():
+        if k not in not_changed:
+            assert getattr(get_units(), k) == v
+            assert getattr(ref, k) != getattr(get_units(), k)
+
+    # reset it to the original
+    for k, v in mapping.items():
+        set_units(k, getattr(ref, k))
diff --git a/astromodels/utils/config_structure.py b/astromodels/utils/config_structure.py
index 09a4a895..4bfb1c20 100644
--- a/astromodels/utils/config_structure.py
+++ b/astromodels/utils/config_structure.py
@@ -27,6 +27,14 @@ class Logging:
     message_style: str = "bold grey78"
 
 
+@dataclass
+class Units:
+    energy: str = "keV"
+    time: str = "s"
+    angle: str = "deg"
+    area: str = "cm2"
+
+
 class AbsTables(Enum):
     WILM = "WILM"
     ASPL = "ASPL"
@@ -60,3 +68,4 @@ class Config:
     logging: Logging = field(default_factory=Logging)
     absorption_models: AbsorptionModels = field(default_factory=AbsorptionModels)
     modeling: Modeling = field(default_factory=Modeling)
+    units: Units = field(default_factory=Units)