diff --git a/pythermalcomfort/models/ankle_draft.py b/pythermalcomfort/models/ankle_draft.py
index 47bea9e..d0cf5cd 100644
--- a/pythermalcomfort/models/ankle_draft.py
+++ b/pythermalcomfort/models/ankle_draft.py
@@ -19,14 +19,14 @@ class AnkleDraft:
 
     Attributes
     ----------
-    PPD_ad : float
+    ppd_ad : float
         Predicted Percentage of Dissatisfied occupants with ankle draft, [%].
-    Acceptability : bool
+    acceptability : bool
         Indicates if the air speed at the ankle level is acceptable according to ASHRAE 55 2020 standard.
     """
 
-    PPD_ad: Union[float, npt.ArrayLike]
-    Acceptability: Union[bool, npt.ArrayLike]
+    ppd_ad: Union[float, npt.ArrayLike]
+    acceptability: Union[bool, npt.ArrayLike]
 
     def __getitem__(self, item):
         return getattr(self, item)
@@ -130,7 +130,7 @@ def ankle_draft(
         from pythermalcomfort.models import ankle_draft
         results = ankle_draft(25, 25, 0.2, 50, 1.2, 0.5, 0.3, units="SI")
         print(results)
-        # AnkleDraft(PPD_ad=18.5, Acceptability=True)
+        # AnkleDraft(ppd_ad=18.5, acceptability=True)
     """
     # Validate inputs using the AnkleDraftInputs class
     AnkleDraftInputs(
@@ -170,7 +170,7 @@ def ankle_draft(
         1,
     )
     acceptability = ppd_val <= 20
-    return AnkleDraft(PPD_ad=ppd_val, Acceptability=acceptability)
+    return AnkleDraft(ppd_ad=ppd_val, acceptability=acceptability)
 
 
 if __name__ == "__main__":
diff --git a/tests/test_ankle_draft.py b/tests/test_ankle_draft.py
index 38e50fd..01036e3 100644
--- a/tests/test_ankle_draft.py
+++ b/tests/test_ankle_draft.py
@@ -15,7 +15,7 @@ def test_ankle_draft(get_test_url, retrieve_data):
         inputs = entry["inputs"]
         outputs = entry["outputs"]
         result = ankle_draft(**inputs)
-        
+
         validate_result(result, outputs, tolerance)
 
 
@@ -30,10 +30,10 @@ def test_ankle_draft_invalid_input_range():
 
 def test_ankle_draft_outside_ashrae_range():
     r = ankle_draft(50, 25, 0.1, 50, 1.2, 0.5, 0.1)
-    assert np.isnan(r.PPD_ad)
+    assert np.isnan(r.ppd_ad)
 
     r = ankle_draft([50, 45], 25, 0.1, 50, 1.2, 0.5, 0.1)
-    assert np.all(np.isnan(r.PPD_ad))
+    assert np.all(np.isnan(r.ppd_ad))
 
 
 def test_ankle_draft_list_inputs():
@@ -48,8 +48,8 @@ def test_ankle_draft_list_inputs():
         units="SI",
     )
     assert isinstance(results, AnkleDraft)
-    assert len(results.PPD_ad) == 3
-    assert len(results.Acceptability) == 3
+    assert len(results.ppd_ad) == 3
+    assert len(results.acceptability) == 3
 
 
 def test_ankle_draft_invalid_list_inputs():