diff --git a/custom_components/versatile_thermostat/pi_algorithm.py b/custom_components/versatile_thermostat/pi_algorithm.py
index c214b1b..9404f2b 100644
--- a/custom_components/versatile_thermostat/pi_algorithm.py
+++ b/custom_components/versatile_thermostat/pi_algorithm.py
@@ -5,8 +5,9 @@ import logging
 
 _LOGGER = logging.getLogger(__name__)
 
+
 class PITemperatureRegulator:
-    """ A class implementing a PI Algorithm
+    """A class implementing a PI Algorithm
     PI algorithms calculate a target temperature by adding an offset which is calculating as follow:
     - offset = kp * error + ki * accumulated_error
 
@@ -16,30 +17,48 @@ class PITemperatureRegulator:
     - call set_target_temp when the target temperature change.
     """
 
-    def __init__(self, target_temp: float, kp: float, ki: float, k_ext: float, offset_max: float, stabilization_threshold: float, accumulated_error_threshold: float):
-        self.target_temp:float = target_temp
-        self.kp:float = kp  # proportionnel gain
-        self.ki:float = ki  # integral gain
-        self.k_ext:float = k_ext # exterior gain
-        self.offset_max:float = offset_max
-        self.stabilization_threshold:float = stabilization_threshold
-        self.accumulated_error:float = 0
-        self.accumulated_error_threshold:float = accumulated_error_threshold
+    def __init__(
+        self,
+        target_temp: float,
+        kp: float,
+        ki: float,
+        k_ext: float,
+        offset_max: float,
+        stabilization_threshold: float,
+        accumulated_error_threshold: float,
+    ):
+        self.target_temp: float = target_temp
+        self.kp: float = kp  # proportionnel gain
+        self.ki: float = ki  # integral gain
+        self.k_ext: float = k_ext  # exterior gain
+        self.offset_max: float = offset_max
+        self.stabilization_threshold: float = stabilization_threshold
+        self.accumulated_error: float = 0
+        self.accumulated_error_threshold: float = accumulated_error_threshold
 
     def reset_accumulated_error(self):
-        """ Reset the accumulated error """
+        """Reset the accumulated error"""
         self.accumulated_error = 0
 
     def set_target_temp(self, target_temp):
-        """ Set the new target_temp"""
+        """Set the new target_temp"""
         self.target_temp = target_temp
         # Do not reset the accumulated error
         # self.accumulated_error = 0
 
-    def calculate_regulated_temperature(self, internal_temp: float, external_temp:float): # pylint: disable=unused-argument
-        """ Calculate a new target_temp given some temperature"""
-        if internal_temp is None or external_temp is None:
-            _LOGGER.warning("Internal_temp or external_temp are not set. Regulation will be suspended")
+    def calculate_regulated_temperature(
+        self, internal_temp: float, external_temp: float
+    ):  # pylint: disable=unused-argument
+        """Calculate a new target_temp given some temperature"""
+        if internal_temp is None:
+            _LOGGER.warning(
+                "Temporarily skipping the self-regulation algorithm while the configured sensor for room temperature is unavailable"
+            )
+            return self.target_temp
+        if external_temp is None:
+            _LOGGER.warning(
+                "Temporarily skipping the self-regulation algorithm while the configured sensor for outdoor temperature is unavailable"
+            )
             return self.target_temp
 
         # Calculate the error factor (P)
@@ -49,7 +68,10 @@ class PITemperatureRegulator:
         self.accumulated_error += error
 
         # Capping of the error
-        self.accumulated_error = min(self.accumulated_error_threshold, max(-self.accumulated_error_threshold, self.accumulated_error))
+        self.accumulated_error = min(
+            self.accumulated_error_threshold,
+            max(-self.accumulated_error_threshold, self.accumulated_error),
+        )
 
         # Calculate the offset (proportionnel + intégral)
         offset = self.kp * error + self.ki * self.accumulated_error
@@ -62,7 +84,6 @@ class PITemperatureRegulator:
         total_offset = offset + offset_ext
         total_offset = min(self.offset_max, max(-self.offset_max, total_offset))
 
-
         # If temperature is near the target_temp, reset the accumulated_error
         if abs(error) < self.stabilization_threshold:
             _LOGGER.debug("Stabilisation")
@@ -70,7 +91,14 @@ class PITemperatureRegulator:
 
         result = round(self.target_temp + total_offset, 1)
 
-        _LOGGER.debug("PITemperatureRegulator - Error: %.2f accumulated_error: %.2f offset: %.2f offset_ext: %.2f target_tem: %.1f regulatedTemp: %.1f",
-            error, self.accumulated_error, offset, offset_ext, self.target_temp, result)
+        _LOGGER.debug(
+            "PITemperatureRegulator - Error: %.2f accumulated_error: %.2f offset: %.2f offset_ext: %.2f target_tem: %.1f regulatedTemp: %.1f",
+            error,
+            self.accumulated_error,
+            offset,
+            offset_ext,
+            self.target_temp,
+            result,
+        )
 
         return result