implementing partial cavity wall fill recommendation

.idea/Model.iml

@@ -7,7 +7,7 @@
       <sourceFolder url="file://$MODULE_DIR$/open_uprn" isTestSource="false" />
       <sourceFolder url="file://$MODULE_DIR$/recommendations" isTestSource="false" />
     </content>
-    <orderEntry type="jdk" jdkName="Python 3.10 (model_data)" jdkType="Python SDK" />
+    <orderEntry type="jdk" jdkName="Python 3.10 (backend)" jdkType="Python SDK" />
     <orderEntry type="sourceFolder" forTests="false" />
   </component>
   <component name="PyNamespacePackagesService">

.idea/misc.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
-  <component name="ProjectRootManager" version="2" project-jdk-name="Python 3.10 (model_data)" project-jdk-type="Python SDK" />
+  <component name="ProjectRootManager" version="2" project-jdk-name="Python 3.10 (backend)" project-jdk-type="Python SDK" />
   <component name="PythonCompatibilityInspectionAdvertiser">
     <option name="version" value="3" />
   </component>

recommendations/WallRecommendations.py

@@ -9,6 +9,7 @@ from recommendations.recommendation_utils import (
     r_value_per_mm_to_u_value, calculate_u_value_uplift, is_diminishing_returns, update_lowest_selected_u_value,
     get_recommended_part, get_wall_u_value
 )
+from recommendations.config import PARTIALLY_FILLED_PERCENTAGE_ASSUMPTION
 
 
 class WallRecommendations(Definitions):
@@ -35,14 +36,6 @@ class WallRecommendations(Definitions):
     # we still consider it as an option
     U_VALUE_ERROR = 0.01
 
-    # TODO: Review this value against RdSAP
-    #       Page 19 of rdsap here:
-    #       https://files.bregroup.com/bre-co-uk-file-library-copy/filelibrary/SAP/2012/RdSAP-9.93/RdSAP_2012_9.93.pdf
-    #       provides default U-values for solid brick walls depending on age band
-    DEFAULT_U_VALUES = {
-        "solid_brick": 2,
-    }
-
     def __init__(
         self,
         property_instance: Property,
@@ -113,6 +106,7 @@ class WallRecommendations(Definitions):
             is_granite_or_whinstone=self.property.walls["is_granite_or_whinstone"],
             is_sandstone_or_limestone=self.property.walls["is_sandstone_or_limestone"],
         )
+
         self.estimated_u_value = u_value
 
         if self.property.walls["is_solid_brick"]:
@@ -127,16 +121,13 @@ class WallRecommendations(Definitions):
         if is_cavity_wall:
             if u_value >= self.BUILDING_REGULATIONS_PART_L_MAX_U_VALUE:
                 # Test filling cavity
-                self.find_cavity_insulation(u_value)
-
-                if insulation_thickness not in ["none", None]:
-                    raise ValueError("Implement me")
+                self.find_cavity_insulation(u_value, insulation_thickness)
 
             return
 
         raise NotImplementedError("Not implemented yet")
 
-    def find_cavity_insulation(self, u_value):
+    def find_cavity_insulation(self, u_value, insulation_thickness):
         """
         This method tests different materials to fill the cavity wall, determining which
         material will give us the best U-value.
@@ -150,11 +141,15 @@ class WallRecommendations(Definitions):
         therefore we'll use 50mm as the base assumption
 
         :param u_value: u_value of the starting wall
+        :param insulation_thickness: describes the insulation level of the wall. If "below average", we have a partially
+        filled cavity wall
         """
 
         cavity_wall_fills = [m for m in self.materials if m["type"] == "cavity_wall_insulation"]
-
         cavity_width = 50
+        if insulation_thickness == "below average":
+            cavity_width = 50 * (1 - PARTIALLY_FILLED_PERCENTAGE_ASSUMPTION)
+
         # Test the different fill options
         lowest_selected_u_value = None
         recommendations = []

recommendations/config.py

@@ -6,3 +6,11 @@ UPGRADES_MAP = {
     'Suspended, no insulation (assumed)': 'Suspended, insulated (assumed)',
     'Solid, no insulation (assumed)': 'Solid, insulated (assumed)',
 }
+
+PARTIAL_CAVITY_DESCRIPTIONS = [
+    "Cavity wall, as built, partial insulation",
+    "Cavity wall, partial insulation",
+]
+
+# We assume that the cavity is partially filled with insulation, and is filled 25% full
+PARTIALLY_FILLED_PERCENTAGE_ASSUMPTION = 0.25

recommendations/rdsap_tables.py

@@ -226,10 +226,10 @@ epc_wall_description_map = {
     "Cavity wall, as built, partial insulation": "Filled cavity",
     "Cavity wall, filled cavity": "Filled cavity",
     "Cavity wall, as built, no insulation": "Cavity as built",
-    "Cavity wall, as built, insulated": "Unfilled cavity with 100 mm external or internal insulation",
+    "Cavity wall, as built, insulated": "Filled cavity",
     "Cavity wall, with external insulation": "Unfilled cavity with 100 mm external or internal insulation",
-    "Cavity wall, insulated": "Unfilled cavity with 100 mm external or internal insulation",
-    'Cavity wall, partial insulation': "Unfilled cavity with 50 mm external or internal insulation",
+    "Cavity wall, insulated": "Filled cavity",
+    'Cavity wall, partial insulation': "Filled cavity",
 
     "Cavity wall,": "Cavity as built",  # General case of cavity wall without further details
     "Cavity wall, filled cavity and external insulation":

recommendations/recommendation_utils.py

@@ -7,6 +7,7 @@ from recommendations.rdsap_tables import (
     epc_wall_description_map, wall_uvalues_df, default_wall_thickness, table_s9 as s9, table_s10 as s10,
     table_s11 as s11
 )
+from recommendations.config import PARTIALLY_FILLED_PERCENTAGE_ASSUMPTION, PARTIAL_CAVITY_DESCRIPTIONS
 
 
 def r_value_per_mm_to_u_value(depth_mm: int, r_value_per_mm: float):
@@ -146,7 +147,9 @@ def apply_formula_s_5_1_1(is_granite_or_whinstone, is_sandstone_or_limestone, ag
     raise ValueError("This should only be called when is_granite_or_whinstone or is_sandstone_or_limestone is True")
 
 
-def get_wall_u_value(clean_description, age_band, is_granite_or_whinstone, is_sandstone_or_limestone):
+def get_wall_u_value(
+    clean_description, age_band, is_granite_or_whinstone, is_sandstone_or_limestone
+):
     """
     Given some features about a wall, this function will query the wall u-value table and return the u-value
     :param clean_description:  Cleaned up description of the wall from the EPC data
@@ -156,13 +159,23 @@ def get_wall_u_value(clean_description, age_band, is_granite_or_whinstone, is_sa
     :return:
     """
 
-    mapped_description = epc_wall_description_map[clean_description]
+    if clean_description in PARTIAL_CAVITY_DESCRIPTIONS:
+        # If we have a partial cavity fill, we linearly interpolate the u-value. This isn't necessarily the perfect
+        # method and how we do this should be explored, however we want to distinguish between the old
+        filled_uvalue = float(wall_uvalues_df[wall_uvalues_df["Wall_type"] == "Filled cavity"][age_band].values[0])
+        unfilled_uvalue = float(wall_uvalues_df[wall_uvalues_df["Wall_type"] == "Cavity as built"][age_band].values[0])
 
-    mapped_value = wall_uvalues_df[wall_uvalues_df["Wall_type"] == mapped_description][age_band].values[0]
+        mapped_value = str(
+            unfilled_uvalue - (PARTIALLY_FILLED_PERCENTAGE_ASSUMPTION * (unfilled_uvalue - filled_uvalue))
+        )
+    else:
+        mapped_description = epc_wall_description_map[clean_description]
 
-    if pd.isnull(mapped_value) and "Park home" in mapped_description:
-        # We don't know enough in this case so we default to 0
-        return 0
+        mapped_value = wall_uvalues_df[wall_uvalues_df["Wall_type"] == mapped_description][age_band].values[0]
+
+        if pd.isnull(mapped_value) and "Park home" in mapped_description:
+            # We don't know enough in this case so we default to 0
+            return 0
 
     if mapped_value == "a":
         # The rdSap documentation indicateswe should use a formula to calculate the u-value

recommendations/tests/test_wall_recommendations.py

@@ -470,3 +470,36 @@ class TestCavityWallRecommensations:
 
         assert np.isclose(recommender.recommendations[1]["new_u_value"], 0.26)
         assert np.isclose(recommender.recommendations[1]["cost"], 1250)
+
+    def test_fill_partial_filled_cavity(self):
+        input_property = Property(id=1, postcode="F4k3", address1="123 fake street", epc_client=Mock())
+        input_property.walls = {
+            'original_description': 'Cavity wall, as built, partial insulation (assumed)',
+            'clean_description': 'Cavity wall, as built, partial insulation',
+            'thermal_transmittance': None, 'thermal_transmittance_unit': None,
+            'is_cavity_wall': True, 'is_filled_cavity': False, 'is_solid_brick': False,
+            'is_system_built': False, 'is_timber_frame': False, 'is_granite_or_whinstone': False,
+            'is_as_built': True, 'is_cob': False, 'is_assumed': True,
+            'is_sandstone_or_limestone': False, 'is_park_home': False,
+            'insulation_thickness': 'below average', 'external_insulation': False,
+            'internal_insulation': False
+        }
+        input_property.age_band = "C"
+        input_property.insulation_wall_area = 50
+
+        recommender = WallRecommendations(
+            property_instance=input_property,
+            materials=cavity_wall_insulation_parts
+        )
+
+        assert not recommender.recommendations
+
+        recommender.recommend()
+
+        assert recommender.recommendations
+        assert recommender.estimated_u_value == 1.3
+        assert np.isclose(recommender.recommendations[0]["new_u_value"], 0.56)
+        assert np.isclose(recommender.recommendations[0]["cost"], 1000)
+
+        assert np.isclose(recommender.recommendations[1]["new_u_value"], 0.57)
+        assert np.isclose(recommender.recommendations[1]["cost"], 1250)