diff --git a/model_data/recommendations/WallRecommendations.py b/model_data/recommendations/WallRecommendations.py
index a5df28bb..f8ae1898 100644
--- a/model_data/recommendations/WallRecommendations.py
+++ b/model_data/recommendations/WallRecommendations.py
@@ -19,7 +19,7 @@ external_wall_insulation_parts = [
         # options for internal wall insulation (e.g. 50mm, 100mm, 150mm), with different material types
         # and costs
         "r_value_per_mm": 0.0278,
-        "r_value_unit": "m2K/W"
+        "r_value_unit": "square_meter_kelvin_per_watt",
     },
     {
         "type": "external_wall_insulation",