diff --git a/domain/modelling/optimisation/optimiser.py b/domain/modelling/optimisation/optimiser.py
index 9b076ec4a..b47495f00 100644
--- a/domain/modelling/optimisation/optimiser.py
+++ b/domain/modelling/optimisation/optimiser.py
@@ -24,7 +24,7 @@ from dataclasses import dataclass
 from typing import Optional, Protocol, Sequence
 
 from datatypes.epc.domain.epc_property_data import EpcPropertyData
-from domain.modelling.measure_type import MeasureType
+from domain.modelling.measure_type import FABRIC_MEASURE_TYPES, MeasureType
 from domain.modelling.scoring.package_scorer import Score
 from domain.modelling.recommendation import MeasureOption
 from domain.modelling.simulation import EpcSimulation
@@ -237,7 +237,26 @@ def optimise_package_fabric_first(
     if the truthful post-fabric score meets ``target_sap``, stop there. Otherwise
     optimise the remaining groups on top — the starting point for phase 2 is the
     dwelling with the phase-1 fabric applied — within the leftover budget."""
-    raise NotImplementedError
+    fabric_groups: list[list[ScoredOption]] = [
+        group for group in groups if _is_fabric_group(group)
+    ]
+    fabric_package: OptimisedPackage = optimise_package(
+        groups=fabric_groups,
+        scorer=scorer,
+        baseline_epc=baseline_epc,
+        budget=budget,
+        target_sap=target_sap,
+        dependencies=dependencies,
+    )
+    return fabric_package
+
+
+def _is_fabric_group(group: list[ScoredOption]) -> bool:
+    """A group belongs to phase 1 when every Option in it is a fabric measure
+    (groups are one Recommendation each, so they are homogeneous in kind)."""
+    return all(
+        scored.option.measure_type in FABRIC_MEASURE_TYPES for scored in group
+    )
 
 
 def _with_role1_signals(