From 06d90bfd295e057e2cacb84879fe1c9c877447f5 Mon Sep 17 00:00:00 2001
From: FBumann <117816358+FBumann@users.noreply.github.com>
Date: Sat, 27 Sep 2025 17:00:15 +0200
Subject: [PATCH 1/8] Step 1

---
 examples/01_Simple/simple_example.py      |  2 +-
 examples/02_Complex/complex_example.py    |  4 +-
 examples/04_Scenarios/scenario_example.py |  2 +-
 flixopt/effects.py                        | 78 +++++++++++------------
 tests/conftest.py                         |  3 +-
 tests/test_effect.py                      | 46 +++++++++----
 tests/test_scenarios.py                   |  4 +-
 7 files changed, 78 insertions(+), 61 deletions(-)

diff --git a/examples/01_Simple/simple_example.py b/examples/01_Simple/simple_example.py
index a201ee8c4..62fa8f6a9 100644
--- a/examples/01_Simple/simple_example.py
+++ b/examples/01_Simple/simple_example.py
@@ -29,6 +29,7 @@
         description='Kosten',
         is_standard=True,  # standard effect: no explicit value needed for costs
         is_objective=True,  # Minimizing costs as the optimization objective
+        share_from_temporal={'CO2': 0.2},
     )
 
     # CO2 emissions effect with an associated cost impact
@@ -36,7 +37,6 @@
         label='CO2',
         unit='kg',
         description='CO2_e-Emissionen',
-        specific_share_to_other_effects_operation={costs.label: 0.2},
         maximum_operation_per_hour=1000,  # Max CO2 emissions per hour
     )
 
diff --git a/examples/02_Complex/complex_example.py b/examples/02_Complex/complex_example.py
index 175211c26..506e7ac78 100644
--- a/examples/02_Complex/complex_example.py
+++ b/examples/02_Complex/complex_example.py
@@ -40,8 +40,8 @@
 
     # --- Define Effects ---
     # Specify effects related to costs, CO2 emissions, and primary energy consumption
-    Costs = fx.Effect('costs', '€', 'Kosten', is_standard=True, is_objective=True)
-    CO2 = fx.Effect('CO2', 'kg', 'CO2_e-Emissionen', specific_share_to_other_effects_operation={Costs.label: 0.2})
+    Costs = fx.Effect('costs', '€', 'Kosten', is_standard=True, is_objective=True, share_from_temporal={'CO2': 0.2})
+    CO2 = fx.Effect('CO2', 'kg', 'CO2_e-Emissionen')
     PE = fx.Effect('PE', 'kWh_PE', 'Primärenergie', maximum_total=3.5e3)
 
     # --- Define Components ---
diff --git a/examples/04_Scenarios/scenario_example.py b/examples/04_Scenarios/scenario_example.py
index f675211e8..73d37fb90 100644
--- a/examples/04_Scenarios/scenario_example.py
+++ b/examples/04_Scenarios/scenario_example.py
@@ -35,6 +35,7 @@
         description='Kosten',
         is_standard=True,  # standard effect: no explicit value needed for costs
         is_objective=True,  # Minimizing costs as the optimization objective
+        share_from_temporal={'CO2': 0.2},
     )
 
     # CO2 emissions effect with an associated cost impact
@@ -42,7 +43,6 @@
         label='CO2',
         unit='kg',
         description='CO2_e-Emissionen',
-        specific_share_to_other_effects_operation={costs.label: 0.2},
         maximum_operation_per_hour=1000,  # Max CO2 emissions per hour
     )
 
diff --git a/flixopt/effects.py b/flixopt/effects.py
index e1bf0b17b..d04b388fe 100644
--- a/flixopt/effects.py
+++ b/flixopt/effects.py
@@ -50,10 +50,10 @@ class Effect(Element):
             without effect dictionaries. Used for simplified effect specification (and less boilerplate code).
         is_objective: If True, this effect serves as the optimization objective function.
             Only one effect can be marked as objective per optimization.
-        specific_share_to_other_effects_operation: Operational cross-effect contributions.
-            Maps this effect's operational values to contributions to other effects
-        specific_share_to_other_effects_invest: Investment cross-effect contributions.
-            Maps this effect's investment values to contributions to other effects.
+        share_from_temporal: Temporal cross-effect contributions.
+            Maps temporal contributions from other effects to this effect
+        share_from_nontemporal: Nontemporal cross-effect contributions.
+            Maps nontemporal contributions from other effects to this effect.
         minimum_temporal: Minimum allowed total contribution across all timesteps.
         maximum_temporal: Maximum allowed total contribution across all timesteps.
         minimum_per_hour: Minimum allowed contribution per hour.
@@ -87,7 +87,7 @@ class Effect(Element):
             label='co2_emissions',
             unit='kg_CO2',
             description='Carbon dioxide emissions',
-            specific_share_to_other_effects_operation={'costs': 50},  # €50/t_CO2
+            share_from_temporal={'CO2': 0.2},  # €0.2 per kg CO2
             maximum_total=1_000_000,  # 1000 t CO2 annual limit
         )
         ```
@@ -110,7 +110,7 @@ class Effect(Element):
             label='primary_energy',
             unit='kWh_primary',
             description='Primary energy consumption',
-            specific_share_to_other_effects_operation={'costs': 0.08},  # €0.08/kWh
+            share_from_temporal={'primary_energy': 0.08},  # €0.08/kWh
         )
         ```
 
@@ -150,8 +150,8 @@ def __init__(
         meta_data: dict | None = None,
         is_standard: bool = False,
         is_objective: bool = False,
-        specific_share_to_other_effects_operation: TemporalEffectsUser | None = None,
-        specific_share_to_other_effects_invest: NonTemporalEffectsUser | None = None,
+        share_from_temporal: TemporalEffectsUser | None = None,
+        share_from_nontemporal: NonTemporalEffectsUser | None = None,
         minimum_temporal: NonTemporalEffectsUser | None = None,
         maximum_temporal: NonTemporalEffectsUser | None = None,
         minimum_nontemporal: NonTemporalEffectsUser | None = None,
@@ -168,11 +168,9 @@ def __init__(
         self.description = description
         self.is_standard = is_standard
         self.is_objective = is_objective
-        self.specific_share_to_other_effects_operation: TemporalEffectsUser = (
-            specific_share_to_other_effects_operation if specific_share_to_other_effects_operation is not None else {}
-        )
-        self.specific_share_to_other_effects_invest: NonTemporalEffectsUser = (
-            specific_share_to_other_effects_invest if specific_share_to_other_effects_invest is not None else {}
+        self.share_from_temporal: TemporalEffectsUser = share_from_temporal if share_from_temporal is not None else {}
+        self.share_from_nontemporal: NonTemporalEffectsUser = (
+            share_from_nontemporal if share_from_nontemporal is not None else {}
         )
 
         # Handle backwards compatibility for deprecated parameters
@@ -394,8 +392,8 @@ def transform_data(self, flow_system: FlowSystem, name_prefix: str = '') -> None
 
         self.maximum_per_hour = flow_system.fit_to_model_coords(f'{prefix}|maximum_per_hour', self.maximum_per_hour)
 
-        self.specific_share_to_other_effects_operation = flow_system.fit_effects_to_model_coords(
-            f'{prefix}|operation->', self.specific_share_to_other_effects_operation, 'temporal'
+        self.share_from_temporal = flow_system.fit_effects_to_model_coords(
+            f'{prefix}|temporal<-', self.share_from_temporal, 'temporal'
         )
 
         self.minimum_temporal = flow_system.fit_to_model_coords(
@@ -407,7 +405,7 @@ def transform_data(self, flow_system: FlowSystem, name_prefix: str = '') -> None
         self.minimum_nontemporal = flow_system.fit_to_model_coords(
             f'{prefix}|minimum_nontemporal', self.minimum_nontemporal, dims=['year', 'scenario']
         )
-        self.minimum_nontemporal = flow_system.fit_to_model_coords(
+        self.maximum_nontemporal = flow_system.fit_to_model_coords(
             f'{prefix}|maximum_nontemporal', self.maximum_nontemporal, dims=['year', 'scenario']
         )
         self.minimum_total = flow_system.fit_to_model_coords(
@@ -418,10 +416,10 @@ def transform_data(self, flow_system: FlowSystem, name_prefix: str = '') -> None
         self.maximum_total = flow_system.fit_to_model_coords(
             f'{prefix}|maximum_total', self.maximum_total, dims=['year', 'scenario']
         )
-        self.specific_share_to_other_effects_invest = flow_system.fit_effects_to_model_coords(
-            f'{prefix}|operation->',
-            self.specific_share_to_other_effects_invest,
-            'operation',
+        self.share_from_nontemporal = flow_system.fit_effects_to_model_coords(
+            f'{prefix}|nontemporal<-',
+            self.share_from_nontemporal,
+            'nontemporal',
             dims=['year', 'scenario'],
         )
 
@@ -659,18 +657,20 @@ def calculate_effect_share_factors(
     ]:
         shares_nontemporal = {}
         for name, effect in self.effects.items():
-            if effect.specific_share_to_other_effects_invest:
-                shares_nontemporal[name] = {
-                    target: data for target, data in effect.specific_share_to_other_effects_invest.items()
-                }
+            if effect.share_from_nontemporal:
+                for source, data in effect.share_from_nontemporal.items():
+                    if source not in shares_nontemporal:
+                        shares_nontemporal[source] = {}
+                    shares_nontemporal[source][name] = data
         shares_nontemporal = calculate_all_conversion_paths(shares_nontemporal)
 
         shares_temporal = {}
         for name, effect in self.effects.items():
-            if effect.specific_share_to_other_effects_operation:
-                shares_temporal[name] = {
-                    target: data for target, data in effect.specific_share_to_other_effects_operation.items()
-                }
+            if effect.share_from_temporal:
+                for source, data in effect.share_from_temporal.items():
+                    if source not in shares_temporal:
+                        shares_temporal[source] = {}
+                    shares_temporal[source][name] = data
         shares_temporal = calculate_all_conversion_paths(shares_temporal)
 
         return shares_temporal, shares_nontemporal
@@ -729,19 +729,19 @@ def _do_modeling(self):
         )
 
     def _add_share_between_effects(self):
-        for origin_effect in self.effects:
-            # 1. temporal: -> hier sind es Zeitreihen (share_TS)
-            for target_effect, time_series in origin_effect.specific_share_to_other_effects_operation.items():
-                self.effects[target_effect].submodel.temporal.add_share(
-                    origin_effect.submodel.temporal.label_full,
-                    origin_effect.submodel.temporal.total_per_timestep * time_series,
+        for target_effect in self.effects:
+            # 1. temporal: <- receiving temporal shares from other effects
+            for source_effect, time_series in target_effect.share_from_temporal.items():
+                target_effect.submodel.temporal.add_share(
+                    self.effects[source_effect].submodel.temporal.label_full,
+                    self.effects[source_effect].submodel.temporal.total_per_timestep * time_series,
                     dims=('time', 'year', 'scenario'),
                 )
-            # 2. nontemporal:    -> hier ist es Scalar (share)
-            for target_effect, factor in origin_effect.specific_share_to_other_effects_invest.items():
-                self.effects[target_effect].submodel.nontemporal.add_share(
-                    origin_effect.submodel.nontemporal.label_full,
-                    origin_effect.submodel.nontemporal.total * factor,
+            # 2. nontemporal: <- receiving nontemporal shares from other effects
+            for source_effect, factor in target_effect.share_from_nontemporal.items():
+                target_effect.submodel.nontemporal.add_share(
+                    self.effects[source_effect].submodel.nontemporal.label_full,
+                    self.effects[source_effect].submodel.nontemporal.total * factor,
                     dims=('year', 'scenario'),
                 )
 
diff --git a/tests/conftest.py b/tests/conftest.py
index cc70ecc17..034d9f789 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -109,7 +109,6 @@ def co2_with_costs_share():
             'CO2',
             'kg',
             'CO2_e-Emissionen',
-            specific_share_to_other_effects_operation={'costs': 0.2},
         )
 
     @staticmethod
@@ -471,7 +470,7 @@ def flow_system_complex() -> fx.FlowSystem:
     # Define the components and flow_system
     costs = Effects.costs()
     co2 = Effects.co2()
-    co2.specific_share_to_other_effects_operation = {'costs': 0.2}
+    costs.share_from_temporal = {'CO2': 0.2}
     pe = Effects.primary_energy()
     pe.maximum_total = 3.5e3
 
diff --git a/tests/test_effect.py b/tests/test_effect.py
index e0b737771..48e057419 100644
--- a/tests/test_effect.py
+++ b/tests/test_effect.py
@@ -154,11 +154,21 @@ def test_shares(self, basic_flow_system_linopy_coords, coords_config):
             'Effect1',
             '€',
             'Testing Effect',
-            specific_share_to_other_effects_operation={'Effect2': 1.1, 'Effect3': 1.2},
-            specific_share_to_other_effects_invest={'Effect2': 2.1, 'Effect3': 2.2},
         )
-        effect2 = fx.Effect('Effect2', '€', 'Testing Effect')
-        effect3 = fx.Effect('Effect3', '€', 'Testing Effect')
+        effect2 = fx.Effect(
+            'Effect2',
+            '€',
+            'Testing Effect',
+            share_from_temporal={'Effect1': 1.1},
+            share_from_nontemporal={'Effect1': 2.1},
+        )
+        effect3 = fx.Effect(
+            'Effect3',
+            '€',
+            'Testing Effect',
+            share_from_temporal={'Effect1': 1.2},
+            share_from_nontemporal={'Effect1': 2.2},
+        )
         flow_system.add_elements(effect1, effect2, effect3)
         model = create_linopy_model(flow_system)
 
@@ -215,17 +225,25 @@ def test_shares(self, basic_flow_system_linopy_coords, coords_config):
 class TestEffectResults:
     def test_shares(self, basic_flow_system_linopy_coords, coords_config):
         flow_system, coords_config = basic_flow_system_linopy_coords, coords_config
-        flow_system.effects['costs'].specific_share_to_other_effects_operation['Effect1'] = 0.5
+        effect1 = fx.Effect('Effect1', '€', 'Testing Effect', share_from_temporal={'costs': 0.5})
+        effect2 = fx.Effect(
+            'Effect2',
+            '€',
+            'Testing Effect',
+            share_from_temporal={'Effect1': 1.1},
+            share_from_nontemporal={'Effect1': 2.1},
+        )
+        effect3 = fx.Effect(
+            'Effect3',
+            '€',
+            'Testing Effect',
+            share_from_temporal={'Effect1': 1.2, 'Effect2': 5},
+            share_from_nontemporal={'Effect1': 2.2},
+        )
         flow_system.add_elements(
-            fx.Effect(
-                'Effect1',
-                '€',
-                'Testing Effect',
-                specific_share_to_other_effects_operation={'Effect2': 1.1, 'Effect3': 1.2},
-                specific_share_to_other_effects_invest={'Effect2': 2.1, 'Effect3': 2.2},
-            ),
-            fx.Effect('Effect2', '€', 'Testing Effect', specific_share_to_other_effects_operation={'Effect3': 5}),
-            fx.Effect('Effect3', '€', 'Testing Effect'),
+            effect1,
+            effect2,
+            effect3,
             fx.linear_converters.Boiler(
                 'Boiler',
                 eta=0.5,
diff --git a/tests/test_scenarios.py b/tests/test_scenarios.py
index ebc633a04..bfc537b8e 100644
--- a/tests/test_scenarios.py
+++ b/tests/test_scenarios.py
@@ -124,8 +124,8 @@ def flow_system_complex_scenarios() -> fx.FlowSystem:
     )
     # Define the components and flow_system
     flow_system.add_elements(
-        fx.Effect('costs', '€', 'Kosten', is_standard=True, is_objective=True),
-        fx.Effect('CO2', 'kg', 'CO2_e-Emissionen', specific_share_to_other_effects_operation={'costs': 0.2}),
+        fx.Effect('costs', '€', 'Kosten', is_standard=True, is_objective=True, share_from_temporal={'CO2': 0.2}),
+        fx.Effect('CO2', 'kg', 'CO2_e-Emissionen'),
         fx.Effect('PE', 'kWh_PE', 'Primärenergie', maximum_total=3.5e3),
         fx.Bus('Strom'),
         fx.Bus('Fernwärme'),

From 0795fc8dc164acf2797b9b0db98e0f2b094b4f1c Mon Sep 17 00:00:00 2001
From: FBumann <117816358+FBumann@users.noreply.github.com>
Date: Sat, 27 Sep 2025 17:17:56 +0200
Subject: [PATCH 2/8] Bugfix

---
 flixopt/effects.py | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/flixopt/effects.py b/flixopt/effects.py
index d04b388fe..0e7457bdf 100644
--- a/flixopt/effects.py
+++ b/flixopt/effects.py
@@ -393,7 +393,10 @@ def transform_data(self, flow_system: FlowSystem, name_prefix: str = '') -> None
         self.maximum_per_hour = flow_system.fit_to_model_coords(f'{prefix}|maximum_per_hour', self.maximum_per_hour)
 
         self.share_from_temporal = flow_system.fit_effects_to_model_coords(
-            f'{prefix}|temporal<-', self.share_from_temporal, 'temporal'
+            f'{prefix}(temporal)->', self.share_from_temporal, '(temporal)'
+        )
+        self.share_from_nontemporal = flow_system.fit_effects_to_model_coords(
+            f'{prefix}(nontemporal)->', self.share_from_nontemporal, '(nontemporal)'
         )
 
         self.minimum_temporal = flow_system.fit_to_model_coords(
@@ -416,12 +419,6 @@ def transform_data(self, flow_system: FlowSystem, name_prefix: str = '') -> None
         self.maximum_total = flow_system.fit_to_model_coords(
             f'{prefix}|maximum_total', self.maximum_total, dims=['year', 'scenario']
         )
-        self.share_from_nontemporal = flow_system.fit_effects_to_model_coords(
-            f'{prefix}|nontemporal<-',
-            self.share_from_nontemporal,
-            'nontemporal',
-            dims=['year', 'scenario'],
-        )
 
     def create_model(self, model: FlowSystemModel) -> EffectModel:
         self._plausibility_checks()

From 9e23bfb133df26d0a91a301b652fe81ffbd290a6 Mon Sep 17 00:00:00 2001
From: FBumann <117816358+FBumann@users.noreply.github.com>
Date: Sat, 27 Sep 2025 17:21:07 +0200
Subject: [PATCH 3/8] Make fit_effects_to_model_coords() more flexible

---
 flixopt/effects.py     | 6 ++++--
 flixopt/flow_system.py | 3 ++-
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/flixopt/effects.py b/flixopt/effects.py
index 0e7457bdf..9620da838 100644
--- a/flixopt/effects.py
+++ b/flixopt/effects.py
@@ -393,10 +393,12 @@ def transform_data(self, flow_system: FlowSystem, name_prefix: str = '') -> None
         self.maximum_per_hour = flow_system.fit_to_model_coords(f'{prefix}|maximum_per_hour', self.maximum_per_hour)
 
         self.share_from_temporal = flow_system.fit_effects_to_model_coords(
-            f'{prefix}(temporal)->', self.share_from_temporal, '(temporal)'
+            label_prefix=None, effect_values=self.share_from_temporal, label_suffix=f'(temporal)->{prefix}(temporal)'
         )
         self.share_from_nontemporal = flow_system.fit_effects_to_model_coords(
-            f'{prefix}(nontemporal)->', self.share_from_nontemporal, '(nontemporal)'
+            label_prefix=None,
+            effect_values=self.share_from_nontemporal,
+            label_suffix=f'(nontemporal)->{prefix}(nontemporal)',
         )
 
         self.minimum_temporal = flow_system.fit_to_model_coords(
diff --git a/flixopt/flow_system.py b/flixopt/flow_system.py
index 09781ae3f..ffd9761d7 100644
--- a/flixopt/flow_system.py
+++ b/flixopt/flow_system.py
@@ -407,6 +407,7 @@ def fit_effects_to_model_coords(
         effect_values: TemporalEffectsUser | NonTemporalEffectsUser | None,
         label_suffix: str | None = None,
         dims: Collection[FlowSystemDimensions] | None = None,
+        delimiter: str = '|',
     ) -> TemporalEffects | NonTemporalEffects | None:
         """
         Transform EffectValues from the user to Internal Datatypes aligned with model coordinates.
@@ -418,7 +419,7 @@ def fit_effects_to_model_coords(
 
         return {
             effect: self.fit_to_model_coords(
-                '|'.join(filter(None, [label_prefix, effect, label_suffix])),
+                str(delimiter).join(filter(None, [label_prefix, effect, label_suffix])),
                 value,
                 dims=dims,
             )

From dfb60b5f11595f127926b13987581061ed1a4243 Mon Sep 17 00:00:00 2001
From: FBumann <117816358+FBumann@users.noreply.github.com>
Date: Sat, 27 Sep 2025 17:23:12 +0200
Subject: [PATCH 4/8] Fix dims

---
 flixopt/effects.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/flixopt/effects.py b/flixopt/effects.py
index 9620da838..579fa095a 100644
--- a/flixopt/effects.py
+++ b/flixopt/effects.py
@@ -393,12 +393,16 @@ def transform_data(self, flow_system: FlowSystem, name_prefix: str = '') -> None
         self.maximum_per_hour = flow_system.fit_to_model_coords(f'{prefix}|maximum_per_hour', self.maximum_per_hour)
 
         self.share_from_temporal = flow_system.fit_effects_to_model_coords(
-            label_prefix=None, effect_values=self.share_from_temporal, label_suffix=f'(temporal)->{prefix}(temporal)'
+            label_prefix=None,
+            effect_values=self.share_from_temporal,
+            label_suffix=f'(temporal)->{prefix}(temporal)',
+            dims=['time', 'year', 'scenario'],
         )
         self.share_from_nontemporal = flow_system.fit_effects_to_model_coords(
             label_prefix=None,
             effect_values=self.share_from_nontemporal,
             label_suffix=f'(nontemporal)->{prefix}(nontemporal)',
+            dims=['year', 'scenario'],
         )
 
         self.minimum_temporal = flow_system.fit_to_model_coords(

From 1d779893d126154d1e56f21c9b8ae32016b4b382 Mon Sep 17 00:00:00 2001
From: FBumann <117816358+FBumann@users.noreply.github.com>
Date: Sat, 27 Sep 2025 17:31:52 +0200
Subject: [PATCH 5/8] Update conftest.py

---
 CHANGELOG.md      | 16 ++++++++++++++++
 tests/conftest.py | 20 ++++++++------------
 2 files changed, 24 insertions(+), 12 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7ecf091eb..2c92c268f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -47,6 +47,18 @@ Several internal improvements were made to the codebase.
 
 ### ✨ Added
 
+**Intuitive effect share syntax:**
+Effects now support an intuitive `share_from_*` syntax for cross-effect relationships:
+```python
+costs = fx.Effect(
+    'costs', '€', 'Total costs',
+    is_standard=True, is_objective=True,
+    share_from_temporal={'CO2': 0.2, 'energy': 0.05},  # Costs receive contributions from other effects
+    share_from_nontemporal={'land': 100}  # €100 per m² land use
+)
+```
+This replaces the less intuitive `specific_share_to_other_effects_*` parameters and makes it clearer where effect contributions are coming from, rather then where they are going to.
+
 **Multi-year investments:**
 A flixopt model might be modeled with a "year" dimension.
 This enables modeling transformation pathways over multiple years with several investment decisions
@@ -116,6 +128,10 @@ The weighted sum of the total objective effect of each scenario is used as the o
   - `minimum_operation_per_hour` → `minimum_per_hour`
   - `maximum_operation_per_hour` → `maximum_per_hour`
 
+### 🔥 Removed
+* **Effect share parameters**: The old `specific_share_to_other_effects_*` parameters were replaced WITHOUT DEPRECTATION
+  - `specific_share_to_other_effects_operation` → `share_from_temporal` (with inverted direction)
+  - `specific_share_to_other_effects_invest` → `share_from_nontemporal` (with inverted direction)
 
 ### 🐛 Fixed
 * Enhanced NetCDF I/O with proper attribute preservation for DataArrays
diff --git a/tests/conftest.py b/tests/conftest.py
index 034d9f789..1b0f23a29 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -100,16 +100,12 @@ def costs():
         return fx.Effect('costs', '€', 'Kosten', is_standard=True, is_objective=True)
 
     @staticmethod
-    def co2():
-        return fx.Effect('CO2', 'kg', 'CO2_e-Emissionen')
+    def costs_with_co2_share():
+        return fx.Effect('costs', '€', 'Kosten', is_standard=True, is_objective=True, share_from_temporal={'CO2': 0.2})
 
     @staticmethod
-    def co2_with_costs_share():
-        return fx.Effect(
-            'CO2',
-            'kg',
-            'CO2_e-Emissionen',
-        )
+    def co2():
+        return fx.Effect('CO2', 'kg', 'CO2_e-Emissionen')
 
     @staticmethod
     def primary_energy():
@@ -387,8 +383,8 @@ def simple_flow_system() -> fx.FlowSystem:
     base_timesteps = pd.date_range('2020-01-01', periods=9, freq='h', name='time')
 
     # Define effects
-    costs = Effects.costs()
-    co2 = Effects.co2_with_costs_share()
+    costs = Effects.costs_with_co2_share()
+    co2 = Effects.co2()
     co2.maximum_operation_per_hour = 1000
 
     # Create components
@@ -417,8 +413,8 @@ def simple_flow_system_scenarios() -> fx.FlowSystem:
     base_timesteps = pd.date_range('2020-01-01', periods=9, freq='h', name='time')
 
     # Define effects
-    costs = Effects.costs()
-    co2 = Effects.co2_with_costs_share()
+    costs = Effects.costs_with_co2_share()
+    co2 = Effects.co2()
     co2.maximum_operation_per_hour = 1000
 
     # Create components

From 9bac31b0a4cff4a6f18f6eb4dd16356cd8318dca Mon Sep 17 00:00:00 2001
From: FBumann <117816358+FBumann@users.noreply.github.com>
Date: Sat, 27 Sep 2025 18:12:33 +0200
Subject: [PATCH 6/8] Typos

---
 CHANGELOG.md | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2c92c268f..e3e1c4414 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -57,7 +57,7 @@ costs = fx.Effect(
     share_from_nontemporal={'land': 100}  # €100 per m² land use
 )
 ```
-This replaces the less intuitive `specific_share_to_other_effects_*` parameters and makes it clearer where effect contributions are coming from, rather then where they are going to.
+This replaces the less intuitive `specific_share_to_other_effects_*` parameters and makes it clearer where effect contributions are coming from, rather than where they are going to.
 
 **Multi-year investments:**
 A flixopt model might be modeled with a "year" dimension.
@@ -129,7 +129,7 @@ The weighted sum of the total objective effect of each scenario is used as the o
   - `maximum_operation_per_hour` → `maximum_per_hour`
 
 ### 🔥 Removed
-* **Effect share parameters**: The old `specific_share_to_other_effects_*` parameters were replaced WITHOUT DEPRECTATION
+* **Effect share parameters**: The old `specific_share_to_other_effects_*` parameters were replaced WITHOUT DEPRECATION
   - `specific_share_to_other_effects_operation` → `share_from_temporal` (with inverted direction)
   - `specific_share_to_other_effects_invest` → `share_from_nontemporal` (with inverted direction)
 

From 39cda0322aaffd2d34db98ca3081330e7ef73ed4 Mon Sep 17 00:00:00 2001
From: FBumann <117816358+FBumann@users.noreply.github.com>
Date: Sat, 27 Sep 2025 18:19:19 +0200
Subject: [PATCH 7/8] Improve Effect examples

---
 flixopt/effects.py | 31 ++++++++++++++++++++++++-------
 1 file changed, 24 insertions(+), 7 deletions(-)

diff --git a/flixopt/effects.py b/flixopt/effects.py
index 579fa095a..7ec275a9b 100644
--- a/flixopt/effects.py
+++ b/flixopt/effects.py
@@ -77,17 +77,21 @@ class Effect(Element):
         Basic cost objective:
 
         ```python
-        cost_effect = Effect(label='system_costs', unit='€', description='Total system costs', is_objective=True)
+        cost_effect = Effect(
+            label='system_costs',
+            unit='€',
+            description='Total system costs',
+            is_objective=True,
+        )
         ```
 
-        CO2 emissions with carbon pricing:
+        CO2 emissions:
 
         ```python
         co2_effect = Effect(
-            label='co2_emissions',
+            label='CO2',
             unit='kg_CO2',
             description='Carbon dioxide emissions',
-            share_from_temporal={'CO2': 0.2},  # €0.2 per kg CO2
             maximum_total=1_000_000,  # 1000 t CO2 annual limit
         )
         ```
@@ -110,7 +114,21 @@ class Effect(Element):
             label='primary_energy',
             unit='kWh_primary',
             description='Primary energy consumption',
-            share_from_temporal={'primary_energy': 0.08},  # €0.08/kWh
+        )
+        ```
+
+       Cost objective with carbon and primary energy pricing:
+
+        ```python
+        cost_effect = Effect(
+            label='system_costs',
+            unit='€',
+            description='Total system costs',
+            is_objective=True,
+            share_from_temporal={
+                'primary_energy': 0.08,  # 0.08 €/kWh_primary
+                'CO2': 0.2,  # Carbon pricing: 0.2 €/kg_CO2 into costs if used on a cost effect
+            },
         )
         ```
 
@@ -137,8 +155,7 @@ class Effect(Element):
         across all contributions to each effect manually.
 
         Effects are accumulated as:
-        - Total = Σ(operational contributions) + Σ(investment contributions)
-        - Cross-effects add to target effects based on specific_share ratios
+        - Total = Σ(temporal contributions) + Σ(nontemporal contributions)
 
     """
 

From 025441629d1b5d56cabcaffa6954c8340d2e6618 Mon Sep 17 00:00:00 2001
From: FBumann <117816358+FBumann@users.noreply.github.com>
Date: Sat, 27 Sep 2025 18:20:57 +0200
Subject: [PATCH 8/8] Add extra validation for Effect Shares

---
 flixopt/effects.py | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/flixopt/effects.py b/flixopt/effects.py
index 7ec275a9b..356bf7e93 100644
--- a/flixopt/effects.py
+++ b/flixopt/effects.py
@@ -593,6 +593,11 @@ def _plausibility_checks(self) -> None:
         # Check circular loops in effects:
         temporal, nontemporal = self.calculate_effect_share_factors()
 
+        # Validate all referenced sources exist
+        unknown = {src for src, _ in list(temporal.keys()) + list(nontemporal.keys()) if src not in self.effects}
+        if unknown:
+            raise KeyError(f'Unknown effects used in in effect share mappings: {sorted(unknown)}')
+
         temporal_cycles = detect_cycles(tuples_to_adjacency_list([key for key in temporal]))
         nontemporal_cycles = detect_cycles(tuples_to_adjacency_list([key for key in nontemporal]))