In the current implementation, there are multiple ways to set the lighting power:

• When use_maintained_illuminance is set to True, the lighting power is computed as lighting_power = maintained_illuminance / lighting_efficiency_lumen.
• When use_maintained_illuminance is False, the value of fixed_lighting_power is used.
• There is also a direct setter for lighting_power that, when invoked, forces use_maintained_illuminance to False.

This design leads to some issues:

• Unclear Dependencies: The relationship between lighting_power, fixed_lighting_power, maintained_illuminance, and lighting_efficiency_lumen is not obvious. Changes to maintained_illuminance, lighting_efficiency_lumen or fixed_lighting_power do not automatically update lighting_power if they are modified after use_maintained_illuminance was enabled.
• Risk of Inconsistency: Since the lighting_power attribute is stored separately and only updated when use_maintained_illuminance is set (or via the explicit setter), there is a risk that the value passed to Modelica does not reflect the latest lighting parameters.
• Non-Intuitive Naming: It is not clear what lighting sources correspond to the old and maintained state. Also, the parameter maintained_illuminance is somewhat misleading. A more intuitive name would be simply illuminance, indicating the target illuminance value, which should be the same for old and maintained lighting sources.
• Redundant Parameter: The fixed_lighting_power attribute appears redundant. Instead of having two separate methods of setting the lighting power, it would be preferable to rely on a single, computed value.

Proposed Changes:

• Rename maintained_illuminance to illuminance: Simplify the naming to clearly indicate that this parameter is the zone illuminance.
• Remove fixed_lighting_power: Eliminate the redundant parameter and compute lighting_power dynamically.
• Adopt a Record-Based Approach for Lighting Sources: Extend the direct setting of lighting_efficiency_lumen with a record that maps lighting source names to their corresponding efficiency (in lm/W). Users can then specify a lighting source like "Incandescent", "Halogen" "LED" or "fluorescent".
• Adopt UseConditions.json: Map old fixed lighting powers to lighting sources and just set a default one for each zone type.
• Remove use_maintained_illuminance

@FWuellhorst @DaJansenGit @HoeppJ what are your opinions on that and should we still allow the direct setting of the lighting_power to an area-specific value, or just have the one setting method with the efficiency?