Hi @Amirhossein and @Aaron Borian Thanks for this post. I am trying to test thermochromic paints with only two options (darker and lighter color), under 28 dergres and over 28 degrees. I followed @Aaron Borian script, but there is a sever error running the simulation.

Do you know how can I fix it?

This is the script that I am using:

 <ForAllExternalSurfaces>
 EnergyManagementSystem:Sensor,
   Surface_Outside_Face_Temperature_<LoopSurfaceVariableName>,
   <LoopSurfaceIDFName>,
   Surface Outside Face Temperature;
<LoopNextSurface>

<ForAllExternalSurfaces>
EnergyManagementSystem:Actuator,
  Surface_Cons_State_<LoopSurfaceVariableName>,
  <LoopSurfaceIDFName>,
  Surface,
  Construction State;
<LoopNextSurface>

EnergyManagementSystem:ConstructionIndexVariable,
  EMS_Cons_High_Abs,    !- Name
  High Absorptance Construction;              !- Material, 3_1_10061

EnergyManagementSystem:ConstructionIndexVariable,
  EMS_Cons_Low_Abs,    !- Name
  Low Absorptance Construction;              !- Material, 19_1_10062

EnergyManagementSystem:ProgramCallingManager,
  Thermo,
  BeginTimestepBeforePredictor,
  Thermo;

EnergyManagementSystem:Program,
  Thermo,
  <ForAllExternalSurfaces>
  if Surface_Outside_Face_Temperature_<LoopSurfaceVariableName> < 28,
  set Surface_Cons_State_<LoopSurfaceVariableName> = Material, 3_1_10061
  elseif Surface_Outside_Face_Temperature_<LoopSurfaceVariableName> > 28,
  set Surface_Cons_State_<LoopSurfaceVariableName> = Material, 19_1_10062,
  endif,
  <LoopNextSurface>
  ;

And this is the error message:

** Severe  ** GetRuntimeLanguageUserInput: EnergyManagementSystem:ConstructionIndexVariable="EMS_CONS_HIGH_ABS invalid field.
**   ~~~   ** Invalid Construction Object Name=HIGH ABSORPTANCE CONSTRUCTION
**   ~~~   ** Construction was not found.
** Severe  ** GetRuntimeLanguageUserInput: EnergyManagementSystem:ConstructionIndexVariable="EMS_CONS_LOW_ABS invalid field.
**   ~~~   ** Invalid Construction Object Name=LOW ABSORPTANCE CONSTRUCTION
**   ~~~   ** Construction was not found.
**  Fatal  ** Errors found in getting EMS Runtime Language input. Preceding condition causes termination.

Thanks! Camila