Hi all, PCM manufacturers often provide the following technical data on their products:

• 'Switching' temperature 23°C
• Latent heat capacity ∆H 330 kJ/m2 at 'switching temperature'
• Specific heat capacity approx. 1.20 kJ/kgK
• Thermal conductivity λ approx. 0.18 W/(mk)

How can one define the enthalpy curve of the material for the use in EnergyPlus based on this? The IDF file takes inputs as shown below. With the ∆H provided for the switching temperature I can describe the jump at 23C but how is the base enthalpy of the material inferred so that data-points for -20C, 20C and 100C can be provided to EnergyPlus.

MaterialProperty:PhaseChange,
PLASTER OR GYP BOARD, !- Name
0.0, !- Temperature coefficient ,thermal conductivity(W/m K2)
-20., !- Temperature 1, C
0.01, !- Enthalpy 1 at –20C, (J/kg)
20., !- Temperature 2, C 33400, !- Enthalpy 2, (J/kg)
20.5, !- temperature 3, C 70000, !- Enthalpy 3, (J/kg)
100., !- Temperature 4, C 137000; !- Enthalpy 4, (J/kg)