Honeybee / EnergyPlus sizing error: PsyPsatFnTemp temperature out of range

ladybug-tools
1

Hi everybody! My master thesis simulation is driving me insane…

AUT_NO_Amstetten.110180_TMYx.epw (1.5 MB)
debug.gh (56.0 KB)
SchoolModel - Pre retrofit - Natural ventilation.gh (214.5 KB)
rhino model Gofile - Cloud Storage Made Simple

whenever I run a simulation I get this warning:

Program Version,EnergyPlus, Version 2

5.1.0-1c11a3d85f, YMD=2026.03.23 13:50,

************* Beginning Zone Sizing Calculations

** Warning ** Temperature out of range [-100. to 200.] (PsyPsatFnTemp)

** ~~~ ** Routine=CalcPurchAirLoads, During Sizing, Environment=AMSTETTEN HEATING DESIGN DAY 99.6% CONDNS DB, at Simulation time=01/21 24:00 - 24:10

** ~~~ ** Input Temperature=-461.96

************* ===== Recurring Error Summary =====

************* ** Warning ** Temperature out of range [-100. to 200.] (PsyPsatFnTemp)

************* ** ~~~ ** This error occurred 1 total times;

************* ** ~~~ ** during Warmup 0 times;

************* ** ~~~ ** during Sizing 1 times.

************* ** ~~~ ** Max=-461.964630 C Min=-461.964630

I tested both scenarios:

  • a predefined/base Honeybee program with working thermostat setpoints

  • a custom HB Setpoint object with simple constant heating/cooling setpoints

In both cases, as soon as the room is conditioned and has valid setpoints, the model enters sizing and the error appears:

Temperature out of range [-100. to 200.] (PsyPsatFnTemp)

Routine=CalcPurchAirLoads

During Sizing

What I found:

  • If the room is unconditioned, the error disappears.

  • If HVAC is assigned but there are no thermostat setpoints, Honeybee reports that the Ideal Loads Air System will not be translated.

  • If the room is conditioned and there is a valid setpoint path (either from a predefined program or from a custom setpoint object), the sizing error appears.

  • So the trigger seems to be the conditioned-zone sizing path with valid thermostat setpoints, not only a custom setpoint object.

  • The issue occurs during sizing, not during the normal run period.

Software:

  • Ladybug Tools version: 1.9.4

  • EnergyPlus version: 25.1.0

The debug script is an extremely reduced version where I tried to cut the script as much as possible to identify the culprit, but I am really lost.

Many thanks to whoever is going to give me some help!