Temperature out of bounds error

Modified on Tue, 26 Aug at 10:06 AM

** Severe ** CalcHeatBalanceInsideSurf: The temperature of -148273.45 C for zone="1STFLOOR:ROOM", for surface="1STFLOOR:ROOM_FLOOR_0_4_0"

** ~~~ ** ..is very far out of bounds during warmup. This may be an indication of a malformed zone.

** ~~~ ** During Warmup & Sizing, Environment=SUMMER DESIGN DAY IN BUILDING (01-01:31-12) JUN, at Simulation time=06/15 20:20 - 20:21

** Fatal ** Program terminates due to preceding condition.

The error you're encountering is a severe temperature out of bounds error during the warmup period. The surface temperature of -148273.45°C is extremely low and indicates a significant problem with your model setup.

This means the surface temperature results became numerically unstable during the simulation. In most cases, the cause is related to model inputs, geometry, or material definitions, or to excessive/unbalanced heat gains without a way for the heat to dissipate

The extreme temperature error is typically caused by several issues:

A building with no or little thermal mass is the most common cause.
Improper surface construction with very thin or lightweight surface materials.
Zones that are not properly enclosed.
Excessive internal heat gains relative to the zone size.
Data center equipment loads without adequate heat removal capacity.
Equipment loads exceeding the HVAC system's capacity.
Low number of simulation timesteps (use 6 or more).

See Unmet Hours Severe Error: Temperature out of Bounds (Low) and EnergyPlus Surface Temperature.

Recommended checks:

Verify Zone Geometry

Ensure your data hall zone is properly enclosed:

All surfaces have appropriate constructions
Floor surfaces are properly defined
Zone volume and floor area are reasonable

Check Internal Heat Gains

Verify that internal heat gains are reasonable:

IT equipment loads should match actual specifications
Ensure loads are in watts, not kilowatts
Check that schedules are applied correctly
Consider if the loads are too concentrated for the zone size

Verify HVAC System Capacity

Ensure your HVAC system can handle the loads:

Check that the cooling capacity is adequate for the data center loads
Verify system availability schedules are "always on"
Ensure adequate airflow rates for heat removal
Check that the supply air temperature is appropriate

If the problem persists, you need to isolate the issue by temporarily removing internal loads to see if the geometry/construction is the problem and check that HVAC operates as expected (e.g., monitor zone air temperatures to confirm they remain within reasonable bounds).

In general, checking the .err for EnergyPlus errors and displaying the temperature/airflow nodes of the systems/ADUs and the zone air temperature output is the appropriate way to ensure that the building is modeled as expected (See the Analysing results in DesignBuilder’s interface and Simulation Manager and Results viewer tutorials).