When to use: Use this when designing an industrial control panel to verify the enclosure can dissipate the internal heat load from PLCs, VFDs, transformers, and power supplies without exceeding the rating of the components inside. The still-air dissipation factor of 0.34 W/(ft²·°F) for painted steel determines how much natural convection can remove. If the internal heat exceeds that capacity, forced-air fans or an enclosure air conditioner are required.