Sensible, latent, and ventilation loads in building systems

Separate the load components

Sensible load changes dry-bulb temperature. Latent load changes moisture content. Ventilation and infiltration can contribute to both, depending on outdoor and indoor conditions.

Equipment total capacity must be compared with total load, while sensible capacity must also satisfy the sensible component. A correct total alone does not prove that humidity and space temperature can both be controlled.

Exam-ready workflow

• Define indoor and outdoor design states.
• Classify envelope, internal, ventilation, and infiltration contributions.
• Keep sensible and latent calculations separate until total load is required.
• Verify airflow, psychrometric, and equipment-capacity units.
• Check whether diversity, schedules, heat recovery, or system configuration changes the stated condition.

Common failure modes

Typical mistakes include treating all outdoor-air load as sensible, adding coincident and noncoincident peaks without checking the premise, comparing sensible load directly with total equipment capacity, or using airflow relationships with inconsistent temperature and humidity units.