The maximum number of people permitted in a building or space, calculated based on building codes to ensure safe egress and fire protection.

Occupant load is the maximum number of people permitted to occupy a building or specific space at any given time, as calculated according to building code requirements based on the intended use and floor area of the space. This calculation is fundamental to building design and safety planning, as it determines requirements for egress systems, fire protection measures, plumbing fixtures, parking spaces, and various other building systems. Occupant load calculations ensure that buildings can safely accommodate their intended population while providing adequate means of egress during emergencies, proper ventilation, and sufficient infrastructure to support the occupants’ needs.

Occupant load calculations are based on occupant load factors specified in building codes, which assign different square footage allowances per person depending on the use and occupancy classification of the space. Common occupancy types include assembly spaces such as theaters, restaurants, and meeting rooms that typically have higher occupant densities, business occupancies like offices that have moderate density requirements, educational facilities with specific requirements based on classroom or assembly use, residential occupancies with lower density calculations, and industrial or storage spaces that generally have the lowest occupant densities. Each occupancy type has specific load factors that reflect the typical use patterns and safety considerations for that type of space.

The calculation methodology for occupant load involves dividing the net floor area of a space by the occupant load factor specified in the building code for that particular use. Net floor area excludes areas such as corridors, stairways, restrooms, and mechanical rooms that do not contribute to the occupiable space. For mixed-use buildings, each area is calculated separately based on its specific use, and the total building occupant load is the sum of all individual area calculations. Special considerations may apply for spaces with fixed seating, outdoor areas, or unusual configurations that require alternative calculation methods.

Fun Fact: The concept of occupant load calculations was first developed after the 1942 Cocoanut Grove nightclub fire in Boston, which killed 492 people, leading to modern building codes that require scientific calculation of building capacity based on egress requirements.

• Average Load (Electrical)
• Dead Load
• Design Load