What does the term 'occupancy' refer to in building regulations?

The term 'occupancy' in building regulations specifically refers to the purpose for which a building is being used. This definition encompasses the different categories of building use, such as residential, commercial, industrial, or assembly. Understanding occupancy is crucial because it influences various aspects of building design, including compliance with safety codes, fire regulations, and zoning laws. Each occupancy type has specific requirements regarding structural integrity, sanitation, fire safety, and accessibility, all aimed at ensuring the safety and well-being of occupants.

The other choices do not accurately define 'occupancy': the layout of the building pertains to spatial organization but does not address its intended use; the materials used in construction relate more to the quality and durability of the building rather than its purpose; and the number of exits in a building is a safety feature influenced by occupancy type, but it does not define the concept of occupancy itself. Hence, option B provides the most accurate definition in the context of building regulations.