The design requirements for standpipes depend on:

The correct answer is driven by the fact that building codes set forth specific requirements for fire safety systems, including standpipe design, based on the conditions and standards at the time of construction. These codes dictate crucial elements such as the size, type, and placement of standpipes to ensure they are effective in providing firefighters with the necessary support during an emergency.

By adhering to the codes established at the time, the design caters to local conditions, the intended use of the building, and the anticipated fire response needs. Compliance with these codes ensures that the standpipe system is properly integrated into the overall fire protection strategy of the building.

Other factors, such as the age of the building, location, and water supply availability, do play a role in the overall fire safety considerations, but they are influenced by the building code requirements that were applicable at the time of construction. The codes encompass provisions related to these aspects, establishing a framework that must be followed for effective fire safety management.