Building Definition Language

68. Functional Requirements

A Functional Requirement defines what a building, system, Assembly, Component, Cartridge, Interface, or Space shall accomplish without prescribing unnecessary implementation details.

Every Functional Requirement shall define:

Requirement ID;

subject;

required function;

initiating condition;

inputs;

required outputs;

operating context;

performance criterion;

priority;

verification method;

responsible authority;

lifecycle stage.

Example:

functional_requirement FR_Kitchen_Water_001 {

subject: @Kitchen_Service_01;

function: provide_potable_cold_water;

destination: @Kitchen_Sink_01;

when: @Building.mode in [occupied, maintenance];

required_flow: minimum 7.5 L/min;

required_pressure: [140 kPa, 550 kPa];

verification: @Kitchen_Water_Commissioning_Test;

priority: mandatory;

}

Functional requirements shall distinguish among:

required;

preferred;

optional;

conditional;

prohibited.

A requirement may remain implementation-neutral:

requirement FR_Ventilation_001 {

subject: @Bedroom_01;

function: maintain_required_ventilation;

implementation: unrestricted;

}

A selected system or Cartridge may later satisfy the requirement.

Requirement satisfaction shall be represented explicitly:

satisfies @Ventilation_Cartridge_01

requirement @FR_Ventilation_001;

A Component shall not be considered compliant merely because its name suggests the required function. Its declared and verified capabilities shall satisfy the complete requirement.