Overview
EN ISO 4157-3:1998 - Construction drawings: Designation systems - Part 3: Room identifiers (ISO 4157-3:1998) defines a standardized system for uniquely identifying rooms, areas, spaces and voids in buildings across the entire building lifecycle. Adopted by CEN, this part of ISO 4157 provides rules to create persistent, computerized-friendly room identifiers that support planning, construction, maintenance, refurbishment and demolition.
Key topics and requirements
- Unique, persistent identifiers: Room identifiers are intended to remain stable throughout a building’s life and must not be revised once assigned.
- Composition and format: An identifier consists of a storey number combined with a typically three‑digit sequence, preceded by the prefix I# (ISO Room Identifier). Example sequencing per storey starts at I#n001 and ascends without gaps.
- Positive integers: Room identifiers are expressed as positive integers and include one more digit than room numbers to clearly distinguish them from room numbering systems.
- Geometry-based definition: Rooms are defined by their physical boundaries or by imaginary planes corresponding to building parts (storey levels, beams, partitions), enabling precise spatial definition.
- Correspondence rules:
- Every room number must have a corresponding room identifier.
- Not all room identifiers need corresponding room numbers or room names.
- Documentation requirements: Owners should maintain a complete list of room identifiers with cross-references to:
- Geometry (x, y, z coordinates - origin, minimum and maximum extensions)
- Dates of erection and demolition
- Room names and room numbers (if any)
- Computer interoperability: Identifiers are designed for interface with computerized information systems (BIM/CAFM).
Applications and users
Practical uses of EN ISO 4157-3:1998 include:
- BIM and CAD authors: consistent tagging of spaces across models and construction drawings.
- Facility and asset managers: linking equipment, maintenance records and space schedules to a stable identifier.
- Architects and building designers: harmonizing room data from concept through handover.
- Contractors and facility operators: tracking changes during construction, remodels and demolition.
- Software vendors: implementing standard identifiers in CAFM, IWMS and BIM tools for reliable data exchange.
- Emergency planners and surveyors: precise location referencing using room coordinates.
Related standards
Using EN ISO 4157-3:1998 helps organizations achieve consistent room identification, improved data interoperability, and reliable lifecycle information management for buildings.