When you've mastered Pr, Ss, and EF, you might think you're done with UniClass hierarchies. Then someone asks you to classify a gas meter room or a lift pit, and you realize there's a whole other set of tables you need to understand.
Location codes: SL (Spaces/Locations), Co (Complexes), and En (Entities). These are the codes for where things are, not what they are.
Let me break it down the way I wish someone had explained it to me.
The Core Concept: Three Ways to Describe Where Something Is
UniClass location hierarchies describe physical places in and around buildings:
- SL (Spaces/Locations) - Individual rooms and defined spaces within a building
- Co (Complexes) - Groups of buildings or facilities that work together
- En (Entities) - Complete buildings or structures as whole units
The same physical location can have different codes depending on the scale you're working at.
My Go-To Analogy (Still Terrible, Still Works)
Think about where you work:
Your Space (SL) is your desk or office, the specific room where you sit. The Complex (Co) is your office campus or business park, multiple buildings working together as one facility. The Entity (En) is your actual office building, the complete structure with its own address.
A Construction Example That Actually Makes Sense
Let's take a hospital project:
- SL (Space/Location): An operating theatre, a specific room with defined boundaries and function
- Co (Complex): The hospital campus, multiple buildings (main hospital, outpatient clinic, car park) functioning as one healthcare facility
- En (Entity): The main hospital building, the complete structure, one building in the larger complex
So when you're classifying spaces: the operating theatre is an SL code, it sits within an Entity (the hospital building), which is part of a Complex (the entire hospital campus).
The Awkward Spaces Problem
This is where most people struggle: gas meter rooms, electrical risers, lift pits, plant rooms.
These are spaces (SL codes), not products. You're not classifying the gas meter itself (that's a Pr code), you're classifying the room that houses it.
Common mistakes:
- Gas meter room ≠ Gas meter (that's equipment, use Pr)
- Gas meter room = Specialized space for utilities (use SL)
Same for:
- Lift pit (the space) vs Lift (the product)
- Electrical riser (the vertical space) vs Electrical distribution board (the equipment)
- Plant room (the space) vs HVAC equipment (the products inside it)
When Do You Use Each One?
- Space planning and room schedules? Use SL (Spaces/Locations)
- Campus master planning or multi-building projects? Use Co (Complexes)
- Whole building classification or facility registers? Use En (Entities)
The Hierarchy in Action:
Here's how they nest together:
- Complex (Co): University Campus
- ↳ Entity (En): Engineering Building
- ↳ Space (SL): Lecture Theatre 3
- ↳ Space (SL): Mechanical Plant Room
- ↳ Space (SL): Electrical Riser
The hierarchy flows from largest (Complex) down to smallest (Space).
Why This Matters for BIM Coordination
When you're populating your Revit model with UniClass codes:
- Rooms and spaces = SL codes
- The building itself = En code
- Multi-building projects = Co code for the overall site
Getting this wrong means your asset registers, space schedules, and facility management data won't make sense because the facility managers can't locate the elements, what space they are in. Across one building or several. In the end the asset data is not made for fun but for the operations and maintenance.
The Bottom Line
If you're asking "where is it?" or "what type of space is this?" you need location codes (SL/Co/En).
If you're asking "what is it?" or "what product is this?" you need Pr/Ss/EF codes.
Do you want to try it out? Go to UniClass Wizard to search across all hierarchies at once. You can also select what category to search.
