When the architectural model lands on your desk, the first job of an HVAC engineer is not to draw ductwork. You first need to know how large each room is, how tall it is and what it is used for. Only then can you size the cooling load and the airflow for it.
Spaces in Revit hold exactly that data. A space is a volume the MEP engineer places in their own model, and its boundary follows the walls, floors and ceilings of the linked architectural model. This article walks through 15 steps in Revit 2027. Switch on Room Bounding for the link, place spaces for a whole floor with one button, patch the regions that report an open boundary, pull the room names across, then build a schedule to check the result. To learn the whole MEP workflow on one building, see the Revit MEP course.
What spaces in Revit are, and how they differ from rooms
Autodesk draws a clear line on the Spaces page: a room is an architectural component, while a space is used exclusively by the MEP disciplines to analyse volume. The two sit on top of each other but stay independent.
| Room | Space | |
|---|---|---|
| Who places it | The architect, in the architectural file | The MEP engineer, in the MEP file |
| Where it lives on the ribbon | Architecture › Room & Area | Analyze › Spaces |
| What data it carries | Room name, area, finishes | Cooling load, airflow, lighting |
| Splitting an open area | Room Separator | Space Separator |
| Allowed inside a link | Yes, rooms belong to the architectural file | No, a space must sit in the open file |
That last row is why you place spaces even though the architect already has rooms everywhere. Autodesk states that every space must live in the host file, because volume computation and load analysis do not read spaces from a linked model.
Spaces are also the mandatory input for three jobs: heating and cooling loads, the supply airflow for each room, and the estimated illumination used when you place lighting fixtures. Without spaces, none of the three runs.
The file to follow along with
You need an MEP file with an architectural model linked in and levels that match. The article on the Revit MEP sample file shows how to take the Institute's sample file and link the Snowdon Towers architectural model that ships in the Samples folder of Revit 2027. Linking and aligning levels is covered in linking Revit models.
The screenshots come from a typical residential floor: a central corridor, apartments on both sides, suspended ceilings in the rooms and in the corridor.
Seven steps to place a revit space on a whole floor
A revit space does not sit on the Systems tab with most of the MEP tools. It lives on the Analyze tab.
Step 1. Open the floor plan of the level you are working on. Spaces can only be placed in plan views; they are not visible in 3D or elevation views.
Step 2. Click the linked architectural model. The status bar reads RVT Links : Linked Revit Model : <file name>, which confirms you picked the whole link and not a single wall.
Step 3. In the Properties palette click Edit Type. In the Type Properties dialog, the Constraints group holds the Room Bounding check box. Tick it and click OK.
Room Bounding is off by default. That is the number one cause of the open region warning below, and the step most often skipped, because the walls of the link keep showing normally in plan either way.
Step 4. Run Analyze › Spaces › Space. The ribbon switches to the Modify | Place Space tab with two panels: Spaces (Place Spaces Automatically, Highlight Boundaries) and Tag (Tag on Placement, Orientation, Leader Line, Space).
Step 5. Set the upper boundary of the space in the Properties palette before you place anything. The Constraints group holds Upper Limit (the level used as the reference) and Limit Offset (the distance measured up from it). Revit 2027 no longer shows an Options Bar for this command; everything sits on the Properties palette and on the ribbon.
Step 6. Check the Tag on Placement button on the Tag panel. With it on, every space gets a tag showing its name and number, which makes the checking step much easier.
Step 7. Click Place Spaces Automatically. Revit sweeps the level, drops a space into every enclosed region and reports how many it created.
Autodesk notes two things about the automatic command. It only creates spaces for enclosed regions larger than 0.25 sq ft, and a space created where a room already exists is flagged as Occupiable.
Automatic placement is fast but generous: shafts, wall cavities and lift wells also become spaces. Review the result and delete the extras in the space schedule, as described below.
Space is not in a properly enclosed region: patch it with a space separator
This is the warning every newcomer meets. It appears at the bottom right corner the moment you click, and the space is still created — but it has no area and no volume, so it is useless for any calculation.
Three causes, in order of frequency:
- Room Bounding is off on the link. The floor has no boundaries at all and every space is broken. Fix it with step 3.
- The region really is open. An open lobby, an open corridor, a balcony without a partition.
- The partition is not a room bounding component. A partition modelled as a Generic Model, or a curtain element imported from IFC, does not enclose anything.
Cases 2 and 3 are handled with the Space Separator, on the same Spaces panel.
Step 8. Place a test space in the suspect region. The warning above tells you the region is not closed.
Step 9. Click Space Separator and draw the missing edge. The separator is a room bounding model line drawn in plan; run it far enough to touch the walls at both ends. Autodesk points out that the separator only controls the horizontal boundary, while the height of the space still comes from floors, ceilings and the Upper Limit and Limit Offset parameters.
Step 10. Go back to the Space command and click inside the region you have just closed. The new space picks up the right boundary and reports area, perimeter and volume straight away.
One region holds one space. Place a second space in the same region and Revit opens the warning Multiple Spaces are in the same enclosed region with three choices: delete the extra space, ignore, or cancel.
Space naming: take the names from the architectural rooms
Spaces created automatically are called Space plus a number. Nobody can read a schedule like that, and typing a hundred room names by hand is slow and error prone. The Space Naming tool copies names and numbers from the architectural model.
Step 11. Run Analyze › Spaces › Space Naming. The dialog offers three options — Names and Numbers, Names Only, Numbers Only — and lets you apply the change to all levels or to selected levels, with the number of affected spaces shown.
Step 12. Click OK. The space tags change to the architectural room names.
Wherever the architect has no room, the space keeps its old name. A tag still reading Space with a number is an immediate sign that the architect left that region unnamed, or that your space drifted into the wrong region.
Run the tool again after every model exchange: if room names or numbers changed, the spaces follow.
The space schedule: finding broken and duplicate spaces
You cannot tell a broken space from a plan view. A schedule can.
Step 13. Run View › Schedules › Schedule/Quantities, pick the Spaces category and click OK.
Step 14. Add the fields worth checking: Number, Name, Volume, Occupiable, Area. A broken space carries no figures in the area and volume cells; it reads Not Placed or Not Enclosed instead.
Step 15. Opening the schedule switches the ribbon to the Modify Schedule/Quantities tab. Its Not Placed/Unenclosed panel holds three buttons: Show, Hide and Isolate. Click Isolate and the schedule lists only the unplaced and unenclosed spaces, which is exactly the list you have to fix. Click Show to bring everything back.
Deleting spaces belongs in this schedule too. Selecting a space in the plan and pressing Delete only removes it from that location; the data stays in the file as an unplaced space. Deleting the row in the schedule removes it for good.
From CAD: drop the area polyline
In CAD you draw a closed polyline along the walls and query its area, or run a lisp routine that adds the areas up and copies them into a load spreadsheet. Every architectural revision means doing it again, and the room height never makes it into the sheet.
| In CAD | Spaces in Revit 2027 |
|---|---|
| A polyline traced along the walls | A boundary that follows the walls, floors and ceilings of the link |
| Area only | Area, perimeter, volume and level |
| Room names typed by hand | Space Naming copies them from the rooms |
| Numbers copied into a spreadsheet | The schedule exports directly and follows the model |
If the architect only sends DWG files you can still place spaces: link the DWG into the plan, trace the walls with the Space Separator until every region is closed, then place the spaces. Exporting the schedule is covered in schedules in Revit.
When spaces do not behave
| Symptom | Cause | Fix |
|---|---|---|
Space is not in a properly enclosed region | Room Bounding off on the link, or a genuinely open region | Tick Room Bounding; close the region with a space separator |
Multiple Spaces are in the same enclosed region | Two spaces in one region | Click Delete Space(s) in the warning |
| Automatic placement creates far too many spaces | Shafts and wall cavities are enclosed regions too | Sort the schedule by area and delete the rows |
| Spaces disappear when the link is unloaded | Their boundary comes from the walls of the link | Keep the link loaded while you run analyses |
| Space Naming renames some rooms and skips others | The architect has no room in that region | Ask for the missing rooms, or type the name in |
| No spaces visible in the plan | Their display is switched off | Type VG, find Spaces, tick Interior and Reference |
| A deleted space is still in the schedule | Deleting in a view only unplaces it | Delete the row in the space schedule |
Three things people often get wrong:
| What you often hear | What Revit 2027 actually does |
|---|---|
| The architect has rooms, so spaces are not needed | Load and volume calculations only read spaces held in the MEP file |
| A space is a 3D box you draw | A space is generated from room bounding components; its height comes from Upper Limit and Limit Offset |
| Once spaces exist you have cooling loads | Spaces are only the input; loads are calculated later, after the spaces are grouped |
Frequently asked questions
How is a space different from a room?
A room belongs to the architectural model, a space to the MEP model. A space carries load, airflow and reflectance data, and it must sit in the MEP file itself.
Why does Revit say space is not in a properly enclosed region?
The region is not closed. The usual reason is that Room Bounding was never ticked in the Type Properties of the linked architectural model.
Do I need spaces in the ceiling void?
Yes, if the void works as a return plenum or holds equipment. Autodesk recommends placing spaces in every area, voids and shafts included, so that internal walls are not mistaken for exterior ones.
Can space names be filled in automatically?
Yes, with Space Naming on the Spaces panel. It copies names and numbers from the architectural rooms to the spaces, for all levels or for selected levels.
Do spaces follow when the architect moves a wall?
The boundary is derived from the room bounding components of the link, so it follows the new walls. Names and numbers, however, only update when you run Space Naming again.
Related articles
- What is Revit MEP — the three MEP systems and what the engineer does in Revit
- Revit MEP sample file — the file used in this walkthrough
- Heating and cooling loads in Revit — the next step after spaces
- Room areas in Revit — the architectural side of the same story