CAFM & operations
Area calculation: which area applies, and when
For the same building, DIN 277, the German Living Space Ordinance and MF-GIF can produce different figures. That is not a contradiction but a question of purpose. Anyone who commissions an area without naming the rule gets a number that is right somewhere and holds nowhere in a dispute.
Three sets of rules, three purposes
DIN 277 describes floor areas in building construction: gross floor area, net room area and its division into usable, services and circulation area. It is the basis for cost estimating, design and almost every operational key figure.
The Living Space Ordinance (Wohnflächenverordnung) determines the living area for residential tenancy and purchase contracts. It counts sloping ceilings in stages and balconies proportionally; DIN 277 knows neither.
MF-GIF is the gif industry guideline for lettable areas in commercial property. Not a DIN standard, but the standard in tenancy agreements: it governs which areas count as lettable and how common areas are apportioned. Since 2023 it has merged the earlier separate guidelines for retail, letting and residential (MF/G, MF/V, MF/W) into one document; older agreements often still refer to MF/G or MF/V. What the contract says governs, and that is exactly what we note in the title block.
The difference between DIN 277 and the Living Space Ordinance always arises at the same three places: sloping ceilings, balconies and ancillary rooms.
Where the area comes into being
Not in the table but at the room polygon. An area that appears only as text in the drawing is visible but cannot be evaluated, and it drops out on import into a target system.
Who asks for which area
| Occasion | Rule | Particularity |
|---|---|---|
| Commercial letting | MF-GIF | with the apportionment of common areas shown |
| Residential letting | WoFlV | sloping ceilings in stages, balconies proportionally |
| Cleaning tender | DIN 277 | usable areas, separated by floor finish |
| Area apportionment in operation | DIN 277 | the only one of the three that describes the whole building |
| Cost estimating and design | DIN 277 | gross floor area |
| Funding applications and evidence | DIN 277 | with a documented survey date |
In practice several are needed. All of them can be derived from one survey; applying a second rule afterwards is work on the same drawing, not a second visit.
How we deliver it
The areas come into being at the room polygon in the as-built drawing, not as text beside it. They are handed over as an area schedule and as a property on the polygon, so that the two match and nothing is lost on import, in the same structure as with the room book.
Which rule applies is fixed before the calculation and noted in the title block, together with its edition and the survey date. An area figure without its rule is worthless in a dispute.
And the basis is a measurement, not an old drawing: anyone copying areas out of existing documents inherits their errors and carries them forward into rent, apportionment and funding. How the survey works is set out under 3D laser scanning.
Further reading
- Room book – the attributes that go with the area
- 2D as-built plans – where the room polygon comes into being
- CAFM data foundation – what the areas are needed for in operation
- 3D laser scanning – the measurement as the basis
- MF-GIF – the guideline for commercial lettable areas, as a glossary entry
- DIN 276 and cost group 400 – how the technical services are ordered
Frequently asked questions about area calculation
Why do DIN 277 and the Living Space Ordinance give different figures?
Because they count differently. The Living Space Ordinance only counts areas under sloping ceilings from one metre of clear height, and between one and two metres only by half; balconies and terraces usually count as one quarter, at most one half. DIN 277 does not know these reductions and states the full floor area. The same attic flat can therefore be noticeably larger under DIN 277 than under the Living Space Ordinance.
Which types of area does DIN 277 recognise?
The gross floor area as the sum of all plan levels, the construction floor area of the components and the net room area as the usable remainder. The net room area divides into usable area, services area and circulation area. For operation and benchmarking the usable area is usually the decisive figure.
What applies to commercial lettable areas?
MF-GIF, unless the tenancy agreement says otherwise. Older agreements often still refer to MF/G or MF/V; then the edition named there applies. We calculate to the rule stated in the contract and show it in the title block.
Can several types of area be calculated from one survey?
Yes, that is the normal case. The geometry comes from the same point cloud; only the counting rules differ. DIN 277 for operation and the Living Space Ordinance for letting from a single visit is standard, and a rule added later needs no new site visit.
Does the area calculation hold up in a dispute?
Yes, if three things are documented: the rule applied together with its edition, the survey date, and the fact that the area arises at the room polygon rather than as a mere text entry. That is exactly how we hand over. The point cloud remains archived as the measurement record.
We already have areas in our old drawings. Is that not enough?
Usually not. Old drawings show the state at the time they were made, not today’s, and their areas were often calculated to rules that have since been superseded. Anyone basing rent, apportionment or funding on them carries the discrepancy forward every year. A fresh calculation from a current survey costs once and holds permanently.