BTA
BTA is the Norwegian abbreviation for gross floor area. It is the building's area measured from the outer face of the external walls on all measurable floors, external walls included. BTA is the largest of the standardised area measures and the one that gives the best impression of the building's physical footprint at floor level, unlike UFA, which measures internally.
The calculation follows Norsk Standard NS 3940, the same standard that governs UFA, P-rom and S-rom and the rest of the Norwegian area terms. A floor or part of a room only counts if it is measurable: clear height of at least 1.9 m and width of at least 0.6 m. The difference between BTA and UFA is precisely the external wall area; a home with 30 cm thick external walls typically gets a BTA that is 5-8% higher than the UFA. This gap grows with the building's perimeter, so slim tower blocks and buildings with a lot of facade get a relatively larger difference.
For homes, BTA was displaced as the standard measure when NS 3940 was revised in 2007/2008 and UFA established itself as the measure used by estate agents, valuers and price statistics. You still meet BTA in three contexts: in older sales prospectuses and valuations from before around 2008, in the matrikkel, where the building's BTA is still registered as one of the building's key figures, and in municipal planning provisions, where the degree of utilisation is sometimes stated as %-BTA instead of %-UFA. The guide to degree of utilisation in circular H-2300 describes how both BTA and UFA can be used as the regulated form of utilisation; the choice of measure is made by the municipality in each individual plan under the Planning and Building Act section 11-9 and section 12-7.
For commercial property, BTA lives on more clearly. Office buildings, logistics property and retail buildings are often reported in BTA because it reflects the total footprint the owner is responsible for: common areas, shafts, corridors, stairs, lifts and technical rooms. The ratio between BTA and lettable area in a commercial building varies from about 1.1 to 1.3 depending on the building's efficiency. In lease agreements it is common to state lettable area or UFA as the lettable surface and show BTA as a reference for common areas and the gross factor. The gross factor (BTA divided by lettable area) is one of the first key figures an investor checks when assessing the quality of an office building.
BTA is also the basis for municipal property tax in many municipalities that calculate the tax using a standardised formula, where the rate is multiplied by the building's area according to the matrikkel. What is measured (BTA, UFA or BOA) is set out in each municipality's decision on property tax and can vary from year to year. Traditional area calculations made before 2008 can therefore differ systematically from today's; a price per square metre from a 1980s prospectus should not be compared uncritically with today's UFA-based figures.
In Placepoint, the building's BTA is shown in the building panel together with UFA, the number of floors and the year of construction, taken from the matrikkel. For office and warehouse buildings, you use this figure to estimate the gross factor and compare efficiency across properties.
How it looks in Placepoint
In Placepoint, you find this in Building panel:
From Placepoint's dictionary: BTA
More information: Standard Norge: NS 3940, Regjeringen: circular H-2300 on degree of utilisation, DiBK: TEK17 section 5-4
English: Gross floor area (BTA, per Norwegian Standard NS 3940).
Frequently asked questions
What is the difference between BTA and UFA?
BTA is measured from the outside of the external wall and includes the external wall area. UFA is measured to the inside of the external wall and is the internal area. BTA is therefore always larger than UFA for the same building.
How large is the difference between BTA and UFA in practice?
Typically 5-8% for homes, depending on the thickness of the external walls. Buildings with a lot of facade per floor area (slim tower blocks, buildings with many corners) get a relatively larger difference.
Is BTA still used for homes?
Rarely. After the NS 3940 revision in 2007/2008, UFA has taken over as the standard measure in prospectuses, valuations and price statistics. BTA appears in older documents and as one of the building's registered figures in the matrikkel.
Why is BTA used more for commercial property?
BTA reflects the owner's entire responsibility, including common areas, shafts and technical rooms. The ratio between BTA and lettable area (the gross factor) is a central key figure for assessing the efficiency of an office building.
Where is BTA measured in Placepoint?
The building's BTA is one of the key fields in the building panel, taken from the matrikkel, together with UFA, the year of construction and the number of floors.