Data quality: an empty register clears nobody
Two searches in the same register give two very different pictures. Learn to see what a figure counts.
4 chapters · 4 questions
Two searches in the same municipality
In Silkeborg Municipality, 25,520 detached single-family houses are in BBR. 8,337 of them have a roof of “fibre cement including asbestos”. Only 24 are registered with asbestos.
Source: BBR + DAR (Datafordeler) — bygningsindeks via Grundfast · fetched
Calculate after
8,337 of 25,520 is 32.7% of the houses. The 24 with asbestos in the register are about 0.3% of the houses with a fibre cement roof. The figure 24 measures how often someone has registered asbestos — not how much asbestos there is.
Source: BBR + DAR (Datafordeler) — bygningsindeks via Grundfast · fetched
The same pattern in Copenhagen
In Copenhagen Municipality there are 14,964 detached single-family houses, 1,659 with a fibre cement roof and 2 registered with asbestos.
Source: BBR + DAR (Datafordeler) — bygningsindeks via Grundfast · fetched
What you write
Assess the risk from the material and the construction year, not from the asbestos field. Write “may contain asbestos” — never “no asbestos” because the field is empty.
Next step: Saneo's guides
Guides on asbestos, PCB, lead and sampling, explained simply and with sources.
Questions 1 / 4
In Silkeborg Municipality, 8,337 detached single-family houses have a fibre cement roof, but only 24 are registered with asbestos. What is the best explanation?