Denmark — BR18
Legal status
Mandatory. BR18 (Bygningsreglementet 2018) is the Danish building regulation. Daylight and view out are covered by Chapter 18, §§ 378–381. The regulation gives two separate functional requirements — view out (§378) and daylight (§379) — plus an exemption (§380) and a solar-overheating/glare provision (§381). The guidance (vejledning) to Chapter 18 sets out the calculation assumptions.
Requirement
View out (§378)
Work rooms, common rooms, teaching rooms, dwelling rooms, etc. must have windows positioned so that people in the room can see out to the surroundings. Windows and solar shading must be designed and built so that a satisfactory view out is maintained for a satisfactory part of the time the room is in use. LUX does not currently assess this requirement — it reports daylight only.
Daylight (§379)
Work rooms, common rooms in institutions, teaching rooms, dining rooms (together "work rooms, etc."), dwelling rooms and kitchens must have enough daylight access that the rooms are sufficiently lit. Compliance is shown by one of these routes:
| Route | Metric | Threshold |
|---|---|---|
| A — glazing area (primary/simplified method) | Glass area, corrected for shading and light transmittance per the vejledning | ≥ 10 % of the relevant floor area, with no shading assumed before correction |
| B — dynamic illuminance (EN 17037 method) | Illuminance / DA | 300 lx reached over ≥ 50 % of the relevant floor area for ≥ 50 % of the daylight hours |
| C — other methods | Any | Accepted if it can otherwise be documented that the room is sufficiently lit — this is where a daylight factor calculation fits in practice, though §379 does not name a DF threshold itself |
| Item | Value |
|---|---|
| Assessment level | Per room |
| Relevant floor area — dwelling rooms | The internal floor area of the room |
| Relevant floor area — work rooms etc. | Only the area where workstations are placed |
| Exemption (§380) | The daylight requirement can be waived where meeting it would be a decisive disadvantage to the business's operation — e.g. where the nature of production does not allow daylight |
| Solar overheating/glare (§381) | Windows must be designed, placed and, where needed, shaded so that sunlight through them does not cause overheating or direct-sun nuisance — not assessed by LUX today |
The DF ≥ 2.1 % figure previously listed here as "Route A" does not appear
in §379 itself — the law's own primary route is the 10 % glazing-area method.
2.1 % may come from a vejledning-derived DF equivalent to that glazing ratio,
but this needs confirming against the current guidance text before being
restated as a named threshold; flagged with ?? below.
| Item | Value |
|---|---|
| Possible DF equivalent (unconfirmed) | ?? — a DF figure around 2.1 % has circulated as a rule-of-thumb equivalent to the 10 % glazing rule, but is not itself in §379 or confirmed against the current vejledning |
Calculation setup
| Parameter | Value | Notes |
|---|---|---|
| Reference plane height | 0.5 m above floor | BR18 guidance (differs from EN 17037's 0.85 m) — ?? confirm against current vejledning |
| Grid spacing | 0.2–0.3 m | Common practice, not prescribed; BR18 guidance is expected to reference the EN 17037 grid, not yet confirmed |
| Wall offset (excluded border) | 0.5 m | |
| Sky model | Route B: climate-based (Perez, hourly weather file) · a DF-based check would use CIE standard overcast |
Reflectances are not stated in BR18/vejledning; see Reflectance for the values LUX uses.
How LUX handles it
Status: 🔜 Planned, not yet supported in LUX Live v0.3.0.
A daylight-factor check (Route C, "other methods") maps directly onto the existing LUX daylight-factor output once the DF equivalent figure above is confirmed; Route A (glazing area) is a simple geometric check LUX does not currently perform; Route B needs the climate-based illuminance pipeline.
Sources
- Bygningsreglementet BR18 — Kapitel 18: Lys og udsyn (§§ 378–381) — Bolig- og Planstyrelsen (free)
- Vejledning om lys og udsyn — Bolig- og Planstyrelsen (free)
- DS/EN 17037:2019 — Dagslys i bygninger — Dansk Standard (paid standard)