📐 The 2H rule, and what has to be subtracted after itDEESEN

Which height governs, which way the setback points, and in what order the taboo zones are subtracted so that whatever stays white will hold up. Only one of the distances in this document is a number written into the law. The rest is planning practice — worth not confusing the two.

To the right of each restriction there is a comment thread. That is where what does not fit in the table belongs — the only thing actually argued about: whether the Behörde in that Land, with that Regionalplan, accepts the value.
STEP 1

Which height is «the height»

The 2H rule is not measured against hub height but against total height — Gesamthöhe, or Anlagenhöhe in the language of the BauGB — which is the blade tip at its highest point:

H = Nabenhöhe + Rotordurchmesser ÷ 2
and the reference distance is 2 × H
The public concern of an optically oppressive effect does not, as a rule, stand in the way of a wind energy project where the distance from the centre of the mast foot to a permissible building use for residential purposes is at least twice the height of the installation. § 249 Abs. 10 BauGB · working paraphrase
Nabenhöhe Rotorradius Ø Rotor ÷ 2 H Gesamthöhe permissible dwelling ≥ 2 × H Mitte des Mastfußes
From where to where it is measured. The origin is the centre of the mast foot, not the rotor axis and not the blade tip; the target is the permissible residential use, not the property line. H includes the rotor radius: mistaking it for hub height leaves the setback about 30 % short.
STEP 2

Which way the setback points

This is where nearly everyone goes wrong. 2H is a distance between a turbine and a dwelling, and as a distance it is symmetric. But the H that governs is always the turbine's, so the setback does not mean the same thing depending on what you centre it on.

A · centred on the EXISTING turbine H known — comes from the MaStR 2H blocks no effect Answers: where would this machine oppress a dwelling? → repowering and defending the existing farm B · centred on the DWELLING H = that of the planned machine — a parameter 2H permissible Answers: where does a new machine NOT fit? → THIS one subtracts potential area
The same distance, two different questions. Panel A is the ring drawn around the 40,100 MaStR turbines, and it serves repowering. Panel B is what produces the white map — and its radius depends on a machine that has not been chosen yet; that is why in the tool it is a control and not a datum.
STEP 3

2H is the new value: it used to be 3H

If you work with regional plans or reports from two years ago you will see 3H. That is not their mistake: it is earlier law. The case law — the OVG Münster line since 2006 — used 3H as the all-clear threshold. The BauGB amendment lowered the reference value to 2H.

Until 2024 · case law oppressive as a rule case-by-case review unobjectionable Since the amendment § 249 Abs. 10 BauGB case-by-case review favourable presumption · «in der Regel» 3H → 2H 0 2H 3H distance turbine → dwelling mast foot
What changed is not the prohibition but the presumption. Below 2H the project is not forbidden: it loses the favourable presumption and requires an Einzelfallprüfung. That is why the 2H ring reads as a review radius and not as a dead zone.
2H is not the only distance to be met. It settles the optical effect alone. Noise (TA Lärm), shadow flicker, species protection and whatever minimums each plan imposes still apply on their own. The governing distance is always the largest of them all.
STEP 4

The subtraction: one union, one difference

The complete white map is a single operation. The taboo zones are grouped into two families — hard, where there is no room for judgement, and soft, where the planner decides and therefore has to justify — then all are unioned and subtracted from the study area in one go.

Weißfläche = Untersuchungsraum − ⋃ (hard taboo) − ⋃ (soft taboo)
✕ chained difference AOI − A, then − B, then − C… slivers at every cut Same area, dirty geometry. The result depends on the order. ✓ union, then one difference AOI − ST_Union(A,B,C…) no seams inside Clean, reproducible geometry. Order stops mattering.
Why the order matters even though the area does not change. Every chained ST_Difference leaves slivers along the shared edges. With a prior ST_Union there is a single outline and the result does not depend on the order in which the layers were loaded.
STEP 5

What it looks like on the ground

Four layers are enough to see the mechanism: a settlement, an industrial estate, a road and a protected area. Each contributes its surface and — except the protected one — its setback too.

1 · the layers and their setbacks ■ Schutzgebiet · no setback ■ Wohnbaufläche + 2H ■ Gewerbe + distance ■ road + Anbauverbotszone − 2 · what stays white 412 ha 108 ha 96 ha ■ Potenzialfläche — the «white» of the white map Final filter: discard anything under 20 ha
The step most people forget: the size filter. After the subtraction there are scraps left that cannot take even one machine with its internal spacing. Discarding them is part of the method, not cosmetic tidying — and the threshold (20 ha here) has to be justified just like a setback.
STEP 6

What to subtract, and on whose authority

This is the part that holds up or falls apart on appeal. What matters is the label: only what is marked as law is an obligation with a number. The rest is planning practice, and it requires reasons for why that value was chosen and not another.

Protected areas are subtracted as surface, with no setback. The rule forbids inside, not around. Adding a ring «just in case» turns a legal prohibition into an unreasoned discretionary decision — exactly what an appeal looks for.
STEP 7

What the data says, and where it stays silent

The MaStR does not publish total height. It publishes nabenhoehe and rotordurchmesser separately, and the height has to be composed. Where either is missing there is no ring: the turbine is still drawn, in grey, with no setback.

QuantityValueNote
Onshore turbines with coordinates40,100offshore separate: 2H does not apply
With computable total height39,43998.4 %
No height → no ring6611.6 %, shown in grey
Total height: min · mean · max5.3 · 163.8 · 363.0 mthe minimum is a Kleinwindanlage
Resulting 2H radius10.6 · 327.6 · 726.0 mthe maximum is twice the «typical» setback
Protected areas (BfN)23,616NSG, NP, FFH, SPA, LSG, Naturpark, Biosphäre
Anlagenschutzbereiche (BAF)2,618binding, § 18a LuftVG

Two traps that raise no error at all

Sources: Marktstammdatenregister (Bundesnetzagentur, dl-de/by-2-0) · OpenStreetMap (ODbL 1.0) · Schutzgebiete of the Bundesamt für Naturschutz · Anlagenschutzbereiche of the Bundesaufsichtsamt für Flugsicherung. The legal citations are working paraphrases, not official text: for a formal application, go to the text in force.