Sunlight, daylight and neighbour law: which rules apply?

Three frameworks for sunlight: sun exposure, daylight and neighbour law

In the Netherlands, three separate frameworks govern sunlight and daylight at a home. Sun exposure (bezonning) measures the number of sun hours and is tested against the TNO standard — a guideline, not a law. Daylight measures the amount of daylight indoors and is laid down nationally in the Building Works Environment Decree (Bbl). Neighbour law (article 5:37 of the Civil Code, BW) governs unlawful nuisance between neighbours, including the withholding of light.

These three are often confused, even though they measure different things and have a different legal status. The table below sets them side by side. After that we go through them one by one, plus the two questions that come up most often: does the size of your window count, and what happens if one façade is built up against?

Sun exposure: how many hours of sun, tested against the TNO standard

Sun exposure is the duration of direct sun at a measurement point, expressed in hours per day on fixed test dates. The test is against the TNO standard: the light standard requires at least 2 sun hours between 19 February and 21 October, the strict standard 3 sun hours between 21 January and 22 November, measured at the middle of the windowsill at a height of 75 cm. This is the most commonly used test in permit decisions, but it is a guideline, not a law.

According to the Information Point for the Living Environment (IPLO), central government has not laid down instruction rules for sun exposure: under the Environment Act (Omgevingswet), each municipality decides for itself how it weighs sun exposure in the environment plan. In the Almelo ruling (18 January 2023, ECLI:NL:RVS:2023:172), the Council of State confirmed that there are “no statutory standards for the sunlight of dwellings”, but that it is “not unusual” to align with the light or strict TNO standard.

A number of municipalities have their own variant. The Hague measures at the façade rather than the window, with a lower limit of 10° solar altitude and a 50% threshold for roof additions. Rotterdam and Eindhoven work with an assessment framework in which a reduction in sun exposure of up to 15% is acceptable. The full explanation of the test dates, the measurement point and the municipal variants is in our article The TNO sunlight standard explained.

Daylight: the only sunlight rule genuinely written into law

Daylight — in full, daylight admission — is the amount of daylight that a habitable room receives, and this is the only sunlight aspect that is nationally and mandatorily written into law. Since 1 January 2024 the requirements have been laid down in the Building Works Environment Decree (Bbl), the successor to the 2012 Building Decree (Bouwbesluit 2012). For new construction, articles 4.146 and 4.147 apply; for existing buildings, articles 3.81 and 3.82.

The requirement is a minimum equivalent daylight area, calculated according to NEN 2057. For new construction with a residential function, a habitable area must have at least 10% of its floor area as equivalent daylight area, and each separate habitable room at least 0.5 m². The calculation corrects the glazed area for orientation, type of glass and the obstruction angle of objects in front of it. Here, therefore, window size does count heavily — unlike with the sunlight standard.

Important for anyone expecting nuisance from the neighbours: the daylight requirement is tested at the moment a building is itself granted a permit. Obstructions on another parcel are, under article 4.147(3), left out of consideration (IPLO). A roof addition or tower built later by the neighbours therefore does not trigger a new daylight test on your existing home. The daylight requirement protects your home at the design stage, not against what a neighbour later puts up next to it. For that, the sunlight framework and neighbour law are the appropriate routes.

Does the size of your window count?

For sun exposure, no; for daylight, yes. That difference is large enough to lead to opposite outcomes for exactly the same home. The TNO sunlight standard measures the sun at a single point — the middle of the windowsill, at 75 cm — and does not look at the window’s surface area. A small window of 10 by 10 cm counts the same number of sun hours at that measurement point as a sliding door of 3 by 2 m, as long as the sun reaches that point.

The daylight requirement in the Bbl works the other way round. There it is precisely the glazed area — corrected for orientation and obstruction — that determines whether a room complies. Three small windows of 10 by 10 cm together provide 0.03 m² of glass, well below the lower limit of 0.5 m² per habitable room. A large south-facing window that is 90% screened plummets in the daylight calculation because of the large obstruction angle.

The result: a room can comply with the sunlight standard on paper through a few small windows on sun-oriented façades, while the actual light intake is dismal and the daylight requirement is missed by a wide margin. This is a well-known limitation of the point measurement. For large windows where the middle of the windowsill is not representative, sunlight consultancies therefore sometimes recommend a sun-duration grid calculation across the entire glazed surface instead of a single measurement point.

A room with windows on several façades: how does that count?

The TNO standard tests per habitable room, not per window. If a living room has several windows — for example a corner room with a window facing south and one facing west — the sun hours of the measurement points are added together, with simultaneous sun counting only once. So it is the sum of the separate time slots, not the maximum and not a double count.

That answers the frequently asked question: if a new building completely blocks your south-facing window but the room still keeps windows on other façades, the room can still meet the light standard — provided those remaining windows together still reach 2 hours. Orientation is decisive here. In the Netherlands a north-facing window receives almost no direct sun, an east-facing window only morning sun and a west-facing window only afternoon sun. The south-facing window is usually the biggest supplier, so it is precisely the loss of it that can push a room below the standard, even if three windows remain.

In addition to this absolute lower limit, some municipalities apply a relative test. Rotterdam (CVDR662444) and Eindhoven accept a reduction in sun exposure of up to 15% relative to the existing situation; above that, a further assessment follows. The loss of a dominant south-facing window quickly reaches that threshold, even when the room only just still reaches the 2 hours.

Neighbours take away your sun: which rule helps then?

If a neighbour builds and takes away your sun, there are two routes — and the daylight requirement is not one of them. It only tests the neighbour’s own building, leaving your home out of consideration. The first route is public law: against an environmental permit you can submit a formal view (zienswijze) or an objection, in which the municipality weighs sun exposure as part of sound spatial planning. The TNO standard is the usual benchmark there. Incidentally, a plan may be permitted even if a single dwelling drops below the standard, as the Council of State ruled in Delft (3 July 2019, ECLI:NL:RVS:2019:2257).

The second route is private law. Article 5:37 BW expressly names the “withholding of light” as possible unlawful nuisance. The threshold is high and the court weighs the nature, severity and duration of the nuisance case by case. A valid permit does not indemnify the builder in this respect: in the Heemstede building-permit judgment (21 October 2005, ECLI:NL:HR:2005:AT8823) the Supreme Court held that a permit does not offer full indemnity against civil liability. In one concrete case, the District Court of The Hague on 17 January 2024 (ECLI:NL:RBDHA:2024:1206) even ordered the demolition of a roof addition that reduced sun exposure by 75 to 80% — despite the permit.

Beware one misconception: article 5:50 BW, which prohibits windows and balconies within 2 m of the boundary, is about outlook and privacy, not about sunlight. It is not an instrument against shadow nuisance. The substantive treatment of the neighbour-law route is in Neighbours’ roof addition: when is shadow legally unlawful?

How Schaduwplan fits into this

Schaduwplan calculates the framework where hard numbers make the difference: sun exposure. The tool tests your address against the light and strict TNO standard and against the The Hague, Rotterdam or Eindhoven variant where it applies, and delivers per measurement point the number of sun hours before and after a planned construction. That is exactly the substantiation you need for a formal view, an objection, or as factual evidence in a neighbour-law dispute over unlawful nuisance.

In addition to sun exposure, Schaduwplan shows for each window a sky-view indication: the proportion of the sky that the window still sees from the outside (the Vertical Sky Component). That is a supplementary, conservative measure of daylight loss — useful as a second line of substantiation, because under art. 5:37 BW the court also weighs daylight, not just sun. It is expressly not the statutory daylight requirement: the internal daylight factor that a court has an expert calculate in such a case (NEN-EN 17037 or the equivalent daylight area according to NEN 2057) is a more complete, internal building-physics figure that our exterior indication does not replace.

What Schaduwplan deliberately does not do is that statutory daylight calculation. That test belongs with a new-build or renovation design and with an expert; if you need it, a building consultancy is the right place. For the question “how much sun and sky light am I losing, and does that still meet the standard?” you calculate it yourself, in a few minutes, on the basis of the same open government data (3DBAG, BAG, AHN) that the Council of State also accepts.