Q: Is the sun position correct all year?

We use suncalc.js, the standard open-source library for sun calculations also used by Shadowmap and ShadeMap. Validation against KNMI tables shows deviations of less than a minute — well within what a sunlight study requires.

Q: What exactly is the TNO sunlight standard?

The TNO standard is the Dutch standard assessment framework for sunlight on homes. The Light norm requires at least 2 hours of sun on the worst days of the assessment period (19 February and 21 October as reference days, measured across the whole day). The Strict norm requires 3 hours of sun on 21 January and 22 November. Both are measured at the centre of the window frame, behind the glass, 75 cm above the floor.

Q: What is the difference between sunlight and daylight?

Sunlight (bezonning) is the number of hours of direct sun on a measurement point, assessed against the TNO standard — a guideline, not a law. The statutory daylight requirement (light entering a habitable room) is set out in the Buildings Living Environment Decree (Besluit bouwwerken leefomgeving, art. 4.146 and 4.147, calculated per NEN 2057); that is an indoor building-physics calculation Schaduwplan does not perform. We do show a sky-view indication per window: how much sky the window still sees from the outside — an additional, conservative daylight indication, not the statutory daylight requirement. Window size counts towards the daylight requirement, but not towards the sunlight norm, which measures one point on the windowsill. More on this in sunlight, daylight and neighbour law.

Question 1

Can a Schaduwplan report be used as evidence?

Accepted Answer

Yes, as supporting evidence with a formal response (zienswijze), objection (bezwaar) or appeal. We apply the TNO sunlight standard — recognised by the Council of State (Raad van State) as a reasonable assessment framework — and use the same open government sources that municipalities and lawyers consult themselves. For an appeal or a complex neighbour-law dispute we strongly recommend involving a lawyer.

Question 2

Which Council of State (Raad van State) rulings are relevant?

Accepted Answer

Three recent precedents set the framework: Ootmarsum 2013 (zoning plan annulled because sunlight substantiation was missing), Almelo 2023 (TNO Light and Strict norms accepted as an assessment framework), and Voorburg 2023 (completeness of the context decisive — a missing neighbouring building in the model led to a correction).

Question 3

Do I need to hire a specialist?

Accepted Answer

For most formal responses and objections, no — a substantiated report is usually enough. For an appeal, more complex neighbour-law cases or damages calculations, a lawyer or building specialist is a good step, and a Schaduwplan report is then a stronger starting point than beginning without data.

Question 4

Does this report also apply to flats and owners-association (VvE) matters?

Accepted Answer

Yes. For flats you place measurement points at the windows or balcony. For owners-association (VvE) matters you can assess several flats at the same address within one report, or separately per flat if they have different owners.

Question 5

Which data do you use?

Accepted Answer

3DBAG (LoD2 building models from TU Delft and 3DGI, updated quarterly), BAG (addresses and buildings via Kadaster/PDOK), AHN (height data accurate to a few centimetres — AHN4 nationwide via PDOK, AHN5/AHN6 per province via Ellipsis Drive, the distribution partner appointed by AHN) and PDOK Locatieserver (for address autocomplete). All sources are publicly accessible and independently verifiable.

Question 6

How accurate is the height information?

Accepted Answer

AHN is accurate to a few centimetres vertically. For buildings with roof shapes we use 3DBAG LoD2.2 where available. In the Voorburg 2023 ruling the Council of State (Raad van State) explicitly accepted height deviations of 3 cm.

Question 7

What happens if a building is not in 3DBAG?

Accepted Answer

Sometimes a recent new build or a small structure is missing. We then fall back on AHN point data. A very recent new build (< 6 months) may not be in the sources yet; in that case you can outline the footprint yourself in the viewer.

Question 8

Is the sun position correct all year?

Accepted Answer

We use suncalc.js, the standard open-source library for sun calculations also used by Shadowmap and ShadeMap. Validation against KNMI tables shows deviations of less than a minute — well within what a sunlight study requires.

Question 9

What exactly is the TNO sunlight standard?

Accepted Answer

The TNO standard is the Dutch standard assessment framework for sunlight on homes. The Light norm requires at least 2 hours of sun on the worst days of the assessment period (19 February and 21 October as reference days, measured across the whole day). The Strict norm requires 3 hours of sun on 21 January and 22 November. Both are measured at the centre of the window frame, behind the glass, 75 cm above the floor.

Question 10

What is the difference between sunlight and daylight?

Accepted Answer

Sunlight (bezonning) is the number of hours of direct sun on a measurement point, assessed against the TNO standard — a guideline, not a law. The statutory daylight requirement (light entering a habitable room) is set out in the Buildings Living Environment Decree (Besluit bouwwerken leefomgeving, art. 4.146 and 4.147, calculated per NEN 2057); that is an indoor building-physics calculation Schaduwplan does not perform. We do show a sky-view indication per window: how much sky the window still sees from the outside — an additional, conservative daylight indication, not the statutory daylight requirement. Window size counts towards the daylight requirement, but not towards the sunlight norm, which measures one point on the windowsill. More on this in sunlight, daylight and neighbour law.

Question 11

Does loss of daylight count in court?

Accepted Answer

Yes, daylight can count. Article 5:37 of the Dutch Civil Code protects against the "withholding of light", not only sun. Note the distinction: the court has the indoor daylight factor calculated by an expert — a more complete figure than the sky view (VSC) that Schaduwplan measures on the outside of the window. With that distinction in mind: the Limburg District Court on 18 October 2023 (ECLI:NL:RBLIM:2023:6456) had such a daylight factor calculated per room and called both sunlight and daylight factor "generally accepted methods"; in 2024 and 2025 building stops followed partly on the grounds of daylight loss. Our sky-view indication is a first, substantiated sign of daylight loss and does not replace that expert calculation. More in less daylight because of your neighbours.

Question 12

Which municipal norms are included?

Accepted Answer

The Hague (Haagse norm), Rotterdam (three-step assessment framework) and Eindhoven have their own calculated variant that Schaduwplan selects automatically based on the address. Some other municipalities — such as Amsterdam, Amstelveen and Krimpen aan den IJssel — refer to the TNO Light norm or have a procedural framework. About 97% of municipalities publish no sunlight norm of their own; there the TNO standard applies as a reference.

Question 13

My municipality has its own norm that is not included — what now?

Accepted Answer

Email hello@schaduwplan.nl with a link to the municipal policy document. We build the norm in within a working week and add it automatically for all users.

Question 14

How exactly is shadow calculated?

Accepted Answer

For each hour of the day the system calculates the sun position (azimuth and elevation), then casts shadows from all surrounding buildings using geometric raycasting, and checks whether each measurement point receives sun. The core formula: h_shadow = h_building - distance * tan(sun elevation). The full methodology is included as an appendix in every report.

Question 15

Can I assess "maximum planning possibilities"?

Accepted Answer

Yes, as a comparison alongside the standards test: the situation the zoning plan permits appears in the report beside the existing and the requested one. As soon as you enter an address, Schaduwplan checks the omgevingsplan (via the Ruimtelijke Plannen API) for a published building plot with a maximum eave and ridge height. If there is one, the permitted volume appears under Layers and you confirm or correct every value — building plot, eave and ridge height, roof form — before anything is calculated with it. Plenty of municipalities have not published their plan as data: with an older plan the building plot exists only on the plan map, the layer stays away and you take the dimensions over yourself. That says nothing about what may be built there — an omgevingsplan always applies, it is simply not always online as data. The paid report then puts the existing, the requested and the permitted situation side by side per measurement point, with the provenance of every value. Two limits remain. Schaduwplan does not derive the envelope from the planning rules itself: the legal interpretation of the building rules stays with you and your architect. And permit-free building (Bbl and bruidsschat), in-plan deviation powers and custom rules are not included in the envelope, so it does not show the complete permitted building volume. The comparison is usable as evidence alongside the standards test; it is not itself a test against a standard and gives no pass/fail verdict of its own. If someone has to interpret the planning rules legally or defend them at a hearing, an agency or lawyer remains the right choice.

Question 16

What data do you keep about me?

Accepted Answer

On our servers: nothing at all as long as you only use the free 3D viewer. Your address, planned buildings, saved projects and any attachments stay functionally in your own browser (sessionStorage, localStorage and IndexedDB) — we have no access to them. One exception: with an error report we send the address you are working on and what you typed in the search bar to our error monitoring, Sentry (EU), so we can fix the error. When you buy a report we need an email address and the address of the report; invoices are kept for seven years (tax retention obligation).

Question 17

Do you use analytics or tracking cookies?

Accepted Answer

No tracking cookies, no Google Analytics, no Meta Pixel, no ad networks. Across the whole site we use cookieless Sentry (EU) for error monitoring, and in the logged-in part of the app (behind /app after signing in) cookieless PostHog (EU) for product analytics — both without IP collection. An error report to Sentry contains the address you are working on and what you typed in the search bar in the same session. The viewer also keeps functional local storage (sessionStorage, localStorage and IndexedDB) on your device. The full list is in the cookie statement.

Question 18

Is my data shared with third parties?

Accepted Answer

Only where functionally necessary: your address is sent to PDOK (Kadaster) for autocomplete; via our Cloudflare cache we fetch 3D models from 3DBAG (TU Delft + 3DGI); height data comes from PDOK (AHN4) and, if needed, from Ellipsis Drive (the official AHN distribution partner for AHN5/AHN6). None of these services record personal data themselves. Payments go through Stripe; invoices are shared with the tax authority when filing.

Question 19

Can I have my data deleted?

Accepted Answer

Yes. Email hello@schaduwplan.nl with the request. We delete everything within the statutory term (four weeks), except for invoices that we must keep for seven years due to the tax retention obligation.

Question 20

What exactly is in a report?

Accepted Answer

An A4 PDF whose length grows with the number of measurement points and norms assessed (the sample report, with 8 measurement points, has 52 pages): a cover with hero render and report ID, assumptions and methodology, before/after shadow diagrams on all TNO reference days from your analysis, a measurement-point table with TNO pass/fail per point, a methodology appendix, and a conclusion with disclaimer and source references. A north arrow and scale bar on every page.

Question 21

How long does an analysis take?

Accepted Answer

A full analysis (address → model → scenario → PDF) takes about five minutes. The heaviest calculation (year-round per measurement point) runs in Web Workers, usually under a second for 10 measurement points.

Question 22

Can I compare several scenarios?

Accepted Answer

Yes. In the scenario editor you can draw planned buildings and compare the current versus planned situation side by side. We deliver one before/after comparison per report — if you want two scenarios formally side by side in one PDF, those are two reports.

Question 23

Does it work on mobile?

Accepted Answer

The 3D viewer works on mobile, but drawing scenarios is more comfortable on a desktop or tablet. The report can also be downloaded as a PDF on mobile.

Question 24

Why does a report cost €49 while Schaduwplan is free?

Accepted Answer

The 3D viewer costs us little to run — open data, computation in your browser. The report export (PDF generation, branded templates, methodology appendix, support) does take time and infrastructure. We deliberately keep that price low.

Question 25

Is this covered by my legal-expenses insurance?

Accepted Answer

Home legal-expenses insurance can cover sunlight reports in disputes about environmental permits (omgevingsvergunning) or neighbour law. Check your policy for "deskundigenrapport" (expert report) or "bouwtechnisch advies" (technical building advice), or email us — we are happy to include an invoice and methodological substantiation as evidence of relevance.

Question 26

What if I am not sure right now whether I need a report?

Accepted Answer

Try Schaduwplan for free first. See whether the situation really is worth it. Only when you want a PDF for the municipality or court do you buy a report. So you only pay after seeing your free analysis and knowing exactly what you get.

Question 27

Does Schaduwplan have a subscription?

Accepted Answer

No. One report, €49 once. No subscription, no automatic renewal, nothing to cancel.

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