Educational tool
VillaLuz, the village
that gets its stars back
A first-person simulator. VillaLuz is an invented village with a single 200-metre street: you walk it at night, adjust its lighting parameters and watch what happens to the street, the sky and the electricity bill at the same time.
The simulator needs a browser with 3D graphics. Even so, everything it calculates and why is set out below.
Not a game: a calculation
Every figure comes from applying Spain's energy efficiency regulation for outdoor lighting. Illuminance is computed point by point on a 25-centimetre grid, the burning hours come from the position of the Sun at this latitude, and the sky brightness from the flux that escapes upwards. What you see on screen is literally what is calculated: the ground texture is the illuminance map.
What the regulation says
ITC-EA-02 sets the reference level for each lighting class and forbids exceeding it by more than 20 %. ITC-EA-03 caps the flux that may escape skywards depending on the zone. ITC-EA-01 rates the installation from A to G. In Castilla y León, Law 15/2010 tightens things further.
The lesson
The optimum the simulator finds has more light points than the starting installation, not fewer: closer together, far weaker, shielded and amber. You win by lighting better, not by lighting less. And the last stretch of sky is only recovered by dimming when nobody needs the light.
Want to simulate your own municipality?
With your real installation data we do exactly this for your whole town.
Want to simulate your own municipality?Bibliography
Where every figure comes from. None of the ones in this simulator is an opinion: these are the regulations it applies and the work its models come from, for anyone who wants to check it or go further.
Regulations
- 01Real Decreto 1890/2008 — Reglamento de eficiencia energética en instalaciones de alumbrado exterior
BOE-A-2008-18634 · texto consolidado
The framework behind everything the surfaces panel evaluates: which lighting level each class of road calls for, how far above it you may go, how much flux may escape upwards, and how an installation is graded for energy efficiency.
- ITC-EA-01 — energy efficiency, the Iε index and the A-to-G label.
- ITC-EA-02 — M, C and P lighting classes, their reference levels, the ban on exceeding them by more than 20 %, the semicylindrical illuminance used for facial recognition, and reduced levels.
- ITC-EA-03 — zones E0 to E4, installed upward light output ratio, total upward flux, obtrusive light into windows and the colour-temperature limit.
- ITC-EA-04 — components: efficacies, luminaire output ratio and utilisation factors.
- ITC-EA-06 — maintenance factor.
- 02Ley 15/2010, de prevención de la contaminación lumínica y del fomento del ahorro y eficiencia energéticos derivados de instalaciones de iluminación
Castilla y León · BOE-A-2010-20074 · texto consolidado
The regional law that applies in Valladolid: upward light output ratio below 3 %, switch-off of ornamental lighting, and municipal lighting zoning.
- 03UNE-EN 13201-2 — Iluminación de carreteras. Requisitos de prestaciones
UNE · norma de pago
The European standard ITC-EA-02 refers to for the definition of semicylindrical illuminance, which is the quantity the simulator uses to measure whether the pedestrian's face can be made out.
Sky models
- 04M. F. Walker (1977), «The effects of urban lighting on the brightness of the night sky»
PASP 89, 405 · doi:10.1086/130142
The empirical law behind the light dome: the glow falls off with distance raised to −2.5, measured over real cities. Inverting it is what gives the kilometres you have to travel to get the sky back.
- 05B. E. Schaefer (1990), «Telescopic limiting magnitudes»
PASP 102, 212 · doi:10.1086/132629
The relation between background sky brightness and the faintest magnitude the eye can reach. It is what decides which catalogue stars light up in the scene.
- 06J. E. Bortle (2001), «Introducing the Bortle Dark-Sky Scale»
Sky & Telescope, febrero de 2001
The nine-class scale used to label the sky, from 1 — pristine — to 9. The simulator uses it as a label, not as a calculation: the number comes from the brightness.
- 07F. Falchi et al. (2016), «The new world atlas of artificial night sky brightness»
Science Advances 2, e1600377 · acceso abierto
The world atlas of artificial night sky brightness. It is the reference to check the calibration of the in-town brightness against.
Data and catalogues
- 08IDAE — Inventario, consumo de energía y potencial de ahorro del alumbrado exterior municipal en España
Instituto para la Diversificación y Ahorro de la Energía
The national inventory of municipal outdoor lighting: light points, consumption and average power. It is the source of the counter's comparison against the Spanish average and of the extrapolation to Valladolid.
- 09Catálogo Hipparcos
ESA, 1997
The 5,044 stars down to magnitude 6.0 seen above VillaLuz are the ones in this catalogue, with their real brightness and colour.
- 10d3-celestial (Olaf Frohn)
BSD-3-Clause
The project the trimmed catalogue is taken from, along with the International Astronomical Union constellation lines and names and the Milky Way outlines.
The technical instructions the simulator applies are the revised wording — the one that brings in zone E0, total upward flux and the CIE M/C/P classification — which is stricter than the original 2008 text still circulating in much popular material: when quoting a limit it is worth saying which version you are quoting. UNE-EN 13201 is a paid standard and there is no public link to send you to.