Everyone seems to go for LEDs to simulate outdoor lighting for this kind of purpose, when there is another way that seems much more elegant to me: fiber-optic solar lighting.

https://www.shieldenchannel.com/blogs/solar-panels/fiber-opt...

Indeed more elegant, but also more pricey. The LED solution was $1000, which could still be affordable for a student living in a bunker. It's also easier to install, especially if you don't own the place and cannot run thick fiber bundles through the walls.

Yeah, it's something best planned with construction, and a bit pricey, but worth keeping in mind for anyone who intends to build a bunker. :)

Also not bad for high efficiency net zero type homes to supplement natural light without too many windows compromising the thermal envelope. I personally like the variability of natural light for how it keeps you connected to the outdoors. You know when a cloud is overhead or the sun is rising or setting. I've simulated sunset and sunrise with LEDs through color temp and timing but I've always wanted to experience the solar fiber type.

I’d prefer not relying on electricity

Presumably you also need a system to produce light indoors at night. You might as well have a single solution for both day- and night-time that uses renewable energy.

This is a nuclear bunker. Electricity might not be available or scarce.

By the time external electricity is not available (assuming it was ever brought in, in the first place), you probably want to lose track of time.

Oh yes, also natural light itself might be scarce.

I bet the air filtration system runs on electricity, they probably have a backup generator that lasts X number of days. After that you won't have clean air so light won't be an issue either.

The bigger cold war era civil defense bunkers around here (Czech Republic) usually have the following design for ventilation: * one or two filtration rooms, powered by electricity with optional manual backup * one or two diesel generators to provide electricity for the filtration system, lighting and other equipment * high pressure oxygen bottles for couple hours of total isolation - intended for the first few hours after a nuclear detonation when the regular filtration equpment could be overwhelmed by short halflife fallout and smoke/lack of oxygen due to the firestorm of the city arround burning

Examples of such shelters: - general purpose shleter Denis (capacity op to 2000 people): https://podzemibrno.cz/en/places-underground/cover-denis-und... - army headquarters shelter in the Vypustek cave (capacity 100+ people): https://vypustek.caves.cz/en - 10-Z shelter, Brno area civil defense headquarters (capacity 100+ people): https://10-z.cz/en/

Smaller shelters that could be found under many 50s era building were much more rudimentary, usually without idepedent source of electricity and just simple hand cranked filtration system.

Sounds to me it is closer to a student housing project that happens to be in a bunker.

You almost certainly need it for ventilation and probably water pumps anyway.

Any bunker worth its salt will have on-prem generators and a lllaaarrrrgggeee fuel supply.