We know that the Builders intended Ember to be inhabited for around two hundred years, maybe a little more, depending on how severe the damage to the earth from the expected war/apocalypse/Harlem-Shake-a-thon is. What we don't know is exactly when Ember was constructed, or if and when the anticipated destruction of the human race occurred. It could've happened in 2014, in 2020, or in 2051 for all we know.
One thing we do know is that people have been in Ember for longer than the Builders had anticipated, thanks to that no-good seventh mayor greedily stealing the box to see if it contained a secret cure for his illness. When that mayor dies, the box ends up in a closet, where "it sat, unnoticed, year after year, until its time arrived, and the lock quietly clicked open" (The Instructions.14).
Thanks to Lina reading a passage about the Gathering Hall clock and thinking about the current date in Ember, we know that "they called this the year 241, but it might have been 245 or 239 or 250" (2.76). This is because not every timekeeper is on the ball, and as a result, things have gotten a tad muddled with Ember's calendar. Whoops.
Regardless, people have been living in Ember for longer than the Builders intended, so they're running out of supplies (including important stuff like food and medicine), and the generator is starting to break down. Do you want worry about whether all light will vanish first from your world first, or you'll run out of food first? No, we didn't think so.
Planning out a city in advance means that its layout makes sense (unlike, say, Boston). But the lack of natural landmarks—like the sun rising in the east and setting in the west—means that some adjustments had to be made.
Doon thinks to himself, while in the Pipeworks, "In Ember, you were taught to remember the directions this way: north was the direction of the river; south was the direction of the greenhouses; east was the direction of the school; and west was the direction left over, having nothing in particular to mark it" (3.12). Hey, man, whatever works.
Lina in particular makes a good tour guide, since she loves to run around the town on her way to and from school (and later, to fulfill her job as a messenger). Here's how the town looks to Lina:
Every corner, every alley, every building was familiar to her. She always knew where she was, though most streets looked more or less the same. All of them were lined with old two-story buildings, the wood of their window frames and doors long unpainted. On the street level were shops; above the shops were the apartments where people lived. Every building, at the place where the walls met the roof, was equipped with a row of floodlights—big cone-shaped lamps that cast a strong yellow glare. (2.2)
So yeah, there's no sunlight in Ember, just electric lights. As a result, pretty much everyone is pale. We know they take daily vitamins with their meals, so we're guessing that vitamin D in particular makes an appearance. There are shortages of almost everything in Ember, and that's pretty disturbing when it comes down to it.
Located underneath Ember, the Pipeworks house the generator that powers all of Ember. It is, to Lina, pretty much the worst place ever. She thinks "going down into the Pipeworks must be like being buried alive" (1.38). And here's how she and most non-Pipeworks-laboring Ember citizens picture the place:
Pipeworks laborers worked below the storerooms in the deep labyrinth of tunnels that contained Ember's water and sewer pipes. They spent their days stopping up leaks and replacing pipe joints. It was wet, cold work; it could even be dangerous. A swift underground river ran through the Pipeworks, and every now and then someone fell into it and was lost. People were occasionally lost in the tunnels, too, if they strayed too far. (1.37)
To Doon, though, the Pipeworks isn't such a bad place to work; he's mostly annoyed that the ancient generator makes no sense to him. Heck, it doesn't make much sense to us either. And living in a world powered by technology you don't understand must be terrifying, especially when you rely on it on a daily basis.
Everyone lives in little apartments above the city's shops, and most of them are full of clutter by now. We're guessing the apartment Lina shares with Granny and Poppy is typical: "It was a small apartment, only four rooms, but there was enough stuff to fill twenty. There were things that had belonged to Lina's parents, her grandparents, and even their grandparents—old, broken, cracked, threadbare things that had been patched and repaired dozens or hundreds of times" (2.28). This makes sense since Ember is a closed-off, totally self-reliant community. If something breaks, you'd better hope you can fix it, since there may not be anything like it in the storerooms to replace it.
The people of Ember are resourceful and skilled, but they also try to inject a little beauty into otherwise dull and colorless lives. Lina covers her apartment's walls with her drawings, for example. After Lina and Poppy move in with Mrs. Murdo, Lina observes this at Mrs. Murdo's place: "On the table was a basket, and in the basket were three turnips, each of them lavender on one end and white on the other. Mrs. Murdo must have put them there, Lina thought, not just because she was going to have them for dinner, but also because they were beautiful" (11.1).
When Lina and Doon finally escape Ember, they emerge into the outer world—our world. The one with the sun and the moon and the stars and boy bands. It's pretty familiar to us, but to the kids, who've never seen the sky before, it's like The Best Thing Ever.
The first sunrise is pretty awe-inspiring:
The edge of the sky turned gray, and then pale orange, and then deep fiery crimson. The land stood out against it, a long black rolling line. One spot along this line grew so bright they could hardly look at it, so bright it seemed to take a bite out of the land. It rose higher and higher until they could see that it was a fiery circle, first deep orange and then yellow, and too bright to look at any longer. The color seeped out of the sky and washed over the land. Light sparkled on the soft hair of the hills and shone through the lacy leaves as every shade of green sprang to life around them. (19.42)
We know from this passage that if there was a nuclear winter or whatever, it's long passed. Or maybe the feared disaster didn't strike this part of the world. The sun is shining, plants are growing, and there are insects, birds, and at least one other mammal (probably a fox). The kids figure out from watching the fox with a fruit in its mouth that they can probably eat the same fruit from a nearby tree, so the land hasn't been poisoned as far as we can tell.
The real mystery, and one we don't see answered in this book, is: what happened to the other people of the earth? Have they all died out? Were others also hidden away? It seems like a shame to Shmoop that no one's around to enjoy this idyllic nature scene with Doon, Lina, and Poppy.