There are a few things that could be the problem. If you notice that other electrical appliances are not working properly, I would check to make sure that the incoming neutral wire in the main electrical panel is tight. A loose neutral connection can cause this phenomenon.
If everything looks OK, I would check the wiring to the lights. Sometimes older buildings have a wire size that is a little too small. This is usually just a symptom of an older swelling wired to accomodate only a few items (one or two lights, a few kitchen appliances, and the occasional vacuum cleaner) now having to pull a LOT more load (computer, tv, HVAC, etc). This can be remedied with a rewiring job (not too cost effective unless a total remodel is planned and this can be thrown in with it).
Finally, if none of these are the cause, I would take a look around at the electric utility serving your building. If there are any large foundries in the area, their melting processes can be causing a phenomenon known as voltage flicker at your facility. Call your local utility representative and discuss the situation with them if this is the case. They might be able to attach some load monitoring equipment to verify whether or noth this is causing the problem. .
why do my lights flicker and interior lights flicker
Your lights may flicker because they power is really low. It is very common for them to flicker when there is a storm out.
Flickering lights, on a Cadillac STS, is usually a sign of a loose wire. When all of the lights flicker, it is an indication of a loose battery ground cable.
Its the hash-slinging slasher.
Possible electrical problem
The alternator is on its way out.
In most vehicles flickering lights is a sign of a failing alternator.
the regulator is getting bad in the alternator
mabie they could be burning out.
The alternator may be on it's way out.