I have an apartment on the top floor of an apartment building (the community roof is right over us). In summer, the place gets very hot! I can't start a community garden upstairs and am dying with the air conditioning bills. Is there some quick cheap way in which I can cool my place?
Adding insulation to your ceiling is probably the ultimate answer, but it may be expensive and disruptive. The master bedroom in our last house was below a flat roof, and I found the following measures made for more comfortable sleeping:
1) Since the cold air from air conditioners tends to sink, use fans to blow it back up to the ceiling. From there it will descend and you will feel it more than if it were just all pooling on the floor. Placing a fan near the A/C source may also help draw a greater flow of cooled air.
2) If you can open windows and the air is cool outside, use fans at the base of the window to blow air upwards. Same principle as before.
3) Humidity is as much your enemy as the heat. Although A/C is supposed to dehumidify, I've found that running a supplementary dehumidifier can help. You'd be surprised how much water you can draw out of the air. No point doing this while the windows are open, though.
Roofs are one of the main sources of heat gain (in summer) and loss (in winter). That is why this is the most important area to insulate.
Since it probably is not possible for you to add to whatever insulation is above your ceiling, you might try adding some below it. If you have enough height, you could create false ceilings below the existing ones. This would require either a wooden or steel structure to support new drywall. An alternative is a suspended ceiling using a track system in which large tiles are inserted.
Between the new ceiling and the old, you can install insulation. Some of the new foam sheets provide very high insulation values, nearly twice as much as fiberglass batts of the same thickness.
Also consider sun-blocking shades if your windows get direct sunlight.
If possible, consider adding a skylight. Mount a ceiling fan below it. On hot days, open the skylight and turn the fan on so that the fan is pushing air up and out the skylight.
Add window tint. They are designed to allow visible light in but cut out 99% of UV light and some of the heat coming into the home. There are different types, different shades and some have insulating properties.
As I recall, we had this huge heat and glare problem in an office I once worked in in Malaysia (tropical). The air conditioning wasn't terribly good and we had a lot of heat producing equipment. Once the film was on the temperature was much improved.
Also, ceiling and wall insulation makes a huge difference. We recently got wall insulation added. A product called air foam. They installed it from the outside and you can hardly tell where they blew it in. It's made an enormous difference.