I assume you mean the roof is exposed to the sun...and that in turn is heating your ceiling?
If so, options:
- make sure the roof is reflective (white/metallic) rather than a dark color (which absorbs heat)
- make sure the roof is insulated
- If the roof can support a green/planted roof, consider that.
- plant trees to shade the roof (obviously may take a few decades to fully work)
- create a cold roof (some form of secondary roof to shade the one below...in many climates this would be an attic type constructions...but almost anything could work...a covered roof deck, for instance--or even just a vented second layer such as standing seam metal panels on top of spacers to allow for airflow underneath.)
Once the ceiling is warm, it means the heat had already entered the living space. Can't really cool the ceiling at that point without getting the heat out of the living space. Exhaust fans could help...along with perhaps a ceiling fan. Cross ventilation with windows/vents. Etc.
A couple of options, which are limited because you're renting.
1) Draw your curtains closed to keep the sun out
2) Air movement really helps! Create a draft by opening doors or windows in the North and south sides of the house. If you don't have them, put some catches on the doors so they don't slam shut with the draft.
3) You might be able to install a ventilator in the attic space that removes the warm air and helps to reduce heat gain from above into your house.
This is a pretty good video. Didn't know about the other problems mentioned.
http://www.youtube.com/watch?v=3Nfvax0Ul5g
4) If 3 isn't an option consider insulate the ceiling (which is good for both summer and winter) - your landlord may pay for it, but if not it may pay for itself in savings to you if you're planning on staying long enough. If it's already insulated then you may benefit by adding more.
This will prevent excess heat entering the home from above (or leaving in winter). This heat gain is especially bad on homes with an iron roof.
For people who own their own homes that have heating/cooling issues.
Trees that shade in summer and drop their leaves in winter help enormously.
As do plants that cover housing like ivy. They keep the heat off of the building and insulate it. Not everyone wants ivy growing on their houses though.
Another option is to install awnings which fold out for summer use and provide shade from the high sun. It's a manual and in my opinion less attractive solution to using plants.
Cool the ceiling or attic space with a ventilator. This removes the hot air and helps prevent it heating up your home. You can get solar ones or passive ones.
Best Answer
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.