Since I don’t know what’s the surrounding of the block is, I would say go above 8 to 14th floor, assuming it’s a 15 floors block. If the majority of your windows are facing: 1) Playground 2) Badminton Court 3) MRT track or station 4) Main roads or expressways Whichever floor you’re staying at, you will get affected. Higher floors will have slightly lesser noise. As for dust, again, it depends on the surroundings, if you’re facing main roads and expressways, more dust. You can consider installing those magnetic insect nets on your windows to reduce dust, however, it will restrict wind flowing into your place. Most of your concerns are addressed based more of the surroundings than the floors itself. Except for privacy, anything above 5 I think it’s good you can’t really see in from ground level. Again, depends if there any elevated areas around your surroundings. Seems like you’re buying a new house soon. Just some tips for you: 1) Don’t take the top floor, if the block gets a lot of the sun, the ceiling will trap the heat. Think greenhouse. 2) Try to choose the sun don’t set facing your bedroom walls. Evening sun heats up your bedroom, hotter, aircon works harder to cool down the room. If possible get a unit that has more natural wind coming in. 3) Experience the surroundings on your own. Go visit the unit or the area at peak periods to see where is the noise coming from.