There are several points you need to consider:
- How big is the area you want to heat or cool
- How many people occupy the space
- What is the material of the roof and insulation
- What direction do your windows face? Are they shaded?
- What other heat generating appliances are you running in the space?
- What is your budget?
- How much space there is in your roof?
If you’d like to heat or cool the entire house, and you have sufficient roof space then a ducted system is the best choice for you. If you only want to heat or cool one or two rooms, or don’t have enough roof space then a wall hung split or multi split system would best suit your air conditioning requirements.