There are several types of air conditioning system, each with advantages and disadvantages, and of course they come in a range of sizes. Some are readily affordable while others are a major home investment, so it is important to choose an appropriate system. Here are five considerations that will guide you toward the system you need.

1: Determine your precise purposes. Air conditioning systems can be used for cooling, heating, humidity control and air filtering. You may want all these features or just one. You may want the whole building under the control of one system or have a particular room in mind. In buildings of multiple occupation, each apartment will likely want individual control but often they can share other equipment.

2: The power requirements are largely determined by the volume of the space. As a rule of thumb, spaces up to 150 square feet may need a 5000 BTU system and for every additional 50 square feet add 2000 BTU. However, numerous other factors need taking into account including the outside climate in that area, the number of windows and the target conditions. If your system is too powerful, it will cycle on and off too frequently, burning fuel and shortening its lifespan.

3: Central systems consist of at least a compressor, condenser, evaporator and ducts. Some types need rooftop installations, cellar space or outdoor units. Do you have the physical space for these? If not, you will need to consider an alternative type such as a ductless or window-fitted solution.

4: All systems benefit from regular maintenance in order to avoid breakdowns and maintain fuel-efficient operation. Be sure you understand the kind of maintenance required and its likely ongoing cost.

Last but not least

5: When you calculate your budget remember to consider the equipment cost, the installation cost, the running costs (taking its fuel efficiency into account) and the ongoing maintenance that will be required.