To buy an air conditioner with suitable capacity, the size of the room such as space for large or small room is the first factor to take into account. However, the calculation of the cooling capacity unit is also concerned so much. This factor is calculated based on the length, width, height of the room is just the initial calculations. The capacity of the unit is dependent on other factors. Therefore, when choosing to buy hot air conditioning, you need to know some basics. First, the field of heat generated from equipment and people. The machinery and the number of people in the room will generate heat flow as well as determine the power capacity of the machine. In addition, the effects of the sun also have the great influence on the power capacity of the machine. The temperature outside factors will affect the level of room air.