Deciding on what size air conditioner you need is not as simple as it looks, but here are some of the factors that we suggest our customers consider. Take for instance an air conditioning unit rated by the manufacturer at 9000 BTUs, which based on normal conditions will cool an area up to 300 square feet with an average ceiling height of 8 feet. However, there are additional factors that can affect how much cooling is necessary to reduce the air temperature in the room to a satisfactory level and maintain it there.
For instance, you would need to add approximately 600 to 800 BTUs for each person in the room. Also, if you have computers running, motors, or lights on, it will add to the heat given off in a room and thus increase your cooling demands. In addition, if the room allows a great deal of sunlight to come in, this will add to the amount of cooling you will need. We recommend turning off unnecessary lights and leaving the shades down on windows on hot days. Ceiling fans can also make for your feeling cooler, although the temperature may remain the same.
Another important thing to consider when cooling an area is the humidity. For example, running your air conditioner on 65 degrees may be necessary for you to feel cool if the humidity is high in the room. However, if the humidity is controlled, let’s say between 40 and 50 percent, most people will find it too cold if the air conditioner cools the room down to 72 degrees. Many people now supplement their central air conditioning with dehumidifiers because the air conditioning units are either oversized for their area or they are the newer models that are designed to dehumidify less so as to attain a better EER energy rating. When an air conditioner dehumidifies the air, heat is given off by the condensation process and more BTUs are required to cool the air, therefore reducing the product’s energy rating. Without having separate dehumidification, it is necessary to set the thermostat way down to 65 degrees so it runs longer and dehumidifies the air. The problem is it ends up being too cold not to mention the energy used. Many people find they can set the thermostat on their central air conditioning on 75 to 80 degrees and be comfortable as long as the humidity is at a comfortable level.