Another consideration is the room to be cooled. Is it properly insulated? There are ways to tell if the room is properly insulated. Do you notice drafts around the windows and doors during windy days? There’s a way to test a room. During a windy day, hold a candle around the windows and doors to see if the flame flickers. A well insulated room needs less BTUs than a badly insulated one.
Rooms that let in a lot of sunlight will require higher BTUs as well. The sun can heat up a room, which makes it harder to cool down in the summertime. Homeowners will need to consider how sunny the room is when making a decision about the size of the air conditioning unit.
The kitchen can be the hardest room to cool in the summer for obvious reasons. Cooking meals on the stove or in the oven can make it very warm. An air conditioning unit that has to cool this space will need to be up to the task.
All of these considerations will impact the size of the unit. In a room that is between 100 and 150 square feet, the BTUs should be around 5,000. For every 100 square feet in a room, 1,000 BTUs should be added to the unit. This means that 100 to 150 square feet requires 5,000 BTUs, and 150 to 250 square feet requires 6,000 BTUs and it increases from there. In a room that is poorly insulated, it should be 8,000. Each factor will impact how easy it is to cool the room during a hot summer day.