To cool a room with an area of 700 to 1,000 square feet, one needs 18,000 BTUs per hour. The number of BTUs needed to cool a room depends upon several factors, the most important being the area. The larger the area, the more BTUs are required.
Area is not the only factor determining the number of BTUs for cooling a room, according to Energy Star. A heavily shaded room requires 10 percent fewer BTUs, or British Thermal Units, and a sunny room needs 10 percent more BTUs than a normally shaded room. Kitchens also need a higher number of BTUs to cool. If it is a room that regularly contains more than one person, add another 600 BTUs per person.