Sunrooms allow the sun’s UV rays to pass through the glass which will heat up the room. This is one of the main reasons people get sunrooms, but during certain times of the year when the temperatures are already warm this extra heat can make the room feel uncomfortable. In this case, you’ll want to find a way to mitigate some of this heat.
First, add some sort of window coverings. Whether this is blinds, shades or even just some adhesive window tinting. Blocking the sunlight from entering the room will vastly slow the rate at which the room heats us.
Second, open the windows and use a fan to increase airflow. When the room is sealed tight all the extra energy from the UV rays just keeps raising the temperature inside the sunroom. If you open the windows with fans going, the median temperature inside the sunroom will be close to the outdoor temperature.
Third, consider adding some sort of heat sink to the room. This way if the sunroom heats up, there will be an some aspect of the room that can absorb the excess heat. One really awesome heat sink for a sunroom is a hot tub with the heater turned off. A 6 person hot tub will have between 300 and 500 gallons of water, and this will draw a lot of energy to raise the temperature even one degree.