Any sunroom can keep a more stabilized temperature if its built on a concrete slab at least 24 inches deep. Concrete absorbs heat coming in through windows from sunlight. Heat will transfer to the concrete even if the concrete floor is covered by tile or indoor-outdoor carpeting.
A high R-value in roof insulation helps sustain a comfortable temperature in a sunroom. Specially constructed panels are available that keep the roof area of sunrooms very well insulated. If you want to build a sunroom out of wood framing yourself, consider buying these insulation panels from a sunroom dealer for the roof area only.
Install sliding windows around your sunroom that are at least 48 inches high. This will provide lots of natural light and openings large enough to suction a breeze on hot days. Caulk well around window seams and insulate all wall areas above and below the windows. No sunroom can be completely airtight or watertight, for that matter, but do your best to seal and secure the room from the elements to save on energy bills.
Heating the Sunroom
Few people are willing to install ductwork for heating and cooling into a sunroom. Cooling is usually provided by fans and open windows. An oil-filled radiator electric heater works well for heating. The heater is safe to touch and inexpensive to operate. By having this type of heater in your sunroom, you can use it three seasons out of the year. If you have an adjoining room with a fireplace, you can harness some of that warmth to heat the sunroom in winter months as well.
Fans Are Important
Open sliding windows work well to cool a sunroom. But, an overhead electric ceiling fan is a good auxiliary backup system to install. The fan can be reversed in cold weather to push heat back down into the room, too. Free-standing fans on tables or pedestals can help to cool a large sunroom. The only drawback of these fans is that they are usually very noisy. A ceiling fan is not noticeably noisy on medium or low speed.
Windows and Privacy
Sliding windows in a sunroom offer no privacy, especially if they surround all walls. You can install a couple of sections of board fence to enhance privacy, if your sunroom is close to neighbors. Another option is to plant a row of shrubs to provide some screening. In some cases, you may want to install curtain rods on all walls and hang medium-weight curtains for privacy at certain times of day. Sheer curtains provide almost no screening and heavy curtains look out of place in a sunroom.