Sunrooms are a great place to relax. After all, it is scientifically proven that sunlight prevents depression. There are times where you have to work inside the home, or can’t leave. A sunroom is a great place to get your vitamin D when you don’t have the time to leave the house.
Figure out if a sunroom will even work. If your solar exposure gives you at least four hours of sunlight around midday in midwinter, the answer is probably yes. However, you may want to research beyond the level of detail presented here to fine-tune your design for your specific climate, especially if you’re trying to optimize your heating potential.
You will want to orient your sunroom toward south, which is usually a few degrees different than “magnetic” south, in order to get the best advantage of the sun’s low angle in winter. There are several methods for finding true south.
Decide what glass to use.
There are several types of glazing you can use for your sunroom, but glass generally is best, because it traps more heat energy than plastic and because it’s durable. Plastics do not work as well as glass for trapping long wave heat energy, polycarbonates can scratch and yellow over time, and films are just too fragile for a house.
Dual glazing should be used in all but the most temperate climates. In colder climates, sometimes even quadruple layers of glass work best. You’ll want to avoid reflective glazings and the newer low-e glass because they prevent much of the solar energy from entering through the glass, and they reduce the solar spectrum. If you want to grow plants in the back area of your sunroom, skylights are a fantastic way to bring in overhead sunlight.
Don’t forget to add thermal mass.
The trick to keeping a sunroom comfortable is to provide thermal mass: dense materials that soak up and conduct heat when the sun is shining on them. Use concrete, stone or tile floors, not carpet or wood. Generally, the thermal mass should be a darker color to absorb heat more readily, but it doesn’t have to be brown or black. Reds, blues and greens work well and create more playful sunrooms.
Realize that water walls are important.
They have different performance characteristics than masonry walls. You can also use large-diameter, vertical pipes or fiberglass tubes. The advantage of using a water wall for thermal mass is that the heat that strikes the surface of the wall is more readily absorbed. The heat energy is convected or mixed within the water vessels rather than slowly conducted through like the solid masonry.
You’ve got to insulate the room.
You can use fiberglass, granular or foam insulation with conventional joist framing for the roof, but you need to prevent inside humidity from being absorbed into the ceiling. Typically, the roof joist space will need to be vented to prevent dry rot.
In the winter, ventilation is necessary to help the heated air go where it is useful. During the heating season, you’ll want to help warm your house.
Vents high and low in the wall adjacent to the house’s interior allow the hot air to flow out the top, and cooled air to return low into the sunroom for another trip. Of course, doors can be opened to create a similar effect.