Energy and Comfort
Because all that glass acts like a giant solar collector when the sun is shining and as an escape route for heat when it isn't, both the sunspace and adjoining rooms can become unbearably hot or too cold to be in without a jacket or coat. Minimizing these uncomfortable temperature swings depends on which direction the structure faces, its design, and the materials used.
Picking your site.
Sunspaces work best facing south, where they'll get direct sunlight. Sunrooms on the north side of a house get no direct sunlight during winter, while those facing due west become overheated by the late afternoon sun. Unfortunately, many houses don't have direct southern exposure; still others won't allow a due-south location for the new room. Southeast or even slightly southwest will work in either case.
Locating a sunspace to take advantage of the sun is important, but don't forget it can also provide incredible views and a feeling of the outdoors. Try to find a spot for your sunspace that takes advantage of both. This room from Lindal Cedar Homes features tinted overhead glass and blinds on the vertical glazing to keep out unwanted sun.
Making the connection.
How a sunspace connects to the rest of the house directly affects its energy performance. For example, if you live in a cold climate and want extra living space without the additional heating costs, separate the sunspace with a wall that includes a door and a fan. The fan pulls heat from the sunspace into the house during the day while the door seals off the area when it cools down at night. But because the temperature inside sunspaces heated only by the sun can fluctuate by 40°F in 24 hours, the space you gain is part-time only.
If you want to add comfortable full-time living space, there are some other options. A popular one is to use the sunspace to enlarge another room — often a kitchen or family room. The sunspace still collects heat during the day. But because it's connected to the rest of the house, it requires backup heating. Baseboard heaters or radiant floor heating are two possibilities.
The more time you'll spend in your sunspace, the more important it is to control heat loss and overheating. Your biggest weapon is the glass itself. Most manufacturers offer several kinds you can match to your climate. Four Seasons Sunrooms, based in Holbrook, New York, sells 16 kinds of glass, from clear double-pane units to triple-glazed low-e glass. (See Window Glazing
for more details.)
In cold-weather climates, choose glass that keeps heat from escaping to the outside. In warm-weather ones, look for glazing that prevents heat buildup—a more common problem than heat loss. Adding shades or blinds to overhead glass can help prevent overheating; most manufacturers sell them as options. If you don't want to invest in shades right away, be certain the design you choose has tracks that make retrofitting easy.
Another option is to eliminate overhead glass altogether. Most manufacturers offer sunspaces with solid roofs—a feature that eliminates much of the heat buildup. Patio Enclosures, based in Macedonia, Ohio, lets customers specify solid-roof sunrooms and then place 3x3-foot glass panels where they want them. The result is both protection against overheating and natural light where needed.
Flooring material also affects how hot the space gets. Adding thermal mass, usually with a masonry material, such as ceramic tile over a concrete slab, absorbs some of the heat from the sun; it releases the heat during cooler evening hours. The Passive Solar Industries Council, a group of manufacturers and building professionals in Washington, D.C., suggests an average of 3 square feet of 4-inch-thick solar mass for every square foot of clear double-glazed glass area. Even then, the temperature within the space can vary as much as 30°F on a clear winter day. And using that much masonry can be a challenge in a typical kitchen expansion, especially because at least 75 percent needs to be exposed to sunlight to be effective.
Most sunspaces require a combination of temperature controls. Discuss these issues with your dealer. And check with a heating and cooling contractor on how the sunspace will affect energy use and comfort in the rest of your home.