Innovative solutions for creating healthy, efficient, eco-friendly homes

Smarter sunrooms

One of the simplest and most affordable upgrades you can make to your home is to add a sunroom, which will expand your living space, open up your home to the outdoors and even increase your home's value. Thanks to a number of design improvements, today's sunrooms are more efficient, more durable, more attractive and easier to build than ever. 

With all these developments, however, deciding which sunroom is best for your home can be a bewildering experience. There are scores of manufacturers and installers from which to choose, and each one uses different criteria to distinguish itself. Identifying exactly what you do and don't want out of your sunroom, and being aware of what's available on the market today, will help you get the right sunroom for your home and your family.

The goal of glass

Deciding whether to add a sunroom when building or remodeling a home requires some consideration of the space's energy impact on the rest of the home.

It's more an issue of too much solar gain in the summer rather than the heat you want to get from the sun in the winter, says James Ruppel, communications director for Four Seasons Sunrooms of Holbrook, N.Y. With this goal in mind, Four Seasons uses installed glass, or glazing, with special coatings designed to block up to 85 percent of the summer sun's heat. The result is a sunroom that is cooler in the summer and warmer in the winter compared with a traditional sunroom, according to Ruppel.

The solar heat gain generated by a glass-enclosed area has been understood since glass was invented in Egypt around 1,500 B.C. Even if you're adding a sunroom to a home in Maine, Montana or Alaska, the ancient principal of the greenhouse effect still applies. That is, when the sun shines through an enclosure made of clear glass or a glasslike material, the sun's warmth is temporarily captured and amplified in that enclosed area. Unfortunately, when the sun disappears, much of the captured warmth is lost back through the glass, which, by itself, isn't a very good insulator.

The rate at which heat is lost back through glazing at night is determined by its R-value, or thermal resistance. Most sunroom manufacturers, however, focus on U-value, a rating of heat transfer through a building material, as opposed to the thermal resistance of the material. If you want to maintain the same temperatures, day and night, in your sunroom as in the rest of your home, a low U-value is important because less heat will be transferred, or lost, back to the outside. If, on the other hand, you want only to have a warm, sunny space to enjoy on clear winter days and are willing to let overnight temperatures drop in the sunroom, the U-value of the glazing is relatively unimportant.

Lowering a glazing's U-value is accomplished in a variety of ways, such as using double-pane or even triple-pane glass. Additionally, the inert gas between the panes has become increasingly exotic in an effort to push the glazing's U-value rating below 0.5, the standard for ordinary double-pane glazings.

It's important to note, however, that a decrease in U-value is invariably accompanied by a decrease in the amount of solar heat transmitted to the room. Therefore, decreases in heat loss are generally at the expense of the very thing many homeowners look to sunrooms to provide -- solar heat.

Several manufacturers, such as Four Seasons and Florian Solar Products, have pulled out all the stops in the quest for low U-value, applying spectrally selective metal coatings to the multiple glass surfaces to achieve winter U-values of 0.10. However, a standard 2-by-6 wall with fiberglass insulation has a U-value of only 0.05, so in a relative sense, all glazings by themselves are heat losers during sunless winter days and nights.

Likewise, a glass enclosure can capture too much of the summer sun's heat. Sunroom manufacturers deal with this problem in a variety of ways. Some provide an insulated roof with overhangs, blocking most of the direct rays of the overhead summer sun. Some offer exterior, screenlike fabric shades that are rolled into place during the summer. Others, such as Four Seasons, treat the glazing to be highly reflective, admitting as little as 10 percent of the sun's energy. And sunporch -- as opposed to sunroom -- manufacturers convert the structure to a screened room in the summer by replacing most of the sun-trapping glazing with ventilating screens.

Insulating the structure

Just as important as the sunroom's glass is the structure holding up the glass. Sunroom structural components can be wood or metal, which is either vinyl-clad or given a baked-enamel paint finish so the metal doesn't degrade from exposure to the elements. The most common metal used is aluminum, though some sunroom manufacturers now offer stainless-steel framing.

But the paramount issue among sunroom structural materials is their ability to insulate. By itself, wood has the advantage of being naturally insulated, in addition to its aesthetic appeal. However, a metal support structure, which is usually composed of square tubing beams that hold the glass in place, has to be insulated artificially, or it will create severe heat loss and condensation problems in the home.

The means by which sunroom metal components are insulated varies widely. Some manufacturers, such as Branstrator of Fort Wayne, Ind., fill the metal tubes with expanded polystyrene foam, which not only insulates but also makes for a quieter structure and is environmentally friendly. Other manufacturers use spun fiberglass or similar materials, or create an internal barrier with dead air inside the tube, which significantly diminishes heat loss.

The final critical component in a sunroom is the sealing material around the glass. Sun, rain, heat and cold are constantly combining to break down glass seals. The glass, metal and sealer expand and contract at various rates with weather changes. Also, acid rain, ultraviolet deterioration and a host of other elements whittle away at the seal's integrity. When a seal breaks down, the glass leaks.

You'd have to be a chemist to understand the advantages and disadvantages of the wide range of sealing materials, and even the chemists sometimes disagree.

So for the average homeowner, a good test of quality is the sunroom's warranty. If a reputable, well-established manufacturer is willing to offer a 20-year, 30-year or even lifetime warranty on the sunroom's components, including the sealing around the glass, there is a pretty good chance the glazing seal will hold up. If it's a five-year warranty, or pro-rated this or conditional-term that, think long and hard before signing on the dotted line.

New features

Among the latest innovations in sunrooms is what's called self-cleaning glass, such as SunClean glass from PPG, which is offered as an option on Florian's sunrooms. The glass surface is treated with both photocatalytic and hydrophilic coatings. The photocatalytic coating uses the sun's ultraviolet rays to facilitate the breakdown of organic dirt, while the hydrophilic coating causes water to sheet evenly over the surface rather than beading up. In combination, the coatings use rainfall to clean the glass, minimizing maintenance.

In addition, improvements to prefab construction have resulted in tighter structures and faster build times. There also are more color options, though that may not sound like a big innovation. But for years, manufacturers of vinyl-clad and metal support systems offered their products only in white and sometimes a neutral bronze tone. Some are now offering a wider range of colors. Wooden support systems, of course, can be painted any color you like.

Costs and installation

In general, sunroom floor space is less expensive than ordinary home space, usually costing about $75 to $175 per square foot compared with $125 to $250 per square foot. Of course, actual costs will depend on the home's location, local economic conditions, design requirements and preferences, local dealer and builder costs, and even local building codes.

Local building codes in many places apply specifically to sunrooms, says Stan Smith, executive director of the National Sunroom Association, a trade organization for manufacturers, dealers and general contractors. Smith notes that local codes can affect everything from specifications for the glass and its impact resistance to structural anchoring techniques and insulation requirements.

Hurricane-prone states like Florida take a particular interest in the durability of sunrooms and their ability to survive when buffeted by high winds and pelted with debris, Smith says. Additionally, counties like Fairfax in Virginia, just outside Washington, D.C., are growing so fast that the mushrooming construction boom demands more regulation of contract work, including sunrooms.

If you're on a budget, many sunroom manufacturers offer prefabricated rooms in a variety of sizes and styles. Some prefab-sunroom manufacturers also allow a semi-custom approach to their products. Within the limits of local codes and structural integrity, a manufacturer will work with customers to adjust stock designs to meet the homeowner's requirements. That, of course, drives up the cost but may be necessary in older homes or those with special design considerations, such as beachfront houses.

Completely custom sunrooms are an option when an architect and builder have extensive experience in the field, although many custom builders use prefab techniques when constructing a sunroom, preferring a heated shop's controlled environment for assembling components. Panelized portions of the sunroom are then trucked to the site and hoisted into place by crane. With huge pieces of double-pane glass making up the bulk of the panels, the building techniques call for a high level of skill and experience to guarantee a leak-free sunroom.

The addition of even a modestly sized sunroom can cost $40,000 or more. However, the cost usually will add the same equity, and sometimes more, to the value of the home. People taking the equity out of their home to build a sunroom are making a good move, Ruppel says of the growing trend in financing sunrooms. With home values rising again in many areas, sunrooms are therefore more affordable and becoming increasingly popular. And thanks to innovative design, they're more efficient as well.