If the word conjures up images of an architectural afterthought, of a long span of smoked, curved glass that is too hot to inhabit in summer and too cold to endure in winter, then it might be time to re-conjure.

Today's sunrooms not only come in a wide variety of shapes and sizes, they also have evolved into comfortable year-round living spaces.

A design that is becoming increasingly popular is the conservatory, an ornate structure of European heritage that not only brings the outdoors inside but does so with flair.

"Conservatories have a classic elegance that appeals to homeowners," says James Ruppel of Four Seasons Sunrooms, based in Holbrook, N.Y. "As people have become more interested in adding a classic architectural style to the exterior of their home, conservatories have become more and more popular."

Virginia and Richard Roberts of Salem, Conn., added a "Victorian" conservatory to their home two years ago and couldn't be happier with the light and airy space.

"We use this room every day, even in the winter," Virginia says. "The only time we didn't use it this winter was when we had that sub-zero week. We could have made it warm enough, but the heat (electric baseboard) would have been running constantly.

"Usually we just leave the sliding doors (to the main house) open and set the heat at 60 degrees, which is very comfortable."

The modern sunroom is an offspring of the greenhouse, a structure that has been around since the year 30, when the Roman emperor Tiberius had one constructed from thin sheets of mica so he could enjoy cucumbers out of season.

In the 1600s, greenhouses began sprouting up in Europe. Because many of them were used to grow oranges, they became known as orangeries.

These structures, constructed of glass and masonry and heated with stoves, became status symbols among the wealthy.

One of the most elaborate greenhouses was constructed at the Palace of Versailles. It was 500 feet long, 42 feet wide and 45 feet high.

In this country, George Washington had a greenhouse at Mount Vernon, which was called a pinery because it he used to grow his favorite fruit, the pineapple. By the middle of the 19th century, greenhouses became more affordable and their popularity really took off.

The main difference between a greenhouse and the modern sunroom is in the glass.

While the greenhouse relies on standard glass, which has little, if any, insulating ability, today's sunrooms are fashioned from materials that deflect and retain heat, insulate, cut down on glare, block UV rays and even self-clean.

For the Roberts' conservatory, something called "MC2 Wonderglass," developed by Four Seasons Sunrooms, was used.

"Wonderglass keeps a room cooler in summer and warmer in winter," says Matt Ostrowski of Norwich, Conn.-based Creative Enclosures, which designed and constructed the Roberts conservatory.

Basically this type of glass works by reflecting and deflecting, so it keeps the heat from the sun out in summer while keeping home-generated heat inside in winter.

The sunroom shell also has changed. The exteriors often are constructed of lightweight aluminum with vinyl cladding, while the interior can feature a wood frame that might be painted or stained.

The choice of materials is, of course, reflected in the cost. Because there are so many variables, it is difficult to nail down a standard price for a sunroom or conservatory.

The Roberts' addition, which is a modified conservatory design called a "double valley," measures 24 feet wide, 16 feet deep at its deepest point and cost $65,000. That is at the higher end of the spectrum.

Virginia Roberts says she wanted a sunroom from the time she was a child, while Richard became intrigued by them while traveling in Europe on business.

After moving into their new house six years ago, the Robertses noticed they seldom used the backyard deck, which was on the north side. "It sat in the shadows most of the day and was usually cold back there," Virginia says.

Eventually the Roberts got together with Ostrowski at Creative Design. Initially, they were just going to add a standard Four Seasons "Victorian" conservatory, but as they became more involved, they decided to expand it on both sides to increase it size.

The entire construction took about two months.

"My mother (who lives with the family) likes to come out here and read," Virginia says. "My daughters have their parties out here, and at Christmas, we put a second tree here. I like to come sit out here when it's raining. It's very relaxing."

Richard says he is partial to the snow. "When it's snowing, you can sit here and look out at the hillside, and you feel like you're in Colorado," he says.

As for maintenance, the Robertses says they wash the glass once or twice a year, but definitely after the winter. The job is done with mops, squeegees and a power washer.

In terms of durability, the Robertses say they had one small leak early on, but that was repaired quickly.

Nor have they had any problem with another early concern: summer heat. "It really doesn't get that hot out here," Virginia says. "We open the windows and put on the fan, or we just leave the sliding door open and use the air conditioning."

Although the Roberts conservatory serves as a kind of 365-days-a-year backyard patio, sunrooms can be used for everything from great rooms to kitchens to dining rooms to coverings for swimming pools.

Finding the right sunroom is a matter of deciding what you are looking for and how much you want to spend, and then finding the dealer who can best meet your needs.

A list of sunroom companies can be found in the Yellow Pages, or with a quick Google search.

For people who are handy, there are manufacturers who sell do-it-yourself kits.

The sunroom might not cure cabin fever or eliminate the need for a winter vacation, but outside of a plane ticket south, it could be the next-best thing.