As cold, haze-filled days of winter give way to hints of spring, homeowners seem to wake up, like bears from hibernation, and think of being outside. There are flowers to plant and trees to prune.

An ever-growing number of Utahns know, though, that outdoors can be brought inside year-round, with a glass-walled room.Call it a greenhouse, a solarium or a sunroom. It doesn't matter. With one, the changing seasons become a part of at-home life.

Businesses have long used solariums. In private homes, solariums are most commonly used to enclose a spa, so that it can be enjoyed regardless of the vagaries of wind, sun and storm, or to expand living areas.

"We enlarge a lot of kitchen and dining room areas with solariums," said Chuck Saling, co-owner of Saling Brothers and its Four Seasons Design and Remodeling franchise. "They can be used as family rooms or larger eating areas. They are used as bathroom additions.

"It saves you a trip to St. George in the winter," he quipped.

With temperature and light controls, the area becomes an ideal spot to grow plants, in traditional greenhouse style.

"The simple fact is, if you go into a house and there's a room with a glass roof, that's the room where you're going to want to be," Saling said. "It feels good."

At Four Seasons, 5645 S. 320 West (I-15 Frontage Road), would-be solarium owners can buy a do-it-yourself kit or contract to have the company do all the work. There are eight basic solarium types and most are shipped from the factory within three weeks. Installation by Saling Brothers' general contractors generally takes about one week and can be done in any season.

Solariums sell well year-round, with the exception of November and December. But springtime is definitely prime time in this business, said Four Seasons' Russell Tychsen.

The smallest solarium available is 8-by-3 feet. Solariums have to meet the same building codes and roof load standards as any other room, but by placing beams for support, the glass rooms have almost limitless size possibilities. Prices start at about $3,000. The average solarium is $15,000.

"It's definitely a luxury item and most people can live without it," Tychsen said. "But it's a nice room, with a good atmosphere to relax and enjoy yourself."

"We call it a high wish-list item," Saling said. "When we show them at home shows, people want them. But it's not something you buy on impulse. It's too big an investment and it takes planning."

According to Remodeling Contractor Magazine, it really is an investment, with a 100-percent return on resale, compared to 90 percent for major kitchen remodeling, 72 percent for room addition and 33 percent for a swimming pool.

A homeowner has to consider physical conditions like property boundaries and where to locate the addition. Heating sources and how the room will be used are major considerations.

Four Seasons uses a special glass called Heat Mirror , which has twice the insulating power of greenhouse glasses. The sun's heat reflects back to keep the solarium cool. Ultraviolet rays are filtered out. In winter, heat stays in.

Tychsen knows a family in Nephi that uses its solarium, along with fans and a wood-burning stove, to provide all the heat for the entire home. Others pipe in heat as they would to other rooms. The options can be built in. Special shades help control temperature and give privacy.

Surprisingly, solariums are low-maintenance. For one thing, the material is strong. "We have never had one of the panes broken out by a kid, although it could be done. The panes are pretty tough. And they are easy to replace so it never looks like a patch job," Saling said.

They're not hard to clean. Tychsen shocks people when he suggests they climb on the solarium roof with window cleaner and buff it up with paper towel. Or just hose it down. Curves require a little extra attention to avoid streaks. But not all solariums have curves.

For Tychsen, the most crucial task in installing a solarium is to make certain that it fits into its surroundings and is aesthetically pleasing. "It should never look like an afterthought," he said.

Saling Brothers does the installation work by hand to avoid destroying surroundings. It costs more and takes a little longer, but it's well worth it, Saling said. If a house is rich with wood, Four Seasons suggests wood accents to the solarium so it enhances the existing home.

They install about one-third of the solariums in the area. Between 40 and 50 times a year, someone asks them to let the sun in.