In South Tampa, new $600,000-plus homes dwarf older ones by a magnitude of three or four times. In suburban Hillsborough, Pasco, Manatee and Sarasota counties, 5,000-square-foot homes in new subdivisions are fast becoming the norm and not just luxury models tucked away in expensive enclaves. Along our beaches, newer homes – with foundations a dozen feet or so higher than the houses they replaced because of federal flood zone rules – tower over simpler beach homes built in the 1950s and 1960s.

Welcome to the age of the monster home.

Whether you call them by the pejorative moniker McMansions or more whimsical names such as Faux Chateaux or Starter Castles, super-sized houses are here – soon to be followed by negative impacts, according to conservationists.

In its March/April issue, Mother Jones magazine culled various sources including census data and industry reports to catalogue the effects of American homes' increasing size. The resulting illustration, featured below with the magazine's permission, seriously suggests that bigger isn't always better.

To some observers, the expanding size of U.S. homes is a sign that more people are living the good life – or at least are hocking themselves up to their eyeballs trying. Who's to say these homes aren't the American Dream made manifest? More people want larger homes, according to real estate surveys.

But environmentalists and smart-growth proponents say McMansions lead to dire implications. The natural resources needed to maintain larger houses and the traffic created by McMansion sprawl should have everyone concerned, from millionaires to paupers, they say.

"We Americans tend to be very wasteful in terms of our space," said Lynn McGarvey, a conservationist with the Tampa Bay chapter of the Sierra Club. "Unfortunately, that's really at odds with the all-of-a-sudden lack of land to develop and any sense of sustainability. That's one of the big problems, using up land that we could use for affordable housing that we really need."

In Hillsborough County alone in 2004, more than 2,300 homes were built that featured more than 5,000 square feet of living space. The largest was a 28,295-square-foot home in Avila built for a gold bullion and coin dealer.

And it's not just those giant luxury homes that are getting bigger.

Throughout West Central Florida, there has been a steady inflation in the size of new homes. In Hillsborough, the average size of a new single-family house has grown 79 percent since 1960, to 2,331 square feet. In Pinellas, the average new home is 2,490 square feet, almost double what it was four decades ago. Pasco County's average new homes are 73 percent bigger over that same period. And in Manatee County, homes have bulked up by 21 percent in the past 10 years alone.

The bottom line: Just as we're using up available properties in our coastal counties, we're making houses bigger and bigger so that fewer fit into those remaining lands.

It is a national problem, not just Florida's, experts say.

"It's a real burden to the community," says Tim Frank, a San Francisco Bay-based senior adviser to the Sierra Club's Challenge to Sprawl Campaign.

Unfortunately in Florida, conservationists say there's not much research that has been done to track the growth of monster houses and their ramifications.

"I don't know if there is anybody who is watching that," said Charles Pattison, executive director of the 1000 Friends of Florida conservation group. "Clearly it has an impact on the urban form, and it tends to displace more reasonably priced housing.

"McMansion" is a loosely defined term that entered the lexicon only in the last decade or so. According to Word Spy, a website devoted to sleuthing new words and phrases, the word has evolved from meaning "a large cookie-cutter house" to "a large opulent house, especially a new house that has a size and style that doesn't fit in with the surrounding houses." To some, it's simply a huge house, usually of at least 5,000 square feet, while to others it implies a certain low construction standard. To those who bristle at the word's connotations, McMansion brings to mind an anti-suburban elitist who is possibly some sort of socialist at heart.

"The term McMansion is nothing more than a spite name, or a sour grapes name, for people who don't like to see homes bigger than theirs or are jealous or don't want to see the neighborhood change at all," said Joseph Narkiewicz, executive vice president of the Tampa Bay Builders Association.

Narkiewicz confirmed that the market has been pushing builders toward larger houses. "The larger homes in our area range from 4,000 to 6,000 square feet as a standard larger home," he said. It is consumer preference: "They're given the choice of a larger lot or a larger home, and they almost invariably choose the larger home."

But, homebuilders say, the energy costs of those larger homes are offset by improvements in the technology of energy efficiency.

"Actually, the new homes are far more energy-efficient than the older homes," Narkiewicz said. "They are a tighter home, less energy loss, compared with smaller homes that leak like a sieve. A lot of those [older] bungalows, you throw in a couple of window units, they're not energy-efficient at all."

There's also a whole palette of new "green" building materials, from better insulations to recycled wood. "Greenbuilding" is both a concerned movement and a neat marketing tool, especially for luxury homes where owners can afford the higher upfront cost of, say, solar energy panels.

"It certainly is becoming more mainstream, but I wouldn't say that most people are aware of greenbuilding as a whole," said Jennifer Roberts, a San Francisco-based writer and author of Good Green Homes.

She said she tries to veer away from judging those who desire bigger homes.

"People with money have always built large homes," Roberts said. "They will always build large homes. I try not to get into judging other people's choices. But if you are going to have a large house, there are a lot of things you can do to make your house environmentally friendly."

From better insulation to solar energy panels, owners of high-end megahomes are increasingly excited about adding features that will limit their consumption.

"If you are going to build a 6,000-square-foot house, why not make it as energy-efficient as you can?" Roberts said. And, at least in California, she is seeing those same energy-efficiency features being built into the affordable housing market.

Florida hasn't come that far, yet, but some communities are moving in a greenbuilding direction. In March, the Sarasota County Commission approved a resolution encouraging homebuilders to use sustainable practices. Contractors who build to a green standard can get their permits fast-tracked and receive half off their building permit fees (up to a $1,000 benefit). The program, however, is limited to 50 homes a year (if all builders receive the maximum) with its $50,000 budget.

Other communities in Florida are using the stick instead of the carrot to limit the growth of megahomes or save smaller homes. In Palm Beach, the town council this year voted that new or redeveloped homes could be no more than 10 percent bigger than the average size of neighboring houses. Bradenton Beach recently extended a one-year moratorium on rezoning its beachfront properties, older single-family houses that were being purchased and torn down for condominium complexes.

McMansions have some groups increasingly worried about their environmental impact. With each new McMansion subdivision, environmentalists warn, more cars are put on the roads to log more trips and more miles, and to use more gasoline. "We're pricing our workers out of housing, and forcing them further and further out where they have to have a car," the Tampa Sierra Club's McGarvey said. "You then need increased government services, not because of more people."

It's not like Tampa Bay's sprawl problem isn't already well documented. According to an analysis of U.S. Census data at Sprawl City (sprawlcity.com), the Tampa-Clearwater-St. Petersburg area ranks eighth in the nation in sprawl. (Atlanta is first.) The two environmental authors who run Sprawl City also found that 15 percent of sprawl in Tampa Bay is not due to population growth but is an actual increase in the amount of urban space needed on a per capita basis. Sierra Club's Tim Frank says McMansions burden other taxpayers in several ways: the cost of infrastructure, increased traffic. They also eat up land, he says.

"You make it more difficult to do more orderly development," Frank says. "Taking five-acre parcels out of commission, it's like creating Swiss cheese in the landscape. You can't develop a neighborhood that has a big hole in the middle."

Meizhu Lui, executive director of United for a Fair Economy, a liberal advocacy group based in Boston, said the demand for larger homes is driving less affluent people out of the home-buying market as developers look to high-end homes for a bigger buck.

"Even though people need smaller houses that are affordable, the market is not as hot for those," Lui says. "They've really reduced affordable housing."

Lui says the personal decision to buy a McMansion puts a burden on other taxpayers, including less affluent ones, who share the cost of extending city services outward. McMansions, she says, "are really subsidized by everyone else."

"It's a lose-lose, and unfortunately, there is very little recognition of that by our public officials," McGarvey said. "They act as if, 'Oh it's not happening.' But it is happening. Florida is becoming a very undesirable place to live."

Karen Shugart of Creative Loafing-Charlotte contributed to this report.

wayne.garcia@weeklyplanet.com