Go green with your home is the new American mantra, says Steven Barrie-Anthony

Feel my windows, Al Rosen tells you.

Feel his windows?

But you do, and the floor-to-ceiling glass enclosing Rosen's den and living room is cool to the touch, despite the blazing weather outside.

This is triple-glazed glass filled with argon gas, and it lets in sunlight (which saves electricity and lightbulbs) and insulates against heat in the summer and cold in the winter.

When Al and Myra Rosen bought this house in 1997 - it had a darker interior filled with heavy marble slabs - they began an eco-remodelling effort that still continues.

Try a glass of the Rosens' chlorine-free purified water from the low-flow kitchen faucet.

Have a seat on the curved blue couch in the sunny living room, built from wheat board and formaldehyde-free foam and upholstered with untreated cotton fabric.

Its pillows are filled with kapok, a natural seed fibre.

One glance through the house will tell you that green building isn't the same thing it was a decade ago.

There is nothing plain, stark or utilitarian about this 4,000-square-foot house; instead, sunlight drifting through windows and skylights illuminates an interior landscape constructed of clean, modern lines and infused with vibrant colour.

It is not palatial, but neither is it ascetic, not by a long shot.

As the Rosens testify, living green is no longer a kind of countercultural penance in which you must forgo comfort, personal style and your retirement savings in order to give back to the environment.

In the last five years, green architecture firms, publications and building materials have leapt from relative niche obscurity to the forefront of culture and design.

Even the big home improvement chains now stock green materials - say, certified wood harvested from renewable sources - and independent green building stores are opening throughout the United States.

Green moves mainstream

Five years ago "you would mention green building and get a lot of blank stares," says Alex Wilson, executive editor of the monthly newsletter Environmental Building News, a veritable bible for anybody leaning toward green.

"Today, it's a known term for an increasingly large portion of the population."

That "known term" is relative, of course.

What "green" means to one person is rarely what it means to another.

By most estimates, green living mixes varying amounts of ecological sensitivity, social responsibility and concern for your health.

A clue to green's newfound popularity lies here with the Rosens.

This is their second stab at eco-renovation; their first project, redoing a Santa Monica condominium in 1992, began as a purely aesthetic endeavour.

They had heard talk of "sick buildings," Rosen says, "of people who lived in mobile homes which were made out of plywood and were very tightly sealed, and these people were getting sick.

"So in the spirit of caution they decided to avoid oil-based paints and materials that contained formaldehyde."

Rosen pulls out an article about a 2004 decision by the World Health Organisation to upgrade formaldehyde - a chemical found in many household products, such as glues, plywood and furniture foam - from a probable carcinogen to a known one.

Once considered junk science, the theory that chemicals in building products tend to "off-gas," or seep into the indoor environment, and thus into our lungs has by now gained significant scientific credence.

"It's that new-car smell," says Monica Gilchrist of the Green Building Resource Centre in Santa Monica.

"It's the smell of a new carpet or a new desk. You bring in a new desk, and the panels are put together with a glue that contains formaldehyde. Off-gassing is the continual emission of the chemicals which are found in blood levels over time."

The health component of green building is intertwined with energy efficiency, with trying to live within our environmental means - after all, a dilapidated planet is perhaps the largest health risk imaginable.

Like a growing number of folks, the Rosens believe that our indulgent lifestyle is hardly sustainable.

As "ozone depletion" and "global warming" enter the mainstream vocabulary, as hybrid cars begin to frequent our freeways, what was once perceived as a leftist rant is becoming a societal priority.

Economical in the long run

Systems like these are expensive, but as Rosen sees it, you have to look at the entire equation rather than simply the start-up cost.

When the photovoltaic cells produce more electricity than is currently being used, the excess energy feeds back into the grid and the calibrated power meter actually runs backward, reducing the couple's utility bill.

By Al Rosen's calculation, he and Myra should recoup their investment in about 10 years - and then start saving money.

"We have done almost everything you can do on the list of environmental and nontoxic construction," Rosen says.

Nearly all of the materials in the house are of natural origin instead of petrochemical alternatives - wood, granite, slate and other stone, copper, steel, glass and ceramic, cork, linoleum.

Virtually all of the paints, sealers, adhesives and coatings are low in toxicity and are environmentally sensitive.

As with many green projects, each new material had to go through a "life cycle analysis" before being used: Where does the product come from? How much energy did it take to create it? What does it do during its lifetime - does it off-gas? How does it end its life, at the dump or by being recycled?

The Rosens can trace the life of many products in their house from birth to death, and the renovation won't have ended until they have constructed an environment that they are happy living in.

Why look for an ending when you're enjoying the process?

Most indications suggest that building is going to get greener, and quickly. Industry has already begun to react to the demand for green products at cheaper prices.

"Mainstream building products have become greener in the last decade," says newsletter editor Wilson.

"The paints, across the board, have much less off-gassing than had been the case. All fibreglass is 20 per cent recycled content."

At the same time, he says, small start-up companies have begun producing innovative products "ranging from shingles made with recycled plastic, to decking materials made from a composite of recycled plastic and wood fibre, to more efficient ventilation systems."

Green values are infiltrating the commercial building landscape too, and for good reason: A slew of recent studies suggest that people learn faster, work harder, purchase more freely and are generally happier in well-ventilated, sunlit environments.

The nonprofit US Green Building Council instituted a green certification programme in 2000 called Leadership in Energy and Environmental Design (LEED).

It certifies building projects using a four-tier rating system. Since its debut, 167 commercial building projects have been LEED-certified - about 5 per cent of the US new construction market.

As science begins to validate the underpinnings of green philosophy, and as trailblazers lead the way toward sustainable engineering that's aesthetically pleasing and affordable, greenies are no longer just the Birkenstock-clad, granola-munching contingent.

They are also real estate investors (Al) and retired busi