Rooftops still predominantly sprout shingles, not solar panels. On highways, hybrids remain the rolling minority.

But overall, the recession seems to be the kind of motivator that proponents of more sustainable, energy-conserving ways of life have hoped for.

There is nothing like the loss of a job — or even the threat of it — to inspire a less-wasteful attitude about consuming.

That is, assuming the change is also wallet-friendly — if not on the front end (residential photovoltaic systems generally cost at least $25,000), at least in the foreseeable future.

"We're actually in a hiring spree right now," said an elated Gerry DeSeve, president of Greener Applications, a software developer in Chestnut Hill, Pa., that helps governments and schools save energy and reduce emissions. Largely because of stimulus funds, "we're in 20 different proposals for state, local, and higher-education opportunities."

At Northern Barriers in Pottstown, an installer of energy-efficient soy-based foam insulation, orders from homeowners, schools, and office buildings have increased about 50 percent since January, said Bari Harvey, manager of business development.

Still, whatever green buying is the direct result of recessionary pain could be short-lived, cautioned Leanne Krueger-Braneky of the Greater Philadelphia Sustainable Business Network.

The average U.S. consumer has "a pretty short memory," she said, so "there's a pretty short window to change behavior."

Tote-bag distributor www.Reusablebags.com is trying to keep the window open. Its Web site is packed with recession-era tips.

For instance, it calculates that packaging a year of disposable lunches will cost $371 (in brown paper bags, snack bags, and bottled water or juice), vs. $36 for a year's worth of lunches in a cloth lunch bag, with a reusable water bottle, recyclable wrap, and a hemp napkin.

The pitch has resonated. The site's sales have grown 300 percent each year since 2004, said spokeswoman Sarah Hubbard. "We've empowered 201,276 customers to save 762,232,212 use-and-toss items."