When you think of sexy technology, the fans, motors and ductwork that provide heating, ventilation and air conditioning (HVAC) in buildings probably don’t come to mind. But HVAC systems account for more than a third of total building energy use in offices and other commercial structures – more than lighting and IT combined. A number of startups have emerged in recent years targeting this sector of the broader green building industry.

Classic definitions of cleantech, and the industries under its umbrella, have gotten long in the tooth. The sector has changed, and taxonomies haven't kept up.

Why is a clean technology taxonomy important? As a list of nested categories, it shows where a clean technology “fits”. It helps vendors understand their competitive sets. It defines and helps investors understand the breadth of the sector and its sub-categories, and helps research and data organizations report consistently.

It's been fashionable to debate whether China will some day surpass the U.S. in clean technology. Yet, after reviewing some of the metrics that really matter, one could conclude that it already has.

At least this was my thesis in moderating a recent Haas School of Business event at U.C. Berkeley in California that explored whether China would become a green economy leader.

Cleantech vendors and marketing firms take note.

Some companies are starting to get savvier about how to introduce their products for maximum market attention and credibility, with a view to speeding their opportunities for success.

I'm pretty fond of where I live.

And I imagine you are too. You've chosen to be there!

So it only stands to reason that we'd want to preserve and better our places.

But there's a professional quandary therein: opportunities in cleantech aren't always in our backyards. We can't always be satisfied with looking globally and acting locally when it comes to cleantech, because important things ARE indeed happening around the planet.

Efforts to repeal California's progressive emissions reduction law are gaining steam heading into the state's general elections this November. Which could make for some real fireworks in California this summer.

The fate of the bill is likely to become a central issue in the elections. Already, both Republican gubernatorial candidates have called for suspending the state's Global Warming Solutions Act of 2006, first introduced as AB 32.

China-based JinkoSolar has postponed plans to go public in the U.S., blaming poor market conditions (see M&As swing to solar this week).

The news comes less than a week after Chinese polysilicon maker Daqo New Energy also halted plans to IPO in the U.S. (see A week's worth of waste and Daqo New Energy lowers IPO price band).

A handful of well known domestic American cleantech companies have recently announced IPOs on U.S. exchanges. What does this mean for them, and the near future of public exits in cleantech?