A green technology analyst about a year ago told me there was no such thing as a green software market.

He was wrong.

While software developers arguably arrived late to the greentech party, their presence and importance grows daily. Like in the computer world, software largely exists to accomplish two goals: to make it easier to get complex data and to fine-tune the control over computers, industrial equipment and other devices. Understand and manipulate.

VCs, of course, love this. Two great coders, a case of Red Bull and positive word-of-mouth can launch a software firm into international prominence.

Where greentech and the computing world differ is how software is sold. Only some companies actually offer software as a discrete service or product. Many bake it into their existing offerings. Expect to see some of these applications get spun out into separate companies or see the parent companies transform themselves into software outfits. The list, however, does not include software from companies like Cisco or Triliant that seem more inextricably bound up in hardware.

Here are my favorites (in something approaching order):

1. eMeter
The company, which has raised $57 million in two rounds, has created a system that crunches the data from electrical meters for the benefit of utilities. It can monitor power consumption, maintenance issues, trends, outages, billing management, etc.  

It has an in-home thermostat application too, but it's not really the interesting part. It's how eMeter manipulates data for utilities that makes it valuable. Plus, it can pave the way for dynamic pricing schemes. Customers include Southern California Edison, TorontoHydro and CenterPoint Energy, among others.

2. Sustainable Spaces
Sustainable currently gets its revenue from energy efficiency retrofits, but the heart of the company is a complex application that allows contractors to determine the optimal repairs for a building.

"It is an expert system for decision support in the field," said president Matt Golden. "We have software meetings all the time." A number of the company's employees came from Google. The company's next task is to certify third-party contractors (i.e., not those working on Sustainable's crew) to get trained on the system. The retrofit market may become as crowded as building management, but for now Sustainable has a head start.

3. Autodesk
Product and building design. In terms of overall impact, the company will likely have a greater influence than anyone else on the list in terms of improving energy efficiency in buildings, reducing the amount of raw materials in manufactured goods, and replacing fossil fuels. But be honest, seeing Sustainable on this list is more of a surprise.

Honorable mention: Bentley Systems, which makes simulation and design tools for HVAC engineers.

4. Intermolecular
Think drug discovery software meets batteries and ultracapacitors. The company harnesses highly parallel computing techniques to devise materials and processes for semiconductor manufacturers and material scientists.

Biosciences companies have used these sorts of programs for years for protein folding simulations. Intermolecular exploits similar techniques to determine, for example, the optimal placement of atoms in a cathode and the potential results from various processing techniques. To date, Intermolecular has mostly worked with chip makers like AMD and Elpida, but it likely become a name solar and battery makers get to know.

5. Architectural Energy's SPOT
Not SPQR, SPOT. It stands for Sensor Placement and Orientation Tool and helps architects place sensors so that occupants can capitalize on daylight. Daylight saves energy-lighting consumes 22 percent of the electricity in the U.S. – but it can also improve worker productivity, moods and retail sales because of the improved quality of light. Ever wonder why everyone looks like a serial killer in a gas station bathroom? It's the poor fluorescents! Sunlight Direct, UC Davis and others also working on this issue.

6. GeoMation
Hitachi's GeoMation crunches satellite data to determine the optimum time to harvest wheat and rice. In tests on the island of Hokkaido, where farmers saw carbon dioxide output during harvesting reduced by 30 percent. In a world plagued by drought and hunger, this will come in handy. Expect to see a lot of lifestyle and heath applications come out of Japan too – weight loss tips, sleep monitors etc.

7. The Building Management 25
Building control systems used to mean the janitor. Now, it's a booming cottage industry with companies offering various combinations of hardware, software and services for curbing power inside commercial buildings, homes and university campuses.

At this point, it's hard to say who will win. Because of the varying customer needs, some sectors of this market will not rapidly consolidate: software for skyscraper management will likely be served by several vendors. The companies that provide software for thermostats may experience a quick bloodbath in the near future.  

Here are some of the more interesting ones: Cimetrics (software and simulation for campuses); Tririga (same); Adura Technologies (lighting controls-moving to total building management); Optimum Energy (air conditioner control) HydroPoint Technologies and Greenleaf (sprinkler systems); Advanced Telemetry (fast food outlets) and Tendril (home energy management consoles).

8. Hara
Why do I like Hara over the other carbon management companies? Because they don't yammer on about the importance of carbon accounting, which, in most parts of the world, remains voluntary.

Instead, the company tries to give a comprehensive view of the "organizational metabolism," according to CEO Amit Chatterjee said. If a company is mostly concerned about reducing energy costs, or water consumption, the remedial recommendations will be skewed toward the desired result or a blend of goals.

"It is not about greenhouse gases always," Chatterjee added.

[pagebreak:The Top Ten in Green Software]

9. Toyota's Prius Dashboard
Until the Prius came out with its eco-friendly dashboard, consumers could only estimate their mileage by dividing the miles they drove by gas purchases. Toyota's dashboard made it dynamically available. It also helped popularize eco-driving techniques. The console will one day be standard in nearly all cars.

10. Sungevity, Global Solar Center and SolarCity
Tie! All three have devised software to reduce the cost of installations. Sungevity and Global have come out with pretty accurate online applications for estimating solar jobs (see the review here). Sungevity works as an installer but has begun to license its application. Global, which only started its beta 90 days ago, has 60 installers in its network already.

Meanwhile, SolarCity exploits a CRM application to organize truck rolls, crews and other real-world tasks to reduce the gear-grinding costs in installation. Expect a partnering and/or OEM strategy someday.

And now the five Honorable Mentions:

11. GridPoint
The company's SmartGrid Platform aims to become a nerve center for utilities: swapping power loads, monitoring renewable production, allowing safe charging for electric cars. Ideally, it is the sort of system that could put demand response companies out of business by giving utilities the tools to control consumption. XcelEnergy selected the company to participate in SmartGridCity. In a lot of ways, you could say it's equal to emeter.

But it's not without controversy. GridPoint got its start making energy management systems for high-end homes. That didn't take off, but GridPoint discovered that its software could scale to handle larger projects. Skeptics – i.e., executives at competing companies – say that that needs to be proven. GridPoint has raised over $200 million since 2003. On one hand, it's a great cushion. On the other, that sort of money tends to bring out critics.

12. Fat Spaniel Technologies
The company monitors PV and thermal solar system performance. It was one of the first companies to identify the software opportunity for solar. Although it now faces competition from building monitoring companies and others, the pioneering has to be acknowledged.

13. eSolar
It's a solar thermal company on paper, but a pillar of its strategy is the software that orchestrates the movement of reflective heliostats to optimize the production of heat in a boiler on top of a tower. The heat needs to remain even, sort of like making a crème brulée. BrightSource Energy has created similar software but the odds are far greater that eSolar will transform itself into a software company. Brightsource has power plant deals and the execs all come from the energy world. eSolar's Bill Gross hails from the internet. But the question is who buys it: Are there customers beyond the handful of solar thermal vendors?

14. GreenRoad
It puts a piece of hardware in your car that studies your driving habits. The data is then downloaded to a software application that tells you on ways that you can save gas and reduce accidents by changing your driving habits. Don't accelerate so much, it might say, or why don't you clean your floor mats. They're gross.

The tough part is justifying the payoff. Commercial companies pay $400 a year for a subscription but can save $1,828 a year in lower insurance premiums, saved gas, etc. A consumer pays $302 a year, but can save $310. Would you put up with an electronic mother-in-law for $8 a year?  

15. Verdiem
The company's software cuts power consumption on PCs. Dull, yes, but it works.