Lighting often takes a backseat to HVAC systems when it comes to discussions about energy efficiency. But there is a lot more that can be done in that space than just swapping in more energy-efficient bulbs.

To expand in the burgeoning field of energy-efficient networked lighting systems, Lumenergi announced on Wednesday the close of a $12.7 million series B round of financing.

The round was led by Braemar Energy Ventures, and includes new investor Townsend VC LLC and continuing investors Low Carbon Accelerator Ltd. and Noventi Ventures. Dennis Costello of Braemar Energy Ventures also joined the Lumenergi board of directors.

The funding comes just a week after the Newark, Calif.-based company announced an agreement to retrofit four government buildings in the Northeast and Western regions of the U.S.

Networked lighting can save about 50 percent to 70 percent of total lighting energy, according to Lumenergi Inc. That savings can be huge for commercial spaces, where keeping on the lights can eat up to 40 percent of total annual electricity consumption.

That savings potential is garnering Lumenergi a lot of attention from government entities, and the latest shot of funding is intended to help the company expand into the commercial side, which has been slower to invest in networked lighting, despite a payback of less than three years.

"It's amazing how much the governments are out front on this. I think they're trying to set benchmarks for how efficient lighting can be," said Michael D'Amour, CEO of Lumenergi.

The latest buildings include two federal buildings in Concord, New Hampshire and two government buildings in Nevada. Both installations are scheduled to be complete by the end of 2010. About 80 percent of Lumenergi's business is currently retrofits, but for new buildings, the payback of networked lighting can occur in just a year's time.

The relative lack of interest of commercial building owners -- until recently, that is -- is at least partially due to the lack of coordination between building owners and their tenants, according to D'Amour. Both sides have trouble coming together and seeing why the other would really want to install the technology.

But the advantages are clear for both, he said. Large public companies are often looking for green office spaces, and networked lighting can actually offer greater control, as employees can have individual widgets to control the lighting about their cubicle.

From the perspective of owners and facility managers, the benefits come not just in terms of energy savings, but in more efficient management of assets. "The facilities managers really like us," said D'Amour. "And the owner cares about the value of the building. We can get rid of a very significant portion of their expenses."

Lumenergi not only adjusts lights for the time of day and the task at hand, but also delivers maintenance information so it tracks the lifecycle of the light to use it as efficiently as possible, and lets facility managers know when bulbs have burned out.

Manipulating lights also makes the technology prime for demand response. But it doesn't involve leaving people in the dark, just as HVAC adjustment doesn't mean turning off the AC all together. Instead, D'Amour said they could set adjustments for decorative or secondary lighting and have it scheduled to shut down at certain price signals or for traditional demand-response events.

The control and convenience of networked lighting is starting to grab the attention of some large building developers, D'Amour noted, as well as a large New York bank that has recently signed on with the company.