If facility managers want to know how an office building or industrial plant is using energy on a more granular level, they'll often invest in submeters. Those additional meters can provide a deep source of information about specific areas of a building and pieces of equipment. But they can also be quite expensive -- up to $1,000 per unit.

That barrier led two doctoral students at the University of California, Berkeley to come up with a more nimble solution: a tiny electrical submeter that can be taped onto a circuit breaker in minutes.

The pair recently formed a company around the concept, called Persistent Efficiency, and they are now beta-testing the meters at a few customer sites, including a 1-million-square-foot office building in Chicago.

The small meter, dubbed the "Power Patch," was developed by Persistent Efficiency CTO and co-founder Richard Xu while he was a graduate student in UC Berkeley's mechanical engineering program. The Power Patch is a stick-on device, roughly the size of a switch panel on a circuit breaker, which measures magnetic fields from individual breakers and uses an algorithm to reconstruct the current and voltage.

The startup says it's the only meter ever built that doesn't require an electrician to access and rewire a panel box -- instead, the device can simply be stuck onto a breaker. It will then start providing data about energy consumption along each circuit in as little as five minutes.

Below is a picture of a very early prototype, developed when Xu was first testing the Power Patch at UC Berkeley:

"We can start getting information out of a building or subsystems just by taping the Power Patch onto the circuit breaker. If we were going to monitor critical equipment, we could install, say, twenty Power Patches and [be able to] monitor pumps and lights without paying electricians," said Jason Trager, the company's co-founder and CEO.

Trager is currently a doctoral candidate at UC Berkeley who has been working on statistical process control analytics for industrial facilities. After realizing the complementary nature of Xu's new metering technology and Trager's data analytics background, the two teamed up to form Persistent Efficiency and create a business model to sell the meter. 

As its name would suggest, Persistent Efficiency sees the device as a cheap way to continuously commission buildings. As part of their pitch during the UC Berkeley startup competition earlier this year, the company's co-founders said they would charge 3 cents per square foot a year to provide data services in order to make buildings more energy-aware.

In that respect, the company's service could eventually be similar to BuildingIQ, Gridium or any number of other building analytics companies. But the early-stage firm has a long way to go before it develops the software and sales channels necessary to touch any of the leading startups (or legacy building-efficiency companies) in the intelligent efficiency sector. 

The stick-on meter itself is where Persistent Efficiency currently has a unique competitive edge. "We're really focused on the device right now," said Trager. "We just want to get it out there and gather the data to eventually work on more analytics."

That may put Persistent Efficiency more competitively in line with companies like MelRok or 38 Zeros, which are trying to drop the cost of metering and data collection in buildings through advanced hardware approaches. It also pits Persistent Efficiency against some of the disaggregation companies, such as Bidgely, PlotWatt, Verdigris Technologies or Opower, which use algorithms to replace or supplement metering systems

Trager says the company has created hundreds of the Power Patches and claims the devices can be deployed for a tenth of the cost of a traditional submeter. He also said that Persistent Efficiency has raised or gotten "verbal commitments" for $50,000 so far to expand the hardware.

Given early successes with testing the tiny meter at customer sites, Persistent Efficiency isn't worried about whether it can compete on a technology cost and performance basis. The big question is whether it can provide competitive services around the energy data -- an issue that every startup must grapple with in the overcrowded intelligent efficiency sector.

"We’re not going to fail because of our technology. The main issue is where to attack the myriad opportunities for this," said Trager.