San Francisco's iconic Mark Hopkins Hotel in Nob Hill, as well as the stylish, modern InterContinental Hotel in SoMa, operate far above current industry standards for energy efficiency, says Harry Hobbs who manages both buildings as director of engineering for InterContinental Hotels. "But that's not good enough," said Hobbs.

Thanks to a pilot installation from San Mateo, Calif.-based Stem, which combines big data analytics with onsite energy storage, the new energy management system will extract entirely new levels of cost savings for the hotels, says Hobbs.

The startup's first commercial system deployment utilizes real-time energy monitoring software and battery storage provided by electric vehicle manufacturer Coda Automotive to allow a building to take advantage of the cheapest form of power available, either from the grid or Stem’s batteries.

Stem’s software gathers data from some 50 variable sources -- including weather data, electricity rates and a building's energy consumption -- to build a comprehensive building energy profile. Through a cloud-based, predictive analytics algorithm, the software can fine-tune the battery’s operation to maximize economic return.

The system displays a building's energy load profile in near real-time and determines the best time to use the local stored energy or power from grid, says Salim Khan, CEO of Stem. The software is not connected to a building automation system but rather connects to the building power line via an inverter without any outside involvement from a building manager.

"Even though we have an automation system in place, there's no need for us to be proactive in how we manage energy," said Hobbs. With electricity bills upwards of $50,000 a month for both San Francisco InterContinental Hotels, Hobbs is optimistic the system can reduce hotel energy bills by 10 to 15 percent.

The Stem energy storage devices are about the size of a refrigerator and can be built modularly depending on the space and energy requirements of a building, says Khan. Installation of the standard lithium-ion battery chassis usually takes a few hours with a standard battery lifetime expectancy of up to 20 years. All software changes are handled remotely and requires little more than downloading a typical Salesforce software update, says Khan.

While Hobbs has a electronic dashboard displaying building automation systems for both InterContinental Hotels and notifications to tap into potential demand response requirements from the company's electric utility, Pacific Gas & Electric, the Stem system includes "current consumption, real-time pricing and helps us make better decisions," says Hobbs. "Information is power, and in this case, power savings."

Stem started three years ago and initially targeted solar power as a source for onsite generation. The company has raised $14.2 million with investments from the Angeleno Group and Greener Capital. Khan, who previously served as chief operating officer with smart grid communications company Trilliant, was named CEO in October. 

The company is targeting commercial customers with a growing stock of building portfolios -- including hotels, franchises, banks, campuses and major retail chains -- and is hopeful to attract utilities concerned about deferring peak load demand.

While there are many new players in building data analytics and energy management -- among them Lucid, BuildingIQ, First Fuel and Viridity Energy as well the likes of Enernoc and Constellation Energy -- Khan says Stem differs in tapping an onsite power source during peak electricity pricing.

Stem also differentiates itself from stand-alone onsite power generation companies like Bloom Energy, who has named AT&T and eBay as customers, given its focus on software and analytics and a smaller footprint for energy storage.

The InterContinental Hotels did look into alternative options to offset electricity demand, says Hobbs, but Stem's pilot offered a "much more economical choice and fit our efficiency goals." While owning a hybrid vehicle himself, Hobbs sees the seamless ability to derive power from a battery or additional power source as the best way "to maximize energy efficiency with the least amount of interruptions."