Over the past five years, Building Robotics has built up a sizable user base for its Comfy app — a smartphone interface that lets office workers complain when it’s too hot or too cold, or too bright or too dark, along with a software platform that can actually adjust HVAC and lighting settings to do something about it. 

On Tuesday, the Oakland, California startup was bought by German industrial giant Siemens for an undisclosed sum. The acquisition, the third this year for Siemens’ building technologies division, will give Comfy a massive new market channel. And it will give Siemens an occupant- and smartphone-based approach to its broader building technologies business. 

Building Robotics CEO Andrew Krioukov has always stressed that Comfy is about occupant comfort and satisfaction as a driver to enable energy efficiency as a byproduct. That’s because building tenants, office owners and managers care much more about comfort than saving energy — a fact underscored by the struggles of startups and giant corporations alike in the commercial building efficiency space. 

Comfy’s ongoing developments emphasize this focus. In 2015 it unveiled new features allowing people to report too-dim or too-bright lighting, along with partnerships with vendors in itsWorks with Comfy partner ecosystem to act on those inputs to adjust lighting to desired levels. 

Siemens bought smart lighting startup Enlighted last month, giving it another venue for this integration, along with access to the startup’s sensor-equipped lighting nodes to add to the data being collected by the system. 

Siemens also bought J2 Innovations last month, giving it a building automation and internet-of-things software platform that’s supporting integration by building equipment manufacturers and system integrators at thousands of installations globally, ranging from offices and high-rise buildings to hospitals and data centers. 

These two acquisitions seem more aligned with Siemens’ existing building automation systems and industrial controls businesses. Building Robotics represents a more unusual step for the German giant — a “consumer-like experience to commercial buildings that simplifies the interaction with buildings to increase employee productivity and engagement," Matthias Rebellius, CEO of Siemens Building Technologies, said in Tuesday's announcement. 

It will also provide Siemens with the unusual data sets Building Robotics has collected on how people behave and interact with the energy-using built environment. While the company doesn’t emphasize energy savings over customer comfort, the app has reduced energy use by more than 20 percent for some of its clients, such as Johnson Controls.  

The Comfy app will not be limited to Siemens' customers in the future. Tuesday’s statement made clear that Building Robotics will “continue to operate as a vendor-agnostic platform provider,” and that its co-founders, CEO Andrew Krioukov and CTO Stephen Dawson-Haggerty, will remain in their current positions. 

Krioukov and his colleague Stephen Dawson-Haggerty started the company in 2012, based on their shared experience as computer science researchers at UC Berkeley. Tasked with building software designed to solve an energy challenge, they built an open-source energy monitoring system for commercial buildings based primarily on inputs from occupants.

The companies didn’t disclose any figures on how much market share Comfy has at present. But a report in Forbes cited a source close to the company who said that the Comfy app is now serving about 56 million square feet of office space in six countries, up from the roughly 20 million square feet it reported under management back in 2016. 

Joe Aamidor, managing director of Aamidor Consulting and long-time GTM contributor on building technologies, noted that the acquisition “demonstrates the hotness [i.e., the popularity] of the experience in the workplace” and technology to manage it.

Building Robotics’ Comfy app has “definitely differentiated” itself from the vast majority of smart building HVAC and lighting systems, by focusing on the occupant experience, rather than the people on the building side of the equation, said Aamidor.

”The question is how much demand there is for that — which may be an open question,” he said. While major competitors in the building HVAC and automation market like Honeywell, Johnson Controls, Trane, Carrier and others are all seeking technological differentiators, the market is still driven by customers’ desire to keep costs as low as possible, he noted.

The lack of financial details on Tuesday’s acquisition leaves unclear how well Building Robotics’ investors (several of which are also customers) made out in the deal. The company raised a $12 Million Series B round in 2016 led by Emergence Capital and involving Microsoft and real estate giant CBRE; a $5.5 million Series A round led by Claremont Creek Ventures and The Westly Group; and a $1.1 million seed round from Google Ventures, Claremont Creek Ventures, Formation 8 and Red Swan Ventures.