In their first year in the energy efficiency business, Carbon Lighthouse founders Brenden Millstein and Raphael Rosen encountered a client who almost stole their thunder.

When Millstein and Rosen began working with Dostart Development, they had not yet created Carbon Lighthouse’s proprietary software — and could not have imagined their CLUES platform would earn FastCo's 2019 World Changing Ideas Award for its AI + data capabilities.Instead, when they first visited Dostart's office building, they found that the owner had already changed out incandescent lightbulbs for LEDs and upgraded their heating, ventilation, and air conditioning (HVAC) system.So they knew that if they were going to land this client for their startup, they were going to need to offer deeper energy savings."We said, 'Let's figure out what's going on behind the scenes and in the guts,'" Rosen recalls.Even with state-of-the-art HVAC and a modern building management system (BMS), they figured there had to be energy inefficiencies. That was a fundamental lesson of physics, which both had studied at Harvard.

But to find the energy inefficiencies, they would need data.

Lots of data — especially temperature data. So they doubled down on temperature loggers and distributed them throughout the HVAC system."We put some sensors in the air going out to heating pumps, some in the air coming back," Rosen says, "and we calculated how much energy the fans were using."If they could turn down a fan or a pump and still keep the working spaces in the building comfortable, they could save their client money — and cut carbon emissions — without replacing any hardware. So the pair began logging the flood of new information into a spreadsheet to model different energy management changes.But as they collected data, their spreadsheets kept growing and growing. They couldn't email them to each other. They couldn't even run their simulations."The spreadsheet was literally so large it couldn't run," Rosen recalls. "We knew there were more savings to be had, but we couldn't model them correctly."

The birth of CLUES

That’s when the founders hired their first software developer to help them crunch all their data in new software they called the Carbon Lighthouse Unified Engineering System (CLUES). It took time to write, but the new system allowed Carbon Lighthouse engineers to build a custom simulator for each client, unlike more general industry standard software.Using spreadsheets, our engineers needed about 80 person-days to build a model for a client, Rosen says. But thanks to the far more efficient, dedicated code in CLUES, engineers can now do the same job in two or three days.This lets Carbon Lighthouse test lots of different ideas for a particular building before recommending the best solution to their clients.And keeping tabs on energy savings is an ongoing thing — since energy use is always changing inside buildings, engineers need a way to monitor existing client's energy and update their management recommendations from time to time.CLUES handles that ongoing flow of information from existing clients — and even alerts Carbon Lighthouse to any unexpected changes. That automation, Rosen says, "opens up a world of much deeper energy savings."