Greenhill
Gas rooftop HVAC units are one of the largest hidden drivers of greenhouse gas emissions in the built environment. Over 15 million of them still dominate U.S. commercial buildings, burning fossil fuels for heat while wasting massive amounts of energy on cooling. Collectively, they lock in tens of millions of tons of CO₂ every year, while spiking peak demand, driving up utility bills, and breaking down often.
Yet despite the urgency, on-the-market heat pump options have failed to scale in this segment. They are either inefficient at commercial sizes or require extensive custom work and weeks of downtime, often driving installation costs into the hundreds of thousands of dollars. Faced with those hurdles, most operators simply replace old gas units with equally inefficient ones, perpetuating the cycle.
The result: adoption has stalled. Only 8% of commercial buildings in the U.S. have heat pumps today, compared to 27% in the residential sector. Operators want to electrify, but the economics have not penciled out.
Greenhill changes this. Model G is a next-generation rooftop heat pump (VRF) that redefines HVAC by capturing and recycling wasted thermal energy. Instead of burning gas or dumping excess heat outdoors, it transforms that energy into a resource while intelligently adjusting output to match a building’s real-time demand. With its plug-and-play design, Model G makes dynamic load matching practical and scalable for millions of commercial buildings.
Greenhill delivers the first solution that matches the upfront price of status-quo replacements while delivering 1.5 -1.7x the efficiency. That means the ROI finally works. Operators see real, measurable savings on utility bills without complexity, downtime, or custom engineering. This is the inflection point for commercial heat pump adoption at scale.
Team Members
Mustafa Sultan (BA, Economics), Prof. Christopher Gregg (PI, Computer Science)