Stasis Energy Group Thermal Energy Storage System (TESS) for Packaged HVAC Systems

Stasis Energy Group LLC



Recipient Location


Senate District


Assembly District



Amount Spent



Project Status

Project Update

In 2021, Stasis Energy Group successfully began its BRIDGE project with installs at ten (10) sites across California. In Q1 2023, the project concluded the baseline data collection period and all TESS (thermal energy storage units) are installed and performance data collection has begun across all 10 sites. The BRIDGE sites, from West Sacramento to San Diego, represent a wide variety of businesses, HVAC equipment, climate zones, and occupancy profiles. Nine of the ten sites are DAC/LIC, underserved communities. Stasis Energy Group has made improvements to both the form factor and thermal storage controller algorithms deployed due to learnings from the baseline data collection period. These changes reflect increased performance, lower installed costs and better occupant comfort across a wider range of installations throughout the State of California.

The Issue

The California Energy Commission (CEC) and California IOUs face a daunting challenge to transition to 100% renewable energy by 2045. California’s climate goals will require reduction of peak period electric usage, when Greenhouse Gas (GHG) emissions are highest. Reducing energy use in existing buildings will be crucial to achieving these goals. Flexible distributed energy resources (DERs) can help California succeed in this transition, and these DERs require thermal batteries such as TESS, electric batteries, and other types of resources. New products and technologies, such as the Recipient’s TESS, must be developed and introduced to the market to reach these goals. Benefits to California’s energy providers and utilities must include reduction in peak energy use when power is the most expensive and when generating power has the highest carbon intensity. Benefits must be shared with ratepayers in the form of lower utility bills.
Packaged HVAC roof-top equipment services as much as 70% of California’s light commercial floor space, accounting for more than 22 billion kWh per year. Up to 95% of these RTUs, approximately 5 million tons of HVAC capacity, are sized at 10 tons or less. Most units have 10-20 years of service life remaining. Few, if any, technologies adequately and economically address this large market. Late afternoon and evening energy used by commercial buildings RTUs have proven to be a hard-to-reach segment of California’s electricity usage.

Project Innovation

This project supports the deployment and demonstration of Thermal Energy Storage Systems (TESS) for packaged HVAC systems at ten commercial buildings, more than half of which are located in disadvantaged or low-income communities. Stasis Energy Group will demonstrate peak shifting performance of its TESS across a wide range of roof-top unit types, climate zones and buildings. This solution is intended to be easily and economically installed or retrofitted into existing packaged HVAC systems to provide a cost-effective solution. In addition, the proposed technology aims to reduce utility bills for building owners, promote grid resilience by shifting electricity load away from peak hours, and to improve the payback period.

Project Goals

Demonstrate 60%+ reduction in peak summer cooling energy demand.
Demonstrate 5-year payback to business owner.
Demonstrate occupant comfort satisfaction and year-round performance of technology with third-party verification of data.

Project Benefits

This project supports development of a first-of-its-kind thermal energy storage system technology. The project targets a critical and hard-to-reach segment of electricity usage - 4-9 pm - for packaged roof-top HVAC systems, when energy demand is highest and renewable generation is diminishing. The technology addresses electricity usage in three ways during the summer 4-9pm peak period: 60% peak demand reduction, 50% - 55% load shift from peak to off- peak period, and 8%-15% energy efficiency savings with cloud-¬based controls. Savings delivered in non-summer periods align with measured summer savings. Significant significant GHG savings are realized because TESS is charged by sustainable energy during normal cooling operations and deployed during the highest cost energy period late in the day. The thermal storage material is a natural, bio-based product and the aluminum packaging of the thermal storage material is made of 75% recycled metal.

Lower Costs


The proposed technology is intended to lower electricity costs of business owners by shifting their use out of peak periods.

Greater Reliability


The product aims to simplify the challenge facing grid operators by increasing use of daytime renewable energy and reducing use of late-afternoon and evening ramp-up energy, thus reducing the risk of energy shortages.



RMS Energy Consulting, LLC


Intertek USA Inc.


Build Smart Group LLC


Winn Energy Controls


Greer Burns & Crain


Rowan Engineering


Match Partners


PureTemp LLC


Contact the Team