Market-leading Adoption of Scalable Low GWP Refrigerant Heat Pump in a Retrofit Application
Developing holistic and scalable solutions for transitioning conventional central plants to heat recovery chiller systems that use low GWP refrigerants
Lawrence Berkeley National Laboratory
Recipient
Berkeley, CA
Recipient Location
9th
Senate District
14th
Assembly District
$677,986
Amount Spent
Active
Project Status
Project Update
In 2025 the project team accomplished the following milestones:
● Investigated and evaluated ultra-low-GWP refrigerant heat pump products for the demonstration site based on refrigerant type, heating and cooling capacities, COP, equipment lead time, manufacturing location, price, and key technical specifications (e.g., supply temperatures, compressor type, and heat exchanger type).
● Developed technologies to reduce hot-water temperature requirements and heating loads, and deployed them at a demonstration site. Initial results show substantial natural gas savings (>30%) along with electricity savings across the range of outdoor temperatures observed to date.
● Developed a user-friendly web-based tool (REACT: Retrofit Energy Analysis and Central Thermal Modeling) to support early-stage heat pump retrofit decisions for non-HVAC experts. More detailed engineering modeling tools based on EnergyPlus and OpenModelica are also under development. The code is available through an LBNL Git repository.
The Issue
Low-GWP heat recovery chillers face several technical and practical challenges in the electrification of large commercial buildings. These challenges include mismatched heating and cooling loads and complex engineering requirements for properly sizing and configuring central plant systems. Many existing central plants are not designed to accommodate heat recovery chillers, as they typically operate with high hot water supply temperatures (around 180°F). Retrofitting these systems can be prohibitively expensive, particularly for standalone buildings with limited financial resources, and often require specialized technical expertise that many building owners lack. Market adoption is further limited by the scarce availability of large-capacity, low-GWP heat pumps in the U.S., along with concerns over the safety and long-term economic performance of these emerging technologies. As a result, building owners and engineers often question whether such investments are truly future-proof.
Project Innovation
This project will develop and demonstrate an integrated solution package. This package includes technologies that reduce hot water temperature requirements, along with software tools for cost-effective system design, control optimization, and heat source planning. These tools are designed to simplify engineering complexity and provide life-cycle cost analysis for various “what-if” design scenarios, making it easier for both HVAC professionals and non-experts to make informed retrofit decisions. To further support adoption, the project also addresses non-technical challenges through a real-world demonstration at Genentech’s Building 42. The resulting cost-benefit analysis and performance data will serve as a strong benchmark for replication. By showcasing best practices, the project aims to promote the safe, scalable, and economically viable deployment of low-GWP heat pumps across the commercial building sector.
Project Goals
Project Benefits
The heat pump retrofit solution package for partial or full electrification of central cooling/heating plants streamlines initial decision-making, reduces engineering work, and provides tailored retrofit paths, ultimately lowering upfront costs and transition times for central plants. By offering cost-effective retrofit solutions accessible to engineers and non-HVAC professionals, it facilitates the adoption of heat recovery technologies while supporting California’s stringent refrigerant regulations and climate goals. The early-adoption initiative also sets a robust benchmark for transitioning away from HFCs, enabling building owners and developers to meet long-term sustainability objectives. The widespread implementation of the tools would accelerate progress toward state climate goals by reducing gas consumption, advancing building decarbonization, and enhancing the sustainability and reliability of California’s energy infrastructure.
Environmental Sustainability
The facilitated adoption of heat pumps through the supporting tools will drive reductions in gas consumption and promote building decarbonization. Additionally, this project enhances long-term sustainability by advancing the phase-out of HFCs.
Economic Development
The holistic solution package would streamline initial decision-making, minimize engineering work, and offer tailored retrofit paths for each site, which ultimately cuts down on upfront costs for ratepayers and central plant transition time.
Key Project Members
Donghun Kim
Kaiyu Sun
Dmitry Bratslavsky
Subrecipients
TRC Engineers, Inc.
County of San Mateo, Office of Sustainability
Genentech, Inc.
University of California, Berkeley, Center for the Built Environment
YMCA of San Francisco
Affiliated Engineers, Inc.
GCI, Inc.
Match Partners
Genentech, Inc.
