Decarbonizing Healthcare with Zero-carbon Reheat Systems
An innovative integrated AHU HEDS technology for dehumidification.
Electric Power Research Institute, Inc.
Recipient
Palo Alto, CA
Recipient Location
13th
Senate District
23rd
Assembly District
$474,611
Amount Spent
Active
Project Status
Project Update
As of Summer 2025, the project team is currently in the design phase for the high efficiency dehumidification system (HEDS) air handling unit retrofit for Naval Medical Center in San Diego in partnership with its facility team and the Defense Health Agency. Other project team members include Conservant (tech vendor), and Couts (design/build/M&V contractor). Subsequent steps will include pre-installation measurement and verification , and equipment procurement in 2025. Then, HEDS deployment and commissioning and post-installation M&V launch will take place in 2026. Tech transfer and final reporting activities will be completed by Q2 2027.
The Issue
Healthcare buildings are the second largest consumer of energy per unit of floor area of all building types. As much as 50 percent of energy use in hospitals is for space heating and cooling. In the United States, the healthcare industry accounts for nearly 10 percent of total greenhouse gas (GHG) emissions, and these emissions increased 30 percent 2006-2016. The large amount of energy needed to precool hot humid air, then dehumidify and reheat, creates an inefficient process. California's energy goals cannot be fully met without addressing inefficiencies associated with air dehumidification and reheating in HVAC systems. A successful demonstration of a high efficiency dehumidification system integrated with the air handling unit (AHU) will provide a credible working example to hospital facilities and HVAC design communities, who need evidence to support shifting to more modern, efficient technologies.
Project Innovation
Sustaining hygienic conditioned spaces is critical to the indoor air quality of healthcare facilities. This project will replace a traditional AHU and demonstrate a more energy-efficient and effective ventilation system at a San Diego hospital. The AHU will be equipped with an energy recovery technology called a High Efficiency Dehumidification System (HEDS). The HEDS technology substantially reduces or completely eliminates the need to provide new, fossil gas-sourced energy to the reheat process that is part of relative humidity control in HVAC systems. By removing heat from the chilled water return line, HEDS also substantially reduces the thermal load on electric chillers, further increasing gas savings at the generation source. HEDS systems also reduce fan and pump requirements and reduce maintenance costs because of their simple construction with fewer moving parts than competing systems. The goal is to reduce or eliminate fossil gas use for the cooling/dehumidification/reheat process. This demonstration could help healthcare facilities and HVAC design and procurement communities overcome the reluctance to adopting new innovative technologies.
Project Goals
Demonstrate how HEDS AHU technology can reduce energy for cooling/dehumidification/reheat processes in healthcare.
Demonstrate a significant reduction in fossil fuel use compared to a traditional system.
Demonstrate how HEDS AHU technology can reduce energy for cooling/dehumidification/reheat processes in healthcare.
Move Technology Readiness Level of the HEDS technology from 7 to 9.
Project Benefits
The proposed HEDS AHU retrofit can reduce the cooling and re-heating load of healthcare and other commercial facilities. Reducing or eliminating the re-heat load can result in year-round reductions in fossil gas and is a major decarbonization opportunity for healthcare. This technology also has the potential to offset cooling energy use. The net impact of this project will be lower operating costs for building operators and reduced greenhouse gas and pollutant emissions.
Affordability
Affordability
The system provides energy savings over traditional AHUs. In the right climate, the system will not require a boiler, will reduce cooling loads and will also experience indirect savings from smaller cooling fans and circulation pumps with lower maintenance requirements. Implementing the technology in California healthcare buildings could result in over $56 million in annual heating and cooling cost savings alone.
Environmental Sustainability
Environmental Sustainability
The contribution of commercial cooling to peak loads is estimated at about 44% of the 19GW peak for commercial buildings, or 8.36GW. Implementing the technology is estimated to reduce cooling load by 24%, corresponding to a total estimated peak reduction potential of 2GW for all of California commercial buildings or 77 MW for healthcare.
Key Project Members
Agatha Kazdan
Technical Leader / Project Manager
Electric Power Research Institute, Inc. (EPRI)
Jeanie Mar
CEC Project Manager
CEC
Aaron Tam
Engineer / Scientist
Electric Power Research Institute
Evan Giarta
Engineer/Scientist
EPRI
