Decarbonizing Healthcare with Zero-carbon Reheat Systems

An innovative integrated AHU HEDS technology for dehumidification.

Front of Thorton Hospital AHU 12 and 13 Rooftop installation site for HEDS AHU at Thorton Hospital. HEDS Puerto Rico

Electric Power Research Institute, Inc.


Palo Alto, CA

Recipient Location


Senate District


Assembly District



Amount Spent



Project Status

Project Update

The existing HVAC system is being monitored following the pre-installation M&V plan. Engineering design for the replacement AHUs is underway, with the basis of design and 90% design development (DD) package completed.

The Issue

Large amounts of reheat and other HVAC related energy are wasted in large buildings such as hospitals and other facilities where control of relative humidity in their conditioned spaces is required. The energy needed to precool hot humid air, dehumidify and reheat, is inefficient. California's energy goals cannot be fully met without addressing inefficiencies associated with air dehumidification and reheat in HVAC systems. A successful demonstration of the high efficiency dehumidification system integrated with air handling unit will provide a working credible example to hospital facilities and HVAC design communities, who need evidence to support modern, efficient technologies.

Project Innovation

Sustaining hygienic conditioned spaces is critical to the indoor air quality of healthcare facilities. This project will demonstrate a more energy-efficient and effective ventilation system called High Efficiency Dehumidification System (HEDS) Air Handling Unit (AHU) at a hospital. The dual goal is to reduce or eliminate natural gas use for the cooling/dehumidification/reheat process. Potential savings to California commercial buildings include: 1) cooling load reduction by at least 24% compared to traditional air handling systems which may result to annual savings of over 3,000 GWH and cost reductions of over $400M; and 2) eliminating the reheat and NG consumption from boiler use could result in annual savings of more than $600M, with emission reductions of greater than 4 million tons of CO2 and over 4,000 tons of NOx. This easily accessible high-stakes working demonstration could help HVAC design and procurement communities overcome the reluctance of adopting new innovative technologies.

Project Goals

Demonstrate new, high-efficiency technology for air dehumidification is a better option than its conventional air handlers

Project Benefits

The proposed HEDS AHU can reduce the cooling and re-heating load in large commercial buildings, such as hospitals. Reducing or eliminating the re-heat load is a major game changer and will result in year round reductions in natural gas use for hospitals and other large buildings. In addition to reducing or eliminating reheat, this technology has the potential of offsetting cooling energy use. The net impact of this project will be lower operating costs for building operators and reducing in greenhouse gas and other emissions.

Lower Costs


The technology has the potential of reducing cooling load by over 24% and eliminate/reduce natural gas use for reheating. Implementation of the technology in CA commercial buildings could result in over $1 billion in savings.

Environmental & Public Health

Environmental Sustainability

The proposed system reduces greenhouse gas emission by over 4 million tons of CO2 and over 4,000 tons of NOx due to higher efficiency than traditional AHUs and the elimination of boiler use.

Key Project Members

Mammoli headshot

Andrea Mammoli

Technical Leader / Project Manager
Electric Power Research Institute, Inc. (EPRI)
Kazden Headshot

Agatha Kazdan

Technical Leader / Project Manager
Electric Power Research Institute, Inc. (EPRI)
Project Member

Jeanie Mar

CEC Project Manager

Contact the Team