Climate appropriate HVAC Systems for Commercial Buildings to Reduce Energy Use and Demand

Climate Appropriate HVAC Systems Could Cut Energy Required to Heat and Cool Buildings

Electric Power Research Institute, Inc.


Palo Alto, CA

Recipient Location


Senate District


Assembly District



Amount Spent



Project Status

Project Result

The project is complete. The test sites were in San Diego, Aliso Viejo and Davis. Bundgard propane chiller, CO2 system and ammonia chillers were tested. Test results show electric savings of about 33 percent. Minor issues were experienced with new Melrok controller.

The Issue

Cooling and heating buildings contribute to a large portion of the electricity bills for California ratepayers. Traditional heating, ventilating and air conditioning (HVAC) systems waste energy. Innovations in HVAC systems, such as variable refrigerant flow and advanced indirect evaporative cooling systems are well suited for California climates. However, the full potential of these innovations has not been realized.

Project Innovation

This project developed and demonstrated a Climate Appropriate Air Conditioning system for commercial buildings that optimizes occupant comfort and can reduce energy use and peak demand. The project applies a combination of Variable Refrigerant Flow (VRF) technology with Indirect Evaporative Cooling (IEC) integrated and operationally optimized through the building control system. The project also investigated alternative non- Ozone Depleting Potential (ODP) or low global warming (GWP) refrigerants and HVAC system designs that could enable their usage in commercial buildings. This project will benefit small and medium commercial buildings, such as retail stores, offices buildings and food service and could be implemented in existing and new commercial buildings through direct replacement of rooftop packaged air conditioners. It is estimated that the HVAC systems for these sectors use 7,000 GWh and contributes 5 GW of peak demand.

Project Benefits

The technology advancement is the intelligent HVAC controller that processes signals from building sensors and system feed-back to maximize system efficiency while also synchronizing operation of the VRF and IEC to reduce energy use and peak energy demand and maximize occupant comfort. The innovative control system utilizes cloud based optimization using weather, grid conditions and occupancy (CO2) as inputs to optimally operate a VRF and the IEC system to reduce both energy and water use. The IEC was set up as a dedicated outdoor air system and incorporated variable speed blower and heat recovery ventilation. These subsystems were intelligently controlled by the building controller. This project evaluated and provided system designs that use alternative refrigerants that have zero ODP or low GWP.

Lower Costs


This project could reduce electricity use for HVAC systems beyond 33 percent. This could mean lower energy costs for commercial building owners or occupants that pay utility bills.

Environmental & Public Health

Environmental Sustainability

This project tested alternative refrigerants (propane, CO2, ammonia, primary/secondary systems and blends like R-32) that could significantly reduce greenhouse gas emissions. Test results are promising. CO2 system tested has slightly lower cooling COP with slightly higher than average cooling capacity and higher heating capacity and higher heating COP. Further improvement to the capacity and COP of the CO2 unit is possible with increases in COP upwards of 20% possible.

Key Project Members

Project Member

Ramachandran Narayanamurthy

Project Manager



Pacific Gas and Electric Company


Morton H. Blatt


Western Cooling Efficiency Center - UC Davis


MelRok, LLC


AireRite Maintenance


Jackson and Blanc


Richard Milward


Match Partners


Electric Power Research Institute, Inc.


Contact the Team