Optimizing Radiant Systems for Energy Efficiency and Comfort

New practical design and operation tools for radiant cooling and heating systems will help capitalize on the energy savings over conventional all-air systems

The Regents of the University of California on behalf of the Berkeley campus


Berkeley, CA

Recipient Location


Senate District


Assembly District



Amount Spent



Project Status

Project Result

The project is complete. The recipient developed: sizing and operation tools to provide reliable methods to calculate energy performance of radiant systems while maintaining comfort, energy, cost, and comfort data to provide real world examples of energy efficient, affordable, and comfortable buildings using radiant systems, and recommendations for Title-24 and ASHRAE Standards advancements. The research team used full-scale laboratory experiments, whole-building energy simulations and tool development, and field studies and control demonstrations to develop guidance and tools to help the building industry adopt radiant systems. Recommendations for revisions to relevant codes and standards will continue to be communicated to the responsible organizations by the research team, who regularly participate in committees and conferences related to Title-24 and ASHRAE

The Issue

Radiant heating and cooling systems deliver or absorb heat through a building's surface. Application of radiant systems has increased in recent years as they provide an opportunity to (1) achieve energy and peak demand savings compared to conventional all-air systems, (2) eliminate duct losses, and (3) circulate less allergens. Despite this growth, operation of radiant systems can be challenging due to a lack of familiarity within HVAC design and operation professions because there is limited guidance and inappropriate tools to assist designers and building operators. New and/or revised definitions and methods for the design, sizing, and control of effective radiant systems are needed.

Project Innovation

This project develops new design and operation tools for radiant cooling and heating systems in order to provide standardized guidance for radiant systems in commercial buildings. The agreement includes full-scale laboratory experiments, whole-building simulations, development of simplified models for radiant system controls, validation of these new methods in field studies, occupant satisfaction surveys, and an update to Title-24 for radiant systems. The project produced: 1) a simplified tool for calculating the cooling load and cooling capacity of a radiant slab system, including calculation methods with significant direct solar radiation, 2) a simplified online operational tool for radiant slab systems, and 3) updates to the Title 24 Alternative Calculation Method Reference Manual to enable improved modeling capabilities of radiant systems.

Project Benefits

Radiant systems can be an integral part of ZNE and other advanced high performance buildings and reduce energy and peak energy use and cost compared to conventional HVAC systems.

Lower Costs


The technology could reduce energy consumption and costs in California commercial buildings by as much as 1.352 GWh/yr and $192M/yr.

Environmental & Public Health

Environmental Sustainability

The technology could reduce CO2e emissions due to reductions in energy use for cooling California commercial buildings. Based on the estimated annual electric savings, implementation of radiant systems could reduce CO2e emissions by up to 360,000 metric tons.

Key Project Members

Project Member

Fred Bauman



New Buildings Institute, Inc.


Taylor Engineering


TRC Engineers, Inc.


Match Partners


The Regents of the University of California on behalf of the Berkeley campus


Price Industries


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