Center for the Built Environment

While forced-air distribution systems remain the predominant approach to heating and cooling in U.S. commercial buildings, radiant systems are emerging as a part of high performance buildings. Radiant systems transfer energy via a surface that contains piping with warmed or cooled water, or a water/glycol mix and separate ventilation through a dedicated outside air system. These systems can contribute to significant energy savings due to relatively small temperature differences between the room set-point and cooling/heating source, and the efficiency of using water rather than air for thermal distribution1. They can also offer peak demand reduction, load shifting, and improved comfort compared to conventional all-air systems.

The California Energy Commission (CEC) EPIC program funded a radiant research project from 2016-2018 to better characterize the energy use, occupant perceptions, opportunities for improvement, and provide data and resources to increase market adoption of radiant for both heating and cooling. The Center for the Built Environment (CBE) at UC Berkeley managed the full research project titled Optimizing Radiant Systems for Energy Efficiency and Comfort. Within this project New Buildings Institute led Task 5: Energy Analysis and Occupant Surveys of Radiant Buildings and conducted the energy analysis and CBE led the occupant satisfaction survey and assessment.

The Task 5 research study included a review of the whole-building design characteristics and site energy use in 23 buildings and surveys of occupant perceptions of indoor environmental quality in 26 buildings with 1645 individuals. The following reports from the Task 5 study are available: 1) Energy Use of Radiant Buildings, 2) Occupant satisfaction with thermal comfort and acoustic quality in buildings using radiant and all-air systems and 3) Nine Building Case Studies of Radiant Heating and Cooling at www.cbe.berkeley.edu and www.newbuildings.org.

This summary provides an overview of the Energy Report Results and of nine case studies on buildings with radiant heating and cooling systems conducted in Task 5.