Rethinking radiant comfort

Radiant cooling and personal comfort systems allow air temperature setpoints to be widened, but current comfort standards and measurement techniques can deny the possibility of fulfilling that potential. Radiant cooling capacity has often been limited by condensation risk from the direct contact of radiant panels with humid air, requiring coupling with air conditioning. Recent studies and experimental systems demonstrated the decoupling of radiant panels using IR transparent membranes that protect sub-dewpoint, non-condensing radiant cooling surfaces. To explore the potential impacts of experimenting with acceptable air temperatures on the energy efficiency of ventilation air delivery, a new comfort mapping framework is presented that allows radiant or ventilation temperatures to be selected as setpoints. It was found that black globe correction methodologies are incorrectly calculated, diminishing the comfort benefits of designing for a higher potential separation of Mean Radiant Temperatures (MRT) from air temperature, embedding systematically biased outputs into the ASHRAE thermal comfort database measurements. The findings highlight the urgent need for more work on radiant heating and cooling systems. Their role in a more resilient future of radiant systems that can save energy while increasing fresh air, occupant health and comfort in buildings is discussed with examples.