Radiant-Floor Heating: When It Does-and Doesn't-Make Sense

During judging of the Northeast Green Building Design Competition last spring, I was struck by the number of residential entries with really stellar passive solar design and super-high-performance building envelopes. Clearly, I thought as I began reviewing the features, we’ve come a long way in high-performance residential green building since my first experience with passive solar in the mid-1970s. But something also seemed odd. A majority of these entries had sophisticated radiant-floor heating systems. After going to all the effort and expense to superinsulate the envelopes of these houses and provide passive solar design, did they still need $10,000 heating systems? And did those systems really make sense from a performance standpoint? I wasn’t sure, and decided to dig into these questions.

I’ve long been a fan of the comfort delivered by radiant-floor heat, and strong arguments are often made about energy savings and indoor air quality advantages.

But is this really the best match for high-performance green homes? In the most energy-efficient buildings, the answer seems to be “no,” though radiant-floor heating can offer both comfort and IAQ benefits. This article provides a quick overview of radiant-floor heating, reviews the benefits of this heat-delivery approach, and reviews when these systems do—and do not—make sense in homes and small commercial buildings.