When does Radiant Floor Heating 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.
When and Where Radiant-Floor Heating Makes Sense
It has been pointed out that radiant-floor heating systems may not be the best choice for extremely well-insulated, passive solar homes. So when do they make sense?
• In houses and small commercial buildings with conventional levels of insulation and standard insulated-glass windows—especially those in climates with minimal cooling loads—where the extra comfort of radiant heat is desired and the budget allows.
• In buildings with large open spaces and tall ceilings.
• In buildings where air-flushing is common, such as garages, fire stations, airplane hangars, and industrial spaces (because the large-area radiant floor allows quick recovery).
• When cost is not an issue and satisfying most or all of the heating load with solar energy is a high priority.
• When building occupants have acute chemical sensitivity or allergies—in which case there may be concern that dust could be distributed through a forced-air system or that high surface temperatures from a gas burner or electric heating element will burn dust particles and cause health problems.
Written by : Alex Wilson