Future-Proofing HVAC with Low-Temperature Hydronic Systems

Hydronic systems, which use water to move energy, are one of the most efficient ways to heat and cool buildings. Water carries far more energy than air, and does so in a small pipe rather than in leaky, bulky ductwork. It can also be engineered to deliver personalized heating or cooling to individual rooms. Many of the hydronic systems used in the U.S., however, are either older systems that use inefficient, oversized boilers to provide water at high temperatures (greater than 140°F), or radiant flooring used in inefficient 5,000+ square foot homes. Neither are ideal, sustainable uses of the technology.

Maximizing the efficiency of hydronic systems in high-performance buildings requires moving to low-temperature (less than 120°F) systems that require less energy to supply heating. In residential applications, water is typically distributed using a “homerun” system where PEX or PERT tubing, such as HyperPure (a recyclable PEX option without crosslinking chemicals and 2017 BuildingGreen Top 10 product), connects individual panel radiators to the heat source, typically a condensing gas boiler. But moving away from burning fossil fuels and toward more efficient electric systems will require a different heat source. According to John Siegenthaler, P.E., “The drive over the last couple decades has been to pair it [hydronic distribution] with renewable energy sources.” Heat pumps, as well as solar thermal and even biomass energy sources are all viable options and are being used by early adopters.