The word “sustainable” can mean a number of things. If describing a hydronic HVAC system, it matters little how it’s used. Water-based heating and cooling systems are environmentally sustainable, financially sustainable and built to last for the life of building.

Green in many hues
“Green” is another term with a lot of uses. For our purposes, it encompasses just about anything that decreases energy consumption or reduces pollution. While many of the components in every hydronic design are “green” all on their own, hydronics allow a building’s heating and cooling system to integrate with most renewable energy sources.

Solar thermal and photovoltaic, CHP (combined heat and power), geothermal, woody biomass and energy recovery can all be easily tied into a central hydronic system. No other type of HVAC system is so flexible. Manufacturers of VRF (variable refrigerant flow) equipment claim the ability to provide heat recovery, but this is only true in the rare instance when adjacent indoor units are in different operating modes (simultaneous heating and cooling).

With a hydronic system comes the ability to supply domestic hot water pre-heat, either as a byproduct of space cooling or as an add-on to its heating element. Thermal storage is also a significant capability, either as a peak-shaving function or means of load-sharing.

The fact that hydronic HVAC systems are capable of integrating with so many green technologies and renewable energy sources makes hydronics the true path to Net Zero.

Simply more efficient
Energy efficiency results in environmental sustainability and lower operating costs. Over the decades, hydronic systems have consistently been proven to use less energy than other heating and cooling technologies.

Even basic water-based systems outperform VRF systems by 30 to 40 percent as it pertains to energy consumption. One of the main reasons hydronic systems beat alternative equipment selection is the ability to transport energy at a low cost. With water’s high specific heat and today’s super-efficient pump choices, refrigerant compressors (VRF) and their associated blowers (forced-air systems) are comparatively less efficient.

VRF and air-source heat pumps, like all air-cooled equipment, rely on outdoor air as a source of heating and cooling capacity. While this approach works well for a small portion of the year, summer and winter are taxing. The efficiency of a hydronic system remains very high year-round, whether the source of energy is a boiler and chiller, condenser water or water-source heat pump loop (boiler/tower or GeoExchange).

Why? Because these systems operate at designed and controlled temperatures, not outside air temperature.

Energy Sharing – today and in the future
If two buildings had exactly the same energy use but one has the ability to recover and repurpose heat, or the ability to adapt to changing technology, it would always win regardless of component efficiency currently available. Sustainability is about the future and hydronic systems are all about sustainability (forward and backward compatibility).

Reducing refrigerant
Mother Nature is no fan of refrigerant. While new refrigerants are less harmful to the environment than earlier chemicals, the threat of ozone depletion is still very real. Water, on the other hand, presents no such risk. And to date, the newer refrigerants, deemed to be less harmful, are at the same time more flammable and also less efficient. Refrigerants will change over time. Be prepared for the life of the building with a hydronic solution.

Plain and simple, hydronic systems use less refrigerant than other technologies. Fossil fuel-based, heating-only hydronic systems generally don’t contain refrigerant at all. When cooling is included, an average hydronic system will include 66 to 75 percent less refrigerant than a VRF system of the same size.

Also, hydronic systems use small, factory-sealed refrigerant circuits, unlike the extensive, field-installed refrigerant circuits in VRF systems. This means far fewer chances of a leak developing.

Test of time
When it comes to shrinking carbon footprint and maximizing ROI, the longevity of a hydronic system is a huge benefit. Because hydronic systems are upgradeable, expandable, and built from universally-available components, they’re able to change and adapt to the needs of the building and advancement of technology.

Countless hydronic systems in the New England states have been comfortably and efficiently serving homes and buildings for nearly 100 years. Though the boilers have been changed over the decades, the piping and heat-emitters remain in place.

On the contrary, VRF components are proprietary, and generally do not interchange between manufacturers' systems.

Refrigerant also becomes obsolete. Water doesn’t. Water was used in hydronic systems 100 years ago and it’ll be used in hydronic systems 100 years from now. The issue with changing refrigerant is that systems of 15 years ago can’t use today’s refrigerant. Factory-sealed refrigerant circuits can be replaced easily, but when refrigerant changes, entire VRF systems must change as well.

Hydronics provide a long term investment.

For sustainability, water always wins. Think hydronic.

For more information, please contact the Radiant Professionals Alliance and the Hydronics Industry Alliance at (877) 427-6601 or info@HIA-C.org