It’s not a new technology, but it’s more popular than ever. While VRF is providing engineers and building owners with a financial payback, the benefits go beyond energy efficiency. 

Since the early 1980s, variable refrigerant flow systems have been a great option for engineers and building owners in need of an alternative to typical heating and cooling in the commercial sector. However, the technology really didn’t take off in the U.S. until about a decade ago.

Whether the need is for more comfort control, energy savings, or just a tricky architectural project, VRF has been filling a need where traditional systems might prove too cumbersome or just didn’t quite hit the mark.

So where are engineers finding the best bang for their buck when it comes to VRF? How is this technology still going strong in the HVAC market? And is there anything we can expect to see from VRF in the future?


Energy and sustainability

According to Michael Enderlin, ductless products business leader for Trane, VRF is one of the fastest growing HVAC segments in North America.

“There is increased demand from building owners and facility directors in the school, lodging, and small vertical markets,” he said. “Trane was one of the first to bring the awareness of this product to the North American market. We continue to support engineers in their effort to select the right system to meet the needs of the facilities they design.”

One of the biggest benefits of VRF for these facilities beyond energy efficiency is the ability to heat and cool at the same time.

“This is a benefit in buildings that have multiple, relatively small and separate zones. It can also be used to retrofit structures not originally designed with ductwork,” said Enderlin.

One example of this is Hunter Industries in San Marcos, CA, manufacturer of irrigation equipment and systems. The company was looking for energy-efficient solutions, as well as a LEED certification, when it came to renovating its 49,000-sq-ft, two building location. Previously, the buildings had low occupancy, but they would be converted into high-occupancy office spaces for the company’s engineering teams.

Officials with Hunter contacted Trane representatives for a solution. They suggested using a VRF system for several reasons. First, the VRF system at Hunter is able to move heated and cooled refrigerant via small pipes in the interior of the building. The refrigerant passes through coils in each of the designated room. Fans then move air past the coils transferring warm or cool air in the rooms seeking heating or cooling.

By eliminating the need to install a new chiller system or ductwork, Trane officials said installation costs were kept down.

With the use of a three-pipe design and vapor injection technology, Trane says its VRF heat recovery system is able to impove heating performance and energy efficiency. The VRF’s asymmetric scroll design is said to increase refrigerant flow rate and heating capacity as much as 20%. The variable speed compressors match output demand levels, allowing Hunter Industries to heat or cool rooms only when in use. This, according to the manufacturer, helps to keep energy consumption in check.

Hunter officials said they are happy with the results. Not only do their employees have greater comfort control, but they have seen a reduction in energy costs and greater efficiency that aligns with the company’s sustainability goals.

Trane officials are optimistic about the future of the VRF market. Enderlin said their team is looking at finding ways to improve air distribution for even greater temperature consistency. Also, the company is looking at the use of next-generation, low-GWP refrigerants. This will help to not only keep systems more efficient but will reduce greenhouse emissions.

Finally, Enderlin said the future will look at introducing open protocol configurations for smoother transition into a BAS.



For Brendan Casey, energy efficiency has definitely been the big selling point for VRF. As the commercial project manager for Fujitsu, Casey has worked with VRF systems for the past six years, and has seen how awareness and acceptance of the product continues to grow.

He echoed the sense that while VRF systems have been available all over the world for some time, including Asia for the past 30 years, it wasn’t until the mid-1990s that it started to find use in the U.S. For example, businesses with small computer rooms were harnessing the technology. But then in 2005, the technology really took off when engineers and facility managers saw the energy savings capabilities.

In fact, Casey said VRF sales grew by 25% each year from 2005, even when the economy was hit hard and building owners were cautious when it came to investing in new systems.

But Casey says energy efficiency is not the only major benefit to these systems. “They are very quiet and very flexible for installation.”

In his position with Fujitsu, Casey has overseen the HVAC market in New York City. He reports that Fujitsu VRFs have typically worked perfectly for the city’s highrises and apartment buildings.

Casey says he has seen examples where an apartment’s building manager will shut down the building’s AC over a long holiday like Memorial Day or Labor Day because there will be no one onsite to monitor a boiler system. That practice is eliminated when an apartment building invests in VRF. Each apartment building tenant will be in charge of controlling their own heating and cooling. In turn, they will also have more control over their own heating and cooling costs.

Casey also points out that in New York City, many buildings cannot properly utilize traditional rooftop systems. A VRF can be a great alternative to space and code issues. He also says they are more affordable to operate than steam systems or chilled water.

There are also safety concerns. In 2014, New York saw an outbreak of Legionnaire’s Disease. The bacteria that cause Legionnaire’s Disease can grow in warm environments, including cooling towers if they are not properly maintained. By opting for VRF, Casey notes that the potential headache of cooling tower maintenance is eliminated along with that particular health risk.

As for the future, Casey believes the introduction of new refrigerants could make VRF technology even more efficient. But currently, he said, VRF is about as efficient as it could be.

“It’s like having a Prius,” Casey said about the current VRF systems on the market.


Learning to customize

The popularity of VRF systems is not lost on Daikin. According to Lee Smith, the vice president of market and applications strategy for the company’s VRV & Light Commercial Division, the systems are one of the fastest growing categories in the HVAC market.

“With the technology now more widely understood, regulated and utilized, we are seeing a vast increase in the number of engineers looking to design around or specify VRF systems, and the technology is quickly becoming one of the first considerations when conceptualizing a building upgrade or design,” he said.

Lee cites the ability to customize the technology as a particular asset for VRF.

“The customization elements include how the system can be zoned, assigned to condensing units, and the scalability of controls form a zone, floor, tenant, building, campus, or network perspective,” he said.

Daikin’s VRF systems have been used in many of these examples, including several schools and school districts. One example is the Hazlewood School District north of St. Louis. The district was looking for a new HVAC technology to replace the systems in its 30 buildings. Some of the systems were close to 25 years old, and maintenance costs were rising.

After investigating options, the district adopted VRV/VRF technology from Daikin. The goal was to use the system’s heat recovery capability for better comfort and reduced tonnage while also saving on energy costs.

Several Hazlewood schools installed the air-cooled recovery systems, with more to follow. The results were as expected — energy savings was maximized, and the reduced tonnage resulted in less maintenance.

But there were other benefits that were more obvious to teachers and staff. The compact systems are quieter and eliminate classroom noise. Also, according to the district, for classrooms receiving more sun during the day, teachers can adjust the system to keep the environment cool. For classrooms that don’t receive much sunlight, the Daikin system can be adjusted for heat if needed. Classrooms no longer need to settle on one temperature for the entire building.

Daikin officials said VRF is going to continue to evolve, especially as an applied solution.

“The systems are being utilized beyond the notion of just basic cooling and heating needs and are being used as a total solution inclusive of building level controls, and to address other thermal needs of the building, whether ventilation, hot water, and other elements,” said Lee.

On a smaller scale, he believes VRF will be used in more traditional “cookiecutter” markets. This includes light commercial applications where VRF can be used in multiple buildings or floorplans in a “consistent and repeatable manner.”


Historic designs         

Ease of installation and maintenance are also at the top of the list for Mitsubishi Electric. The company manufacturers the City Multi VRF system, which comes in several configurations, including heat pump and heat recovery. They also include Inverter™ technology, a driven compressor in the outdoor VRF unit that helps to vary speed and allow for better zone control while reducing energy consumption, according to Kevin Miskewicz, senior manager for commercial marketing at Mitsubishi Electric.

Miskewicz said the company’s systems fit a number of applications, from large residential to commercial projects, as well as the mixed-use and high-rise buildings mentioned by Fujitsu’s Casey.

“The compact design of the outdoor units leads to lighter weight, which translates to an easier and more affordable installation,” Miskewicz continues. “Compared to the common three-pipe design, Mitsubishi Electric’s unique two-pipe design makes installation of heat recovery systems even easier, leading to reduced installation costs for a building owner.”

In turn, the compact design of the outdoor units also affects the indoor units, providing a more discreet look, according to the company. 

In some applications, the compact design of the system is a must. In fact, building owners may not want the HVAC system to be visible. One example is in historic buildings.

Miami University in Oxford, OH, was looking for a simple HVAC solution when it decided to upgrade two residence halls. The three-story Elliott Hall was built in 1825, and nine years later, the university built a second residence hall, Stoddard (“Old South”).  Both halls were remodeled several times over the years, and in 1972, they were both placed on the National Register of Historic Places.

To grow the campus and reduce energy costs, Miami made geothermal heating and cooling part of its sustainability strategy. The plan also included improving the efficiency of the Elliott and Stoddard Halls. VRF zoning systems from Mitsubishi Electric were chosen as the best fit.

Not only was the university impressed with how the VRF system would save on energy and provide heating and cooling, but how the system would not compromise the historical structures.

Seventeen, 600-foot-deep geothermal wells were placed under the sidewalks surrounding the halls. As modern footings were unknown 150 years ago, the hand-dug basements had no space for the Mitsubishi Electric heat pumps. A mechanical room was built into the attic of each hall for the three heat pumps and the centralized controller. To maintain the architectural integrity, custom cabinets were designed and built to house the indoor units for each room.

Without the two-pipe system design of the Mitsubishi system, installers said the interior of the university halls would have been severely cut up with a hydronic four-pipe system. The result was energy efficiency without disturbing the structural integrity.

The manufacturer says it sees the HVAC industry continuing to embrace VRF in the United States.

“Looking around the world, where VRF has up to 90% market share in certain countries, we see a model for how this would look in the United States,” said Miskewicz. “VRF systems can be applied to both new construction and renovations. In both applications, our products are a great way to ear LEED points — a hot topic in the industry given the public’s general interest in green building design.”

Mitsubishi also sees more advanced controls in VRF’s future, allowing greater energy efficiency and enticing more customers to invest in the technology. ES