Initial costs of a VRF installation vary from $16.50 to $33 per square foot, PNNL notes. Systems should last at least 15 years, so any payback period inside that time frame is ideal, the report adds. But aside from simple payback, there are several factors that contribute to a successful installation.
“Depending on the style of the building, VRF zoning systems tend to have fewer components than conventional HVAC systems, reducing equipment costs and complexity as well as installation time,” Smith explains.
According to PNNL, the major energy savings potential comes from the following aspects:
- Variable speed compressors provide high part-load cooling and heating efficiency.
- Reduced fan energy results from low static pressure and elimination of ductwork for space cooling and heating reduces fan energy.
- Refrigerant, rather than water or air, requires less energy to move the heat transfer fluid.
- Some units are capable of heating and cooling at the same time to different zones without reheat and providing heat recovery between zones in heating and cooling at the same time.
VRF systems require occasional maintenance of the fan coil unit, which entails filter changes, cleaning of condensate removal systems, and the replacement of fan motors and coils.
“I’ll knock on my desk because to this point I’ve had no maintenance issues,” explains Rogers, adding that he has only needed to clean coils and change filters. ‘They’ve just hummed along.”
Since the installation, Rogers has observed many intangible benefits aside from the $36,000 annual energy savings.
“Now people can do what they want,” he says. “Since the installation, I haven’t had anyone call me to complain that they’re too hot or cold.”
Occupant satisfaction brings value by attracting and retaining people at your facility.
“Early adopters looking for an edge against older designs will just reap that many more benefits in the future,” says Kevin McNamara, vice president of commercial air conditioning for manufacturer LG. “VRF can really help owners, operators, and occupants have a much better building experience.”
Case Study #1
TOM CRANE PHOTOGRAPHY
Strawberry Mansion – Philadelphia, PA
Built in 1789 as a summer home for a renowned lawyer and abolitionist, this is the largest of seven historic Fairmount Park houses. It spans 10,000 square feet across four levels and 23 rooms.
One aspect of its four-year extensive renovation was replacement of the 1930s radiators, steam, and condensate piping in favor of central HVAC. Climate control for antique collections was needed, but the system could not intrude on the architecture.
The project already included a geothermal system, but VRF offered even more efficiency. The VRF system and discrete indoor units easily fit inside old chase walls and ceilings with no space for ductwork. The two-pipe design saved $50,000 upfront compared to the four-pipe proposal.
Case Study #2
|Photo Credit: Mitsubishi
City Hall – Chandler, AZ
This five-building, 137,000-square-foot civic center campus includes city offices, council chambers, television studio, printing center, community art gallery, courtyard, and parking facility.
For the city hall’s vital nerve centers – 17 electrical rooms and nine data closets located throughout all the buildings – an efficient HVAC system was needed to handle constant heat gain and also meet the city’s energy reduction goals.
Traditional systems turn on and off depending on whether the room is too cool or warm, but VRF constantly modulates refrigerant temperature, allowing the nerve centers to remain at a constant 75 degrees F. more efficiently than other options.
Case Study #3
Lewis County Public Utility District – Chehalis, WA
This two-story, 23,700-square-foot office building was constructed in the 1940s. The site includes 72 individual climate zones that were being served by seven rooftop heat pump units.
The goals of the retrofit were to increase zoning for better comfort, reduce carbon footprint and energy usage, keep hard ceilings intact, and provide a simple control system that was easy to operate.
The phased installation allowed the building to remain occupied during construction. The system operates more quietly, and
occupants are also satisfied with increased comfort and control.
SOURCE: BONNEVILLE POWER ADMINISTRATION
Case Study #4
Pacific University’s Burlingham Hall –
Forest Grove, Oregon
This 49-unit, 59,000-square-foot dormitory serves college
An efficient HVAC system was needed for the historical campus architecture. VRF presented structural advantages that other modern options did not. The facility was also pursuing LEED Gold certification.
Compared to the baseline model, the new VRF system uses 33.5% fewer kWh. Electricity costs are also $11,600 lower annually than forecasted. Because the system can heat in temperatures as low as -14 degrees F., no backup heat is necessary.
SOURCE: WASHINGTON STATE UNIVERSITY
Chris Curtland firstname.lastname@example.org is
assistant editor of BUILDINGS.