Ventilation and Air Distribution
Use Variable Refrigerant Flow as HVAC
What Is It?
Variable refrigerant flow (VRF), or variable refrigerant volume (VRV), is a form of highly efficient HVAC. Instead of using air ducts, VRF uses a single outdoor condensing unit in order to provide heating and cooling. Refrigerant is circulated through pipes in the ceiling to fan coil systems in each room, and each fan coil can be maintained at a different temperature. VRF systems are meant to be used in buildings with diverse heating and cooling zones. They have the ability to heat and cool simultaneously and efficiently using recovered heat from cooling processes, increasing efficiency.
The size of the system makes it attractive for many consumers: VRF condensing units are small and easily portable, and can be kept on the roof without the need for an indoor machine room. The elevated equipment also leads to increased resiliency in case of flooding. The lack of air ducts means that the space required between floors is lessened. The systems also claim a 30-45% energy savings from a ducted system, as energy loss within the air ducts requires air to be heated or chilled to more extreme temperatures than needed.
VRF systems are widely used in Asia and are just beginning to gain popularity in the US. Half of all office buildings in Japan use VRF technology. In the US, where most buildings were established with ducted HVAC systems, VRF systems are not an effective retrofit. However, in new construction or historic buildings without space for air ducts, VRF systems can contribute to extensive energy savings, for a relatively short payback time of 10-15 years.
Benefits
- VRF provides 30-45% energy savings with approximately 10-15 years in payback time in new construction. Also has high part-load efficiency and eliminates losses from air ducts (EE Reports).
- Removes the need for a machine room as components are all stationed on the roof.
- An effective retrofit for older or historic buildings with operable windows for ventilation and no air conditioning installed.
- Lightweight and portable, easily installed.
- Simultaneous heating and cooling can be achieved with heat recovery systems. In this system, heat created from cooling processes is used to heat other spaces.
Drawbacks
- Higher initial costs than chiller systems.
- Shorter service life.
- Reduced effectiveness in extreme cold (subzero temperatures).
- Not an effective retrofit in buildings with HVAC systems already in place (however, retrofitting is effective in buildings without a previously installed system.)
Regulatory Impacts and Requirements
Potential regulatory touchpoints in Boston and Massachusetts include:
- Building code/permit
- Fire Department
Financing Options, Incentives, and Rebates
- A tax deduction of up to $1.80 per square foot is available for buildings that save at least 50% of the heating and cooling energy of a system or building that meets ASHRAE Standard 90.1-2001 (for buildings and systems placed in service before January 1, 2016) or 90.1-2007 (for buildings and systems placed in service before January 1, 2017). Partial deductions of up to $.60 per square foot can be taken for measures affecting: the building envelope, lighting, or heating and cooling systems.
- Mass Save: Custom Upgrades Incentives, Custom Projects - Adding or Replacing End-of-Life Equipment
News
- “NYC Church Blesses the Comfort, Environmentalism of VRF,” ACHR News, January 2017
- “LG Electronics Contributes To Baltimore Community Facility,” Facility Executive, July 25, 2017
Resources
- ASHRAE: Variable Refrigerant Flow Systems (PDF)
- Washington State University, Energy Efficiency Emerging Technologies: Variable Refrigerant Flow (VRF) Heat Pumps
- EE Reports: The Variable Refrigerant Flow Primer
Project Examples
- The Foundry buildings, Providence, RI, recently completed renovations including a VRF system which allowed for recreational uses for spaces that would otherwise be occupied by traditional HVAC equipment.
A Sample of Providers
- Most HVAC suppliers provide a form of VRF.
