Rhode Island Convention Center • Providence, Rhode Island
What’s VRF?
Session: HVAC Technologies
Mira VowlesBonneville Power Administration
August 10, 2016
Energy Exchange: Federal Sustainability for the Next Decade
Why should I care about VRF?
VRF systems:• can be very energy efficient• can improve comfort and IAQ• can be cheaper to install
in existing buildings
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Energy Exchange: Federal Sustainability for the Next Decade
How is VRF different?
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• Outdoor units condition multiple zones• Uses refrigerant to transfer heat • Good part‐load, and
cold‐climate performance
• Provides cooling and heating– Some can provide hot water and ventilation – Some can provide simultaneous heating & cooling
Energy Exchange: Federal Sustainability for the Next Decade
What kinds of VRF systems are there?
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VRF systems can be:1. air‐source,2. water‐source or 3. ground‐source
VRF system types: 1. VRF heat pumps and2. VRF with heat recovery (HR)
simultaneous heating and cooling
Energy Exchange: Federal Sustainability for the Next Decade
What are the components of VRF systems?
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DOAS –Dedicated Outside Air System
Energy Exchange: Federal Sustainability for the Next Decade
How much energy will a VRF system save?
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• Fan savings• Good part‐load efficiency and • Eliminates electric resistance heat due to good cold‐climate performance
‐difficult to verify savings!
Energy Exchange: Federal Sustainability for the Next Decade
How much do VRF systems cost?
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• Installed costs range between $10 and $22 per square foot
• Incremental costs range between $0 and $12 per square foot
• Utility incentives range between $100 and $800 per ton, based on incremental costs and energy savings
Costs vary a lot!
Energy Exchange: Federal Sustainability for the Next Decade
Who’s installed VRF?
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Washington State Utility HQ’s
VRF system with HR and DOAS– Existing building retrofit– Replaced packaged rooftop heat pumps– $12 per square foot incremental cost– Energy models predicted 25,000 kWh per year of savings– 56‐ton VRF‐HR system with DOAS– Retrofit occurred at night; so no need to re‐located occupants
Lessons Learned:– Train more than one person– Integrate control of VRF and DOAS– Install maintenance software for remote diagnostics– Design indoor units for condensate drainage– Remotes get lost
Energy Exchange: Federal Sustainability for the Next Decade
Who’s installed VRF?
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Oregon Multi‐Family Building
VRF system with HR and DOAS– New building with 35 apartments, a community
room and office space– Energy models predicted 80,000 kWh per year of savings
Lessons Learned:– Don’t let the refrigerant manifold be accessible to tenants.– Check the VRF model hourly reports to ensure the results are
reasonable. – VRF systems offer flexibility, save space and don’t require large
ducts. – The wall‐hung indoor‐units and an innovative ventilation solution
allowed higher ceilings and bigger windows, eliminating the costs associated with a dropped ceiling.
– The indoor and outdoor units are very quiet.
Energy Exchange: Federal Sustainability for the Next Decade
Who’s installed VRF?
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Washington State Office Remodel
VRF system with DOAS– $9.75 per square foot cost– LEED Platinum building– EUI of 21– Very low fan power
Lessons Learned: Integrated design reduced building loads and VRF system size.
Energy Exchange: Federal Sustainability for the Next Decade
Who’s installed VRF?
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Washington State Office Remodel
VRF system with DOAS– $14 per square foot cost– EUI of 26
Lessons Learned: Integrated design reduced building loadsand VRF system size.
Energy Exchange: Federal Sustainability for the Next Decade
Who’s installed VRF? (VRF = Variable Refrigerant Flow )
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Oregon College BuildingNew building with classrooms, offices and
common areas
VRF with HR and DOAS– $3.50 per square foot incremental cost– 9 VRF systems, totaling 120‐tons – 5‐year payback
Lessons Learned: – VRF system eliminated amount of required ductwork, freeing up
ceiling space for other utilities.– VRF system difficult to integrate with building energy
management system.
Energy Exchange: Federal Sustainability for the Next Decade
VRF systems promise
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• Energy savings,• Cost effective, flexibility,• Demand response potential, and• Quieter, better comfort and IAQ
‐ VRF systems are very promising,
but only with good design and operation.