vrf system optimization - · pdf filevariable refrigerant flow systems have gained popularity...
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VRF system optimization
Ryan R. Hoger, LEED AP
Ryan R. Hoger, LEED AP
Thank you to our Sponsors
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SeventhwaveG175
VRF system optimizationC2496
Ryan Hoger12/1/15 (then available on-demand)
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Credit(s) earned on completion of this course will be reported to AIA CES for AIA members. Certificates of Completion for both AIA members and non-AIA members are available upon request.
This course is registered with AIA CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner ofhandling, using, distributing, or dealing in any material or product._______________________________________
Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation.
Variable refrigerant flow systems have gained popularity in the United States over the past 8 to 10 years for a variety of reasons including energy efficiency and flexibility. Learn more about the various types of VRF systems, how they work and how they compare to other technologies.
CourseDescription
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LearningObjectives
• Discuss various types of VRF systems.
• Identify VRF energy improvement opportunities.
• Analyze and identify the proper applications for VRF systems.
• Describe real-world examples of VRF systems in action.
At the end of the this course, participants will be able to:
GBCI cannot guarantee that course sessions will be delivered to you as submitted to GBCI. However, any course found to be in violation of the standards of the program, or otherwise contrary to the mission of GBCI, shall be removed. Your course evaluations will help us uphold these standards..
Approval date:
Course ID: 0920005911
VRF system optimization
Seventhwaveby
10/23/2015
Approved for:
1.5General CE hours
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Agenda…
• VRF History & Heat Pumps Basics
• VRF Fundamentals
• Heat Pump vs. Heat Reclaim
• System Operation
• Common Applications
• Economic Comparisons
• AHRI Rating System
• VRF vs. Geothermal
• ASHRAE 15 Refrigerant Safety
• Case Study: ASHRAE (Atlanta, GA)
• Case Study: Seventhwave (Madison, WI)
ASHRAE hdqtrs renovation includes Heat Recovery VRF
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Heat Pumps
“Reverse Cycle” Heating
Outdoor“Evaporator”Coil
Indoor“Condenser”Coil
Compressor
Thermostatic Expansion Valve
Hot Gas
SupplementaryHeater
Heating Cycle
Cooling Cycle
Cold Days in Northern Climates
Temperature Bin Hours (‐20˚F to +65˚F )For Midwestern Cities
Duluth, MN 7,650 4,510 59% 5,770 75%
Eau Claire, WI 6,601 4,033 61% 5,154 78%
Fargo, ND 6,864 3,956 58% 5,070 74%
International Falls, MN
7,638 4,438 58% 5,567 73%
Minneapolis, MN 6,522 3,990 61% 5,045 77%
Rochester, MN 6,783 4,314 64% 5,321 78%
City Total Bin Hours
Hours Above 30˚
% of Total Hours
Hours Above 20˚
% of Total Hours
South Bend, IN 6,349 4,829 76% 5,879 93%
Moline, IL 6,034 4,520 75% 5,390 89%
Chicago, IL 6,014 4,553 76% 5,405 90%
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Full or Part Load?
What is VRF? (VRV)
• Single or tandem outdoor units• Multiple indoor units on same refrigerant network• Variable speed inverter compressors• Various sizes and styles of indoor units• Daisy chain communication• Heat pump (2-pipe) or…• Heat Recovery with SIMULTANEOUS heating and cooling (3-pipe)
Variable Refrigerant Flow or
(VRV) Variable Refrigerant Volume
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System Operation
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Heat Pump
(2-pipe)
2-way Heat Pump System
ACR Soft Copper (Insulated)
18ga 2W(S)18ga 2W(S)
Ball Valves
Condensate
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VRF Heat Pump Operation
3T Nom1T Load
3T Nom1T Load
2T Nom0T Load
2T Nom1T Load
Compressor Capacity = 3T
8 Ton
Load
EEV
Fan
Heat Recovery (3-pipe)
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3-way Heat Recovery System(Simultaneous Heat/Cool)
ACR Soft Copper (Insulated)
18ga 2W(S)
18ga 5W
18ga 2W(S)
Ball Valves
Condensate
Different types of VRF piping systems
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Heat Balance Control- Heat Recovery
AC
DC
Cooling
2Tons
Cooling
2Tons
Cooling
1Ton
Cooling
1Tons
Cooling
2Tons
Cooling
ALL I/U COOLING
8 ton
DCV1,2:OpenSCV1,2:Close
AC
DC
Heating
2Tons
Heating
2Tons
Heating
1Ton
Heating
1Tons
Heating
2Tons
ALL I/U HEATING
8 ton
DCV1,2:CloseSCV1,2:Open
Heat Balance Control- Heat Recovery
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AC
DC
Cooling
2Tons
Cooling
2Tons
Heating
1Ton8 ton
:Close
DCV1:OpenDCV2,SCV1,
2:Close
COOLING:4Tons>HEATING:1TonsComp. Capacity=Cooling Capacity=4Tons
O/U Heat Ex. Capacity=Cooling-Heating=3Tons
3Tons
4Tons
AC
DC
Heating
2Tons
Heating
2Tons
Heating
1Ton
Heating
1Tons
Cooling
2Tons8 ton
DCV1,2:CloseSCV1,2:Open
HEATING:6Tons>COOLING:2TonsComp. Capacity=Heating Capacity=6Tons
O/U Heat Ex. Capacity=Heating-Cooling=4Tons
4Tons
6Tons
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AC
DC
Heating
2Tons
Heating
2Tons
Cooling
1Ton8 ton
DCV1,2,:CloseSCV1:OpenSCV2:Open
HEATING:4 Tons = COOLING:4 TonsComp. Capacity=Heating Capacity=4Tons
O/U Heat Ex. Capacity=Heating-Cooling=0Tons
Cooling
3Tons
STOP
4PS
VRF Applications
• Zoning / Variable Occupancy– Schools
– Office Buildings
– High End Residential
– Historic Buildings
– Mid and High Rise
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Example Midwest Installations• CHA Kenmore
• 600 W. Van Buren
• Belmont House
• IIT Food Safety Lab
• Thornton High School Addition
• Winnetka Village Hall
• Roseland Hospital
• VA Hines Offices
• JF Ahern Mechanical
• Madison Children’s Museum
• United Airlines Loading Bridges
• Historic 1800s Stone Farmhouse
• Indiana Harbour Belt (IHB Office)
WEBINAR REMINDERS
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System Cost
•Consider Total Building Cost–Energy usage
–Installation labor vs. ductwork
–Building Automation System
–Electrical switchgear and electrical service•Natural gas service not needed
–Usable space•Ceiling height
•Mechanical rooms
•Duct and pipe chases
System Comparison – Rooftop / VAV
plus controls
controls included
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System Comparison – Chiller / VAV
plus controls
controls included
Economic Performance
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Efficiencies of Typical Equipment Types
Cooling
• Small Split System– 13 - 21 SEER (3.2 - 4.3 COP)
• Large DX Split or RTU– 9.5 - 13 EER (2.8 - 3.8 COP)
– 10 - 14 IEER (2.9 - 4.1 COP)
• A/C Chiller– 9.5 - 10.5 EER (2.8 - 3.1 COP)
– 13 - 15.5 IEER (3.9 - 4.7 COP)
– Does not include distribution (pump/fan) energy
Heating
• Electric Heat– 1.0 COP
• Gas Furnace or Boiler– 80 - 97% AFUE or TE
– Approx. 0.80 - 0.97 COP
• Gas RTU– 80 - 82% TE
– 0.80 - 0.82 COP
• Heat Pump– 7 - 13 HSPF
– 2 - 3.8 COP
– @ 47 deg outdoorVRF
• Cooling?
• Heating?
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www.ahridirectory.org
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AHRI VRF Terminology
• AHRI System Types– HMSV-A-CB (heat pump, air-to-air)
– HMSV-W-CB (heat pump, water-to-air)
– HMSR-A-CB (heat recovery, air-to-air)
– HMSR-W-CB (heat recovery, water-to-air)
AHRI VRF Terminology
• Energy Efficiency Ratio (EER)– Full load cooling efficiency @ 95db OA
– Note COP = EER / 3.412
• Integrated Energy Efficiency Ratio (IEER)– Part load cooling efficiency
– IEER = (0.020 · A) + (0.617 · B) + (0.238 · C) + (0.125 · D) • A = EER at 100% capacity
• B = EER at 75% capacity
• C = EER at 50% capacity
• D = EER at 25% capacity
• Coefficient of Performance (COP)– Heating efficiency at 47db/43wb OA
– Heating efficiency at 17db/15wb OA
– Heating efficiency at 68db loop temp (water-source units)
– Excludes supplemental heat
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AHRI VRF Terminology
• Simultaneous Cooling and Heating Efficiency (SCHE)– Only applies to Heat Reclaim systems
– Ratio of total capacity (heating and cooling) to the effective power when in heat recovery mode
– 50% heating and 50% cooling
– Tested at 47db/43wb outdoor
– Units are BTU per watt hr, same as EER and IEER
COP during Heat Recovery Operation
Heat Balance Point
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Sample AIR-SOURCE VRF Efficiencies in Directory
Sample WATER-SOURCE VRF Efficiencies in Directory
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VRF AIR-SOURCE Cooling Efficiencies in 90.1-2013
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VRF WATER-SOURCE Cooling Efficiencies in 90.1
VRF WATER-SOURCE Cooling Efficiencies in 90.1
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VRF AIR-SOURCE Heating Efficiencies in 90.1-2013
VRF WATER-SOURCE Heating Efficiencies in 90.1
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Modeling VRF
• Technology and performance are proprietary
• Hard to model bin data for load sharing
• VRF modules/wizards now available in:– EnergyPro (5 brands built in)
– EnergyPlus
– eQuest
– Carrier HAP
– Trane TRACE
Cold Climate Heat Pump Application Tip
• Locate “outdoor unit” inside building• Single supplemental heater in
mechanical room instead of every zone
• Simplifies heater fuel choices• Optimal room setpoint around 0
degrees depending on utility costs• Need condensate system
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ASHRAE 15 Refrigerant Safety
• Yes, ASHRAE 15 is applicable to these systems
• What is the smallest zone?
• What is the charge of the system?
• Refrigeration Concentration Limit (RCL) per circuit– RCL defined by ASHRAE 34 and referenced by ASHRAE 15
– 25 lbs per 1,000 ft3 for R-410a
– 12.5 lbs for institutional occupancies
– Exemptions for equipment with less than 6.6 lb total charge
– Exemptions for laboratory spaces
ASHRAE Journal
July 2012
Stephen W. Dudaof SSPC-15
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ASHRAE 15 Tips for VRF
• Remove the smallest zone from the VRF system and use a dedicated unit for that zone (PTAC, DFS, etc.)
• Use a common ducted indoor unit to serve the two smallest rooms
• Use above ceiling unit so the ceiling cavity can be included in the calcs
• Use multiple, smaller VRF systems to serve the building
• Interconnect spaces with permanent openings
• Consider what spaces the pipes are routed thru, not just the rooms that have the indoor units installed
Case Study #1ASHRAE Headquarters (Atlanta, GA)• Building renovated in 2008 and rated LEED NC Platinum
• VRF conditions spaces on 1st floor, GSHP on 2nd floor, and ventilation DOAS serves both
• Energy performance data collected from 2011 to 2013
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Case Study #1ASHRAE Headquarters (Atlanta, GA)• GSHP (2nd floor)
– Avg. system heating COP = 3.3
– Avg. system cooling EER = 14.2
– Space energy use 1.5 kWh/ft2-yr
– Services mostly offices
• VRF (1st floor)– Avg. system heating COP = 2.0
– Avg. system cooling EER = 8.5
– Space energy use 2.7 kWh/ft2-yr
– Serves mostly offices and infrequently used meeting rooms
– Note: indoor fan speed control was sub-optimal
• A
Case Study #1ASHRAE Headquarters (Atlanta, GA)
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Case Study #2University Crossing (Madison, WI)• Ground-source VRF with cooling EER of 22
• Six miles of piping in perimeter ring borefield– 250-ft. deep bores were used (instead of 400 ft.) because site
location is in a city wellhead protection zone
• No supplemental heating system
• Energy performance data collected from 2013 to 2015
Case Study #2Seventhwave (Madison, WI)• DOAS for ventilation air
– GSHP with enthalpy ERV wheel
– Airflow modulates with CO2-based DCV in densely occupied spaces and lighting system’s motion sensors in select zones
• Driving decisions to use VRF Geo included: energy savings, mechanical room space, and maintenance
• Seventhwave occupies half of 3rd floor– 3 condensing units mechanical room
– Fan coil zones throughout space
– Sub-metered by Madison Gas & Electric
– Live publically available data monitoring
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Case Study #2Seventhwave (Madison, WI)
Case Study #2Seventhwave (Madison, WI)
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Ryan R. Hoger, LEED [email protected]
Ryan R. Hoger, LEED [email protected]
Special Thanks to those who allowed me to use their slides or graphics today…
Special Thanks to those who allowed me to use their slides or graphics today…
Ryan R. Hoger, LEED AP
Ryan R. Hoger, LEED AP
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This concludes The American Institute of Architects Continuing Education Systems Course
www.seventhwave.org/education/events