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VRF Applications in PNW RTF RTUG Meeting October 26, 2011 Kevin Campbell Reid Hart, PE Technical Research Group. Modeled Office Building. Basic Qualities. Simulation Runs RTU, no economizer RTU, with Economizer and fan control VRF, Heat Pump, no Economizer
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VRF Applications in PNWRTF RTUG MeetingOctober 26, 2011Kevin CampbellReid Hart, PE Technical Research Group
Modeled Office Building Basic Qualities Simulation Runs • RTU, no economizer • RTU, with Economizer and fan control • VRF, Heat Pump, no Economizer • VRF, Heat Recovery no Economizer
Impact of VRF on HVAC Energy • Fans have significant savings! (even more if no RTU fan control) • Heating savings in northern climates (switch gas to Electric) • Cooling savings except PNW where OSA economizer wins • Both cooling and heating benefit from variable compressor
Small Office ComparisonTwo Models in PNW • Duct leakage: ES high; PECI none • Separate ventilation fan: PECI 2.5”’; ES ? • ES: refrigerant piping loss factor; PECI none
PNW Office Energy End Use Comparison *PECI small office utilizes economizer and fan controls. Energy Solutions small office includes duct leakage.
Differences AreNot Suprising A simple fan VSD measure had a wide range of savings when load variation was considered. Differences indicate need for: • Regional standard buildings • Range of loads to capture variation • Expected value savings or other process to generate population values
Modeled Medical Clinic Basic Qualities Simulation Runs • VAV (dX) Electric Reheat + Economizer + SAT reset • VRF Heat Pump • VRF Heat Recovery Building • Patient rooms with variable occupancy • More perimeter zones • Diagnostic equipment room
Impact of VRF on HVAC Energy • Fans have significant savings! • Heating always savings since no reheat with VRF • Cooling savings due to improved part load efficiencies and high cooling requirements of VAV reheat
PNW Office VRF Energy Use per SF *PECI VAV with electric reheat and SAT reset. Energy Solutions VAV with electric reheat.
Other Heat Recovery Options:Domestic Hot Water VRF Water Heater • Standard to 115°F • Booster to 160°F Applicable for buildings with both: • Heat rejection (server; equipment; kitchen; cooling) • Hot Water Load (Restaurants, Dorms, Hotel, Medical) Efficiency Improvement • VRF water heating percentage savings vs. gas
Exhaust Air Heat Recovery Adapt the old run- around or loop heat pump concept • In heat mode, cool exhaust air • In cool mode, heat exhaust air • Feed general loop or pre conditioning at DOAC • Need to verify airside pressure tradeoffs • This strategy not in models
Conclusions • Modeling tools and load/system assumptions have significant impact on predicted savings • VRF systems can provide significant HVAC savings with lower fan energy and better part load efficiencies • Buildings with low heating loads in economizer friendly climates have less significant savings • Exhaust and DHW heat recovery applicable Notes: • Proper control set-up & commissioning is important, as simulations are based on perfect control operation • Simulations are not monitored results
Questions? Contact: Kevin Campbell PECI firstname.lastname@example.org 503-575-4169