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Energy Solutions

VRF Energy Modeling Savings Estimates Regional Technical Forum Variable Capacity Heat Pump Sub-Committee Meeting August 31, 2011. Energy Solutions. Outline. Requested Analysis Modeling Parameters Assumptions Results. 2. 2. Requested Analysis.

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Energy Solutions

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  1. VRF Energy Modeling Savings EstimatesRegional Technical Forum Variable CapacityHeat Pump Sub-Committee MeetingAugust 31, 2011 Energy Solutions

  2. Outline • Requested Analysis • Modeling Parameters • Assumptions • Results 2 2

  3. Requested Analysis • Model VRF energy savings for buildings in Seattle and Spokane using EnergyPro 5 • Based on SCE analysis • Mitsubishi VRF heat pump and heat recovery systems • Small office • 7,200 sf • Medium office • 41,500 sf 3 3

  4. Baseline Systems • Small office • Packaged rooftop air conditioner with gas furnace and constant volume fan • ASHRAE system type 3 • 4 units, 6-8 tons each, fixed temp economizer, 1080 cfm of OSA • Modeling software included conductive duct losses for electric cooling • Fan energy increased to compensate for duct leakage • Packaged rooftop heat pump and constant volume fan • ASHRAE system type 4 • 4 units, 6-8 tons each, fixed temp economizer, 1080 cfm of OSA • Modeling software included conductive duct losses for both electric cooling and heating • Fan energy increased to compensate for duct leakage 4 4

  5. Baseline Systems • Medium office • Packaged rooftop VAV with gas boiler reheat • ASHRAE system type 5 • 6 units, 19-26 tons each, fixed temp economizer, 6015 cfm of OSA • Increased electric cooling energy to compensate for conductive duct losses • Fan energy increased to compensate for duct leakage • Packaged rooftop VAV with electric resistance reheat • ASHRAE system type 6 • 6 units, 19-26 tons each, fixed temp economizer, 6015 cfm of OSA • Increased electric cooling energy to compensate for conductive duct losses • Fan energy increased to compensate for duct leakage 5 5

  6. VRF Systems • Small office • VRF heat pump system with DOAS • 2 units, 10 to 12 tons each, no economizer, 1080 cfm of OSA • VRF heat recovery system with DOAS • 2 units, 10 to 12 tons each, no economizer, 1080 cfm of OSA • Medium office • VRF heat pump system with DOAS • 6 units, 12 to 16 tons each, no economizer, 6015 cfm of OSA • VRF heat recovery system with DOAS • 6 units, 12 to 16 tons each, no economizer, 6015 cfm of OSA • No duct conductive losses or leakage 6 6

  7. Modeling Parameters • ASHRAE 90.1 - 2007 Baseline • Small office – Packaged RTU w/ gas heat or heat pump • Separate baseline models created using 90.1 parameters • Base case had 4 total zones and 4 rooftop units • VRFs were modeled with 8 zones and 2 outdoor units • Baseline equipment was modeled on typical sizes, VRFs were based on actual Mitsubishi equipment in EnergyPro • Medium office – VAV w/ boiler or electric reheat • Used standard VAV energy models auto-generated by EnergyPro for the VRF simulation baselines • Program assigned the same number of VAV air handlers as VRF outdoor units – 6 total; more AHUs than normal for capacity • Baseline VAV capacities were sized by EnergyPro to satisfy peak block loads for assigned zones; capacities did not fall into typical VAV size categories 7 7

  8. Modeling Parameters • Energy savings • Baseline energy use: cooling, electric heating, fans, and pumps • VRF and DOAS system energy use: cooling, heating, fans, and branch selector boxes • Peak demand analysis • Evaluated summer and winter, comparing total building peak demand between measure and base 8 8

  9. Assumptions • 28% increase in electric heating and cooling energy to account for duct losses1 • Not included for VAV electric reheat • 37% increase in fan energy due to air leakage from ducts2 • Fisk, William J, et al., Duct systems in large commercial buildings: physical characterization, air leakage, and heat conduction gains, LBNL-42339, page 110, November 1999 • Diamond, Rick, et al., Thermal Distribution Systems in Commercial Buildings, LBNL-51860, page 12, May2003 9 9

  10. Energy Usage – Small Office 10 10

  11. Energy Usage – Medium Office 11 11

  12. Results – Small Office 12 12

  13. Results – Medium Office 13 13

  14. Savings Summary 14 14

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