Walmart Experimental Stores

1
Walmart Experimental Stores

• Michael Deru, PhD
• National Renewable Energy Laboratory
• ASHRAE Region IX Conference
• August 15, 2008

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What is NREL

• A National Laboratory for the United States
  Department of Energy dedicated to Renewable
  Energy and Energy Efficient Technologies
• www.nrel.gov

3
Walmarts Sustainability Goals

• Lee Scott Walmart CEO, Oct, 2005
• Supplied by 100 renewables
• Create Zero Waste
• Sell Products that Sustain our Resources and
  Environment

4
Walmarts Immediate Goals

• Reduce GHG emissions in existing stores by 20 in
  seven years
• Reduce energy use in new stores by 25-30 and
  GHG emissions by 30 in four years
• Increase fleet efficiency by 25 in three years
  and 50 in 10 years

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Experimental Store Vision Statement

• Reduce the amount of energy and natural resources
  required to operate and maintain the stores
  during a three-year time period following the
  grand opening.
• Reduce the amount of raw materials needed to
  construct the facility.
• Substitute, when appropriate, the amount of
  renewable materials used to construct and
  maintain the facility.

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Walmart Experimental Stores

• McKinney, Texas monitored by ORNL
• Aurora, Colorado monitored by NREL
• Both Opened in 2005
• Three years of monitoring complete in 12/08

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Aurora Experimental Store

• Over 50 energy, water, material, and operational
  experiments
• Not an integrated design

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Long-Term Monitoring
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Short-term Testing

• Illuminance levels and lighting energy
• Temperature stratification
• Solarwall performance
• ECU performance

10
Lighting Systems

• Standard Design
• T8 lighting, skylights, daylighting on sales floor

11
Lighting Lessons Learned I

• T5HO lamps
• Fewer lamps required
• No energy savings compared to reference store
• Lamp/ballast issues need to worked out

12
Lighting Lessons Learned II

• Daylighting
• Saw tooth roof provides view of the sky but
  expensive with poor light distribution
• Standard Walmart skylights work well, but can be
  improved
• Daylighting energy savings 100 MWh/year

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Walmart Lighting and Daylighting

• T5 HO lamps
• Maintenance issues
• Similar Performance to T8s
• Daylighting Savings 100 MWh/year

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HVAC Systems

• Standard Design
• Packaged roof top units (3 AHUs 32 RTUs)

• Experiments
• Waste-oil boilers (auto oil kitchen grease)
• Co-Gen system
• Six 60 kW microturbines
• 120 ton double-effect absorption chiller
• Add-on heat exchanger
• Radiant heating and cooling
• Evaporative cooling in 9 AHUs
• Transpired solar collector
• Displacement ventilation with fabric ducts
• CO2 controlled ventilation
• Snowmelt system

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HVAC Lessons Learned I

• Waste-oil boilers
• Need steady supply of oil
• Difficult with kitchen oil
• Limited applicability
• Looking into waste-to-energy

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HVAC Lessons Learned II

• Evaporative space cooling
• Provides 60 to 70 of the cooling in the sales
  floor area
• New maintenance issues
• Works well in dry climates

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HVAC Lessons Learned III

• Transpired Solar Collector
• Over sized
• Implementation issues
• Control issues
• Provides preheating and some space heating

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HVAC Lessons Learned IV

• Displacement ventilation with fabric ducts
• No stratification
• High fan energy to keep ducts inflated

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Co-Gen Lessons Learned

• Reduces peak demand 200 kW
• Efficient when thermal electric load match
• Need thermal load following and peak reduction
  controls
• Provides back-up power to refrigeration system
• Lower CO2 emissions in Colorado (off sets coal)
• Expensive
• New maintenance issues

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Refrigeration Systems

• Standard Design
• Two independent systems (medium low temp.), Air
  cooled condensers

• Experiments
• Evaporatively cooled condenser
• Secondary loop on medium temperature rack
• More doors on medium temperature cases
• LED lights in cases
• Enhanced coils and fan motors
• Improved door glass with no defrost required
• Integrated demand control for start up on
  microturbines

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Refrigeration Lessons Learned

• Immediate winners
• LED case lights with occupancy sensors, 70
  energy savings
• More case doors
• Improved case coils and motors
• Evaporatively cooled condensers
• Winners but still need work
• Secondary loop
• Savings
• 20 energy
• 80 kW summer peak demand reduction

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On-Site Renewable Energy

• Experiments
• 50 kW wind turbine
• 50 kW Powerlight PV system
• 52 kW Schott PV system
• 33 kW Unisolar PV system
• Monument sign power system

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Renewable Lessons Learned

• Need good installation and commissioning plans
• Electricians are not familiar with systems
• Need automatic monitoring system to know when the
  system is down
• Aurora is not a good wind location

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Current Walmart Building Activities

• Opening four 20 more efficient stores in 2007
• Two already open
• Aggressive new store designs coming in 2008
• Climate sensitive designs
• Aggressive retrofit measures
• Submetering
• Refrigeration system improvements
• HVAC improvements
• Refrigeration
• First secondary loop CO2 system in U.S.

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Walmart Sustainability Efforts

• 14 internal sustainability networks
• Working with experts in every field
• Sharing experiences with everyone

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The Walmart Effect

• Single handedly changing markets
• Large buying power
• Largest private electricity consumer
• Demanding changes from suppliers
• Sustainability scorecards
• Success encourages competitors
• Changing consumer habits

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Questions?