The document summarizes an NREL report on achieving 90% energy savings in a parking garage through design strategies. The 1,806 space garage uses daylighting with perforated aluminum panels and a top floor PV array to provide 1.13 MW of renewable energy. Lighting and daylighting were key, using 0.05 W/ft2 lighting power density and occupancy/photocell controls. Measured energy use of 158 kBtu/space/yr was 90% below code. Fine-tuning controls and an integrated design process focusing on structure, lighting, and systems were emphasized to successfully achieve the ambitious energy reduction goal.

1. NREL Parking Garage Performance Review:
Achieving 90% Energy Savings in a Parking Structure
Shanti Pless
NREL Commercial Buildings Research Group
March 28, 2013
NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.

2. Design Solution—Metrics for Performance
• Parking Spaces
o
o
1,806 total spaces
90 preferred spaces for carpooling and vanpooling, 90
preferred spaces for low-emitting vehicles, 36 electric
vehicle charging stations
• Renewable Energy Ready
o
1.13 MW PV (net zero energy for RSF complex)
o
158 kBtu/space/yr, designed
90% energy reduction versus ASHRAE Standard 90.1-2007
• Energy Performance
o
• Lighting and Daylighting are the key strategies to
ensure successful performance
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3. Design Solution—Structure
Elevation:
Aluminum perforated panels optimized by daylight model
• 40% openness
• North, east, and west positioning
Top floor PV roof, Jennifer Scheib, NREL
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4. Design Solution—Structure
Interiors:
• Light concrete but no paint on ceiling or columns
• Slab and beam versus flat slab
Interior perspective, Jennifer Scheib, NREL
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5. Design Solution—Structure
Interiors: Atrium staircase leading to bus shelter
Atrium and bus shelter, Dennis Schroeder, NREL
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6. Design Solution—Systems
•
0.05 W/ft2 LPD
CBEA specification was used for
reference when reviewing lighting
fixture submittals
•
Lights are only on when needed
o
Occupancy sensors (OS)
o
Photocells (PS)
LED fixture, Jennifer Scheib, NREL
Lighting plan, courtesy ME Group and RNL
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7. Design Solution—Systems
Light well images, Dennis Schroeder, NREL
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8. Design Solution—Systems
Light well, Dennis Schroeder, NREL
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9. Design Solution—Systems
Light well, Dennis Schroeder, NREL
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10. Design Solution—Systems
Light well, Dennis Schroeder, NREL
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11. Design Solution—Systems
Light well, Dennis Schroeder, NREL
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12. Design Solution—Systems
Light well, Dennis Schroeder, NREL
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13. Design Solution—Systems
Light well, Dennis Schroeder, NREL
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14. Energy Performance
Predicted versus Measured, Summer 2012
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15. Lighting Energy Performance Last 48 Hours
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16. EVCS Energy Performance Last 48 Hours
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17. Getting it all to work
• Ensure photocells are placed appropriately
o
o
Hard to control to 1 FC…
A single global photocell with local zone configuration is
now our preferred method
• Be prepared to fine tune occupancy controls
o
o
30 seconds to 50%, 2 minutes to off works well
Do occupancy sensors sense the right things?
– Full coverage?
– Sensor shields to minimize false ON
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18. Discussion About Innovation and Replication
• Process innovation
o
o
Use performance-based procurement (energy goal with
performance incentives)
Require integrated design with energy modeling, starting in the
predesign phase, to maximize efficiency feature early
• Design innovation
o
o
o
o
Focus on structure first (structure type, perimeter configuration to
maximize high daylight, bay width, structure depth, finishes, colors,
percent fly ash)
Achieve a low LPD with good nighttime cutoff
Implement a lighting control scheme that improves occupant
experience in terms of aesthetics and safety
Reduce need or time of use for elevators, heat trace, ventilation,
miscellaneous loads
• Result: Cost-competitive, energy-efficient, beautiful garage
with carefully considered neighborhood interface
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19. Resources Available at:
www.nrel.gov/sustainable_nrel/buildings_garage.html
• Low-Energy Parking Structure
Design Guide
• DOE High-Efficiency Parking
Structure Lighting Specification
• Energy-Goal-Based Building
Procurement Webinar: Achieving
90% Energy Savings in a Parking
Structure
• NREL Parking Garage Fact Sheet:
• NREL Feature News Story
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20. Thank you for your time
Questions?
And then the tour!
Shanti Pless: shanti.pless@nrel.gov