Comparison of Air Distribution Comparison of Air Distribution - - PDF document

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Comparison of Air Distribution Comparison of Air Distribution - - PDF document

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Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA Comparison of Air Distribution Comparison of Air Distribution Systems Systems Underfloor Air vs. Ceiling-Based

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2002-2003 AE Senior Thesis Allison M Clarke

Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA

Comparison of Air Distribution Comparison of Air Distribution Systems Systems

Underfloor Air vs. Ceiling-Based Systems

2002-2003 AE Senior Thesis Allison M Clarke

Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA

Presentation Outline

  • Existing Building & Systems
  • Underfloor Air Distribution
  • Ceiling-Based System
  • Comparison
  • Conclusion & Recommendations

Introduction Existing Building & Systems Underfloor Air System Ceiling-Based System Comparison Recommendation Conclusions

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2002-2003 AE Senior Thesis Allison M Clarke

Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA

Project Team

Owner - Capital One Financial Corporation Owner’s Rep - Jones Lang LaSalle Architect - Ai Architecture GC - James G. DAVIS Construction Structural Engr - Rathgeber/Goss Associates MEP Engr - Ai Engineering

Introduction Existing Building & Systems Underfloor Air System Ceiling-Based System Comparison Recommendation Conclusions 2002-2003 AE Senior Thesis Allison M Clarke

Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA

Architecture

Introduction Existing Building & Systems Underfloor Air System Ceiling-Based System Comparison Recommendation Conclusions

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2002-2003 AE Senior Thesis Allison M Clarke

Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA

Location & Site

  • 1600 Scotts Crossing Road

McLean, VA

  • 26 Acres
  • Borders I-495 Capital Beltway

Introduction Existing Building & Systems Underfloor Air System Ceiling-Based System Comparison Recommendation Conclusions

Structure

  • Base Building – Floors 1 & 2

Cast-in-Place Concrete with Post Tension Beams

  • Tower – Floors 3 – 14

Steel Structure Concrete Slab on Metal Deck 18” Raised Concrete Core Typical Floor Space

2002-2003 AE Senior Thesis Allison M Clarke

Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA

Introduction Existing Building & Systems Underfloor Air System Ceiling-Based System Comparison Recommendation Conclusions

Mechanical

  • Underfloor Air Distribution System in Tower
  • Four 600 ton Chillers
  • 4-Cell Cooling Tower
  • Two 22,000 cfm AHU’s per Typical Floor
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2002-2003 AE Senior Thesis Allison M Clarke

Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA

Underfloor Air Distribution

  • Background Information
  • System Components
  • Construction Methods/Schedule
  • Energy Use
  • Costs
  • Lessons Learned

Introduction Existing Building & Systems Underfloor Air System Ceiling-Based System Comparison Recommendation Conclusions 2002-2003 AE Senior Thesis Allison M Clarke

Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA

Background Information

  • Alternative to conventional ceiling-based air distribution

systems

  • Previously used for spaces with high heat loads
  • Introduces air at floor level

Occupied Zone – floor to head level Unoccupied Zone – head level to ceiling

Introduction Existing Building & Systems Underfloor Air System Ceiling-Based System Comparison Recommendation Conclusions

Occupied Zone Unoccupied Zone

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2002-2003 AE Senior Thesis Allison M Clarke

Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA

Background Information

Benefits

  • Improved thermal comfort for occupants
  • Improved ventilation efficiency & indoor air quality
  • Reduced energy use from mechanical systems
  • Reduced life cycle building costs
  • Reduced floor-to-floor height in new construction
  • Improved occupant satisfaction and productivity

Introduction Existing Building & Systems Underfloor Air System Ceiling-Based System Comparison Recommendation Conclusions 2002-2003 AE Senior Thesis Allison M Clarke

Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA

Background Information

Barriers

  • New & unfamiliar technology
  • Perceived higher costs
  • Lack of information & design guidelines
  • Limited applicability to retrofit construction
  • Problems with applicable standards & codes
  • Problems with spillage and dirt entering underfloor plenum
  • Concerns of condensation and dehumidification problems

Introduction Existing Building & Systems Underfloor Air System Ceiling-Based System Comparison Recommendation Conclusions

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2002-2003 AE Senior Thesis Allison M Clarke

Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA

System Components

Typical Floor

  • Two 22,000 cfm AHU’s
  • 28 fan powered terminal boxes supply

perimeter

  • Static pressure sensors
  • 22,500 sf Access floor panels
  • Passive & VAV floor diffusers

Introduction Existing Building & Systems Underfloor Air System Ceiling-Based System Comparison Recommendation Conclusions

Source: Tate Access Floors

Typical Mechanical Room Section 2002-2003 AE Senior Thesis Allison M Clarke

Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA

Construction Methods/Schedule

  • Local Jurisdiction Code Requirements

Underfloor is a plenum

  • Supply Air Diffusers

Redundant installation

  • Underfloor Air Space

Moisture concerns

  • Above Ceiling Air Space

Suspended ceiling not absolutely necessary

Introduction Existing Building & Systems Underfloor Air System Ceiling-Based System Comparison Recommendation Conclusions

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2002-2003 AE Senior Thesis Allison M Clarke

Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA

Construction Methods/Schedule

Typical Floor Schedule 219 Work Days

Introduction Existing Building & Systems Underfloor Air System Ceiling-Based System Comparison Recommendation Conclusions 2002-2003 AE Senior Thesis Allison M Clarke

Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA

Construction Methods/Schedule

Tower Schedule 289 Work Days

Introduction Existing Building & Systems Underfloor Air System Ceiling-Based System Comparison Recommendation Conclusions

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2002-2003 AE Senior Thesis Allison M Clarke

Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA

Energy Use

Typical Floor Design Loads

720 60 Total Tower Load (tons) Typical Floor Load (tons)

Introduction Existing Building & Systems Underfloor Air System Ceiling-Based System Comparison Recommendation Conclusions

Design Load Distribution

39% 29% 14% 10% 8% OA Load (tons) Lighting Load (tons) Equipment Load (tons) Envelope Load (tons) Occupant Load (tons)

2002-2003 AE Senior Thesis Allison M Clarke

Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA

Energy Use

Annual Energy Consumption

  • Binmaker Weather Data
  • 3,120 hours

Introduction Existing Building & Systems Underfloor Air System Ceiling-Based System Comparison Recommendation Conclusions

701,352 58,446 Total Ton-hours Total Tower Typical Floor

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2002-2003 AE Senior Thesis Allison M Clarke

Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA

Cost

Construction Costs

  • $ 13.66 per square foot

$ 5,136,160 Tower Cost Operating Costs

  • Energy Consumption

2,912,721 kWh

  • Annual Cost

$ 206,803 Lifecycle Cost

  • 30 years

$ 9,084,118

Introduction Existing Building & Systems Underfloor Air System Ceiling-Based System Comparison Recommendation Conclusions 2002-2003 AE Senior Thesis Allison M Clarke

Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA

Lessons Learned

  • Moisture detection in underfloor plenum
  • Outdoor air load oversized

20 cfm/occupant needed 43 cfm/occupant used

  • “Green” technology

Recognized by USGBC

Introduction Existing Building & Systems Underfloor Air System Ceiling-Based System Comparison Recommendation Conclusions

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2002-2003 AE Senior Thesis Allison M Clarke

Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA

Introduction Existing Building & Systems Underfloor Air System Ceiling-Based System Comparison Recommendation Conclusions

Ceiling-Based System

  • Background Information
  • System Components
  • Construction Methods/Schedule
  • Energy Use
  • Costs
  • Lessons Learned

2002-2003 AE Senior Thesis Allison M Clarke

Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA

Background Information

  • Traditional approach to HVAC design
  • Air supplied & returned at ceiling

Conditions entire space

Introduction Existing Building & Systems Underfloor Air System Ceiling-Based System Comparison Recommendation Conclusions

Conditioned Space

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2002-2003 AE Senior Thesis Allison M Clarke

Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA

Background Information

Benefits

  • Designers & contractors more familiar
  • Cheaper to build
  • Available standards & codes
  • Suspended ceiling systems made access easier
  • Currently found in most U.S. buildings

Introduction Existing Building & Systems Underfloor Air System Ceiling-Based System Comparison Recommendation Conclusions 2002-2003 AE Senior Thesis Allison M Clarke

Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA

Background Information

Barriers

  • No individual control
  • Expensive to modify or reconfigure
  • Can be noisy
  • Usually cramped into ceiling plenum with other systems

Introduction Existing Building & Systems Underfloor Air System Ceiling-Based System Comparison Recommendation Conclusions

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2002-2003 AE Senior Thesis Allison M Clarke

Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA

Introduction Existing Building & Systems Underfloor Air System Ceiling-Based System Comparison Recommendation Conclusions

System Components

Typical Floor

  • Two 22,000 cfm AHU’s
  • VAV box & thermostat controlled zones

Perimeter zones Interior zones

  • Ducted supply, return air plenum

Source: Trane

2002-2003 AE Senior Thesis Allison M Clarke

Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA

Construction Methods/Schedule

Typical Floor Schedule 181 Work Days

Introduction Existing Building & Systems Underfloor Air System Ceiling-Based System Comparison Recommendation Conclusions

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SLIDE 13

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2002-2003 AE Senior Thesis Allison M Clarke

Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA

Construction Methods/Schedule

Tower Schedule 290 Work Days

Introduction Existing Building & Systems Underfloor Air System Ceiling-Based System Comparison Recommendation Conclusions 2002-2003 AE Senior Thesis Allison M Clarke

Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA

Introduction Existing Building & Systems Underfloor Air System Ceiling-Based System Comparison Recommendation Conclusions

Energy Use

Typical Floor Design Loads

720 60 Total Tower Load (tons) Typical Floor Load (tons)

Design Load Distribution

39% 29% 14% 10% 8% OA Load (tons) Lighting Load (tons) Equipment Load (tons) Envelope Load (tons) Occupant Load (tons)

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2002-2003 AE Senior Thesis Allison M Clarke

Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA

Energy Use

Annual Energy Consumption

  • Binmaker Weather Data
  • 3,120 hours

Introduction Existing Building & Systems Underfloor Air System Ceiling-Based System Comparison Recommendation Conclusions

701,352 58,446 Total Ton-hours Total Tower Typical Floor

2002-2003 AE Senior Thesis Allison M Clarke

Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA

Cost

Construction Costs

  • $ 10.18 per square foot

$ 3,827,680 Tower Cost Operating Costs

  • Energy Consumption

3,470,577 kWh

  • Annual Cost

$ 246,410 Lifecycle Cost

  • 30 years

$ 8,531,753

Introduction Existing Building & Systems Underfloor Air System Ceiling-Based System Comparison Recommendation Conclusions

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2002-2003 AE Senior Thesis Allison M Clarke

Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA

Lessons Learned

  • Major mechanical equipment are correct sizes

Due to underfloor system being oversized

Introduction Existing Building & Systems Underfloor Air System Ceiling-Based System Comparison Recommendation Conclusions 2002-2003 AE Senior Thesis Allison M Clarke

Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA

Comparison

Introduction Existing Building & Systems Underfloor Air System Ceiling-Based System Comparison Recommendation Conclusions

$ 3,827,680 $ 246,410 $ 8,531,753 $ 5,136,160 $ 206,803 $ 9,084,118 Costs: Construction Operating Lifecycle 3,470,577 kWh 2,912,721 kWh Energy Use 181 work days 290 work days 219 work days 289 work days Construction Schedule: Typical Floor 12 Floors Two AHU’s/floor Supply duct Control zones Two AHU’s/floor Access floor panels Swirl diffusers System Components

Ceiling-Based System Underfloor System

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2002-2003 AE Senior Thesis Allison M Clarke

Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA

Recommendation

Dedicate chiller plant equipment to areas utilizing underfloor air distribution Two systems:

  • Base building – Floors 1 & 2

Supply air temperature at 58˚F

  • Tower – Floors 3 – 14

Supply air temperature at 65˚F

Introduction Existing Building & Systems Underfloor Air System Ceiling-Based System Comparison Recommendation Conclusions 2002-2003 AE Senior Thesis Allison M Clarke

Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA

Recommendation

Reduction in Cooling Coil Load Underfloor system requires almost ½ the load

Introduction Existing Building & Systems Underfloor Air System Ceiling-Based System Comparison Recommendation Conclusions

Underfloor System: Load = (1.08) x (44,000cfm) x (77-65F) / (12,000 Btu/hr/ton) Load = 48 tons Ceiling-Based System: Load = (1.08) x (44,000cfm) x (77-55F) / (12,000 Btu/hr/ton) Load = 87 tons

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2002-2003 AE Senior Thesis Allison M Clarke

Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA

Recommendation

“Snowball Effect” Cooling Coil Load Decreases Air Handling Unit Size Decreases Chiller Size Decreases Less Cooling Water Needed / Lower GPM Smaller Pumps

Introduction Existing Building & Systems Underfloor Air System Ceiling-Based System Comparison Recommendation Conclusions 2002-2003 AE Senior Thesis Allison M Clarke

Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA

Conclusions

Underfloor air distribution system

  • Easy to reconfigure office space
  • More productive workers
  • Potential for energy savings

Future phases of project use design changes

Introduction Existing Building & Systems Underfloor Air System Ceiling-Based System Comparison Recommendation Conclusions

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2002-2003 AE Senior Thesis Allison M Clarke

Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA

Acknowledgements

DAVIS Construction Ron Juban, Bill Moyer, Josh Peters, Mike Pittsman AE Faculty

  • Dr. Messner, Prof. Freihaut, Jonathan Dougherty

My Classmates Especially Becky & Joe

Introduction Existing Building & Systems Underfloor Air System Ceiling-Based System Comparison Recommendation Conclusions 2002-2003 AE Senior Thesis Allison M Clarke

Capital One Northern Virginia Campus Consolidation Capital One Northern Virginia Campus Consolidation McLean, VA McLean, VA

Questions

Introduction Existing Building & Systems Underfloor Air System Ceiling-Based System Comparison Recommendation Conclusions