Comparison of Air Distribution Systems

Transcription

1 of Air Distribution s vs. s & s Presentation Outline & s Distribution Conclusion & s

2 & s 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 & s Architecture

3 & s Location & Site 1600 Scotts Crossing Road 26 Acres Borders I-495 Capital Beltway 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 & s Mechanical Distribution in Tower Four 600 ton Chillers 4-Cell Cooling Tower Two 22,000 cfm AHU s per Typical Floor

4 & s Distribution Background Information Components Construction Methods/Schedule Energy Use Costs Lessons Learned & s 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 Unoccupied Zone Occupied Zone

5 & s 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 & s 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

6 & s 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 Source: Tate Access Floors Typical Mechanical Room Section & s Construction Methods/Schedule Local Jurisdiction Code Requirements Underfloor is a plenum Supply Air Diffusers Redundant installation Space Moisture concerns Above Ceiling Air Space Suspended ceiling not absolutely necessary

7 & s Construction Methods/Schedule Typical Floor Schedule 219 Work Days & s Construction Methods/Schedule Tower Schedule 289 Work Days

8 & s Energy Use Typical Floor Design Loads Typical Floor Load Total Tower Load 14% 60 10% Design Load Distribution 29% 39% 720 8% OA Load Lighting Load Equipment Load Envelope Load Occupant Load & s Energy Use Annual Energy Consumption Binmaker Weather Data 3,120 hours Typical Floor Total Tower Total Ton-hours 58, ,352

9 & s Cost Construction Costs $ 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 & s Lessons Learned Moisture detection in underfloor plenum Outdoor air load oversized 20 cfm/occupant needed 43 cfm/occupant used Green technology Recognized by USGBC

10 & s Background Information Components Construction Methods/Schedule Energy Use Costs Lessons Learned & s Background Information Traditional approach to HVAC design Air supplied & returned at ceiling Conditions entire space Conditioned Space

11 & s 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 & s Background Information Barriers No individual control Expensive to modify or reconfigure Can be noisy Usually cramped into ceiling plenum with other systems

12 & s 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 & s Construction Methods/Schedule Typical Floor Schedule 181 Work Days

13 & s Construction Methods/Schedule Tower Schedule 290 Work Days & s Energy Use Typical Floor Design Loads Typical Floor Load Total Tower Load 14% 60 10% Design Load Distribution 29% 39% 720 8% OA Load Lighting Load Equipment Load Envelope Load Occupant Load

14 & s Energy Use Annual Energy Consumption Binmaker Weather Data 3,120 hours Typical Floor Total Tower Total Ton-hours 58, ,352 & s Cost Construction Costs $ 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

15 & s Lessons Learned Major mechanical equipment are correct sizes Due to underfloor system being oversized & s Components Construction Schedule: Typical Floor 12 Floors Underfloor Two AHU s/floor Access floor panels Swirl diffusers 219 work days 289 work days Two AHU s/floor Supply duct Control zones 181 work days 290 work days Energy Use 2,912,721 kwh 3,470,577 kwh Costs: Construction Operating Lifecycle $ 5,136,160 $ 206,803 $ 9,084,118 $ 3,827,680 $ 246,410 $ 8,531,753

16 & s 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 & s Reduction in Cooling Coil Load Underfloor : Load = (1.08) x (44,000cfm) x (77-65F) / (12,000 Btu/hr/ton) Load = 48 tons : Load = (1.08) x (44,000cfm) x (77-55F) / (12,000 Btu/hr/ton) Load = 87 tons Underfloor system requires almost ½ the load

17 & s Snowball Effect Cooling Coil Load Decreases Air Handling Unit Size Decreases Chiller Size Decreases Less Cooling Water Needed / Lower GPM Smaller Pumps & s Underfloor air distribution system Easy to reconfigure office space More productive workers Potential for energy savings Future phases of project use design changes

18 & s Acknowledgements DAVIS Construction Ron Juban, Bill Moyer, Josh Peters, Mike Pittsman AE Faculty Dr. Messner, Prof. Freihaut, Jonathan Dougherty My Classmates Especially Becky & Joe & s Questions