The Hearst TowerNew York, NY
Introduction
Background
Current System
Proposed System
Cost Analysis
Electrical Breadth
Structural Breadth
Conclusions
Presentation Outline
Jessica LucasMechanical Option
Background
Current System
Proposed System
Cost Analysis
Electrical Breadth
Structural Breadth
Conclusions
The Hearst TowerNew York, NY
Introduction
Background
Current System
Proposed System
Cost Analysis
Electrical Breadth
Structural Breadth
Conclusions
Site and Location
Jessica LucasMechanical Option
Located along 8th Avenue between 56th & 57th Street in Midtown Manhattan
Constructed through the center of the original Hearst Headquarters (1928)
Landmark building will be hollowed with new Tower constructed through center
The Hearst TowerNew York, NY
Introduction
Background
Current System
Proposed System
Cost Analysis
Electrical Breadth
Structural Breadth
Conclusions
Project Team
Building Owner: Hearst Corporation
Architect: Foster and Partners
Associate Architect: Adamson Associates
MEP: Flack+Kurtz
CM: Turner Construction
Jessica LucasMechanical Option
The Hearst TowerNew York, NY
Introduction
Background
Current System
Proposed System
Cost Analysis
Electrical Breadth
Structural Breadth
Conclusions
Size and Architecture
Jessica LucasMechanical Option
• 42 stories• 856,000 SF• 2000 Hearst Employees
Most notable features:• Diagrid Facade• LEED Gold certification
Architectural Program• Open Office• Auditorium• Test Kitchens• Television Studio
The Hearst TowerNew York, NY
Introduction
Background
Current System
Proposed System
Cost Analysis
Electrical Breadth
Structural Breadth
Conclusions
Existing Mechanical System
Jessica LucasMechanical Option
Central Chilled Water Plant serving a low temperature Variable Air Volume system
Waterside System
• 4-1000 ton cooling towers on roof level
• 2-1200 ton & 1-400 ton electric chillers in basement chiller plant
Airside System
• 4-110,000 CFM AHU’s, serve office tower
• Indoor Design Conditions
• 75F for cooling/50% RH cooling
• 70F for heating
• Air supplied to spaces at 45F
The Hearst TowerNew York, NY
Introduction
Background
Current System
Proposed System
Cost Analysis
Electrical Breadth
Structural Breadth
Conclusions
Proposed Mechanical System:
Combining Steam Driven Absorption Cooling with a Dedicated Outdoor Air/ Radiant Floor System
Jessica LucasMechanical Option
Replace electric chillers with double effect steam driven absorptionReplace the central VAV AHU’s with dedicated outdoor air (DOAS) unitsInstall radiant floors to parallel DOAS for both heating & cooling
The Hearst TowerNew York, NY
Introduction
Background
Current System
Proposed System
Cost Analysis
Electrical Breadth
Structural Breadth
Conclusions
Goals of Proposed System
• Ensure ASHRAE Std. 62.1-2004 compliance
• Obtain the LEED point for IAQ
• Lessen the Tower’s dependence on an overextended electric grid
• Lower annual operating cost
• Meet the original criteria to create a reliable Class “A” office building
Jessica LucasMechanical Option
The Hearst TowerNew York, NY
Introduction
Background
Current System
Proposed System
Cost Analysis
Electrical Breadth
Structural Breadth
Conclusions
Proposed Mechanical System:Dedicated Outdoor Air System
(DOAS)
Jessica LucasMechanical Option
What is DOAS?
• 100% OA unit based on ASHRAE Std.62.1
• Decouples Sensible & Latent Loads
• Utilizes Energy Recovery
DOAS for Hearst:
• Std. 62.1 +30% OA for IAQ LEED point
• Utilize an Enthalpy Wheel for total energy recovery
• Maintain 45F supply air temperature
The Hearst TowerNew York, NY
Introduction
Background
Current System
Proposed System
Cost Analysis
Electrical Breadth
Structural Breadth
Conclusions
Proposed Mechanical System:
Jessica LucasMechanical Option
The resulting DOAS Design:
• 3-40,000 CFM Semco units with a molecular sieve desiccant coated enthalpy wheel
• Chiller plant downsized by 30%
• Cooling coil load decreased from 44 tons to 10.5 tons
• Supply Air at 45F and saturation
The Hearst TowerNew York, NY
Introduction
Background
Current System
Proposed System
Cost Analysis
Electrical Breadth
Structural Breadth
Conclusions
Proposed Mechanical System:Radiant Floor Heating and Cooling
Jessica LucasMechanical Option
Optimize layout based on daylighting study using AGI32 software
The Hearst TowerNew York, NY
Introduction
Background
Current System
Proposed System
Cost Analysis
Electrical Breadth
Structural Breadth
Conclusions
Proposed Mechanical System:Absorption Chillers
Jessica LucasMechanical Option
3-600 ton Double-effect chillers arranged in parallel
Lithium Bromide/Water- no CFC’s or HCFC’s
New chiller plant requires 60 kW of electric input, compared to 1,941 kW used in the electric chiller plant
Con Edison offers incentives for steam driven cooling during the cooling season
The Hearst TowerNew York, NY
Introduction
Background
Current System
Proposed System
Cost Analysis
Electrical Breadth
Structural Breadth
Conclusions
Proposed Mechanical System:Additional Alternative
Jessica LucasMechanical Option
Can I save even more with an Electric Chiller Plant w/DOAS System?
• Still 30% reduction in chiller plant size
• Still only minimum CFM
• Higher COP with vapor compression cycle
The Hearst TowerNew York, NY
Introduction
Background
Current System
Proposed System
Cost Analysis
Electrical Breadth
Structural Breadth
Conclusions
Proposed Mechanical System:Cost Analysis
Jessica LucasMechanical Option
Electric w/VAV
Electric w/DOAS
Absorption w/DOAS
Total Electricity
$93.1 M $41.2 M $33.9 M
Total Steam
$31 M $29.4 M $39.4 M
Total O&M
$25.6 M $14.5 M $15.9 M
20 year LCC
$156.4 M $93.4 M $98.8 M
The Hearst TowerNew York, NY
Introduction
Background
Current System
Proposed System
Cost Analysis
Electrical Breadth
Structural Breadth
Conclusions
Proposed Mechanical System:Mechanical Summary
Jessica LucasMechanical Option
Electric/DOAS
• Lowest LCC
• Lowest Operating Cost
• Higher COP
However…
• Still dependent on electric grid
• Black-outs = diminished reliability
Recommendation: Absorption/DOAS Radiant
The Hearst TowerNew York, NY
Introduction
Background
Current System
Proposed System
Cost Analysis
Electrical Breadth
Structural Breadth
Conclusions
Electrical System Breadth
Jessica LucasMechanical Option
Current Electrical System:
• 4-4000 amp service take-offs
• Each takeoff is served by 1-6000 amp service switch
• Each takeoff provides 480/277 V 3 phase service from primary
transformers
Daylighting & Occupancy sensors used throughout for energy conservation
High efficiency ballasts, helped obtain rebates from NYSERDA
The Hearst TowerNew York, NY
Introduction
Background
Current System
Proposed System
Cost Analysis
Electrical Breadth
Structural Breadth
Conclusions
Electrical System Breadth
Jessica LucasMechanical Option
Existing Chiller Plant
Chiller 1&2: 2000 A fuses, 6 sets of 3- 400 MCM with 1-#3/0 ground in 3”conduit
Chiller 3: 800 A fuse, 2 sets of 3-500 MCM with 1-#2/0 ground in 3.5” conduit
Cost of wiring & conduit: $932.00/LF
New Plant
Chiller 1,2,3: 40 A fuses, 1 set of 3-#6 with 1-#10 ground in 1”conduit
Cost of wiring & conduit: $46.80/LF
The Hearst TowerNew York, NY
Introduction
Background
Current System
Proposed System
Cost Analysis
Electrical Breadth
Structural Breadth
Conclusions
Electrical System Breadth
Jessica LucasMechanical Option
Existing VAV System
8 supply fans- 124 FLA
4 return fans- 65 FLA
MCC total connected load of 1,697 FLA
Proposed DOAS System
3 supply fans- 77 FLA
3 return fans- 65 FLA
MCC total connected load of 632 FLA
The Hearst TowerNew York, NY
Introduction
Background
Current System
Proposed System
Cost Analysis
Electrical Breadth
Structural Breadth
Conclusions
Electrical System Breadth:Conclusions
Jessica LucasMechanical Option
Downsizing equipment results in:
First cost savings for wire & conduits
Decreased switch sizes
Increased distribution board space
Allows for easier installation
The Hearst TowerNew York, NY
Introduction
Background
Current System
Proposed System
Cost Analysis
Electrical Breadth
Structural Breadth
Conclusions
Structural System Breadth:Current System
Half of the foundation is supported by spread footings, half by caissons
Primary latera l support provided by the perimeter Diagrid
Secondary lateral system defined by bracedframe at the service core
Structure below 10 th floor uses a mega-column systemto support a large unbraced height
Jessica LucasMechanical Option
The Hearst TowerNew York, NY
Introduction
Background
Current System
Proposed System
Cost Analysis
Electrical Breadth
Structural Breadth
Conclusions
Structural System Breadth:Effect of Radiant Floors
Jessica LucasMechanical Option
• International Fire Code 2003 2 hour fire rating
• Vulcraft Deck 6” slab
• Radiant tubes 1.5” concrete cover
• Check deck, beams, girders with additional concrete load
• LRFD Manual example for Composite W-shape flexural
member design (unshored construction)
The Hearst TowerNew York, NY
Introduction
Background
Current System
Proposed System
Cost Analysis
Electrical Breadth
Structural Breadth
Conclusions
Structural System Breadth:Conclusion
Allowable Shear Stud Capacity greater than Maximum shear under applied loading
Vu < ΣQn i.e. 42.8 k < 451 k
Allowable Flexural Capacity exceedsMaximum moment under the appliedfactored loading
Mu < ФMn i.e. 428 ft-k < 450 ft-k
No changes needed to member sizes!
Jessica LucasMechanical Option
The Hearst TowerNew York, NY
Introduction
Background
Current System
Proposed System
Cost Analysis
Electrical Breadth
Structural Breadth
Conclusions
Conclusions
Jessica LucasMechanical Option
Proposed mechanical system satisfied criteria set forth at the beginning of the design process:
Lower annual operating costs
Obtain LEED point for IAQ
Lessen dependence on electric grid
Increase reliability
Maintain Class “A” market status
Positively impact electrical system by lowering first cost & allowing for easier installation
No nominal impact on Structural system
The Hearst TowerNew York, NY
Introduction
Background
Current System
Proposed System
Cost Analysis
Electrical Breadth
Structural Breadth
Conclusions
Acknowledgements
Jessica LucasMechanical Option
A huge Thank You to:
JJ, Dr. Freihaut, Dr. Bahnfleth, Dr. Mumma, Dr. Srebric and the rest of the AE Faculty.
My fellow classmates especially Jenny, Jayme, Yulien, Dave, Bryan, and Adam.
Paul Reitz of Flack+Kurtz