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Technology and Engineering Development (TED) Building
Thomas Jefferson National Accelerator Facility
Newport News, VA
David Blum | Mechanical Option
Dustin Eplee | Adviser
Architectural Engineering | The Pennsylvania State University
Presentation Overview
Project Background
• Site, use, and architecture
Existing Mechanical System
• Air system, hydronic system, geothermal system
Horizontal Directional Drilling (Depth 1)
• An alternative geothermal solution
Radiant Floor Slab Cooling (Depth 2)
• An exploration of slab thermal capacity
Construction Schedules and Costs for Alternatives (Breadth 1)
• Presented after each depth
Final Conclusions
General Building Information Architecture Design and Use
Size: 70,000 SF
Stories Above Grade: Two
Project Team
Owner: Jefferson Lab CMGC: Mortenson ConstructionA/E: EwingColeCost Consultant: Crawford Consulting Services, Inc
Dates of Construction: 8/4/2010 – 9/30/2011
Cost: $16 million
Project Delivery Method: Design-Bid-Build
Site
1st Floor• Research Workspaces
• Highbay Area
2nd Floor• Offices, Conference, and
Administration
• Health Club, Break Room
• Main Mechanical RoomThomas Jefferson National Accelerator Facility Newport News, VA
Hydronic System Hybrid Condenser SystemAir System
Vertical Bore Geothermal
• 3 Fields
• 192 Wells
• 300 ft Depth
• Full Heating Load
• 72 % Cooling Load
Closed Circuit
Cooler• 28% Cooling Load
Variable Air Volume with Terminal Reheat• AHU 1: 32,000 CFM serves 1st Floor and Highbay
• AHU 2: 32,000 CFM, 2nd Floor
• Fan Powered Boxes serve perimeter zones
• VAV Boxes serve interior zones
Outdoor Air Pre-Conditioning• OAU 1: 7,500 CFM serves AHU 1
• OAU 2: 6,800 CFM serves AHU 2
• Total Energy Wheel exchanges latent and sensible heat with exhaust
12 Central Water to Water Heat Pumps• Chilled Water: 42 F Supply, 50 F Return
• Cond. Water: 85 F Entering, 95 F Leaving
• Hot Water: 120 F Supply, 110 F Return
• Cond. Water: 55 F Entering, 45 F Leaving
• EER: 14
• 10 Chilled Water, 6 Hot Water
Boiler• Backup heat source
Existing and Proposed Geothermal Fields
Field TypeDepth 1: Full Load Geothermal Design
Goals
• Add field to meet full cooling load: 67 additional tons
• Minimally invade tree line (per owner)
• Compare energy use and first costs to current hybrid condenser system
Horizontal Trench• 2500 ft2/ton and $600 to $800 / ft2
• 167,500 ft2 required is too large
Vertical Bore• 250 ft2/ton and $900 to $1100 / ft2
• 16,750 ft2 required eliminates trees
Horizontal Directional Drilling• Horizontal bores under obstacles
• Up to 600 ft long and 45 ft deep
• Stacked vertically in ground176,000 ft2
Existing
Proposed
Bores• Total Length: 21441 ft
• Length per Bore: 450 ft
• No. Bores: 48
• No. Rows: 16, 3 stacks (15 ft, 30 ft, 45 ft)
• Spacing: 15 ft
• Diameter: 5”
• Pipe: 1” HDPE
• Grout: Bentonite (k = 1.0 hr-ft-F/Btu)
Pumps• 1100 GPM
• VFD
Layout
Annual Energy Use• Closed Circuit Cooler (1599 hrs): 89,429 kWh
• Total Current HVAC: 646,138 kWh
• Total Proposed HVAC: 556,709 kWh
• Savings: 13.8%
Geothermal Design Energy and Operation
Life Cycle• Operational Savings: -$5,982/ yr
• Additional First Costs: $178,096
• Simple Payback: 30 years
HDD Geothermal Construction
Cost• Current Condenser: $756,074
• Closed Circuit Cooler: $51,054
• Vertical Bore Field: $687,936
• Pumps: $17,084
• Proposed Condenser: $934,170
• HDD Field: $229,150
• Difference: +$178,096 (+7.3% HVAC Budget)
Installation Process Budget and Schedule Impact
Schedule Impact
• Field Installation and Equipment Mobilization:62 Days (~12.5 Weeks)
Depth 2: Radiant Floor Cooling Slabs
Goals
• Explore the capabilities of floor slab thermal storage
• Analyze cooling capacity and effects on air system
• Compare daily cooling energy use and power demand profile with current HVAC system
Radiant Slab Implementation Radiant Slab Design Conditions
1st Floor
2nd Floor
Floor Surface Temperature: 68 F
Indoor Air: 78 F, 50% RH, 58 F DP
1st Floor 5” NW Slab on Grade
• Covering: Conductive Concrete (ESD)
• 3/8“ PEX Tubing Depth: 4” Below Surface
• CHWS Temp: 61 F
2nd Floor 3 ¼” LW Elevated Slab on Metal Deck
• Covering: ¼” Carpet
• 3/8“ PEX Tubing Depth: 1 ½” Below Surface
• CHWS Temp: 55 F
Load and Energy Model Required Cooling Airflow Proposed Systems
Excel Spreadsheet Model• Adapted RSTM method
• Hourly slab temperature from heat balance
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
20000
Current Design
Radiant Floor Slab
Required Vent Air
Radiant Slab System• Distribution Pump: 187 GPM, 7.5 HP
• 3 Heat Pumps, EER: 16
• Slabs in series
Parallel Air Systems
• AHU 1: 16,825 CFM
• AHU 2: 15,446 CFM
• CHW Distribution Pump: 350 GPM, 15 HP
• 6 Heat Pumps, EER: 140
10
20
30
40
50
60
70
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
Time (hr)
Ch
ille
d W
ater
Flo
w (
GP
M)
67.00
68.00
69.00
70.00
71.00
72.00
73.00
74.00
75.00
Sla
b T
emp
erat
ure
(F
)
Chilled Water Flow (GPM)
Slab Temperature (F)
Breadth: Radiant Floor ConstructionDaily Energy UseDaily Energy Use by Component
Currently Designed System Radiant Slabs System
Current Design
283 kW
3,725 kWh
Radiant Slabs
205 kW
3,238 kWh
Peak Demand:
Total Usage:
Savings
27.5%
13.1%
Cost• Current HVAC System: $2,450,000
• AHUs: $372,290
• Pumps: $12,336
• Radiant Slab HVAC System: $2,613,000 (+6%)
• AHUs: $185,920
• Pumps: $18,126
• Radiant Floor: $319,625
Schedule Impact• 26 weeks with one crew
• 2 weeks with Climate Mat
Final Conclusions
Geothermal Systems• Hybrid geothermal systems can reduce first costs
while still reducing energy use
• Horizontal Directional Drilling offers ability to install geothermal fields with little land disturbance
Radiant Floor Slabs• Can be used to flatten demand profile
• Controllability becomes important because cooling effect is not instant
Acknowledgements
A special thank you to the following people and parties that made this project possible:
Jefferson Lab, TED Owner
EwingCole, Architects, Engineers, and Interior Designers
Eric Joesten, Director of Mechanical Engineering, EwingCole
Kate Mondock, Mechanical Engineer, EwingCole
Dustin Eplee, Thesis Adivsor
Mentors on the Thesis Class Discussion Board