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