1. Feasibility of Energy Recovery in Conjunction With The Application of A Redesigned Central Cooling And Heating Plant

2. Outline Introduction/Background Existing Conditions Problem Statement
Energy Recovery System
(ERS) Design
Central Plant Redesign
Electrical Analysis
Structural Analysis
Life-Cycle Cost Analysis
Conclusions and Recommendations

3. Project Team Owner: QIAGEN Sciences, Inc.
Architect: Capital Design Assocs., Inc.
CM: Whiting-Turner
GC: CDI Engineering Group
Mech. Contractor: Pierce Associates
MEP Engineer: Herzog-Hart Corp.
Structural: Cagley and Associates

4. Outline Introduction/Background Existing Conditions Problem Statement
Energy Recovery System
(ERS) Design
Central Plant Redesign
Electrical Analysis
Structural Analysis
Life-Cycle Cost Analysis
Conclusions and Recommendations

5. Existing Overall Conditions
Location: 118 Germantown Road, Germantown, Maryland
Size: 213,000 Ft2
Cost: $52.5 Million
Use : Research and production of biotechnological products such as RNA and DNA, state of the art research facilities and laboratory spaces, chemical and biotech storage, and administrative offices

6. Building 1
Building 2

7. Existing Mechanical Conditions
16 Air-handling units; 4,770 to 46,105 CFM
5 – 100% Outdoor air units; 4,770 to 18,105 CFM
2 – 900 ton electric driven centrifugal chillers
Constant speed primary, variable speed secondary chilled water distribution system
2 – 2,700 GPM induced draft cooling towers
2 – 400 boiler horsepower fire-tube steam boilers
2 – 400 GPM shell and tube steam-to-water heat exchangers
Variable speed primary hot water distribution system

8. Outline Introduction/Background Existing Conditions Problem Statement
Energy Recovery System
(ERS) Design
Central Plant Redesign
Electrical Analysis
Structural Analysis
Life-Cycle Cost Analysis
Conclusions and Recommendations

9. Problem Statement
Large energy consumption from the 100% outdoor air air-handling units
Energy recovery measures are currently not in place to take advantage of the conditioned air being removed from the spaces
Existing 100% Outdoor Air Air-Handling Unit

10. Existing Chiller Plant
Problem Statement
Peak summer energy costs coincide with peak central cooling plant loads
Currently no approach to reducing peak demand and energy costs
Existing Chiller Plant

11. Outline Introduction/Background Existing Conditions Problem Statement
Energy Recovery System
(ERS) Design
Central Plant Redesign
Electrical Analysis
Structural Analysis
Life-Cycle Cost Analysis
Conclusions and Recommendations

12. Energy Recovery System (ERS)
4 existing 100% outdoor air air-handling units modified with total energy recovery wheels
Preheat coil located before enthalpy wheel for fail safe frost protection of the wheel substrate
SEMCO TE3 EXCLU-SIEVE® Total Energy Wheels selected to recover both sensible and latent energy

13. ERS Wheel Selection
SEMCO provided performance charts used to select proper wheel size
Selection based on supply and return air quantities
Return air from general room exhaust, not fume hoods
Optimum face velocity of 800 FPM across wheel

14. Microscopic view of 3Å molecular sieve
ERS Performance
Controlling cross-contamination is critical for laboratory spaces
Adjustable Purge Air Section
3Å Molecular Sieve Desiccant
Independent Testing Results
Microscopic view of 3Å molecular sieve
Purge Air Schematic
Testing Results

15. ERS Energy Analysis
Energy analysis for the mechanical system utilizing the ERS is done in conjunction with the central plant redesign
The peak preheating load is reduced from 7,015 MBH to 4,650 MBH, a 2,365 MBH reduction
The peak cooling load is reduced from 1,045 tons of cooling to 885 tons, a reduction of 160 tons
Carrier’s Hourly Analysis Program (HAP) V4.10 used to model base building and ERS design loads

16. ERS First Cost
First cost information is used in the life-cycle cost analysis later on in the presentation
Cost information was obtained from Spencer Goland at Rotor Source, Inc.

17. Outline Introduction/Background Existing Conditions Problem Statement
Energy Recovery System
(ERS) Design
Central Plant Redesign
Electrical Analysis
Structural Analysis
Life-Cycle Cost Analysis
Conclusions and Recommendations

18. Central Plant Redesign
The central plant redesigns take into account the load reductions from the ERS design
3 alternatives are analyzed, along with the existing plant
Case B
Case C
Case A
2 – 700 nominal ton electric driven centrifugal chillers
Associated primary and secondary chilled water pumps
2 – 2100 GPM cooling towers
Associated condenser water pumps
1 – 400 and 1 – 300 boiler horsepower fire-tube steam boilers
Associated hot water pumps
1 – 675 nominal ton gas-fired double-effect absorption chiller-heater
1 – 700 nominal ton electric driven centrifugal chiller
Associated primary and secondary chilled water pumps
1 – 2700 GPM cooling towers
1 – 2100 GPM cooling tower
Associated condenser water pumps
1 – 400 boiler horsepower fire-tube steam boiler
Associated hot water pumps
2 – 675 nominal ton gas-fired double-effect absorption chiller-heaters
1 – 200 nominal ton electric driven centrifugal chiller
Associated primary and secondary chilled water pumps
2 – 2700 GPM cooling towers
1 – 600 GPM cooling tower
Associated condenser water pumps
1 – 100 boiler horsepower fire-tube steam boiler
Associated hot water pumps

19. Central Plant Redesign Modeling
The Engineering Equation Solver (EES) is used to model the equipment for each plant case
Electric driven chiller modeling
DOE2 model for evaluating chiller performance
Cooling tower modeling
Curve fitting of manufacturer performance curves
Pump modeling
Curve fitting of manufacturer curves as well as application of pump affinity laws for variable speed application
Fire-tube steam boiler modeling
Constant efficiency model

20. Central Plant Redesign Modeling
Gas-fired absorption chiller-heater modeling
Unique aspect of central plant modeling
Chiller-heaters can provide simultaneous heating and cooling
York YPC double-effect absorption chiller-heater model
Curve fit part load performance charts provided by York for individual and simultaneous operation
Individual Performance (York)
Individual Performance (EES)
Simultaneous Performance (York)
Simultaneous Performance (EES)

21. Central Plant Redesign Modeling
Procedures written in EES for base building and 3 redesign case operating sequences
Base building and Case A use conventional system
Electric driven centrifugal chillers
Gas-fired fire-tube steam boilers
Case B uses chiller-heaters as main plant
Case C utilizes gas-electric hybrid plant
Absorption chiller-heater used as primary chiller

22. Central Plant Redesign Energy Analysis
Utility rates are taken from service providers
EES produces hourly energy consumption for central plant components
Microsoft Excel is used to calculate energy costs

23. Central Plant Redesign Energy Analysis
Total Annual Energy Costs
kW Demand charge reductions
Central plant gas usage
Peak demand kW reductions

24. Central Plant Redesign First Cost Analysis
First cost information for chillers from Jim Thompson at York International
R.S. Means
First cost for central plant redesign cases
Includes main plant equipment
Chillers
Boilers
Heat Exchangers
Cooling Towers
Pumps
Chilled Water
Condenser Water
Hot Water
Plant first cost used in life-cycle cost analysis

25. Outline Introduction/Background Existing Conditions Problem Statement
Energy Recovery System
(ERS) Design
Central Plant Redesign
Electrical Analysis
Structural Analysis
Life-Cycle Cost Analysis
Conclusions and Recommendations

26. Electrical Analysis
The effect of the central plant redesigns on the existing electrical system is analyzed
2 direct points of connection on main switchgear #2 for existing electric driven chillers
Existing electrical loads on switchgear #2
Power Panel PP4
Chillers #1 and #2
Emergency Distribution Panel EDP #3
Serves 4 Emergency Motor Control Centers (EMCC)
Spare connection

27. Electrical Analysis
Air-conditioning and refrigeration equipment analyzed per NEC 440
Grounding sized according to NEC Table
Conduit sized according to NEC Chapter 9
kVA demand is calculated for load on switchgear
NEC Table used to determine the full load current for the motors connected to EMCC’s
Feeder sizing done for each case
NEC Table used for wire ampacity
Branch Conductor
NEC D at 125% of the full load current
Overload Protection
NEC and NEC Table ; time delay 175% FLC
Disconnect
NEC at 115% of full load current

28. Electrical Analysis Case A shows no reduction in electrical service
Case C reduces load by 558 kVA
2500 kVA transformer downsized to 2000 kVA
$6,015 savings
Wire size reduced
$8,960 savings

29. Outline Introduction/Background Existing Conditions Problem Statement
Energy Recovery System
(ERS) Design
Central Plant Redesign
Electrical Analysis
Structural Analysis
Life-Cycle Cost Analysis
Conclusions and Recommendations

30. Structural Analysis
Analyze the impact of the central plant redesigns on structural system
Equipment foundations for centrifugal chillers and gas-fired absorption chiller-heaters
Centrifugal chiller foundation design
4 times the equipment weight in concrete for vibration
Reinforcing for temperature and shrinkage
Absorption chiller-heater foundation design
Few moving parts, vibration not critical
Foundation needs to support equipment operating weight

31. Structural Analysis
Chiller-heater foundation depth reduced 24” from centrifugal chiller foundation despite weight increase of over 42,000 lbs
Reduced depth saves $1,840 compared to base building and Case A foundations
Concrete costs
Reinforcing steel costs
Case C absorption chiller-heater foundation
Use 12” depth
1 chiller-heater weighing 65,500 lbs
Existing centrifugal chiller foundation
36” depth
2 chillers weighing 27,000 lbs each
Design Parameters
ACI
Shrinkage and Temperature Reinforcing
Wide Beam Shear
Flexure
Punching Shear
Case A centrifugal chiller foundation
Use 36” depth as in existing building
2 chillers weighing 23,400 lbs each

32. Outline Introduction/Background Existing Conditions Problem Statement
Energy Recovery System
(ERS) Design
Central Plant Redesign
Electrical Analysis
Structural Analysis
Life-Cycle Cost Analysis
Conclusions and Recommendations

33. Life-Cycle Cost Analysis
Used to determine most attractive redesign option
First cost information combined with annual energy costs calculated in central plant redesigns
First costs for ERS design, central plant equipment, structural and electrical redesigns
Analysis Method
20 year life cycle
ERS replacement at 10 years
NIST Energy Price Indices
3.9% discount rate

34. Life-Cycle Cost Analysis
Case A redesign has instant payback
Case C payback; 9 months
Case C net savings over Case A; $133,132
Difference in LCC savings and first cost savings of 2 cases
Case C hybrid plant has lowest LCC
Result of reduced annual energy costs
$864,475 savings over base building
$230,756 savings over Case A redesign

35. Outline Introduction/Background Existing Conditions Problem Statement
Energy Recovery System
(ERS) Design
Central Plant Redesign
Electrical Analysis
Structural Analysis
Life-Cycle Cost Analysis
Conclusions and Recommendations

36. Conclusions and Recommendations
Energy Recovery System Design
Effective response to high energy consumption of 100% outdoor air units
Decreases size of central cooling and heating plant
Central Plant Redesign
Case B central plant first cost and required area too high; not a feasible option
Cases A and C both provide significant life-cycle cost savings
Case C hybrid plant shows best annual energy costs

37. Conclusions and Recommendations
Final Recommendation
Implement Case C gas-electric hybrid central plant redesign
Short payback period attractive to owner
Highest net savings of all options evaluated
Flexibility of using either gas-fired chiller-heater or electric driven centrifugal as primary chiller
Future electric utility rates may be more or less favorable

38. Acknowledgements AE Faculty Industry Professionals
William P. Bahnfleth, Ph.D., P.E.
Stanley A. Mumma, Ph.D., P.E.
James D. Freihaut, Ph.D., P.E.
Walt Schneider, P.E.
Industry Professionals
Dave Johnson, P.E. – QIAGEN Sciences, Inc.
John Saber, P.E, – Encon Group, Inc.
Jim Thompson – York International Corporation
Spencer Goland – Rotor Source, Inc.
5th Year AE Students
Andy Tech – Mechanical
Jim Meacham – Mechanical/CM
242 South Atherton St. – Multi-disciplinary
Family, Friends, and People I Forgot

39. Questions?

40. Thank You For Attending!

41. Energy Recovery System

43. Central Plant Redesign
DOE 2 electric chiller modeling
Correction factors based on chilled water and condenser water temperatures
Regression coefficients
Capacity correction
Efficiency correction

44. Central Plant Redesign
Marley Cooling Tower Curves
Cooling Tower Modeling
Curve fitting using manufacturer plots
Linear regressions for each constant range on plot
Condenser water temperature is a function of range and wet bulb temperature
Curves for full and half speed

45. Central Plant Redesign
Bell & Gossett Pump Curve
Pump Modeling
Curve fit existing plot
Head and efficiency as a function of flow
Affinity laws for variable speed pumping
Head is function of flow rate and motor speed

46. Electrical Analysis kVA demand calculations
Incorporate demand factor and voltage

47. Structural Analysis Reinforcing design
Chapter 7 specifies minimum area of steel for shrinkage and temperature

48. Structural Analysis Wide beam shear check
Chapter 11.3 – Shear strength for non-prestressed members
Chapter – Special provisions for slabs and footings
Chapter 15.4 – Shear in footings

49. Structural Analysis Flexure check Chapter 15.4 – Moments in footings
Chapter 12 – Development and splices of reinforcement

50. Structural Analysis Punching shear check
Assumes 8”x8” vibration isolation pads at 4 corners
Chapter 15.5 – Shear in footings
Chapter – Special provisions for slabs and footings

51. Life-Cycle Cost Analysis
First cost information
Manufacturer cost data
R.S. Means cost data
Base building first cost
Case C first cost
Case A first cost