LA Fitness, West Oaks
Houston, Texas
David Melfi
Mechanical Option
The Pennsylvania State University
Department of Architectural Engineering
Senior Thesis
Spring 2006
Presentation Outline
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Building Description
Goals & Metrics
Design Parameters
Air Side Alternatives
Hot Water Alternatives
Discussion of Original Design
Desiccant Dehumidification
Recommendation
Building Description
Building Information
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45,000 ft2
Exercise Facility
Houston, TX
Construction
Cost of Building:
Started: 5/9/05
$4.5 Million
Finished: 12/09/05
Primary Project Teams
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Owner:
General Contractor:
Construction Manager:
Architects:
MEP Engineers
Structural Engineers:
Civil Engineers:
Interior Designers:
LA Fitness International, LLC
Ridgemont Construction
LA Fitness International, LLC
Heights Venture Architects, LLP
Advanced Technologies, Inc.
BGA Engineers
Cobb Fendley & Associcates
Senninger Walker Architects
Presentation Outline
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Building Description
Goals & Metrics
Design Parameters
Air Side Alternatives
Hot Water Alternatives
Discussion of Original Design
Desiccant Dehumidification
Recommendation
Goals & Metrics
Design Goals
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Energy Reduction Compared to Original Design
Lower Environmental Impact
Economic Feasibility
Gain Practical Experience Designing and Integrating
Mechanical Systems
Metrics
• Annual Energy Consumption
• Emissions
• Economics Analysis
Presentation Outline
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Building Description
Goals & Metrics
Design Parameters
Air Side Alternatives
Hot Water Alternatives
Discussion of Original Design
Desiccant Dehumidification
Recommendation
Design Parameters
• Ventilation Requirements
• Standard 62.1-2004 Reevaluation
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Cooling & Heating Loads
Lighting Loads
Building Envelope
Humidity Control
Critical Zones
Design Parameters
Ventilation
ASHRAE Standard 62.1-2004
Requirements:
Voz
Vot
Actual Design OA
Total Airflow
Design %OA
62.1n %OA
RTU-1
154
154
500
5000
10.0
3.1
RTU-2
950
1188
700
5000
14.0
23.8
RTU-3
3620
3620
3500
10500
33.3
34.5
RTU-4
807
807
3350
8300
40.4
9.7
RTU-5
629
629
750
7500
10.0
8.4
RTU-6
1368
1368
750
6000
12.5
22.8
RTU-7
1419
1419
1000
10000
10.0
14.2
RTU-8
651
651
500
4000
12.5
16.3
RTU-9
2420
2420
1675
6600
25.4
36.7
RTU-10
2420
2420
1675
6600
25.4
36.7
RTU-11
944
1049
750
5500
13.6
19.1
RTU-12
524.5
524.5
500
3500
14.3
15.0
RTU-13
1380
1380
750
5900
12.7
23.4
Entire Building
17286
17628
16400
84400
19.4
20.9
Design Parameters
Critical Zones
• Indoor Pool & Locker Room
Spaces
• Relatively Negative Pressure
• 4-6 Air Changes/Hour
• 800F & 55% Relative Humidity
• Pool Water Temperature: 820F
• Latent Load From Pool
102,950 Btu/hr
Presentation Outline
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Building Description
Goals & Metrics
Design Parameters
Air Side Alternatives
Hot Water Alternatives
Discussion of Original Design
Desiccant Dehumidification
Recommendation
Air Side Alternatives
Original Design
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Cooling Loads Met by 13 Packaged Rooftop Units
Constant Volume
Primarily Single Zone
Economic Advantage Over Other Equipment
OA Rebalance and Redistribution Is Necessary
End-Use
Lighting
HVAC
Energy
Consumption
368,172
4,285
Unit of
Energy
kWh
MMBtu
Enery
First Cost
Cost/Unit Cost/Year of System
$0.078
$28,717
N/A
$14.660
$62,818
$419,000
Building Emissions lbm
Fuel
Coal
Natural Gas
Totals
Particulates/yr
166
0
166
SO2/yr NOx/yr
CO2/yr
1,929
1,119
324,728
8
1,469
774,865
1,937
2,589 1,099,593
Air Side Alternatives
Hydronic System – Water Cooled Chiller
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Screw Compressor
200 ton Chiller Performing at 0.66 kW/ton
Cooling Tower Necessary
4 AHU Needed to Condition the Air
Higher Associated Maintenance Cost/Year
End-Use
HVAC
Original Design
Differential
Energy
Consumption
843,084.0
4,285.0
-412,777.7
Fuel
Coal
Natural Gas
Totals
Differential
Unit of
Energy
kWh
MMBtu
kWh
Enery
First Cost of
Cost/Unit
Cost/Year System
$0.078
$65,761
$433,345
$14.660
$62,818
$419,000
N/A
$2,942
$14,345
Building Emissions lbm
Particulates/yr
SO2/yr NOx/yr
CO2/yr
546
6,347
3,682
1,068,328
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0
0
0
546
6,347
3,682
1,068,328
380
4,410
1,094
-31,267
Air Side Alternatives
Hydronic System – Air Cooled Chiller
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Screw Compressor
200 ton Chiller performing at 1.22 kW/ton
Less Maintenance Cost Compared to WC Chiller
Less Efficient Performance
Relatively Good Part Load Performance
Energy
End-Use
Consumption
HVAC
1,018,379.0
Original Design
4,285.0
Differential
-237,482.7
Fuel
Coal
Natural Gas
Totals
Differential
Unit of
Enery
First Cost of
Energy Cost/Unit Cost/Year System
kWh
$0.078
$79,434
$427,990
MMBtu $14.660
$62,818
$419,000
kWh
NA $16,615
$8,990
Building Emissions lbm
Particulates/yr
SO2/yr NOx/yr
CO2/yr
625
7,266
4,215 1,222,938
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625
7,266
4,215 1,222,938
459
5,329
1,627 123,344
Air Side Alternatives
Discussion of Energy Sources
• Hydronic Systems
• Lower Annual Energy Consumption?
No
• Lower Annual Energy Costs?
No
Presentation Outline
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Building Description
Goals & Metrics
Design Parameters
Air Side Alternatives
Hot Water Alternatives
Discussion of Original Design
Desiccant Dehumidification
Recommendation
Hot Water Alternatives
Original Water Heating
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Three Natural Gas Fired Water Heaters
1200F Water
300 MBH
100 gal of Storage Each
Solar Water Heating
• Three Types Commercially Available
• Unglazed Flat Plate Collector
• Glazed Flat Plate Collector
• Evacuated Tube Collector
• Model Established Using RETScreen Solar Water
Heating Program
Hot Water Alternatives
Solar Water Heating
• Results of Analysis:
Technology
Unglazed Flat
Plate Collector
Glazed Flat
Plate Collector
Evacuated
Tube Collector
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Model
Heliodyne
Mojave 410
Heliodyne Gobi
408
Thermomax
Mazdon 20
Energy Delivered % Demand
Payback
Per Year (MMBtu) Per Year
First Cost Period (Years)
18.94
29.9%
$4,752
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33.94
53.6%
$5,589
5.3
43.26
68.3%
$16,999
11.6
Use Glazed Flat Plate Collector In Final Design
Issues of Solar Reliability
Use Existing Water Heaters as Storage Tanks
Structural Analysis Necessary for Flat Roof
Presentation Outline
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Building Description
Goals & Metrics
Design Parameters
Air Side Alternatives
Hot Water Alternatives
Discussion of Original Design
Desiccant Dehumidification
Recommendation
Discussion of Original Design
Original Rooftop Unit Design
• Pros:
• Lowest annual primary energy
• Lowest emissions
• Lowest first cost
• Cons:
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High load on DX coil
RTU-1 & RTU-2 lose humidity control
Wasteful to cool & dehumidify air  reheat the air
cfm/ton limitations
Discussion of Original Design
• Original Rooftop Unit Design
• RTU-1 & RTU-2
Discussion of Original Design
• Original Rooftop Unit Design
• Reheat & Humidity Sensor Option
Discussion of Original Design
Is there a better way to meet the air side loads
while satisfying the design criteria?
Up until this point in the analysis, the focus of study
was to find a completely new base system that
could better meet the airside loads.
Paradigm shift:
Instead of finding better alternative from scratch
the question became:
How can the existing “good enough” equipment be
modified to have better performance for this site?
Presentation Outline
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Building Description
Goals & Metrics
Design Parameters
Air Side Alternatives
Hot Water Alternatives
Discussion of Original Design
Desiccant Dehumidification
Recommendation
Desiccant Dehumidification
• Another means to control
humidity
• Low surface vapor pressure
attracts moisture from air
• System can be configured in a
rotating “honeycomb” wheel
arrangement
• Sensible Heat Gain from
Process
• Active or Passive?
• Decision Made to Use Active
Desiccant
• Sensible Wheel Also
Necessary
Desiccant Dehumidification
Active Desiccant Configuration with Sensible Wheel
• Air processed by desiccant leaves very hot and dry
• Sensible wheel used to restore a hot, dry temperature
• Air heater used to reactivate desiccant for further use
• Result of process: significant reduction of latent load
Desiccant Dehumidification
• Psychrometric Analysis of Wheels
Presentation Outline
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Building Description
Goals & Metrics
Design Parameters
Air Side Alternatives
Hot Water Alternatives
Discussion of Original Design
Desiccant Dehumidification
Recommendation
Recommendation
Initial idea to modify each unit:
• Requires 26 wheels for the 13 units
• This idea was too expensive and labor intensive
Rather:
• Use 1 central dehumidification station to handle all of the OA
for the building
• Duct the OA from this central unit to the OA intakes of the 13
originally scheduled units
Recommendation
Recommendation
Economic Analysis
Energy Consumed/Year Includes New System Components:
• Motor energy for wheels
• Fan energy
Energy
End-Use
Consumption
HVAC
3,190.4
Original Design
4,285.0
Differential
-1,094.6
Unit of
Enery
First Cost of
Energy Cost/Unit Cost/Year System
MMBtu
$14.66
$46,771
$563,662
MMBtu
$14.66
$62,818
$419,000
MMBtu
NA ($16,047)
$144,662
Payback Period Analysis
• Conservative Payback Period: 11 Years
• Interest Used: 6%
• Natural Gas Escalation Rate: 3%
• Modified Payback Period: 8.5 Years
• Interest Used: 6%
• Natural Gas Escalation Rate: 8%
Many Thanks To...
• Advanced Technologies, Inc
• Penn State AE Mechanical Faculty
• Dr. James D. Freihaut
• Mike Prinkey
• Tony Daniels
• Karen Schulte
• My Family
• Friends and Colleagues
Questions
Integration of Design
• The entire building requires 17,630 cfm of OA to meet the
corrected Standard 62.1 requirements
• Using an Active Desiccant Configuration, 6000 cfm of
counterflow air is necessary
• EF-5 from the original design was a perfect fit (6,300 cfm)
• This exhaust air stream is centrally located near 7 of the 13
rooftop units
Energy Rates
• Energy Rates
Natural Gas Rates
• May 2005 Texas Commercial Rate:
• Dec 2005 Texas Commercial Rate:
$8.67/MMBtu
$14.68/MMBtu
Electric Rates
• May 2005 Texas Commercial Rate:
• Dec 2005 Texas Commercial Rate:
$22.86/MMBtu
$23.45/MMBtu