Building Systems Integration
- Energy and Cost Analysis
The Milton Hershey School New Supply Center
Justin Bem
AE Senior Thesis – Spring 2007
Mechanical Option
Penn State University
Project and Building Background
Owner
- The Milton Hershey School
Location
– The Milton Hershey School Campus, Hershey, PA
Project Size
- 110,000 square feet
Total Cost
- $23,500,000
Design-Bid-Build Contract
Construction Dates
- July 2006 – July 2007
Justin Bem – Mechanical Option
Project and Building Background
The Supply Center
- General Office and Conference Rooms
- Kitchen/Food Preparation Center
- Bakery
- Clothing Store and Alterations Seamstress
- Mail Distribution Center
- General Building and MHS Campus Storage
Justin Bem – Mechanical Option
Existing Conditions
Air Side Mechanical System
14 Total Air Handling Units
- 10 VAV Units – Serving General Office and Clothing Areas
- 4 CAV Units – 100% Outdoor Air Make-Up Units for Kitchen/Bakery
- Chilled/Hot Water Coils
- Housed in Elevated Mechanical Mezzanine Floor
McQuay Custom Air Handling Unit
Justin Bem – Mechanical Option
Existing Conditions
Existing Chiller Plant
(2) 270 ton Water Cooled Centrifugal Chillers
- Primary-Secondary Pumping
- 45°F Chilled Water Serves AHU Coils and Walk-in Freezer Condenser
- Electric Driven Vapor Compression Machines
- Housed in 1st Floor Mechanical Room
Existing Boiler Plant
(3) Natural Gas Fired Steam Boilers
- Handles All Building HVAC Heating Demands
- Meets Domestic Hot Water Heating Demands
Justin Bem – Mechanical Option
Trane Centrifugal Chiller
Existing Conditions
Walk-in Freezer Condenser Water Loop
Rejected Heat from Condenser to water loop
- Removes Additional Heating Load from Kitchen Space
- Load Is Met Directly By Chilled Water Plant Via Plate-Frame HX’s
- Water Side “Free” Cooling Is Utilized in the Winter for Heat Rejection
Justin Bem – Mechanical Option
The Redesign Outline
Mechanical Redesign
Effect on Structural System and Building
Construction
(3) #10 & 1#10 GD
(4) # 350 kcmil
(3) #6 1#8 GD
(4) #400 kcmil
(3) #10 1#10
Justin Bem – Mechanical Option
Effect on Electrical System
Mechanical System Redesign Objectives
Goals
- Increase Energy Efficiency
- Low Life Cycle Cost
- Affordable – (Low First Cost or 2-4 Year Payback Period)
Integration of Building Systems with HVAC System
- Recover Waste Heat
- Perform Multiple Functions from One Fuel Source
Justin Bem – Mechanical Option
Mechanical System Redesign
DOAS/ Water Source Heat Pumps
Dedicated Outdoor Air Systems at The Supply Center
-10 Existing VAV Air Handling Units Replaced with 2 DOAS Units
- Saves in First Cost
- Saves in Fan and Chiller Energy
Water Source Heat Pumps at The Supply Center
- Water Source Loop Integrates Other Building Systems
--Condenser Water Loop Heat Recovery
- Gives Ability to Heat and Cool Simultaneously
Justin Bem – Mechanical Option
Mechanical System Redesign
DOAS/ Water Source Heat Pumps
Justin Bem – Mechanical Option
Mechanical System Redesign
Condenser Loop Heat Recovery
Walk-in Freezers Reject Heat to a Condenser Water Loop
- Must Be Cooled for Continues Operation of Freezers
- Potential for a Large Amount of Energy Recovery
135gpm Flow Rate
84°F Hot Temperature
65°F Operating Temperature
1282 MBH of Possible Heat Recovery
Justin Bem – Mechanical Option
Mechanical System Redesign
Condenser Loop Heat Recovery
Heat Recovery In Water Source Loop
- Water Source Heat Pump Loop Requires Winter Time Heat Addition
- Operating Temperature of 68°F
- Condenser Water Loop Serves as Heat Source Via Heat Exchanger
45°F Chilled
Water
Condenser Water
Loop Return
65°F
Walk-In Freezer
Condenser Water
Loop Supply
84°F
Condenser Water
Loop Return
78°F
Water Source
Loop
To Heat Source/Sink
Justin Bem – Mechanical Option
Mechanical System Redesign
Condenser Loop Heat Recovery
Heat Recovery In Domestic Hot Water Pre-Heat
- High Domestic Hot Water Demand at The Supply Center
- Condenser Loop Pre-Heats Water to 76-81°F (Saves 35% Heating Energy)
45°F Chilled
Water
Condenser Water
Loop Return
65°F
Domestic Hot
Water
Pre-Heated
Condenser Water
Loop Return
78-65°F
Condenser Water
Loop Return
78°F
Walk-In Freezer
Condenser Water
Loop Supply
84°F
Water Source
Loop
To Heat Source/Sink
Justin Bem – Mechanical Option
Mechanical System Redesign
Absorption Chiller-Heater Technology
Direct Natural Gas Fired Absorption Chiller-Heaters
- Utilizes Natural Gas Service at The Supply Center
- Typical Double Effect LiBr/Water Absorption Cycle
- Includes Heat Exchanger in High Temperature Generator for
Simultaneous Cooling and Hot Water Production (Up to 210°F)
Justin Bem – Mechanical Option
Mechanical System Redesign
Absorption Chiller-Heater Technology
Direct Natural Gas Fired Absorption Chiller-Heaters
- Simultaneous Heating Comes at the Expense of Cooling Production
- Chiller-Heater Must Run at 30% Cooling Capacity Minimum
Justin Bem – Mechanical Option
Existing System Chiller Plant Load Profile
Redesign Plant Load Profile
300
250
Plant Load (Tons)
200
150
100
50
0
0
4
8
12
Hour
Justin Bem – Mechanical Option
16
20
24
Mechanical System Redesign
Redesigned Chiller/Boiler Plants
Chiller-Heater Selection
- Sized to Meet Cooling and HVAC/Domestic Hot Water Needs
- (2) 240 ton Chiller-Heaters Used
- Meets Cooling Load with Enough Capacity to Produce Hot Water
Justin Bem – Mechanical Option
Mechanical System Redesign
Redesigned Chiller/Boiler Plants
Redundancy and Reliability
-If one Chiller-Heater Is Off Line, Second Meets Critical Load
-- Walk-in Freezer’s Condenser System 106 tons
-- All other cooling loads are not critical
-Back-up Boiler to Meet Heating Demand
-- HVAC and Domestic Hot Water
INTEGRATES HEATING, COOLING, CONDENSER WATER, AND
DOMESTIC WATER SYSTEMS!
Justin Bem – Mechanical Option
Mechanical System Redesign
Redesigned Chiller/Boiler Plants
Justin Bem – Mechanical Option
Mechanical System Redesign
Life Cycle Cost Analysis
Energy Rates
Natural Gas
$/Therm
Winter
Spring/Fall
Summer
1.13
.85
.50
Electricity Rates
$0.06 / kW-hr
Justin Bem – Mechanical Option
Mechanical System Redesign
Life Cycle Cost Analysis
Annual Operating Cost Comparison
Existing System
Cooling Cost
HVAC Heating Cost
Hot Water Heating Cost
Combined Heating and Cooling Cost
Air System Fan Cost
Pump Cost
Cooling Tower Cost
Total
$67,577
$23,016
$58,371
N/A
$21,303
$29,274
$9,920
$209,461
Redesign w/
Chiller-Heater
N/A
N/A
N/A
$117,370
$12,318
$20,480
$16,440
$166,608
$42,800 Annual Cost Savings!
Justin Bem – Mechanical Option
Mechanical System Redesign
Life Cycle Cost Analysis
Annual Energy Consumption
Cooling
HVAC Heating
Domestic Heating
Pumps/Fans/CT
Total
Difference
Justin Bem – Mechanical Option
Existing System
Redesign System
17,100,000 kbtu
17000000 kbtu
6,260,800 kbtu
1,700,000 kbtu
2,200,000 kbtu
2,800,000 kbtu
27,260,000 kbtu 19,800,000 kbtu
7,460,000 kbtu
Mechanical System Redesign
Life Cycle Cost Analysis
Initial Cost Comparison
Equipment (Quantity and Type)
Chillers (2 Centrifugal)
Chiller-Heaters (2)
HVAC Boiler (1 4500 MBH)
HW Boiler (2 6500 MBH)
Supplemental Boiler (1 9000 MBH)
Heat Exchangers (for HW system)
DOAS AHUs (2)
VAV AHUs (10)
Plate-Frame HX
VAV Boxes w/reheat
Heat Pumps
TOTAL
Existing
System
178,000
21,800
61,000
10,000
309,310
10,000
32,730
$622,840
$60,000 More Expensive
Justin Bem – Mechanical Option
Redesign Chiller-heater
Option
450,000
85,000
47,840
20,000
60,045
$682,885
Mechanical System Redesign
Life Cycle Cost Analysis
Redesign O&M Costs additional $3,000 more per year
20 Year Life Cycle Cost Comparison, 6% Interest
Existing System
NPW
Initial Cost
20 Yr LCC
$2,266,510
$622,840
$2,889,350
Redesign System
$1,829,863
$682,885
$2,512,748
$376,600 Savings Over 20 Years!
Justin Bem – Mechanical Option
Mechanical System Redesign
Life Cycle Cost Analysis
Mechanical Redesign Conclusions
- Integrates Multiple Building Systems
- More Expensive Up Front
- Cheaper to Operate
- Least Expensive 20 Year Life Cycle Cost
Payback In Just Under 2 Years!
Justin Bem – Mechanical Option
Effect on Structural System and Building Construction
Justin Bem – Mechanical Option
Structural/Construction Breadth
AHU Relocation
Existing System
Creates
SpaceininMezzanine
MezzanineFloor
Floor
14 Total Wasted
AHUs housed
10 VAV
4 CAV
Redesigned System
6 Total AHUs
2 DOAS
4 CAV
Move AHUs to Roof
- Creates Structural Work
- Potential to Save Initial Cost
Justin Bem – Mechanical Option
Structural/Construction Breadth
AHU Relocation
Steel K-Series Joist are Replaced with W-flanged Beams
Justin Bem – Mechanical Option
Structural/Construction Breadth
Mezzanine Floor Cost
No Need to Construct Mezzanine Floor
Only Held Air Handling Units
Justin Bem – Mechanical Option
Structural/Construction Breadth
Mezzanine Floor Cost
Large First Cost Savings for Not Construction Mezzanine Floor
Steel Members
1-1/2” Steel Decking
139 C.Y. of 4000psi Concrete
TOTAL FLOOR COST
Justin Bem – Mechanical Option
Total Construction Cost
$122,986.1
$19,762.75
$11,709.6
$154,458.45
Effect on Electrical System
(3) #10 & 1#10 GD
(4) # 350 kcmil
(3) #6 1#8 GD
(4) #400 kcmil
(3) #10 1#10
Justin Bem – Mechanical Option
Electrical Breadth
Power System Alterations
Less Electric Driven Mechanical Equipment
- Chillers, 8 AHUs, Boiler Accessories
- Changes Load on Distribution Panels
- Saves Cost on Feeder and Wire Sizes
Justin Bem – Mechanical Option
Electrical Breadth
Power System Alterations
Additional Electrical Cost
ADD ON
(3) #10 & 1#10 GD
(4) # 350 kcmil
(3) #6 1#8 GD
(4) #400 kcmil
(3) #10 1#10
3 sets of (4) #300
kcmil
3#10 & 1#10 GRD
3#12 & 1#12 GRD
3#12 & 1#12 GRD
3#12 & 1#12 GRD
Justin Bem – Mechanical Option
Cost per 100 LF
229
2650
379
3000
229
9000
229
137
137
137
Length (ft)
20
65
60
65
20
15
30
30
30
30
Total
Total Cost $
45
1722
227
1950
45
1350
68
41
41
41
$5,534
Electrical Breadth
Power System Alterations
Electrical Cost Savings
Electrical Cost Savings
$9,189
New Equipment Electrical Cost
$5,534
Total Electrical Cost Savings
$3,600
Mechanical Redesign Creates Electrical Cost Savings!
Justin Bem – Mechanical Option
Conclusions and Recommendations
Final Cost Analysis
Overall Building System Redesign Cost Analysis
Existing System
Redesign
Mechanical 1st Cost
$622,840
$682,885
Mezzanine Cost
$154,458
N/A
Additional Structural Cost
N/A
$277
Additional Electrical Cost
$3,600
N/A
$780,898
$683,173
Total 1st Cost
Justin Bem – Mechanical Option
Conclusions and Recommendations
Final Cost Analysis
Conclusions Compared to Existing System
- Mechanical Redesign Saves Energy and Cost Over 20 Years
- Integrates Other Building Systems
- Creates Overall First Cost Savings!
$ 98,000 Initial Cost Savings
$ 42,800 Yearly Cost Savings
$ 531,000 Saved Over 20 Years!
Redesign Is Beneficial
Justin Bem – Mechanical Option
Acknowledgments
Thank You!
AE Department
- Advisor Dr. Bahnfleth
H.F. Lenz Company
- Tom Hovan, P.E.
Deckman Company
- Scott Adams
My Great Friends for Their Support!
Justin Bem – Mechanical Option
Building Systems Integration
The Milton Hershey School Supply Center
Questions?
Justin Bem – Mechanical Option
Mechanical System Redesign
Redesigned Chiller/Boiler Plants
Plant Load Analysis
- Walk-in Freezer’s Heat Rejection Creates 106 ton Base Load
- Peak Cooling Load at 390 tons
-High Hot Domestic Hot Water Demand
-- Excellent Opportunity for Simultaneous Heating and Cooling!
Justin Bem – Mechanical Option
Mechanical System Redesign
Redesigned Chiller/Boiler Plants
AHU
Outdoor Air Supplied
3
3640
4
5585
5
3000
7
3000
9
1000
10
1125
11
1045
12
1250
13
3000
14
800
Total
23,445
DOAS 1
6176
DOAS 2
3615
Total
9,791
Difference
13,654
Justin Bem – Mechanical Option
Existing System Chiller Plant Load Profile
Daily Cooling Load Profile
450
400
350
Plant Load (Tons)
300
250
200
150
100
50
0
0
4
8
12
Hour
Justin Bem – Mechanical Option
16
20
24
Existing System Chiller Plant Load Profile
Redesign Plant Load Profile
300
250
Plant Load (Tons)
200
150
100
50
0
0
4
8
12
Hour
Justin Bem – Mechanical Option
16
20
24
New System Chiller Plant Load Profile
Peak Plant Load per Month
450
June
400
April
July
August
Sept
350
Peak Plant Load (Tons)
300
May
October
250
200
March
January February
150
100
50
0
Justin Bem – Mechanical Option
Nov
Dec
AHU Relocation
- Beams sized to limit deflection to avoid ponding
Δ = 5wl4/(384EI)
Δ = L/240
Justin Bem – Mechanical Option
Structural/Construction Breadth
AHU Relocation
Additional Cost of Redesign Is Small!
BEAM/JOIST
K series Joist
LENGTH
37
W – Flange
Justin Bem – Mechanical Option
37
AMOUNT
22
22
Difference
TOTAL COST
$7,577.6
$7,855.1
$277.5