Retro-Commissioning Final Report
8/17/2012
Located at:
Presented to:
Sponsored by:
Project # 0391001
Submitted By:
Final Retro-commissioning Report Disclaimer
Disclaimer
Part of the intent of the Retro-commissioning Report is to identify recommended retro-commissioning
measures related to energy savings, O&M, comfort and indoor air quality for the customer’s
consideration. While the energy savings associated with the findings in this report have been reviewed
for technical accuracy and are believed to be reasonably accurate, the actual results may vary. As a result,
and/or Hammel, Green and Abrahamson, Inc. (HGA) are not liable if estimated energy
savings or economics are not realized. All energy savings and opinions of cost in the report are
“ballpark” and for informational purposes, and are not to be construed as a design document or as
guarantees.
The shall independently evaluate any advice or suggestions provided in this report. In
no event will and/or HGA be liable for the failure of the customer to achieve a specified
amount of energy or demand savings, the operation of the customer’s facilities, or any incidental or
consequential damages of any kind in connection with this report or the installation of evaluated
measures.
Final Retro-commissioning Report Contents
Contents
Section Page
EXECUTIVE SUMMARY ......................................................................................................................................... I
SECTION 1 PROJECT CONTACTS ............................................................................................................. 1-1
SECTION 2 INTRODUCTION ....................................................................................................................... 2-1
SECTION 3 PROJECT OPPORTUNITIES SUMMARY ............................................................................ 3-1
SECTION 4 FACILITY DESCRIPTION ....................................................................................................... 4-1
4.1 GENERAL FACILITY INFORMATION ............................................................................................................... 4-1 4.2 ENERGY SYSTEMS ........................................................................................................................................ 4-3 4.3 ENERGY USE AND COSTS ............................................................................................................................. 4-9 4.4 BUILDING DOCUMENTATION ...................................................................................................................... 4-13 4.5 BUILDING EQUIPMENT ................................................................................................................................ 4-14
SECTION 5 INVESTIGATION RESULTS ................................................................................................... 5-1
5.1 INVESTIGATION ACTIVITIES .......................................................................................................................... 5-1 5.2 AIR HANDLING UNITS .................................................................................................................................. 5-1 5.3 CHILLED WATER SYSTEM ............................................................................................................................ 5-6 5.4 VAV SYSTEM .............................................................................................................................................. 5-8 5.5 SNOW MELT ................................................................................................................................................. 5-9 5.6 DOMESTIC HOT WATER ............................................................................................................................... 5-10 5.7 LIGHTING ................................................................................................................................................... 5-10 5.8 MASTER LIST ............................................................................................................................................. 5-11
SECTION 6 APPENDICES ............................................................................................................................. 6-1
APPENDIX A: DETAILED FIM CALCULATIONS ....................................................................................................... 6-1
Final Retro-commissioning Report Executive Summary
i
Executive Summary
The is located at 2
. The 187,000 square foot building has four stories, and it was completed in 1994.
The building includes 27 classrooms varying in size from a 16-seat conference room to a 387-seat
auditorium. Each classroom is equipped with technology including projectors and audio systems. The
building also houses one of the largest information technology centers on campus.
The goal of this retro-commissioning study is to identify energy and operational savings, meet current
building requirements, while improving or maintaining occupant comfort and indoor air quality. The
study focuses on the existing HVAC equipment and the Building Automation System (BAS) but also
touches on envelope and lighting system. It identifies issues and opportunities to make the entire
facility run more efficiently.
The facility was evaluated in heating and in cooling mode. It was found that
has significant potential for reducing energy consumption and a resulting overall short return
on investment. The measures that result in the largest energy savings include modifications to the
control sequences for the fan powered reheat boxes and building scheduling modifications.
A summary of the savings and implementation cost for the calculated measures is shown in Table 1.
Please note that the energy savings associated with each measure can in most cases not be added as
most measures will impact the energy savings associated with another measure.
Final Retro-commissioning Report Facility Description
- 2012ii
Table 1: Summary of Calculated Measures
FIM
No.
Recommended
Improvement
Opinion of
Implemen-
tation Cost
Annual
Energy
Cost
Savings
(End User
Cost)
Simple
Payback
(years)
(End User
Cost)
Annual
Energy Cost
Savings
(Mid-American
Cost)**
Simple
Payback
(years)
(Mid-American
Cost)
1
Modify AHU
schedules in
summer to 6a-6p,
7 days/week.
$100 $37,141 0.1 $8,031 0.1
2
Implement AHU
duct static
pressure reset
$4,000 $5,409 0.7 $2,884 1.4
3
AHU-1 Demand
Control
Ventilation &
Occupancy Sensor
Control
$12,000 $2,348 5.1 $1,141 10.5
4
Add variable
frequency drive to
CW P-6 / CW
Leaky Valves
$4,465 $15,743 0.3 $2,428 1.8
5
Modify fan
powered VAV
box sequence
$19,500 $97,800 0.2 $32,383 0.6
6 Modify snow melt
control $1,000 $20,758 0.1 $10,359 0.1
7
Domestic Hot
Water Recirc
Pump Control
$1,000 $321 3.1 $161 6.2
8 Artwork Lighting $1,100 $314 3.5 $168 6.6
Total* $43,165 $179,834 0.24 $57,555 0.75
* The individual energy savings cannot be added as many of the measures will impact the energy savings
associated with the other measures. The energy savings in this table are added together as a total to
illustrate the order of magnitude of the energy savings and simple payback.
** Mid-American Cost Savings is calculated using $0.0427/kW-hr and $6/MMBtu for steam with 80%
efficiency conversion.
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Section 1 Project Contacts
Table 2: Roles, responsibilities and contact information for RCx participants
Name Role Organization Contact Information
Final Retro-commissioning Report Facility Description
2012 1-2
Name Role Organization Contact Information
Final Retro-commissioning Report Introduction
2012 2-1
Section 2 Introduction
Retro-commissioning (RCx) is a systematic, documented process that identifies operational and
maintenance improvements in existing buildings and brings the buildings up to the design intentions of
its current usage.
RCx typically focuses on energy-using equipment such as mechanical equipment, lighting and related
controls, and usually optimizes existing system performance, rather than relying on major equipment
replacement, typically resulting in improved indoor air quality and comfort, reduced amount of O&M,
as well as added control, energy, and resource efficiency.
RCx includes a study of past utility bills, interviews with facility personnel, a review of the controls
system, and auditing the entire building, in heating and in cooling modes. Then, diagnostic monitoring
and functional tests of building systems are executed and analyzed. Building systems are retested and
re-monitored to fine-tune improvements. This process helps find and repair operational problems.
Final Retro-commissioning Report Project Opportunities Summary
2012 3-1
Section 3 Project Opportunities Summary
Numerous action items related to the operation and maintenance of the
were discovered during the RCx investigation phase. Some of these measures are directly related to
optimizing energy efficiency, while others are meant to ensure the building systems meet the
requirements for climate control and occupant comfort.
There is substantial opportunity for utility costs to be reduced with a modest initial investment. For the
purposes of this report, savings are calculated based on two utility rate structures as detailed in Table 3:
Utility Pricing. Table 4, below, summarizes the energy efficiency measures.
Table 3: Utility Pricing
Pricing End User Pricing
Electric $0.0427/kW-hr $0.0801/kW-hr
Chilled Water 0.9 kW-hr/ton $24.35/MMBtu
Steam $6/MMBtu $15.04/MMBtu
Final Retro-commissioning Report Project Opportunities Summary
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Table 4: Master List of Calculated Energy Saving Measures
FIM
No.
Recommended
Improvement
Electric
Savings
(kWh)
Chilled
Water
Savings
(MMBtu)
Steam
Savings
(MMBtu)
Opinion of
Implemen-
tation Cost
Annual
Energy
Cost
Savings
(End User
Cost)
Simple
Payback
(years)
(End User
Cost)
Chilled
Water
Savings
(kWh)
Annual
Energy Cost
Savings
(Mid-American
Cost)**
Simple
Payback
(years)
(Mid-American
Cost)
1
Modify AHU
schedules in
summer to 6a-6p,
7 days/week.
60,392 1,192 218 $100 $37,141 0.1 89,400 $8,031 0.1
2
Implement AHU
duct static
pressure reset
67,534 - - $4,000 $5,409 0.7 - $2,884 1.4
3
AHU-1 Demand
Control
Ventilation &
Occupancy Sensor
Control
7,800 5.7 106 $12,000 $2,348 5.1 428 $1,141 10.5
4
Add variable
frequency drive to
CW P-6 / CW
Leaky Valves
11,101 610 - $4,465 $15,743 0.3 45,750 $2,428 1.8
5
Modify fan
powered VAV
box sequence
204,093 1,894 2,347 $19,500 $97,800 0.2 142,050 $32,383 0.6
6 Modify snow melt
control 2,849 - 1365 $1,000 $20,758 0.1 - $10,359 0.1
Final Retro-commissioning Report Facility Description
2012 3-2
FIM
No.
Recommended
Improvement
Electric
Savings
(kWh)
Chilled
Water
Savings
(MMBtu)
Steam
Savings
(MMBtu)
Opinion of
Implemen-
tation Cost
Annual
Energy
Cost
Savings
(End User
Cost)
Simple
Payback
(years)
(End User
Cost)
Chilled
Water
Savings
(kWh)
Annual
Energy Cost
Savings
(Mid-American
Cost)**
Simple
Payback
(years)
(Mid-American
Cost)
7
Domestic Hot
Water Recirc
Pump Control
406 - 19 $1,000 $321 3.1 - $161 6.2
8 Artwork Lighting 3,924 - - $1,100 $314 3.5 - $168 6.6
Total* 358,099 3,702 4,055 $43,165 $179,834 0.24 277,628 $57,555 0.75
* The individual energy savings cannot be added as many of the measures will impact the energy savings associated with the other measures. The
energy savings in this table are added together as a total to illustrate the order of magnitude of the energy savings and simple payback.
** Mid-American Cost Savings is calculated using $0.0427/kW-hr and $6/MMBtu for steam with 80% efficiency conversion.
Detailed lists of all RCx findings can be found in Section 5.8. They are divided into two categories; the first category contains issues that have
low implementation costs and are generally related to operational and equipment sequence modifications. The second category deals with
additional measures that were not calculated.
Final Retro-commissioning Report Facility Description
2012 4-1
Section 4 Facility Description
4.1 GENERAL FACILITY INFORMATION
The P houses the at the in
. Completed in 1994, it is an 187,000-square-foot (17,400 m2) postmodern facility that
houses the .
The building embodies the style of the Pentacrest structures with its use of aggregate stone and is a
modern twist on the turn-of-the century buildings found at the heart of campus. Its style is also
reminiscent of financial institutions such as the New York Stock Exchange and its use of a "money-
green" paint scheme reinforces its financial focus.
includes 27 classrooms varying in size from a 16-seat conference room to a
387-seat auditorium. Each classroom is equipped with technology including projectors and audio
systems. The building houses one of the largest information technology centers on campus, as well as
offices, the , which serves breakfast, lunch and
dinner. The open atrium spaces, study corners and outdoor patio provide places for students to study or
relax. The building also includes a below grade parking garage. An illustration of the facility’s plan is
provided in Figure 1.
The facility is closed on holidays, and normally operates under the schedule detailed in Table 5.
Table 5: Hours (except library)
Monday - Thursday 6:30 am - 11 pm
Friday 6:30 am - 9 pm
Saturday 7:30 am - 6 pm
Sunday 7:30 am - 11 pm
Table 6: Hours
Monday - Thursday 8 am - Midnight
Friday 8 am - 7 pm
Saturday Noon - 5 pm
Sunday Noon - Midnight
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Figure 1:
Final Retro-commissioning Report Facility Description
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4.2 ENERGY SYSTEMS
4.2.1 Building Automation Systems
The central HVAC equipment in the building is controlled by a Johnson Controls Extended
Architecture Building Automation System (BAS). This includes the following:
• Air handling units: AHU-1 through AHU-5
• Fan coil units
• Chilled water distribution
• Hot water converters
• Hot water pumps
• VAV boxes with full DDC devices
• Snow melt systems
• Generator room
• Smoke damper
4.2.2 Facility Heating, Cooling, and Ventilation
Air Handling Units
has five (5) air-handling units (AHUs). AHU-1 is a single-zone constant
volume unit that serves the . AHU-2 through AHU-5 are variable air volume
units that provide ventilation and conditioning to the rest of the building. Table 7 provides details for
each of the AHUs. The discharge air temperature for AHU-2 through AHU-5 is currently maintained
at 55°F. The static pressure setpoints are not reset on any of these units. Spaces served by AHU-2
through AHU-5 have variable air volume fan-powered boxes. Boxes in perimeter areas have hot water
reheat coils, while some of those in interior zones lack reheat. Spaces that need year round cooling
such as computer labs and server rooms are also served by fan coil units.
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Table 7: Air Handling Units List
HVAC System
AHU Service Area SF HP SF
VFD RF HP RF VFD CFM
Minimum
OA Schedule
Design
CW
Flow
(gpm)
Design
CW
∆T (F)
Heating
Coil
AHU-1 Buchanan Auditorium
(NW Ground Floor) 15 5 11,000 7a-10p 71 15 Steam
AHU-2 NW 1st,2nd and 3rdFloors 75 √ 30 √ 50,000 10,000 5a-10p 286 14.6 None
AHU-3 North Center 1st,2nd,3rd
and 4th Floors 75 √ 30 √ 50,000 10,000
5a-11p (M-F)
7a-10p
(Wknd)
286 14.3 None
AHU-4 South Center 1st,2nd,3rd
and 4th Floors 75 √ 30 √ 50,000 10,000
5a-11p (M-F)
7a-10p
(Wknd)
286 14.3 None
AHU-5 South 1st,2nd and 3rd
Floors 75 √ 30 √ 50,000 10,000
5a-10p (M-F)
7a-10p
(Wknd)
286 14.3 None
Final Retro-commissioning Report Facility Description
2012 4-5
Heating System
Heating hot water is provided by two (2) steam to hot water heat exchangers. Steam is provided by the
campus steam plant. Heating hot water is circulated by a pair of lead-lag 15-horsepower pumps (P-1
and P-1a) with VFDs. The heating hot water supply temp is reset from 135°F to 180°F as shown in
Table 5.
Table 8: Hot Water Temperature Reset Schedule
When Outdoor Air Temp is: Hot Water Supply Temp is:
20°F 180°F
65°F 135°F
Chilled Water system
Chilled water is supplied to the building by the campus chilled water plant. Pumps P-2 and P-2a are
the main chilled water pumps for the building. These 40-horsepower pumps with operate in lead-lag
during the cooling season. P-2 has a VFD and P-2a is a constant volume pump. During the heating
season, the chilled water coils on the AHUs are drained and the pump P-6, a 3-horsepower constant
volume pump, is used to supply the fan coil units with chilled water.
Parking Garage Ventilation
Ventilation for the parking garage is provided by an exhaust fan that is controlled by a carbon
monoxide sensor. No heating is provided to the garage space. The entrance/exit ramp is equipped with
a glycol snowmelt system.
The heating, cooling, and ventilation systems have electrically actuated direct digital controls, and are
scheduled and operated by a networked building automation system.
Snowmelt System
Five main entrance areas and the entrance/exit ramp for the parking garage are equipped with a glycol
snow and ice melt system. The glycol loop is heated by a 20 gpm hot water to glycol heat exchanger.
The loop supply temperature is linearly reset from 140°F to 105°F based on outdoor air temperature as
shown in Table 9. A control valve on the heating hot water side of the heat exchanger is modulated to
control the loop supply temperature.
Final Retro-commissioning Report Facility Description
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Table 9: Snowmelt System Temperature Reset Schedule
When Outdoor Air Temp is: Snowmelt Loop Supply
Temp is:
45°F 140°F
0°F 105°F
The glycol is circulated by a pair of lead-lag 10-horsepower pumps with VFDs. According to the
controls drawings, the VFD modulates to maintain a constant differential pressure in the loop.
However, the controls drawings indicate that there are no control valves in the glycol side of the loop.
Trend data confirms that the pumps do not modulate.
Domestic Hot Water Heating
Domestic hot water is provided by a small A.O Smith 40 gallon water heater. The unit has an integral
steam coil. The unit also has recirculation pump that runs 24/7.
Variable Air Volume Boxes
The VAV terminal units at are electronic with full DDC devices and
control. There are 237 fan-powered VAV reheat terminals to provide zone thermal adjustments.
Boxes in perimeter areas have hot water reheat coils, while some of those in interior zones lack reheat.
The University installed new occupancy sensors in most of the spaces during the winter of 2011-2012.
The proposed design calls for these sensors to turn off lighting and allow the space temperature to
float ±3ºF when the space is vacant (vs. ±1ºF when occupied). Part of the funding for the project came
from Federal money and the project was completed in April of 2012.
Supplemental and Perimeter Heating
A limited number of hot water unit heaters are located in entrance areas to provide supplemental heat.
There are no unit or fin tube heaters located in the office or classroom areas.
There are also approximately 10 unit heaters located above the drop ceiling in the parking garage.
These heaters are used to provide floor heating in the winter months to avoid cold floors in the interior
spaces above the garage.
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4.2.3 Chilled Water System
Cooling for the building is provided by chilled water from the campus chilled water plant.
has a dedicated chilled water interface and chilled water meter. The supply
temperature from the chilled water loop is typically between 42 and 43°F.
The building ∆T (difference between loop return temperature and building supply temperature) is a
function of outdoor air temperature. The ∆T ranges between 2°F in the winter months and 25°F in the
summer months.
Figure 2: Chilled Water Performance, 2010-11
Chilled water is used for all the air handlers as well as a limited number of fan coil units used for
server room cooling.
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4.2.4 Steam System
Steam from the campus steam plant is used for air handler steam heating coils and in the steam
convertors to heat water for the hydronic hot water system. The hot water temperature is
automatically reset based on outside air temperature.
has dedicated steam meter which was replaced in April of 2007.
4.2.5 Electrical
Power is fed to local distribution panels from two 1,500 kVA, oil-filled transformers. Two high
voltage switches and two 480 volt isolation switches isolate the transformers. Standard conductors
feed modern 3,000 amp, double-ended switchgear through an interior feed selector. The switchgear
powers three 1,200 amp vertical bus ducts. TPower is distributed to various electrical closets at
480/277 volts.
4.2.6 Lighting
The interior lighting at is quite varied in design and effect. The lighting
scheme has a unified design theme and dramatic appearance.
According to facilities personnel, the building stocks twenty-four (24) different types of lamps. Many
areas of the building were originally designed with occupancy sensors. It appears that many of these
sensors no longer work. The University is currently pursuing a project to install new occupancy
sensors in each space. The proposed design calls for these sensors to turn off lighting and allow the
space temperature to float when the space is vacant. Part of the funding for the project is from Federal
money and the project was completed in the Spring of 2012.
3.2.5 Other Loads
Room C220J is a server room with 16 servers. There are also computers in offices, classrooms, the
computer lab and email checking stations.
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4.3 ENERGY USE AND COSTS
marginal cost of electricity from is $0.0427 per kWh.
Steam for the building is supplied by the campus’s coal and biomass plant, and chilled water is
supplied by the campus chilled water plan. For the purposes of this report, savings are calculated
based on end user utility rates of $0.0801 per kWh for electricity, $24.35 per MMBtu of chilled water,
and $15.04 per MMBtu of steam.
4.3.1 Electricity Use and Costs
Figure 3 illustrates the monthly electricity consumption at over the past
five fiscal years. Electricity consumption varies between 150 and 329 MWh per month and shows no
significant seasonal variation. The relative consistency of electricity consumption seasonal is due to
the building being supplied with district chilled water. The average monthly (and annual) electricity
consumption has remained fairly constant since fiscal year 2006/2007. It appears that the billing
cycles were standardized in fiscal year 10-11, as the monthly variations have been greatly reduced.
Due to the reduced activity in the building in the summer, there is likely a potential to reduce electric
energy consumption during the summer months by shutting off lighting, equipment and fans.
Figure 3: Electricity Use Profile –
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4.3.2 Steam Use and Costs
Figure 4 illustrates the monthly steam consumption at over the past five
fiscal years. Steam consumption reflects a strong seasonal variation peaking in December and January
and at a minimum in the summer months. The average maximum monthly steam consumption in the
past 2 years is approximately 1,800 MMBtu/month, while the summer monthly minimum has
fluctuated between 140 and 500 MMBtu. Steam consumption at
increased dramatically in the winter months beginning in the winter of 2009. This increase coincides
with the start-up of a snow melt system used at the building entrances and steps at the West side
auditorium entrance. It should also be noted that a new steam meter was installed on March 7th, 2007.
Summer steam consumption is used primarily for VAV box reheat coils via the steam convertors and a
small amount for domestic hot water.
Figure 4: Steam Consumption Profile –
4.3.3 Chilled Water Use and Costs
Figure 5 illustrates the monthly chilled water consumption at over the
past five fiscal years. Chilled water consumption reflects a strong seasonal variation, peaking in the
summer months as the building cooling and dehumidification demands increase, and dipping in the
winter months, when cooling needs are limited to server rooms. The chilled water consumption rate is
steady during the heating season (November through March), approximately 300 MMBtu per month.
A significant portion of the winter chilled water usage can be eliminated by fixing leaking cooling
valves as illustrated by the reduced chilled water consumption in FY12 December, January and
February after we manually valved off the valves that were observed to leak (March was an unusually
Final Retro-commissioning Report Facility Description
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warm month in 2012).
Figure 5: Chilled Water Consumption Profile –
4.3.4 Total Energy Use and Costs
Figure 6 illustrates the total yearly energy expenses for for the fiscal
year 2011.
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Figure 6: Energy Cost (electricity, chilled water and steam) –
Based on the 2011 fiscal year, is paying $3.11/ft2, which is higher than
would be anticipated for this type of building.
4.3.5 Energy Benchmarking
HGA could not enter into Portfolio Manager because higher educational
facilities and libraries are not among the building types currently supported by the program. However,
Portfolio Manager may add this and other building types in the future. HGA is available to advise and
assist with Portfolio Manager benchmarking if the tool expands its offerings to include higher
educational facilities and library buildings.
As a point of comparison, according to the 2003 Commercial Buildings Energy Consumption Survey
(CBECS) conducted by the U.S. Department of Energy’s Energy Information Administration, the
national average energy intensities by fuel type for K-12 educational buildings were 31.5 kBtu/square
foot for electricity and 48 kBtu/square foot for natural gas, for a total average intensity of 83.1
kBtu/square foot. ’s energy intensity is 154 kBtu/square foot, 1.8 times
the national average for K-12 educational facilities. However, the CBECs average for educational
buildings does not take into account the presence of IT server rooms, which elevate the energy load in
the facility. The also has an extended schedule when compared to K-12
educational facilities. During the school year, the building is in operation until 11p with the computer
lab open until 1:30a, which is approximately double the occupancy time of a typical K-12 school.
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4.4 BUILDING DOCUMENTATION
The Facilities Department posted documentation pertaining to
on-line on SharePoint. The documentation includes the following:
• Mechanical Drawings
• Electrical Drawings
• AHUs Locations and Zones Served
• Hawks Energy Team Reports
• No systems manual is available for at this time.
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4.5 BUILDING EQUIPMENT
Table 10: Air Handling Units List
HVAC System
AHU Service Area Location SF
HP
SF
VFD
RF
HP
RF
VFD CFM
Min
OA
(cfm)
Schedule
Design
CW
Flow
(gpm)
Design
CW
∆T (F)
Heating
Coil
AHU-1
Buchanan
Auditorium
(NW Ground
Floor)
W14 15 5 11,000 7a-10p 71 15 Steam
AHU-2 NW 1st,2nd and
3rdFloors W406A 75 √ 30 √ 50,000 2,000 5a-10p 286 14.6 None
AHU-3
North Center
1st,2nd,3rd and
4th Floors
W406A 75 √ 30 √ 50,000 2,200
5a-11p (M-F)
7a-10p
(Wknd)
286 14.3 None
AHU-4
South Center
1st,2nd,3rd and
4th Floors
S406C 75 √ 30 √ 50,000 2,200
5a-11p (M-F)
7a-10p
(Wknd)
286 14.3 None
AHU-5 South 1st,2nd
and 3rd Floors S406C 75 √ 30 √ 50,000 2,200
5a-10p (M-F)
7a-10p
(Wknd)
286 14.3 None
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Table 11: Exhaust Fans
Exhaust Fans
Exhaust Service Area CFM HP Location SP (w.c.)
EF-1 See Plans 2,725 2 In Line 1.5
EF-2 See Plans 3,125 3 In Line 1.5
EF-3 Ground “B” 700 1/6 Wall 24” SQ .25
EF-4 A,B,C,D See Plans 18,000 2 Wall .25
EF-5 Ground “C” 1,150 1/2 In Line SQ .5
EF-6 See Plans 2,000 1/2 Wall .5
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4.5.1 Heat Exchanger Schedule
has three shell and tube heat exchangers that produce hot water from the
steam from the campus steam plant.
Heat exchangers HX-1 and HX-1A are located in ground floor mechanical room. They serve the
building’s main hot water loop (associated pumps are P-1 and P-1A). HX-2 is a water to water heat
exchanger that serves the slab snow melting system. The shell flow rate of HX-2 is 17.5 gpm at 1.9 psi
pressure drop based on 40% propylene glycol, entering water temperature 80F and leaving water
temperature 110F.
Table 12: PBB Heat Exchanger Schedule
PBB Heat Exchanger
Humid-
ifier
Service
Area
Tube Side Shell
Model Number
GPM EWT LWT PD lb/hr Pressure
HX-1 HWS 500 150 180 2’ 7353 10 psig B&G SU165-2
HX-1A HWS 500 150 180 2’ 7353 10 psig B&G SU165-2
HX-2 GWS 20 120 150 1’ CHX-636-2S
4.5.2 Direct Steam Humidification
The steam humidifier schedule for AHU-1, 2, 3, 4 and 5 at is as follows:
Table 13: PBB Steam Humidifier Schedule
PBB Steam Humidifiers
Humid-
ifier
Service
Area
Outdoor
CFM kW
#/hr Cap.
Required
Manu-
facturer Model Number
H-1 AHU-1 30 85.2 Dri-Steam VPC-101010 Single
Tube
H-2 AHU-2 2,000 42 121 Dri-Steam VPC-141414
H-3 AHU-3 2,200 42 121 Dri-Steam VPC-141414
H-4 AHU-4 2,200 42 121 Dri-Steam VPC-141414
H-5 AHU-5 2,200 42 121 Dri-Steam VPC-141414
Due to recurring maintenance issues and the high cost of operating the electric humidifiers, they are no
longer in use. HGA recommends that the humidifiers remain out of service, as there are no requirements,
Final Retro-commissioning Report Facility Description
- 20124-17
such as local codes or ASHRAE standards that require such a facility to be humidified to maintain
occupant comfort or functional needs.
Final Retro-commissioning Report Facility Description
- 20124-18
4.5.3 Pumps and Valves
Table 14: Pumps
Pumps
Pump Service Type GPM HP RPM
Feet
of
Head
P-1 Hot Water Supply B&G 1510 4E 500 15 1750 75
P-1A Hot Water Supply B&G 1510 4E 500 15 1750 75
P-2Chilled Water
Supply B&G 1510 8x10x101/2 1200 40 1750 80
P-2AChilled Water
Supply B&G 1510 8x10x101/2 1200 40 1750 80
P-3 Condensate Pump Roth 90S Duplex - 35
gallon rec. 40 2 1750 69
P-4 Domestic Hot water B&G PD385 15 1/2 1750 30
P-5 Sump Aurora 511 20 1/3 1800 20
P-6Chilled Water
Supply B&G 1510 1Y4BC 70 3 1800 80
P-7 Fire Aurora 6-481-18B 1500 125 1770 231
P-8 Fire Aurora JP-231-5 5 1.5 231
P-9 Sump Aurora 522 Duplex 80 1 25
P-10 Sump Flyght M3102-212
Grinder 60 5 60
P-11 Snow Melt B&G 1535 353T 17.5 3 65
P-12 Snow Melt Viking FH456M 3 1 1800 50
Final Retro-commissioning Report Investigation Results
- 2012
5-1
Section 5 Investigation Results
5.1 INVESTIGATION ACTIVITIES
This section presents the recommendations for repairs and modifications to optimize the building
performance based on HGA’s observations.
5.2 AIR HANDLING UNITS
5.2.1 AHU-2, 3, 4, 5 – Schedule Modifications
AHU-2 through 5 are the main air handlers for the building and serve all areas except the ground floor
auditorium space. Currently, these AHU’s run on the following schedules:
AHU Tag Weekdays Weekends
AHU-2 5a-10p 5a-10p
AHU-3 5a-11p 7a-10p
AHU-4 5a-11p 7a-10p
AHU-5 5a-10p 7a-10p
These schedules fairly closely match the building schedule, except in the summer months when the
building is open from 6:30a-6p and 7:30a-6p on the weekends. Therefore, it is recommended that
AHU-2 through 5 operation schedules are modified in the summer months from approximately June 1
through August 31. The new summer schedule would be from approximately 6a-6p. The energy
savings for this measure includes air handler fan savings, air handler chilled water savings, fan
powered box fan savings and fan powered box reheat savings. Based on the proposed schedule, the
total savings and opinion of cost for this measure would be as follows:
Annual
Electricity
Savings (kWh)
Annual Chilled
Water (MMBtu)
Annual Steam
Savings
(MMBtu)
Implementation
Costs ($)
60,392 1192 218 $100
Additional savings opportunities exist for AHU schedule modifications. Because the building has fan
powered boxes with reheat coils throughout the building except in core spaces, in the winter months it
Final Retro-commissioning Report Investigation Results
- 2012
5-2
is feasible to keep the AHU’s off until the building has significant occupancy at approximately 7a.
The fan powered boxes could provide the heat for the warm-up period from 5a-7a. At 7a the AHU’s
would turn on to provide the ventilation air for the building.
It should also be noted that in the summer of 2012 there are M.B.A night classes occurring in the
building outside of the published building hours. It is recommended that the various University
departments better coordinate building use in the summer months so that not all the buildings are
being used at extreme part load. Better coordinating building usage would allow more buildings to be
shut down during the summer, resulting in significant energy savings.
Final Retro-commissioning Report Investigation Results
- 20125-3
5.2.2 AHU-2, 3, 4, 5 – Reset Duct Static Pressure Setpoint
AHU-2 through 5 are variable air volume air handlers with variable speed drives on both the supply
and return fans. The supply fan speed is controlled to maintain a constant duct static pressure when
the unit is on. For AHU-3, 4 and 5 this pressure is maintained at 1.2”. AHU-2 is maintained at 2.2”.
Because the majority of the boxes served by the AHU’s have fan powered box, the discharge air static
pressure setpoint typically can be set lower than a traditional VAV system.
To further evaluate the feasibility of a discharge air static pressure reset, the box damper positions
were evaluated on 5/3/2012 when there was a relative high cooling load on the building. The graph
below illustrates the damper positions of all the building boxes.
Figure 7: VAV Box Damper Positions
The majority of the damper positions are between 15%-35% open. There were some boxes that were
100% open but some of these boxes were not communicating with the BAS system, resulting in false
readings. If all the boxes are working properly, it is likely that the discharge static pressure setpoint
can be significantly reduced using reset schedule based on damper position. It is expected that the
range of reset would be from 0.5”-1.0”. However, most of the run hours would be at the lower end of
this range. The current setpoint for the majority of the air handlers is 1.25”. The new average duct
static setpoint would be expected to be .7”. Based on the proposed measure, the total savings and
opinion of cost for this measure would be as follows:
Final Retro-commissioning Report Investigation Results
- 20125-4
Annual
Electricity
Savings (kWh)
Annual Chilled
Water (MMBtu)
Annual Steam
Savings
(MMBtu)
Implementation
Costs ($)
67,534 - - $4,000
Final Retro-commissioning Report Investigation Results
- 2012
5-5
5.2.3 AHU-1 – Implement Demand Control Ventilation and Occupancy Control
AHU-1 serves the basement auditorium and is used as a large lecture hall. The unit typically runs
from 7a-10p during the school year. This unit is a constant volume unit with fixed speed supply and
return fans. When the unit is operating, the outside air dampers are set at a fixed position unless the
unit is economizing. The minimum outside air damper position is based on auditorium peak
occupancy. However, the space is rarely at full occupancy and is therefore, over-ventilated much of
the time when the unit is running.
To implement demand control ventilation, a CO2 sensor would be located in the space. The outside air
damper minimum position would be reset based on the space CO2 levels in a manner consistent with
those outlined in ASHRAE standard 62. Typically, CO2 levels are maintained at levels no higher than
1,100ppm.
In addition to the demand control ventilation, it is recommended to turn off AHU-1 when the
auditorium is vacant, but the unit is scheduled to be on. This would be accomplished by installing
occupancy sensors in the auditorium. When the room is vacant for over 15 minutes, the air handler
would turn off. If the room was occupied for over 5 minutes, the AHU would turn back on. Some fine
tuning of the sensor delays and control scheme would be required to avoid excessive cycling of the air
handler and avoid occupant complaints.
For the purposes of the calculation, the following assumptions were made:
- The minimum outside air quantity is 35% of the unit total supply cfm
- The demand control ventilation would result in an average outside air quantity of 15% of design
- The occupancy sensor would results in the AHU running only 80% of the scheduled time
- The unit would be economizing when the outside air is between 70°F and 30°F, and therefore no
savings from the demand control ventilation would be achieved
- AHU-1 is scheduled to run during the school year from 7a-10p
- Return air is 70°F and discharge air is 55°F in cooling and 65°F in heating
Annual
Electricity
Savings (kWh)
Annual Chilled
Water (MMBtu)
Annual Steam
Savings
(MMBtu)
Implementation
Costs ($)
7,680 5.7 106 $12,000
Final Retro-commissioning Report Investigation Results
- 2012
5-6
5.3 CHILLED WATER SYSTEM
There are two identical 40 HP chilled water pumps that serve the chilled water loop at
, P-2 and P-2A. They work on a lead/lag configuration. P-2 is on variable frequency
drive and maintains a constant differential pressure of 12 psi during the cooling season, per sequence
of operation. P-2A is the constant volume back up pump. Additionally, there is a smaller 3-HP
chilled water pump, P-6, that serves PBB during the winter months, when the building cooling load is
reduced to the fan coils serving the IT rooms.
Table 15: Chilled Water Pumps Characteristics
Pump Service Type GPM HP RPM
Feet
of
Head
P-2 Chilled Water
Supply B&G 1510 8x10x101/2 1200 40 1750 80
P-2A Chilled Water
Supply B&G 1510 8x10x101/2 1200 40 1750 80
P-6 Chilled Water
Supply (Winter) B&G 1510 1Y4BC 70 3 1800 80
5.3.1 Chilled Water Pump P-6 VFD Installation
Chilled water pump P-6 is used in the winter and at times of low cooling requirements to provide chilled
water to primarily to the fan coil units serving the server rooms. This pump is a constant volume pump.
During the first visit in November of 2011, it was found that the system differential pressure was 2-3
times the setpoint maintained by the main chilled water pump VFD’s in the summer operation mode.
With such a high differential pressure the chilled water valves on AHU-3 and AHU-4 did not close
completely and allowed (or increased the amount of) chilled water leaking through the valve when it was
commanded close. In order to reduce the system differential pressure, the throttling valve after P-6 was
closed almost all the way to match the differential setpoint in the summer mode of operation. After
throttling the pump, the leakage on 2 valves was eliminated. The graph below illustrates the chilled
water savings by eliminating the valve leakage.
Final Retro-commissioning Report Investigation Results
- 20125-7
Figure 8: Chilled Water Savings from Pump Throttling
HGA recommends that a VFD is installed on this pump to reduce the pump speed to maintain the
differential pressure setpoint that is used on P-2 in the normal summer mode. All required differential
pressure sensors are already installed which reduces the project cost.
The energy and cost savings associated with adding the VFD to P-6 and eliminating the chilled water
valve leakage is estimated to be:
Annual
Electricity
Savings (kWh)
Annual Chilled
Water Savings
(MMBtu)
Annual Steam
Savings
(MMBtu)
Implementation
Costs ($)
11,101 610 - $4,465
Final Retro-commissioning Report Investigation Results
- 2012
5-8
5.4 VAV SYSTEM
HGA reviewed each variable air volume box at on the BAS system. The
following is a summary of potential issues discovered.
5.4.1 Modify Fan Powered Box Sequence of Operation
Prior to retrocommissioning the VAV boxes, U of I completed an energy efficiency project which
installed occupancy sensors throughout the spaces. The occupancy sensors control the room lights and
are also tied into the majority of the zone fan-powered VAV box. The newly implemented fan-powered
box sequence functioned the same way as without the occupancy sensor with the following
modifications:
• The boxes are now scheduled independently of the AHU serving it. Box schedules may be
reduced from the AHU schedule.
• When the rooms served by the box are unoccupied, the box will continue to run but the
temperature deadband is increased from ±1°F to ±3°F.
While the sequence implemented at PBB for the occupancy sensor controlled fan-powered boxes saves
some energy, there are additional sequence modifications that can be implemented to significantly
increase the energy savings from the occupancy sensor installation. Specifically, the follow changes are
recommended:
• The fan is allowed to go off when the room is vacant and the temperature setpoints are
maintained.
• The supply damper is closed when the room is vacant and the zone temperature is below cooling
setpoint temperature (i.e. either neutral or heating).
Energy savings calculations were performed for this measure using trend data from the BAS. The
savings from implementing this measure include AHU fan savings, AHU chilled water savings, fan
powered box fan savings and fan powered box reheat savings. There would also be improvements in
occupant comfort in the core areas that do not have reheat coils, as the spaces would be overcooled when
the rooms are vacant, as is currently occurring. The total savings and opinion of cost for this measure is
estimated to be:
Annual
Electricity
Savings (kWh)
Annual Chilled
Water Savings
(MMBtu)
Annual Steam
Savings
(MMBtu)
Implementation
Costs ($)
204,093 1,894 2,347 $19,500
The implementation cost assumes that the existing VAV controllers can be used to implement the
proposed control strategy. The costs would be significantly higher if new VAV controllers were
required. U of I controls staff are currently investigating the feasibility of implementing this new control
strategy.
Final Retro-commissioning Report Investigation Results
- 2012
5-9
5.4.2 Temperature Setpoints
HGA observed that some spaces had a very narrow deadband of just 1 degree (±0.5°F) Fahrenheit
between heating and cooling temperature setpoints, rather than the 4 degree deadband recommended by
AHSRAE. There seems to be no specific reason for this reduced value, as there are no know critical
spaces at . Spaces with a one degree deadband included rooms W7, W13,
C202 SW, C207East, C207 West, C220 SW, C220A Middle N, and C220D Middle S.
HGA recommends increasing deadband to 5°F. This range could be seasonally adjusted, for example
using 70°F and 75°F setpoints in winter and 68°F and73°F in the summer.
Finally, there is a wide variation in space temperatures and setpoints, ranging from 67°F through 75°F,
even in non-critical spaces.
HGA recommends evaluating the reason for this wide range of temperature setpoints as well as sensor
accuracy in order to maintain a more uniform temperature throughout the building. This would reduce
the amount of spaces where one terminal unit is heating while another is cooling.
5.5 SNOW MELT
5.5.1 Modify Snow Melt Control
An extensive snow melt system was installed throughout the building exterior in the summer of 2009. In
the past, the snow melt was scheduled to run when the outside air temperature was less than 40°F.
However, of all the hours the snow melt system is active, less than 20% of this time does the heating
provide any function. While snow melt sensors can be installed, it is recommended that the system be
controlled manual using a timer programmed into the BAS. A possible procedure could be that when
there is a forecast for snow accumulation in the next 36 hours, an assigned department from the facilities
staff, landscape services or energy management office would start the snow melt system. The system
would for example run for 48 hours and then turn off. Some timer adjustment may be necessary based on
the time it takes to heat the concrete slab.
The energy savings associated with this measure was calculated based on the average building steam use
prior to the snow melt installation compared to before the installation, normalized for weather. The snow
melt system is estimated to cost over $26,000/yr to operate when the system runs if the outside air is
below 40°F. If the system is operated manually, it is estimated that the annual operation cost is
approximately $6,000/yr. The table below summarizes the energy savings and opinion of cost for this
measure:
Annual
Electricity
Savings (kWh)
Annual Chilled
Water Savings
(MMBtu)
Annual Steam
Savings
(MMBtu)
Implementation
Costs ($)
2,849 - 1,365 $1,000
Final Retro-commissioning Report Investigation Results
- 2012
5-10
5.6 DOMESTIC HOT WATER
5.6.1 Schedule DHW Recirculation Pump
The current domestic water recirculation pump runs 24/7. It is recommended that the pump is scheduled
either through a stand-alone time clock or tied into the building automation system. The implementation
of this measure will not only save pump energy, but will also save the steam that is used to reheat the
recirculating hot water.
The table below summarizes the energy savings and opinion of cost for this measure:
Annual
Electricity
Savings (kWh)
Annual Chilled
Water Savings
(MMBtu)
Annual Steam
Savings
(MMBtu)
Implementation
Costs ($)
406 - 19.2 $1,000
5.7 LIGHTING
5.7.1 Artwork Spotlight Lamp Replacement
There are 14 50W halogen bulbs used throughout the building to accent artwork. It is recommended that
the bulbs are replaced with LED lamps with equivalent light output. The LED bulbs, while more
expensive, will have approximately 10x longer life and use approximately 15% of the energy compared
to the halogen lamps.
The table below summarizes the energy savings and opinion of cost for this measure:
Annual
Electricity
Savings (kWh)
Annual Chilled
Water Savings
(MMBtu)
Annual Steam
Savings
(MMBtu)
Implementation
Costs ($)
3,924 - - $1,100
Final Retro-commissioning Report Investigation Results
Pappajohn Business Bldg. RCx - 2012 5-11
5.8 MASTER LIST
5.8.1 Low Cost Measures
Table 16: Master List – Low Cost Measures
FIM
No.
Recommended
Improvement
Electric
Savings
(kWh)
Chilled
Water
Savings
(MMBtu)
Steam
Savings
(MMBtu)
Opinion of
Implemen-
tation Cost
Annual
Energy
Cost
Savings
(End User
Cost)
Simple
Payback
(years)
(End User
Cost)
Chilled
Water
Savings
(kWh)
Annual
Energy Cost
Savings
(Mid-American
Cost)**
Simple
Payback
(years)
(Mid-American
Cost)
1
Modify AHU
schedules in
summer to 6a-6p,
7 days/week.
60,392 1,192 218 $100 $37,141 0.1 89,400 $8,031 0.1
2
Implement AHU
duct static
pressure reset
67,534 - - $4,000 $5,409 0.7 - $2,884 1.4
3
AHU-1 Demand
Control
Ventilation &
Occupancy Sensor
Control
7,800 5.7 106 $12,000 $2,348 5.1 428 $1,141 10.5
Final Retro-commissioning Report Investigation Results
- 2012
5-12
FIM
No.
Recommended
Improvement
Electric
Savings
(kWh)
Chilled
Water
Savings
(MMBtu)
Steam
Savings
(MMBtu)
Opinion of
Implemen-
tation Cost
Annual
Energy
Cost
Savings
(End User
Cost)
Simple
Payback
(years)
(End User
Cost)
Chilled
Water
Savings
(kWh)
Annual
Energy Cost
Savings
(Mid-American
Cost)**
Simple
Payback
(years)
(Mid-American
Cost)
4
Add variable
frequency drive to
CW P-6 / CW
Leaky Valves
11,101 610 - $4,465 $15,743 0.3 45,750 $2,428 1.8
5
Modify fan
powered VAV
box sequence
204,093 1,894 2,347 $19,500 $97,800 0.2 142,050 $32,383 0.6
6 Modify snow melt
control 2,849 - 1365 $1,000 $20,758 0.1 - $10,359 0.1
7
Domestic Hot
Water Recirc
Pump Control
406 - 19 $1,000 $321 3.1 - $161 6.2
8 Artwork Lighting 3,924 - - $1,100 $314 3.5 - $168 6.6
Total* 358,099 3,702 4,055 $43,165 $179,834 0.24 277,628 $57,555 0.75
Final Retro-commissioning Report Investigation Results
- 2012
5-- 13 -
5.8.2 Capital Investment Measures
There were no capital investment measures that were recommended for the . Significant energy savings can be
achieved through low cost measures documented in the low cost measure master list above.
5.8.3 Other Measures
Other measures include improvements that were considered for the low cost improvements master list, but not included for one of the following
reasons:
- Insufficient information was available to calculate the potential savings and the savings were not considered significant.
- Calculations were performed but the savings was small and the paybacks periods were over 10 years. For these measure, the
recommendation in the table below is listed as “Review at later date”.
Table 17: Other Measures
FIM
No.
Equipment or
System ID Description of Finding Recommended Improvement Recommendation
9 VAV Boxes Boxes serving common areas have
different temperature set points
Software interlock temperature set points for
common areas to avoid simultaneous heating and
cooling
Implement
10 VAV Boxes
Boxes without occupancy sensors
serving typically unoccupied spaces
are not controlled efficiently.
Spaces would include mechanical
rooms, janitor closets, etc…
Modify programming so that these boxes are
allowed to go to a minimum cfm of 0 and have the
fan go off when the temperature set points are
satisfied. Also, the temperature set points can be
relaxed for these spaces, such as 68°F for heating
and 76°F for cooling during the scheduled
occupancy times.
Implement
Final Retro-commissioning Report Investigation Results
- 2012
5-- 14 -
FIM
No.
Equipment or
System ID Description of Finding Recommended Improvement Recommendation
11 VAV Boxes
Minimum flow on VAV boxes is
40%, which is likely higher than that
required by ASHRAE std 62.1.
Recalculate required minimum flow rates based
on room occupancy. This will reduce the amount
of cooling cfm required and also reduce the
amount of reheat occurring to maintain the
temperature set points. AHU outside air
requirements can also be recalculated at this time.
Implement
12 Steam Traps
Steam trap survey was recently
performed on the Pappajohn steam
traps.
Continue to perform steam trap survey at a
regular interval, such as every 3-5 years. Completed
13 Utility Room
Lighting
T12 fluorescent lamps are used in
the mechanical rooms.
Replace T12 lamps and ballasts with T8
equivalents.
Review at later
date
14 Atrium
Lighting
Atrium areas are lit with eight 250W
metal halide fixtures.
Replace metal halide fixture with LED
replacement.
Review at later
date
15 Parking
Lighting
Parking garage is lit with 124, 100W
high pressure sodium lamps.
Replace high pressure sodium lamps with LED
equivalent. Note: This lighting is the
responsibility of Transportation and Housing
Department, and not UE&M. However, it is still
mentioned here as a potential improvement that
would be undertaken by Transportation and
Housing.
Review at later
date
16 Classroom
Lighting
Classrooms use dimmable
incandescent lights
Replace with dimmable LED lamps with
equivalent output
Review at later
date
Final Retro-commissioning Report Investigation Results
- 20125-- 15 -
FIM
No.
Equipment or
System ID Description of Finding Recommended Improvement Recommendation
17 Steam Piping Steam pipe valves in ground floor
mechanical room are not insulated
Insulate steam pipe valves and all other piping
accessories with removable blankets Implement
18 AHU-2
On AHU-2, the abandoned
humidifier penetrations at the air
handler discharge in the mechanical
room are leaking discharge air.
Seal all unused penetrations on AHU-2 and the
other air handlers. Implement
19 AHU’s AHU’s start early to bring spaces to
temperature
Implement optimum start on AHU’s for cooling
only.
Review at later
date
20 Garage Unit
Heaters
Unit heaters located above the drop
ceiling in the garage are not on DDC
control
Install DDC controls on the 10 unit heaters in
order to more effectively control the space
temperature and avoid heating the space during
unoccupied times.
Review at later
date
Final Retro-commissioning Report Appendices
- 20126-1
Section 6 Appendices
APPENDIX A: DETAILED FIM CALCULATIONS
Note: A CD has been included with the excel spreadsheet calculations and all the associated weather
data. The information presented in this appendix is a summary of the calculation.
Final Retro-commissioning Report Appendices
- 2012
6-2
FIM #1: AHU Scheduling
Current
AHU ScheduleAHU Schedule-
Fall/Spring Semester
AHU Schedule -
Summer
AHU-2 5a-10p/ 7 days No change5a-6p M-F
7a-5p Wknd
AHU-35a-11p/ M-F
7a-10p (Wknd)No change
5a-6p M-F
7a-5p Wknd
AHU-45a-11p/ M-F
7a-10p (Wknd)No change
5a-6p M-F
7a-5p Wknd
AHU-55a-10p/ M-F
7a-10p (Wknd)No change
5a-6p M-F
7a-5p Wknd
Proposed
Note: To simplify the calculation, it w as assummed that all AHU
schedules are shutoff at 6p, rather than 10p in the summer.
Final Retro-commissioning Report Appendices
- 2012
6-3
Savings AHU-2 AHU-3 AHU-4 AHU-5 FP VAV's Total/Avg Comments
CFM of Supply Air 28,174 28,174 28,174 28,174
112,695
Per Trend Data from
5/6-5/9 w hen ON
and per Query of
BAS 4/19-4/25
CFM of Outside Air 9,297 9,297 9,297 9,29737,189
OA based on design
values
CFM of Return Air 18,876 18,876 18,876 18,876
AHU SF Motor Size (hp) 75 75 75 75300 Nameplate hp
AHU SF Motor Eff iciency 94.1% 94.1% 94.1% 94.1%94%
AHU RF Motor Size (hp) 30 30 30 30 120
AHU RF Motor Eff iciency 91.0% 91.0% 91.0% 91.0% 91%
AHU Motor Load Factor 30% 30% 30% 30% 30%
Hrs/Wk OA is Supplied: 28.0 28.0 28.0 28.0
28
4 hrs less run
time/day in summer,
7 days/w eek
Wks/Yr OA is Supplied: 12 12 12 1212
summer schedule is
12 w eeks long
Heating Balance Point (F): 55 55 55 55 55
TMY3 Night Heating Degree Hours: 0 0 0 00
No heating coil in
AHU
AHU on chilled w ater plant loop? Yes Yes Yes Yes N/A
AHU Discharge Air Temp: 55 55 55 55 55
Conversion Factor 1,000,000 1,000,000 1,000,000 1,000,000 1,000,000
Chilled Water Used for Outside Air
Sensible Cooling (MMBtu/yr)75 75 75 75
See TMY3 Data Tab
for calculation
Chilled Water Used for Outside Air
Latent Cooling (MMBtu/yr)78 78 78 78
Chilled Water Used for Return Air
Sensible Only (MMBtu/yr)145 145 145 145
75°F Return air
based on BAS data,
unless economizing
Total Chilled Water Used
(MMBtu/yr)298 298 298 298 1,192
Ignore additional
cooling due to fan
energy
Average Chilled Water Rate $24.35 $24.35 $24.35 $24.35 $24.35
Chilled Water Cost (MMBtu based) $7,258 $7,258 $7,258 $7,258 $29,033
Schedule Reduction of AHUs 2, 3, 4, 5 on Summer Nights
Scheduling of AHUs
Currently AHU-2 through 5 run until 10p year round. This calculation estimates the savings of turning off the AHU's at 6p on summer weekdays and weekends, which better corresponds to the building schedule. This calculation includes savings from the following: AHU fan savings, AHU chilled water savings, fan powered box fan savings
and fan powered box reheat savings. Assume that AHUs do not need to kick on to meet setpoint temperature for at least the first 4 hours.
Final Retro-commissioning Report Appendices
- 2012
6-4
Electrical AHU Fan Consumption
(kWh/yr)8,472 8,472 8,472 8,472
33,890
Average Electrical Rate ($/kWh) $0.080 $0.080 $0.080 $0.080 $0.080
Electrical Cost at the Fan $679 $679 $679 $679 $2,715
Number of FPVAV Boxes 264
Average FPVAV Motor (HP) 0.267
Fan Speed Setting Average
(Hi/Med/Low )0.75
Total FPVAV Motor HP 52.9
Total FPVAV Motor kW 39.4
Average FPVAV Motor Eff iciency 50%
FPVAV Fan Electrical Consumption
(kW/hr)26,502
FPVAV Fan Electrical Cost $2,123
Airf low reduction for spaces in heating
mode due to overcooling of air at Low
Occupancy (cfm)
40,000
Per Query of BAS
4/19-4/25
Defined as any zone
in low er half of
heating/cooling
setpoints is either
just in heating or w ill
be heating.
Temperature difference betw een
discharge air and neutral air (°F)15
Steam reheat savings (MMBtu) 218
Steam reheat cost savings
($/yr)MMBtu)$3,266
Total Annual Energy Cost $7,937 $7,937 $7,937 $7,937 $5,389 $37,136
Project cost Estimate $25 $25 $25 $25 $100
Incentive $0
Simple Payback 0.0 0.0 0.0 0.0 0.0
Final Retro-commissioning Report Appendices
- 20126-5
FIM #2: AHU-2 through AHU-5 Duct Static Pressure Reset
Reduce Static Pressure for AHU-2, AHU-3, AHU-4 & AHU-5notes
AHU-2 through AHU-5
Supply fan motor power (HP) 300
Motor load factor 60.0%
Supply fan motor efficiency 95.0%
VFD efficiency 95.0%
VFD credit 0.5
Reduction of energy used compared to constant
volume system, based on IEEE study
Operating schedule (hrs/day) 17
Operating schedule (days/yr) 356
Current electricity consumption (kWh/yr) 450,229
Percent reduction from static pressure reset 15%
low end estimate based on ASHRAE and California
PIER studies
Electricity Savings (kWh/yr) 67,534
Electricty Saving from Fans (kWh) 67,534
Additional Steam for Heating (MMBtu/yr) -115
not clear why there would be additional steam,
AHU discharge 55°F regardless
Chilled Water Savings (MMBtu/yr) 115
Average electric consumption per ton (kWh/ton-hr) 0.90
Assume chillers have similar COP to campus
chilled water system.
Electricity Savings for Chilled Water (kWh/yr) 8,643
Opinion of Cost Notes
Functional Testing $5,000
Programming $3,000
Improvements in critical zone not included in this estimate
Total ($) $8,000
Incentive Calculation Notes
Total Electric Savings (kWh) 76,178
Electric Rate ($/kWh) $0.04270
Potential Annual Cost Savings ($) $3,253
Steam Savings (MMBtu) -115
Opinion of Project Cost ($) $8,000
Efficiency Partners Incentive ($) $4,747
Final Retro-commissioning Report Appendices
- 2012
6-6
FIM #3: Demand Control Ventilation
For the purposes of the calculation, the following assumptions were made:
- The minimum outside air quantity is 35% of the unit total supply cfm
- The demand control ventilation would result in an average outside air quantity of 15% of design
- The occupancy sensor would results in the AHU running only 80% of the scheduled time
- The unit would be economizing when the outside air is between 70°F and 30°F, and therefore no
savings from the demand control ventilation would be achieved
- AHU-1 is scheduled to run during the school year from 7a-10p
- Return air is 70°F and discharge air is 55°F in cooling and 65°F in heating
725450 CEDAR RAPIDS MUNICIPAL AP
Removed summer break, one month for winter break, thanksgiving, weekends, 10p-7a
Supply cfm 11000
assummed design oa cfm 3850
demand control oa cfm avg 1650
supply fan and return fan kW 16 Total Total
5.72 106
Date (MM/DD/YYYY) Time (HH:MM) Day Hour Dry-bulb (F)
Cooling
delta T
Demand
Control
Sensible
Cooling
Heating
CFM
reduction
Heating
Savings
(Btu) kW-hr Savings
1/20/1999 7:00 4 7 19.4 0 0 2717 133807 7680
1/20/1999 8:00 4 8 19.4 0 0 2717 133807
1/20/1999 9:00 4 9 21.2 0 0 2816 133208
1/20/1999 10:00 4 10 23 0 0 2915 132224
1/20/1999 11:00 4 11 24.8 0 0 3014 130856
1/20/1999 12:00 4 12 24.8 0 0 3014 130856
1/20/1999 13:00 4 13 26.6 0 0 3113 129102
1/20/1999 14:00 4 14 28.4 0 0 3212 126964
1/20/1999 15:00 4 15 28.4 0 0 3212 126964
1/20/1999 16:00 4 16 28.4 0 0 3212 126964
1/20/1999 17:00 4 17 28.4 0 0 3212 126964
Demand Control Savings
See excel spreadsheet for continued data.
Final Retro-commissioning Report Appendices
- 2012
6-7
FIM #4: Chilled Water VFD and Leaky Valves
notes
Pump Totals CWP-6
Motor Power (HP) 5 5
Motor Efficiency -- 89.5%
Weeks per year operating -- 30
Energy use with throttling valve (current) (kWh/year) 15,456
From HiSAVE VFD Energy Savings
Estimator 15,456
Energy use with VFD (kWh/year) 4,355
From HiSAVE VFD Energy Savings
Estimator 4,355
Savings (kWh/year) 11,101 11,101
Opinion of Cost Totals
VFD Installed cost (labor and materials) $3,465 RS Means 2007 Electrical Cost Data $3,465
Install cost per differential pressure sensor $0 RS Means 2008 Mechanical Cost Data $0
Tap for sensor $0 RS Means 2008 Mechanical Cost Data $0
Additional piping for sensor $0 RS Means 2008 Mechanical Cost Data $0
Engineering design $1,000 $1,000
Number of 3-way valves to replace 0 tbd
3-way valve conversion cost per valve (parts and labor) $0 tbd
Valve converstion total $0
Programming cost $300.00 Assumption: $300 per loop
Total $4,465
Add VFDs to CW Pumps and HW Pumps
CW Pumps
Valve leakage calculation: Chilled Water Billed Use per Month MMBTU
FY 03 FY 04 FY 05 FY 06 FY 07 FY 08 FY 09 FY 10 FY 11 4-yr avg FY 12 savings
June 1,295 713 905 1,069 902 1,201 1,070 1,197 1,057 964
July 1,858 1,790 1,094 1,233 1,386 1,140 1,186 1,189 1,202 1,373
August 1,669 1,324 956 1,148 1,229 1,318 1,316 1,118 1,230 1,126
September 1,422 940 1,022 938 705 1,025 860 991 879 780
October 494 546 519 569 503 609 661 465 654 504
November 453 287 349 387 332 353 410 441 436 370
December 272 710 324 335 330 329 342 405 375 363 223 140
January 180 166 187 324 285 426 267 334 370 349 105 244
February 223 165 167 225 244 359 282 367 195 301 75 226
March 384 292 249 283 456 431 406 246 273 499
April 912 420 547 563 427 529 448 648 321 -
May 713 735 596 661 792 668 1,034 770 640 -
FY Total 9,875 8,088 6,915 7,735 7,591 8,388 8,282 8,171 7,632 6,019 610
CDD 1253 995 771 1365 1154 1165 931 752 1025
Rate 11.6206$ 12.3760$ 14.1403$ 15.6673$ 18.3073$ 20.2583$ 20.3555$ 22.0007$ 24.3518$ 14849
Annual Cost 114,753$ 100,097$ 97,780$ 121,187$ 138,971$ 169,927$ 168,584$ 179,768$ 132,912$
Annual Eff iciency 838 635 73 70 485 1,066 1,180 (293)
Final Retro-commissioning Report Appendices
- 2012
6-8
FIM #5: Modified Fan Powered VAV Sequences
Additional data used for this calculation is in the excel spreadsheet.
Savings for Alternate Sequence of Occupancy Sensor Controlled Fan-Powered VAV boxesNotes
Number of Spaces suitable for Occupancy Sensors 195 Total FPVAV boxes with Occ Sensor from BAS
Average FPVAV Motor (HP) 0.267 Weighted average based on boxes installed
Fan Speed Setting Average (Hi/Med/Low)0.75
Low=.5 Rated Power, Med=.75 Rated Power,
High = Full Power
Total FPVAV Motor HP 39
Average FPVAV Motor Efficiency 50%
Conversion Factor (kW/HP) 0.746
Current Fan Runtime (hr/day) 14 Average from BAS Trend
Days/Year 355 Building is shut down on holidays
Est. Current FPVAV Fan Consumption (kWh/year) 289,556
Percent of time during occupied mode that space is neutral & vacant 30% Per Query of BAS 4/19-4/25
FPVAV Fan Savings (kWh) 86,867
Design Supply Airflow to FPVAV Boxes (cfm) 200,000 Total based on schedules
Design Min Outside Airflow (cfm) 66,000 Total based on schedules and design temps
Total Design AHU Fan HP 420 AHUs 2-5, Supply+Returns
Annual Average Operating Speed 56% Per Trend Data from 5/6-5/9 when ON
Average AHU Fan Operating HP 72.5
Average Airflow to FPVAV Boxes (cfm) 112,695
Per Trend Data from 5/6-5/9 when ON and per
Query of BAS 4/19-4/25
Reduction of Airflow when FPVAV Boxes are scheduled occupied, in
neutral or heating mode, & vacant (cfm) 26,675 Per Query of BAS 4/19-4/25
Avg Airflow to FPVAV Boxes when Zones are occupied, neutral, &
vacant (cfm) 86,020
Reduction in VFD Efficiency, Motor Efficiency, and Fan Mechanical
Efficiencies from average operating speed. 80%
Average AHU Fan Operating HP with Zones occupied, neutral, & vacant
(HP) 41.8
Conversion Factor (kW/HP) 0.746
Hours/Day 14
Days/Year 365
Est. Current AHU Fan Consumption (kWh/year) 276,458
AHU Fan Savings (kWh) 117,227
Final Retro-commissioning Report Appendices
- 2012
6-9
Hours OA>70°F and High Occupancy 748 High Occupancy defined as weekdays 7am-5pm
Hours OA>70°F and Low Occupancy 681
Low Occupancy defined as weekdays 5pm-11pm
and weekends 7am-11pm
High Occupancy Airflow Reduction (cfm) 14,000 Per Query of BAS 4/19-4/25
Low Occupancy Airflow Reduction (cfm) 50,000 Per Query of BAS 4/19-4/25
Economizer savings, 55°F<OAT<70°F (MMBtu) 450
Return Air Temperature when OA>70°F (°F) 75 Per Query of BAS
Discharge Air Temperature (°F) 55
Specific Heat & Conversion Factor (Btu-min/ft 3̂-hr-°F) 1.08
Chilled Water Energy Savings (MMBtu) 1,412.07
Average electric consumption per ton (kWh/ton-hr) 0.90 From Seamens RCx Report
Electricity Savings for Chilled Water due to reduction in airflow
(kWh/yr) 105,906
Total Occupied Hours when fans are on 5,840
Hours when OA>55°F 3,947
Percent of Fan Savings resulting in additional cooling savings 68%
Chilled Water Savings due to FPVAV boxes turned off when vacant
(MMBTU) 200
Chilled Water Savings due to AHU Fan cfm reduction when vacant
(MMBTU) 270
Electricity Savings for Chilled Water due to reduced fan energy
(kWh/yr) 35,298
Airflow reduction for space in heating mode due to overcooling of air at
Low Occupancy (cfm) 40,000
Per Query of BAS 4/19-4/25
Defined as any zone in lower half of
heating/cooling setpoints is either just in heating
or will be heating.
Airflow reduction for space in heating mode due to overcooling of air at
High Occupancy (cfm) 6,000
Defined as any zone in lower half of
heating/cooling setpoints is either just in heating
or will be heating.
Hours at Low Occupancy 3,230
Hours at High Occupancy 2,610
Temperature difference between discharge air and neutral air (°F) 15
Steam reheat savings at Low Occupancy (MMBtu) 2,093
Steam reheat savings at High Occupancy (MMBtu) 254
Total steam savings due to eliminate reheat for spaces that are
vacant (MMBtu) 2,347
Opinion of Cost Notes
Occupancy Sensors Tie-In Programming Cost $19,500.00 Assumed $100 per VAV
Total $19,500
Incentive Calculation Notes
Total Electric Savings (kWh/year) 345,297
Electric Rate $0.08000
Potential Annual Electrical Cost Savings $27,624
Electric Savings Eligible for Incentive (kWh/year) 345,297
Electric Rate $0.04270
Eligible Annual Electrical Cost Savings $14,744
Steam Savings (MMBtu) 2,347
Steam Rate $15.01
Potential Annual Steam Cost Savings $35,228
Opinion of Project Cost $19,500
Project Cost eligible for incentive $5,753
Efficiency Partners Incentive $0
Prescriptive Incentive NA
Project Cost after EP Incentive $19,500
Project Cost after Prescriptive Incentive NA $20 per OS, but must control >400 watts
Simple Payback before incentive (years) 1.3
Simple Payback with EP incentive (years) 1.3
Simple Payback with Prescriptive Incentive (years) NA
Final Retro-commissioning Report Appendices
- 2012
6-10
FIM #6: Snow Melt Control Modification
Steam Savings from Alternate Snow Melt Control
Summary
Currently the snow melt system runs when the outside air is less than 40°F.
SEG proposes that the energy control center take control of the snow melt control, with input from the facilities staff.
It is proposed that the snow melt be turned on when the forecast predicts at least 1" of snow accumulation.
This calculation evaluated only the west side auditorium snow melt, there is another small snow melt system at the garage entrance that was not evaluated as part of this calculation
Calculation methodology
Steam consumption at increased dramatically in the winter months beginning in the winter of 2009.
This increase coincides with the start-up of a snow melt system used at the building entrances and steps at the West side auditorium entrance.
The difference in steam use before and after the implementation of the snow melt system normalized for weather is used to determine savings.
Steam Savings Calculation
hdd MMBtu hdd MMBtu hdd MMBtu hdd MMBtu hdd MMBtu hdd MMBtu
November 671 537 749 918 1088 633
December 771 773 1,650 1,764 2019 1,362
January 878 951 1,705 2,057 2358 1,606
February 964 887 995 1,576 1665 1,221
Total HDD 4373 3,284 4831 3,148 4779 5,099 4651 6,315 4693 7130 3806 4822
MMBtu/hdd 0.75 0.65 1.07 1.36 1.52 1.27
2007-2010 avg hdd 4496
normalized steam use 3,377 2,930 4,797 6,105 6,831 5,697
average steam use before snow melt (MMBtu) 3,701
avg. steam use after snow melt (MMBtu) 6,211
avg. yearly steam consumption from
snow melt system (MMBtu) 1,757
Steam Cost ($/MMBtu) $15
avg. yearly steam cost from snow melt
system ($/yr) $26,422
June 2011-May
2012
FY 11 FY 12
Before snow melt After snow melt
June 2006-May 2007
June 2007-May
2008
June 2008-May
2009
June 2009-May
2010
June 2010-May
2011
FY 07 FY 08 FY 09 FY 10
Final Retro-commissioning Report Appendices
- 2012
6-11
Now need determine the reduction in runtime due to manual control and subtract this cost from the current control method cost.
Assume that snow melt must be started 48 hours before snow event and be run for 12 hours afterwards.
Assume staff can shovel when accumulation is less than 1"
Assume that each snow event is at least 48 hours from precedding snow event
from http://www.ncdc.noaa.gov/ussc/USSCAppController#PERIOD
Historical # of Days with snow greater than:
Trace >.1" >1"
November 1.9 1.3 0.7
December 3.2 3.9 2.3
January 3.7 4.6 2.6
February 3.1 3.5 2.2
Total Days with snow 11.9 13.3 7.8
Actual snow melt run time 23.4 days
# of days in Nov-Feb 121
# of days that outside temp was <40°F 105 days
Amount of time snow melt runs with
new control/
amount of time snow melt ran with old
control 22%
Steam Consumption (MMBtu) 392
Steam Savings (MMBtu) 1,365
Snow Melt Cost (new control) $5,888
Snow Melt savings relative to old control $20,533
Final Retro-commissioning Report Appendices
- 2012
6-12
FIM #7: Domestic Hot Water Recirculation Pump Control
EXISTING Example
Feet of Pipe 200 1,200 estimated based on building size and hw fixture location
Diameter of Pipe, inches 1.5 0.75
Heat loss rate 25.2 8.0
Motor Hp 0.250 0.264 197 W pump
Motor Eff 66.0% 66.0%
Motor Load Factor 0.65 0.65
Pump Operating hrs/yr 8,760 8,706
% yr loses from pipes
help to heat the facility:25% 25%
Water heater Eff iciency 65.0% 80.0%
Conversion Factor 100,000 100,000
Conversion Factor 0.746 0.746
Avg heat loss th/yr 509 784
Average therm Rate $0.950 $1.504 This is equivalent to $15.04/MMBtu
kW 0.18 0.19
kWh/yr 1,577 1,654
Average kWh Rate $0.080 $0.043
Annual Energy Cost $610 $1,250
PROPOSED
Proposed hrs/yr 3,500 6,570 Assumme pump can be turned off 6 hours/day, 365 days/yr
Avg heat loss th/yr 203 592
kW 0.18 0.19
kWh/yr 630 1,248
Annual Energy Cost $243 $944
SAVINGSth/yr 306 192
kW 0.00 0.00
kWh/yr 947 406
Annual Cost Savings $366 $306
Project cost Estimate $375 $1,000
Incentive $0 $0
Simple Payback 1.0 3.3
Red triangles in the upper right corner means there is a comment explaining the cell.
These spreadsheets are meant as a rough est imate of energy use and savings potent ial. FOE nor its contractors can guarantee the results calculated by this tool.
For a reasonableness check, contact a Preferred Ally or your FOE Energy Advisor.
Circulation Pump Timer
Yellow cells indicate that information from your facility is required for calculations.
Service water heating systems often have pumps that circulate hot water through a facility to make sure hot water is quickly available at taps. Often these pumps run 24 hours a day 7days a week regardless of the operational status of the facility. Pumping hot water through the facility can lead to significant heat loss. By
installing a low cost timer, the pump can be turned off during facility unoccupied hours.
Final Retro-commissioning Report Appendices
- 2012
6-13
FIM #16: Replace Classroom Incandescent Lights with LED’s
EXISTING Example Classroom
lighting
Lighting Type Incand Incand
Location Office Classroom
Number of Fixtures 6 86
Lamps per Fixture 2 1
Fixture Wattage 120 150
LF - Load Factor 0.95 0.95
Annual Operating Hours 1,350 1,000 light are on occ sensor so usage is not high
Conversion Factor 1,000 1,000
kW 0.68 12.26
kWh/Yr Use 918 12,260
Average kWh Rate $0.088 $0.043
Annual Energy Cost $81 $524
PROPOSEDLighting Type CFL LED
Number of Fixtures 6 86
Lamps per Fixture 2 1
Fixture Wattage 30 30
Conversion Factor 1,000 1,000
kW 0.17 2.45
kWh/Yr Use 230 2,450
Annual Energy Cost $20 $105
SAVINGSkW 0.51 9.81
kWh/Yr Use 688 9,810
Annual Energy Cost $61 $419
Project cost Estimate $48 $7,500
Incentive $0
Simple Payback 0.8 17.9
Red triangles in the upper right corner means there is a comment explaining the cell.
These spreadsheets are meant as a rough est imate of energy use and savings potent ial. FOE nor its contractors can guarantee the results calculated by this tool.
For a reasonableness check, contact a Preferred Ally or your FOE Energy Advisor.
Yellow cells indicate that information from your facility is required for calculations.
Replace Classroom Incandescent with LED's
Appendices