Exhibit U - SCSU Chilled Water Study Report - St. Cloud State ...

St. Cloud State University 

Chilled Water Study Report 

ST. CLOUD, MINNESOTA 

NOVEMBER 11, 2011 

FOR THE LIFE OF YOUR BUILDING

Contents 

SECTION 1. EXECUTIVE SUMMARY 

CAMPUS CHILLED WATER MAP 

SECTION 2. CHILLED WATER SYSTEM SUMMARY 

SECTION 3. CHILLED WATER PLANT 

SECTION 4. DISTRIBUTION LOOP 

SECTION 5. 51 BUILDING 

SECTION 6. ADMINISTRATIVE SERVICES BUILDING 

SECTION 7. ATWOOD MEMORIAL CENTER 

SECTION 8. BROWN HALL 

SECTION 9. CENTENNIAL HALL 

SECTION 10. EDUCATION BUILDING 

SECTION 11. ENGINEERING & COMPUTER CENTER 

SECTION 12. GARVEY COMMONS 

SECTION 13. KIEHLE VISUAL ARTS CENTER 

SECTION 14. LAWRENCE HALL 

SECTION 15. MILLER LEARNING RESOURCES CENTER 

SECTION 16. PERFORMING ARTS CENTER 

SECTION 17. RIVERVIEW 

SECTION 18. STEWART HALL 

SECTION 19. STUDENT RECREATION CENTER 

SECTION 20. WICK SCIENCE BUILDING 

SECTION 21. WICK ADDITION 

ST. CLOUD STATE UNIVERSITY CHILLED WATER STUDY 

TABLE OF CONTENTS

1. Executive Summary

1. Executive Summary 

Background 

McKinstry was asked to perform an independent assessment of the chilled water system on the St. Cloud 

State University campus. The purpose of this study was to determine if the planned expansion of the chilled 

water generating plant was necessary to accommodate the added load from the new ISELF building (now in 

the development phase of its construction). Funding for the chilled water plant expansion design had been 

secured, but data related to the current capacity of the plant and its relation to the existing campus load was 

incomplete. McKinstry’s assignment was to assess the existing load and determine when the University would 

truly require additional capacity. 

McKinstry’s approach was to address three separate yet interconnected systems: individual building loads, the 

chilled water distribution system, and the chilled water plant itself. It appears that the existing chilled water 

system is capable of satisfying the added load requirements of ISELF without adding capacity, but it lacks 

sufficient capacity to add loads associated with the planned upgrades to Shoemaker Hall, Eastman Hall, and 

Halenbeck Hall. The timing of the upgrades to ISELF and Shoemaker, both expected to come online in 2013, 

dictates that capacity expansion will be needed before the 2013 cooling season. If completion of either 

planned upgrade is delayed until fall of 2013, added capacity will not be required until the 2014 cooling 

season. 

Initial Observations 

The design of the chilled water plant, the manner in which its control program was written, how chilled water 

is distributed, and how it is used in the individual buildings all contribute to a system that is fighting itself in 

several ways and in several places. The fact that the campus is being cooled, and in some cases cooled well, is 

a tribute to the skills of the staff assigned to operate it. In many cases, however, excessive energy input is 

being used to offset system inadequacies. 

McKinstry’s evaluation of the distribution system indicates that adding a third chiller, regardless of size, will 

not satisfy the load addition of ISELF; the system is currently operating at the limit of its distribution 

capability. Modifications to the distribution loop will be necessary to add load, both now and in the future. 

These modifications need to include re-distribution of chilled water to reduce flow rates in some areas and 

increase it in others. 

Modifications may also include replacement or reconfiguration of the existing distribution pumps. The existing 

pumps do not appear to satisfy the current and future cooling flow requirement when operating in parallel. 

The intended design flows of the system appear to have been for these pumps to operate in parallel. 

Modification of the individual building systems—those with tertiary pumps operating and those without—will be 

necessary. Recirculation lines within the individual buildings and the use of three-way valves are negatively 

affecting the system’s performance. 

Control system improvement will also be needed to accommodate these modifications. The use of return water 

control valves and end-of-main bypasses causes unnecessary pump energy use and creates problems with 

overall distribution system performance. 

Correction of these deficiencies may sufficiently improve the performance of the system so as to satisfy the 

addition of ISELF without adding another chiller. An additional chiller will be necessary to add other loads such 

as Halenbeck Hall and any of the residence halls. Other options, such as thermal energy storage and 

distributed heat recovery chillers, appear to be viable alternatives to adding another chiller as well. 

1


Conclusion 

McKinstry’s team recommends upgrading and expanding the capacity of the existing chilled water plant. The 

added load of ISELF will be closely followed by added loads for Shoemaker, Halenbeck, and Eastman Halls. 

Because improvements to the distribution loop will be part of that upgrade, we recommend increasing chilled 

water plant capacity now. First-cost economics tend to favor adding a third chiller to the existing chilled water 

plant. Total Cost of Ownership (TCO) may demonstrate a different, more lucrative, solution. 

Engineering design needs to begin soon to add a third chiller to the existing plant and properly plan for the 

upcoming load increases. Evaluation of alternative cooling solutions should be done simultaneously and to a 

sufficient degree to determine merit. 

A plan must be developed to correct distribution loop and building deficiencies. Prompt attention to these 

issues will allow timely verification of existing equipment performance and help define further actions that 

may be necessary. 

Recommendations 

CAMPUS-WIDE 

• Install chilled water BTU meters in each building where the chilled water enters the building. 

• Properly tune individual air handling unit (AHU) control valves. 

• Balance water flow to all AHUs. 

• Fill and vent the chilled water system. 

• Rebalance the entire chilled water system. 

• Document new performance data. 

CHILLED WATER PLANT 

• Determine if two distribution pumps operating in parallel on a common differential pressure 

transmitter (DPT) signal will deliver the desired flow to manage two chiller operations. 

BUILDING 51 

• Open south-end chilled water valves and reverse flow through building. 

• Replace the three-way cooling valve on the rooftop unit (RTU) with a two-way valve or install a shutoff 

valve in the return leg of the three-way to make it perform as a two-way. 

• Add variable frequency drive (VFD) control to the tertiary pumps along with a properly located DPT to 

control it. 

• Balance water flow to tertiary pumps. 

ADMINISTRATIVE SERVICES BUILDING 

• Command the return water temperature control valve open and remove its control parameters. 

ATWOOD MEMORIAL CENTER 

• Replace the six-inch distribution supply and return pipe from the mains into the mechanical room with 

new eight-inch pipe up to and through the tertiary pumps. 

• Increase the pipe size on the downstream side of the tertiary pumps to eight inches up to the first 

piping take off. 

• Command open the return water temperature control valve and remove its control parameters. 

• Reset control parameters for pump VFDs and verify performance. 

2


BROWN HALL 

• Cross-connect chilled water piping in mechanical rooms and eliminate small tertiary pump. 

• Replace the three-way valve on AHU-1 with a new two-way valve, or insert a shutoff valve in the 

return leg of the valve. 

• A VFD, integrated to the direct digital control (DDC) system, should be applied to the tertiary pump 

along with a properly located, installed, and calibrated DPT to manage the flow of chilled water to the 

AHUs. 

CENTENNIAL HALL 


• Command closed the RTU-4 bypass valve, or manually close it and disconnect the actuator. 

EDUCATION BUILDING 

• Evaluate the control parameters for the AHUs. Determine why there is no apparent night or weekend 

setback in system control. 


ENGINEERING & COMPUTER CENTER 

• A balancing contractor should be instructed to measure the system supply pressure and determine if it 

is adequate to overcome the pressure drop to RTU-6, the most remote air handling unit. 

• If it is determined that system pressure is adequate, the pump should be removed and connection to 

the distribution piping should be restored. A total building balancing, along with proper 

documentation, will need to be completed. 

• If it is determined that system pressure is inadequate to overcome the pressure drop, the pump piping 

should be modified to remove the control valve and bypass. A VFD should be applied to the pump 

along with a properly located, installed, and calibrated DPT to manage the flow of chilled water to the 

AHUs. Total building re-balancing will be required. 

• All six AHUs are equipped with two-way electronically actuated DDC control valves that appear to be 

functioning properly. It is anticipated that the retro-commissioning study being conducted will address 

calibration of these valves in routine. 

KIEHLE VISUAL ARTS CENTER 

• Command closed the AHU-3 bypass valve, or manually close it and disconnect the actuator. 

LAWRENCE HALL 

• Take override control of fan coil unit (FCU) chilled water control valves with the DDC system. 

MILLER LEARNING RESOURCES CENTER 

• Command the return water temperature control valve open and remove its control parameters. 

PERFORMING ARTS CENTER 

• The Comprehensive Planning Report recommends upgrading the building in 11 to 25 years. The AHUs 

are unlikely to provide satisfactory service for that length of time given their age and condition. We 

normally would recommend upgrading controls to DDC and installing new two-way control valves on 

existing AHUs. In this case, we recommend new AHUs with VAV boxes and new controls throughout. 

3


RIVERVIEW 

• Identify the source of heat in AHUs during off-periods and correct. 

• Evaluate the AHU schedule and modify it to more uniformly parallel occupancy schedules. 

STEWART HALL 

• Replace the three-way valves with two-way valves. 

• Add VFD control to tertiary pumps. 


• Close or blank off supply to return cross-connect. 

STUDENT RECREATION CENTER 

• Investigate and resolve issues with scheduling and system performance. 

WICK ADDITION 

• Investigate and resolve questions with scheduling and system performance. 

• Review and reconfigure tertiary pump operation after distribution loop modifications are made. 

WICK SCIENCE BUILDING 

• Evaluate impact of distribution system modifications on Wick chilled water supply. 

4

St. Cloud State University Chilled Water System 

KVAC 

KIEHLE VISUAL ARTS CENTER 

LH 

LAWRENCE HALL 

SH 

STEWART HALL 

51B 

51 BUILDING 

(BUSINESS BUILDING) 

R 

RIVERVIEW 

BH 

BROWN HALL 

AUXILIARY CHILLER 

92 GPM 

DIRECT BURY PIPE 

776 GPM 


S-1 

EST.* 100 GPM 

S-2 

111 GPM 

5-INCH STEEL 

FROM TUNNEL 

S-3 

300 GPM* 

89 GPM 

FCU 

92 THUS 

155 GPM 

AHU 2 

AHU 1 

36 

57 

GPM 

GPM 

FLOW 

METER 

6-INCH STEEL 

FROM TUNNEL 

248 GPM 

8-INCH STEEL 

879 GPM 

S-3 

128 

GPM 

S-2 

92 

GPM 

S-1 

92 

GPM 

S-8 

131 

GPM 

S-4 

205 

GPM 

S-5 

231 

GPM 

TO BUSINESS BLDG (51) 

8-INCH STEEL 

FROM STEWART 

68 GPM 

RTUI 

68 

GPM 

8-INCH 

DIRECT 

BURY 

VALVED 

OFF 

CURRENTLY 

SF 1 

76 GPM 

SF 2 

76 GPM 

4-INCH 

DIRECT BURY 

152 GPM 

AHU 4 

92 

GPM 

AHU 1 

750 

GPM 

AHU 2 

26 

GPM 

TUNNEL 

TO LAWRENCE 

& KIEHLE 

51B 

GC 

GARVEY COMMONS 

AHU 1 

AHU 2 

AHU 3 

42 

136 GPM 

120 GPM 

125 GPM 

GPM 

SHERBURNE HALL 

TAKE OFF 

MITCHELL 

HALL 

KIEHLE 

VISUAL ARTS CENTER 

KVAC 

4” CHWS&R 

5” CHWR 

5” CHWS 

LAWRENCE 

HALL 

LH 

6” CHWR 

6” CHWS 

6” CHWR 

6” CHWS 

SH 

6” CHWS 

6” CHWS&R 

STEWART 

HALL 

6” CHWR 

BUILDING 51 

8” CHWS 

8” CHWR 

R 

RIVERVIEW 

4” CHWS 

4” CHWR 

EASTMAN 

HALL 

8” CHWR 

8” CHWS 

WSB 

WICK SCIENCE BUILDING 

AHU 1 

150 

GPM 

AHU 2 

160 

GPM 

AHU 3 

170 

GPM 

AHU 4 

150 

GPM 

AHU 5 

170 

GPM 

AHU 6 

150 

GPM 

AHU 7 

175 

GPM 

AHU 8 

140 

GPM 

TO WICK 

ADDITION 

AMC 

6-INCH 

FROM 

TUNNEL 

6-iNCH STEEL FROM TUNNEL 

ATWOOD MEMORIAL CENTER 

AHU 

AHU 5 

13 

31 

AHU 

GPM 

21 

AHU 3 

101 

AHU 

AHU 

AHU 2 

GPM 

11 

22 

177 

GPM 

AHU 

AHU 

AHU 

AHU 1 

12 

24 

23 

182 

GPM 

AHU 4 

140 

GPM 

NORTH 

BENTON 

HALL 

HOLES 

HALL 

CAROL 

HALL 

BENTON HALL 

STEARNS 

HALL 

SHERBURNE 

HALL 

CASE 

HALL 

3” CHWS 

3” CHWR 

GARVEY 

COMMONS 

HILL 

HALL 

6” CHWS&R 

GC 

6” CHWS 

6” CHWR 

AMC 

6” CHWS&R 

ATWOOD 

MEMORIAL CENTER 

PERFORMING 

ARTS 

CENTER 

6” CHWS 

6” CHWR 

PA 

8” CHWS 

8” CHWR 

6” CHWS&R 

CENTENNIAL 

HALL 

CH 

12” CHWR 

12” CHWS 

BH 

BROWN HALL 

4” CHWS&R 

HH 

HEADLEY 

HALL 

12” CHWS 

12” CHWR 

12” CHWR 

8” CHWS 

8” CHWR 

ROBERT H. WICK 

SCIENCE BUILDING 

12” CHWS 

WICK ADDITION 

ISELF 

8” CHWS&R 

8” CHWS&R 

WA 

WSB 

6” CHWS&R 

6” CHWS&R 

ECC 

12” CHWS 

12” CHWS 

12” CHWR 

12” CHWR 

GREENHOUSE 

18” CHWS&R 

ENGINEERING 

AND COMPUTER 

CENTER 

20” CHWS 

20” CHWR 

SHOEMAKER HALL 

MAINT. 

BUILDING 

20” CHWS 

20” CHWR 

HEATING 

PLANT 

20” CHWR 

20” CHWS 

CHILLED 

WATER 

PLANT 

8” CHWS 

CWP 

8” CHWR 

8” CHWS&R 

HUSKY STADIUM 

WA 

8-INCH DIRECT BURY 

702 GPM 

AHU 1 

702 

GPM 

8-INCH DIRECT BURY PIPE 

1,265 GPM 

WICK ADDITION 

AHU 1 

702 

GPM 

ADMINISTRATIVE 

SERVICES 

BUILDING 

6” CHWS 

6” CHWR 

6” CHWS 

6” CHWR 

SRC 

STUDENT 

RECREATION 

CENTER 

AS 

EB 

CH 

CENTENNIAL HALL 

EDUCATION 

BUILDING 

HALENBECK HALL 

CWP 

CHILLED WATER PLANT 

6-INCH 

TO PAC DIRECT BURY 

491 GPM 

STATE- 

VIEW 

NORTH 

STATE- 

VIEW 

SOUTH 

MC 

12” CHWS 

CWR TEMP CONTROL VALVE 

12” CHWR 

CENTENNIAL 

1,413 GPM 

922 GPM 

RTU 4 


313 

GPM 

AHU 1 

148 GPM 

FMS 

RTU 3 

313 

GPM 

JAMES 

W. MILLER 

LEARNING 

RESOURCES 

CENTER 

AHU 2 

148 GPM 

PA 

PERFORMING ARTS CENTER (PAC) 

6-INCH 

491 GPM 

DIRECT BURY 

MC 

MILLER 

LEARNING RESOURCES CENTER 

AS 

ADMINISTRATIVE SERVICES 

HH 

HEADLEY HALL 

EB 

EDUCATION BUILDING 

ECC 

ENGINEERING AND 

COMPUTER CENTER 

SRC 

STUDENT RECREATION CENTER 

F 5 F 15 

F 7 

F 12 

F 3 

24 

GPM 

9 

GPM 

47 

GPM 

40 GPM 

DUAL TEMP Hx 

43 

GPM 

25 

GPM 

PAC 

F 14 123 

F 17 31 

F 10 

59 

GMP 

GMP 

GMP 

FROM 

CENTENNIAL 

F 1 

90 

GPM 

AHU 1 

226 

GPM 

AHU 2 

291 

GPM 

853 GPM 

12-INCH 


AHU 3 

AHU 9 

AHU 6 

88 

62 

22 

GPM 

GPM 

GPM 

AHU 5 

115 

GPM 

AHU 4 

49 

GPM 

2 COILS 

153.5 ea 

307 GPM 

SF 1 

SF 2 

2 COILS 

95.5 ea 

191 GPM 

CW RETURN 

TEMP CTRL VALVE 

FROM 

HEADLEY 

6-INCH 

DIRECT BURY 

498 GPM 

RTU 

1 

4-INCH 

FROM 

TUNNEL 

RTU 

2 

AHU 2 

AHU 3 

AHU 

1 

6-INCH 

DIRECT BURY 

CW RETURN 

TEMP CTRL 

304 GPM 

6-INCH 

DIRECT BURY 

AHU 2 

52 

GPM 

AHU 3 

38 

GPM 

AHU 1 

52 

GPM 

RTU 5 

89 

GPM 

AHU 4 

31 

GPM 

RTU 6 

42 

GPM 

AHU 1 

413 

GPM 

FUTURE 


516 GPM 

AHU 2 

103 

GPM 

November 2011 | Prepared by McKinstry | 8451 Xerxes Avenue N., Brooklyn Park, MN 55444 | 763.767.0304 | mckinstry.com

2. Chilled Water System

2. Chilled Water System 

System Observations 

This study addresses three separate yet interconnected systems: individual building loads, the chilled water 

distribution loop, and the chilled water plant itself. While there is independent activity and function in each of 

the three systems, they do—and must—interact continuously with each other. This section identifies how that 

interaction occurs and how system controls must interact continuously to provide the desired performance. 

When properly designed and installed, the chilled water system should efficiently and effectively provide the 

desired cooling to all connected buildings. 

Many parts of the chilled water system are properly designed and installed, and the system works well despite 

certain problems. In some cases, these problems result from additions or alterations made to parts of the 

system without adequately addressing their impact on overall system operation. Examples of this include the 

inadequacy of delivery pipe size in Atwood Memorial Center, the temperature disparity that occurs in the 

chilled water supply to buildings, and the inability to maintain the supply temperature setpoint on design days. 

Each of these problems needs to be corrected before adding capacity to the chilled water plant. McKinstry’s 

team is concerned that the chilled water system may be incapable of handling added load. McKinstry and the 

University must determine what to do if the system cannot handle added load and identify the best approach 

to adding capacity. 

McKinstry documented the capacity of the chilled water plant and identified two key issues: the outlet water 

temperature setpoint and flow control between the chiller production loops and the system distribution loop. 

We have quantified the building loads and identified their peak load as connected to the current distribution 

loop. Within the confines of building and campus diversity, both systems are somewhat matched. 

Deviation occurs in connecting the chilled water plant output to the individual building input requirements. 

System distribution pumps do not adequately deliver to buildings the proper 

water volume at the proper temperature. The distribution system’s pumps 

inadequacies are augmented by the deficient control within the buildings’ 

tertiary pumps and control valves. 

Graph 1 below demonstrates the desired differential in PSI, between the 

system supply water pressure and system return water pressure. The intent of 

this control point is to adjust the system distribution pump speed to maintain 

this value at the differential pressure sensor/transmitter located in the system 

distribution loop out on the campus. 

GRAPH 1 

PSI 

6 

4 

2 

0 

Delta P Setpoint 

5


Graphs 2, 3, and 4 below demonstrate the month, week, and day values of what the actual system differential 

pressure is over time. With a setpoint of 5.5 PSI, the system hunts from nearly 15 PSI to negative 2 PSI. The 

system is often below setpoint and frequently in the negative range. The month and week data demonstrate 

the impact of three-way valves and starting and stopping tertiary pumps. 

GRAPH 2 

PSI 

16 

14 

12 

10 

8 

6 

4 

2 

0 

-2 

Chilled Water Plant 

August 5–September 5, 2011 

CHW Differential Pressure 

7/31/2011 

8/5/2011 

8/10/2011 

8/15/2011 

8/20/2011 

8/25/2011 

8/30/2011 

9/4/2011 

9/9/2011 

6


GRAPH 3 

PSI 

16 

14 

12 

10 

8 

6 

4 

2 

0 

-2 

Chilled Water Plant 

August 28–September 3, 2011 


8/27/2011 

8/28/2011 

8/29/2011 

8/30/2011 

8/31/2011 

9/1/2011 

9/2/2011 

9/3/2011 

9/4/2011 

9/5/2011 

Graph 4 demonstrates the system performance for a 24-hour period. The differential pressure appears to 

come under control during the lighter night load, but it bottoms out and remains in the negative range for 

virtually the entire day load. 

7


GRAPH 4 

PSI 

16 

14 

12 

10 

8 

6 

4 

2 

0 

-2 

Chiller Plant 

September 1, 2011 


7:12 PM 

12:00 AM 

4:48 AM 

9:36 AM 

2:24 PM 

7:12 PM 

12:00 AM 

The speed at which the control valves—and in some cases the tertiary pumps—respond to control signals 

within each building is much faster than the response of the VFDs on the system distribution pumps; the 

result is wild swings in pressure between supply and return. 

The frequency of data points in the negative range is proportional to the time tertiary pumps over-pressure 

the return system. The flow controls (changes in flow modulation) on the tertiary pumps, whether it is VFDs 

controlling the actual pump speed or two-way valves controlling the output, are too fast for a corresponding 

adjustment by the differential pressure sensor and the system pump to respond to properly. The system 

cannot stabilize and wild swings result. 

Three-way valves themselves will cause the differential pressure sensor to see a continuous low reading and 

transmit a signal to continuously increase VFD speed. Pump speed can increase to its limit and line voltage, 

yet never achieve the desired setpoint. As long as a control valve only diverts water around a load, as 

opposed to restricting flow, differential pressure cannot be achieved. 

Control valves that actually reduce flow through a system instead of diverting it around a load would cause 

the pressure change necessary to control the system distribution pumps. A two-way control valve does this. 

As load decreases, two-way control valves close. As they close back, pressure is created that will be greater 

on the supply pipe than on the return pipe. This pressure difference is transmitted to the distribution pump 

VFD which—as actual pressure exceeds setpoint—causes the VFD signal to reduce, thereby slowing the pump. 

As the distribution system pump slows, less water flows. When the load increases and more cooling is 

required, the control valve begins to open, the system pressure differential begins to drop, and the pump 

begins speeding up. 

When the distribution pump is at constant speed and near-constant flow rate, the chilled water plant needs to 

supply the proper quantity of chilled water to the pump inlet. If the chilled water plant pump and the system 

distribution pump were the same size, operated at the same speed, and had the same head requirement, the 

system would have proper flow balance. Load change would only impact the chiller itself and the function 

would be that of a constant volume system. 

8


In this system, the distribution loop pumps are 33% larger than the chilled water plant pumps and flow 

correspondingly more water, 3,600 gallons per minute (GPM), at maximum speed (design flow). The campus 

distribution system was designed as a variable flow system. 

During low load periods, one chiller can support the cooling requirements of the campus. With one chiller 

operating, the primary chilled water flow would be 2,400 GPM, the constant flow requirement of the chiller. 

This low load period ought to translate into a lower flow requirement for the cooling system as well. The 

distribution pump ought to slow down to match or nearly match the flow through the chiller. 

With the distribution pump receiving a signal to run at maximum speed, it will always flow more water than 

does the chiller. To support the required flow in the system distribution pump, the water will return from the 

system at the same rate it is supplied and, as it cannot go through the chiller, must go back into the 

distribution loop. This warm return water blends with the cold chiller water via the decoupler loop and the 

distribution pumps will then supply warmer-than-desired chilled water. When the buildings receive warm 

water via the distribution system, the AHUs cannot achieve discharge air setpoints and spaces served by these 

AHUs will get too warm. The response to this circumstance has been to reduce the chilled water setpoint on 

the chiller. Colder water blended with warmer water may result in chilled water being supplied to the AHUs at 

the proper temperature. 

A second chiller starts as the load increases and the parameters established for multiple chiller operations are 

met. The second chiller provides an additional 2,400 gallons to the distribution system, now exceeding the 

flow capacity of the system distribution pumps by 1,200 GPM. The distribution pumps no longer blend return 

and supply water, and the supply water temperature approaches setpoint. Water unused by the distribution 

pump blends with return water at the decoupler and returns to the inlet of the chillers at a reduced 

temperature. 

It would be appropriate to start the second distribution pump and parallel both pumps on a properly applied 

differential pressure signal, but the system requirements and the pumps’ capabilities do not appear to operate 

in this mode. 

9

3. Chilled Water Plant

3. Chilled Water Plant 

10


Chilled Water Plant Details 

The central chilled water plant consists of the following equipment: 

• Two Trane Model 1280 Centrifugal Chillers 

• One Bell & Gossett Primary Chilled Water Pump serving each chiller 

• One Bell & Gossett Condenser Water Pump servicing each chiller 

• Four BAC cooling towers, commonly linked, serving both chillers 

• Two Bell & Gossett Secondary Distribution Pumps 

• Interconnecting piping 

• Digital controls 

This chilled water plant was designed to produce 4,500 tons of cooling for distribution to the campus. The 

chilled water piping entering and leaving the chilled water plant is adequately sized for this capacity, as is the 

condenser piping. Physical space is available to add a chiller. Piping runouts were provided for this purpose. 

The structural capability of the roof to support additional cooling tower capacity is still under investigation. 

The existing chillers are capable of producing 2,560 tons (1,280 x 2) under design conditions. Selection data 

provided by Trane indicate that the chillers were designed to operate at 44°F leaving water temperature. 

Campus cooling issues have caused leaving water temperatures to be reset down to 40°F to satisfy space 

cooling needs. This temperature reset results in de-rating the chiller capacity. At 40°F outlet temperature, the 

chillers are only capable of producing 1,020 tons each, a 20% reduction in output capacity. 

The intent of the chilled water plant design was to operate the plant in a primary/secondary decoupled flow 

condition. The primary loop consists of two individual loops with one chiller and one chilled water pump on 

each. Flow through each chiller is assumed to be at a constant rate and must be proven to the chiller control 

panel before start-up is permitted. Flow rate through each chiller is the rated output of its associated chilled 

water pump, documented to be 2,400 GPM at 45 feet of water head pressure, the head required to overcome 

the pressure drop across the evaporator and interconnected piping. 

The secondary piping loop consists of two distribution pumps sized to deliver 3,600 GPM at 116 feet head 

pressure. The head pressure rating selected is intended to distribute the required volume of chilled water to 

the building loads throughout the campus. Both secondary pumps are equipped with VFDs that allow the 

pumps to be individually slowed down or sped up to supply the desired volume of chilled water. A DPT located 

in the secondary system controls the VFD output current and thereby the speed of the pumps. A decoupler 

acts as the bridge between the primary and secondary pumping loops. Its purpose is to allow water to flow in 

either direction between the primary and secondary loops, depending on flow requirements of the secondary 

loop and the number of chillers operating. 

During our investigation we noted that the shut-off valve in the decoupler was closed. We speculate that this 

valve was closed in response to the same concern that resulted in chiller outlet temperatures being reset 

lower: a need for additional cooling. The decoupler can allow warmer-than-desired supply water to be 

distributed to the loads in single chiller operation when distribution pumps are not being controlled properly. 

Closing this valve forces water flow though the chillers, whether they are operating or not. This would have 

only been partially successful in improving campus cooling system performance since we observed water 

flowing through the idle chiller and blending with the outlet water of the operating chiller, causing warm water 

to be distributed anyway. We opened the shut-off valve during the investigation to measure impact on the 

distribution system and individual buildings. McKinstry conducted additional tests to determine how flow could 

be balanced between chillers and distribution loops. 

By design, when one chiller is operating, the distribution pump VFD should reduce the speed of the 

distribution pump to match the flow of water through the chiller. This was not occurring during our initial 

tests. Indications are that the pressure differential never achieved setpoint and data from the transmitter 

often displayed a negative value. Until the setpoint is reached, the VFD will continue to increase pump speed, 

11


resulting in full speed operation at all times. It appears that control of the three-way valves and tertiary 

pumps allow the return loop to be over-pressured, which would account for the negative readings observed. 

We attempted to operate two distribution pumps simultaneously; this test was also not successful. Differential 

pressure control could not be applied to both pumps simultaneously. Pump control is individually written in the 

DDC program for each pump and cannot be combined without re-programming. Our desired outcome would 

have been to operate both pumps in parallel, responding jointly to the control signal from the differential 

pressure transmitter. 

We attempted to manually operate the distribution pumps in parallel. McKinstry’s team hypothesized that two 

pumps in parallel would need to run at approximately 60% of their rated speed to produce the same flow one 

pump produced at 100% speed. This condition was not achieved either. Both pumps were ramped up over 

85% of their range before the flow meter being observed achieved the flow rate one pump previously 

manifested. It appears the distribution pumps were selected to operate redundantly and never in parallel. 

Further analysis is necessary, but it appears the chilled water distribution system is limited to the output 

capacity of one distribution pump at this time. 

Chiller performance appears to be approaching the limit of their combined capability considering the reduced 

capacity noted above. The chart below demonstrates the load profile for three consecutive design days in July. 

It indicates that the plant operates with both chillers drawing at or near their capacity. Chiller 2 appears to lag 

slightly below Chiller 1, even when it is designated lead chiller. It could indicate increased fouling of either 

evaporator or condenser bundles. 

GRAPH 1 

120 

Chiller Performance 

July 18–July 22, 2011 

100 

80 

% RLA 

60 

40 

20 

Chiller 1 %RLA 


0 

7/18/11 0:00 

7/18/11 7:30 

7/18/11 15:00 

7/18/11 22:30 

7/19/11 6:00 

7/19/11 13:30 

7/19/11 21:00 

7/20/11 4:30 

7/20/11 12:00 

7/20/11 19:30 

7/21/11 3:00 

7/21/11 10:30 

7/21/11 18:00 

7/22/11 1:30 

7/22/11 9:00 

7/22/11 16:30 

12


A similar pattern manifests on a design day with fall classes in session. The graph below indicates Chiller 1 

being added at approximately 7:00 AM September 1st and remaining on until approximately 10:00 PM. For a 

four- to five-hour period between 2:30 and 8:00 PM the system was unable to achieve setpoint for chilled 

water output temperature. 

GRAPH 2 

CHW Temperature (°F) 

55 

53 

51 

49 

47 

45 

43 

41 

39 

37 

35 

7:12 PM 

12:00 AM 

Chillers — September 1, 2011 

Setpoint vs. Leaving Temperatures 

4:48 AM 

9:36 AM 

2:24 PM 

7:12 PM 

12:00 AM 

Setpoint 

Chiller 1 Leaving Temp 

Chiller 2 Leaving Temp 

The graph below indicates that during the period where chilled water setpoint was not being maintained, the 

running load amps (RLA) of both chillers was near 100%. Distribution pump speed was at 60Hz or 100% of its 

capability as well. 

GRAPH 3 

Chillers—September 1, 2011 

%RLA vs. Pump Speed 

120 

100 

80 

60 

40 

20 

0 



Pump Speed 

12:00 AM 

2:30 AM 

5:00 AM 

7:30 AM 

10:00 AM 

12:30 PM 

3:00 PM 

5:30 PM 

8:00 PM 

10:30 PM 

13

4. Distribution Loop

4. Distribution Loop 

Distribution Loop Details 

The chilled water distribution system begins with two VFD-equipped secondary pumps located in the chilled 

water plant. Each of these pumps is sized to deliver approximately 3,500 GPM to the campus. These pumps 

are designated as secondary because they are not directly connected to the primary chiller circuit and can 

operate independently of the water flow requirements of the chillers. 

Chilled water exits the chilled water plant through a single 20-inch supply pipe and returns through a 20-inch 

return pipe. The supply and return piping split into four separate legs to distribute water to various campus 

building loads. Table 1 indentifies the buildings on each leg and their associated chilled water flow design 

requirements in GPM. 

TABLE 1 

Design East Leg 

Design Central Leg 

Design West Leg 

Design South Leg 

Bldg 

GPM Bldg 

GPM Bldg 

GPM Bldg 

GPM 

Eastman Hall 

0 Wick Science 

1265 Wick Annex 

702 Student Rec Ctr 

516 

Riverview 

151 Brown Hall 

789 ECC 

302 Total 

516 

Total 

151 Atwood Center * 1037 Education 

* 577 

Garvey Commons 

Sherburne Hall 

51 Building 

Stewart Hall 

Lawrence hall 

Kiehle Hall 

427 Headley 

* 65 

* 28 Centennial 

922 

228 PAC 

500 

879 Administration 

498 

248 Miller 

849 

* 343 Total 

4,415 

Total 

5,244 

* Calculated Values 

*Where design data is missing or not available calculations using industry standards define the anticipated 

loads. 

The data presented in Table 1 represents the design data for each listed building’s connected load. Design 

data consists of the cooling load for each building based upon a fully occupied state on a day when outside air 

temperatures are at design conditions: an 85°F dry bulb temperature and 68°F wet bulb temperature. 

The potential for a building to operate at its design condition is relatively remote as it is highly unlikely that all 

conditioned areas of a building will be fully occupied at all times. Lights are not on everywhere all the time; 

equipment loads, refrigerators, computers, printers, and so on will not be simultaneously operating at peak 

output all the time. Classrooms, corridors, offices, and meeting rooms will not be at occupancy capacity all the 

time. 

Operating cooling load conditions are accounted for through application of diversity factors which are typically 

individual building based. When buildings are served by a shared cooling source such as a campus distribution 

system, the effect of building diversity is amplified and will significantly impact the distribution system 

operation relative to connected load. Determining the variance in cooling flow requirements by modeling can 

be cost prohibitive. Utilization of empirical data and known changes for estimating system cooling flows can be 

cost effective and are generally applied to these conditions. 

The current campus distribution system connected cooling load requires a 10,875 GPM flow rate to satisfy all 

of the buildings at their design load. Current observed system operation utilizes one of two secondary pumps 

to provide the required chilled water. Trend data indicates that the peak flow rate is 3,900–4,300 GPM with 

pump VFD operating at 60Hz. Hot day (design day) trend data shows the single distribution pump reaching 

maximum capacity at 6:00 AM and continuing until 9:00 PM. 

14


As individual building flow data is not available, distribution is based upon the ratio of each building’s design 

load. Table 2 below represents the minimum distribution criteria for each building based upon the trend value 

of 3,900 GPM. In each individual building, the chilled water flow rate is between the minimum value listed in 

Table 2 and the design value listed in Table 1. As demand increases in one building it reduces in another, 

thereby maintaining a degree of equilibrium. On those occasions when demand exceeds available capacity, 

deviation from cooling setpoints occurs. 

TABLE 2 

Current East Leg 

Current Central Leg 

Current West Leg 

Current South Leg 

Bldg GPM Bldg GPM Bldg 

GPM Bldg 

GPM 

Eastman Hall 




186 

Riverview 

55 Brown Hall 

271 ECC 

110 Total 

186 

Total 

55 Atwood Center * 548 Education 

* 209 


Sherburne Hall 

51 Building 


Lawrence hall 

Kiehle Hall 

Total 

153 Headley 

* 23 

* 23 Centennial 

333 

82 PAC 

177 

317 Administration 

180 

90 Miller 

308 

* 125 Total 

1,593 

2,066 


Redistribution of chilled water as it applies to the East and Central legs of the distribution loop is possible 

because of the extension of direct-buried supply and return piping from Riverview to Building 51. Table 3 

demonstrates what the distributed flow rates would be with the valves at the South end of Building 51 opened 

and the valves at the Stewart Hall take-off in the tunnel closed. 

TABLE 3 

Bldg 

Eastman Hall 

Riverview 

New East Leg 

New Central Leg 

New West Leg 

New South Leg 

GPM Bldg 

GPM Bldg 

GPM Bldg 

GPM 




516 

151 Brown Hall 

789 ECC 

302 Total 

516 

51 Building 


Lawrence hall 

Kiehle Hall 

Total 

* 228 Atwood Center * 1037 Education 

* 577 

879 Garvey Commons 427 Headley 

* 65 

248 Sherburne Hall 

28 Centennial 

922 

* 343 Total 

3,546 PAC 

500 

1,849 Administration 

498 

Miller 

Total 

This new distribution plan would provide adequate chilled water supply to satisfy the needs of the East and 

Central legs as they are currently defined and provide some level of expansion and increased chilled water 

demand in the future. 

Future loads must be considered as campus growth and alterations to existing buildings occur. Data provided 

in the Campus Comprehensive Plan indicated the following education buildings were scheduled to be added or 

identified for remodel and/or upgrade of their infrastructure: Eastman Hall, ISELF, Headley, and Halenbeck. 

The GPM requirements of these buildings were determined from plans in development or data derived from 

standardized cooling applications. These additional loads must be considered in the distribution system 

analysis. Halenbeck Hall is currently being studied for upgrades that are expected to include air conditioning. 

The data provided is based upon square footage that may or may not be included. The GPM flow is contingent 

upon chilled water supply temperatures of 42°F. 

849 

4,415 


15


TABLE 4 

Bldg 

Eastman Hall 

ISELF 

Headley 

Halenbeck 

GPM 

265 

950 

302 

XXX 

Residence halls on campus represent the next level of potential load for the chilled water system. These 

buildings are currently heated from the central heating plant, but do not have air conditioning installed except 

for the common areas of Sherburne Hall. 

TABLE 5 

Residence 

Bldg S.F. 

(Gross) 

Cooling 

Tons 

Chilled 

Water 

GPM 

CHW 

Delta T Net S.F. S.F. / Ton 

CFM/S.F. 

(combined) 

Mitchell Hall 107,890 188 452 10 106,342 565 0.75 

Hill Hall 47,807 59 142 10 30,700 520 0.71 

Case Hall 40,492 66 159 10 34,304 517 0.73 

Stearns Hall 81,180 138 332 10 70,249 508 0.74 

Holes Hall 80,213 134 322 10 68,312 510 0.74 

Benton Hall 40,595 44 107 10 21,936 494 0.68 

North Benton Hall 20,297 22 53 10 14,328 645 0.75 

Sherburne Hall 125,573 162 390 10 77,574 478 0.76 

Shoemaker Hall 107,428 191 458 10 89,881 471 0.78 

Totals 651,475 1006 2414 513,626 

Table 5 represents estimated operational load with demand-controlled ventilation (DCV). While the values 

shown in Table 5 are inclusive of all load requirements, it is unlikely that dormitory rooms in the residence 

halls will be added to the central chiller system. The cost of distributing constant volume or variable air 

volume (VAV) air handling systems to dorm rooms may be prohibitive. It is more likely that common areas, 

lobbies, activity areas, etc., would be retrofitted with AHUs than the dorm rooms because those areas would 

benefit from a distributed chilled water source. The total calculated load is included in the distribution plan at 

this time to allow for new technology that may make dorm room connections to a distributed system viable. If 

it is determined that package terminal air conditioning (PTAC) units or other similar technology will be used, 

the displaced chilled water can represent excess capacity. 

These loads are likely to be added to the existing distribution system based upon their proximity to the three 

primary loops plus the addition of Halenbeck to the South loop. 

16


TABLE 6 

Future East Leg Future West Leg Future Central Leg 

Future South Leg 

Bldg GPM Bldg GPM Bldg 

GPM Bldg GPM 

Eastman Hall * 265 Wick Annex 

702 Wick Science 1265 Student Rec Ctr 516 

Riverview 152 ISELF 

950 Brown Hall 750 Halenbeck Hall * XXX 

51 Building * 300 ECC 

304 Atwood Center * 1517 Total 

Stewart Hall 879 Education 

* 580 Garvey Commons 423 

Lawrence hall 248 Headley 

* 302 Sherburne Hall * 390 

Mitchell Hall 452 Centennial 

922 Hill / Case Hall * 243 

Kiehle Hall 345 PAC 

491 Stearns Hall * 271 

Total 

2,641 Administration 

498 Holes Hall * 321 

Shoemaker 

* 458 Total 

4,345 


Miller 

Total 

853 

6,060 

This table represents the design flow requirements of all the buildings identified for possible addition to the 

chilled water system, but does not address their potential diversity. If an increase in student body population 

is significant, if research activity expands and requires increased ventilation, and if standards for outside air 

increase again, system load will increase substantially. 

The tables on the following page demonstrate flow ranges in the individual loops. As long as diversity remains 

as currently defined, the chilled water distribution system can function as intended. 

17


Design 

GPM 

Current 

GPM 

Cumulative 

High GPM 

Cumulative 

Low GPM 

Existing 

Pipe Size 

Max 

Flow 

Bldg 

Eastman Hall 0 0 1,924 724 8 1500 

Riverview 152 57 1,924 724 8 1500 

51 Building * 228 113 1,772 667 8 1500 

Stewart Hall 879 331 1,472 554 6 900 

Lawrence hall 248 93 593 223 6 900 

Kiehle Hall * 345 130 345 130 6 900 

Total 

1,924 724 

New East Leg Flow Range 

Design 

GPM 

New Central Leg Flow Range 

Current 

GPM 

Cumulative 

High GPM 

Cumulative 

Low GPM 

Existing 

Pipe Size 

Max 

Flow 

Bldg 

Wick Science 1265 476 3,987 1,512 12 3500 

Brown Hall 750 282 2,722 1,036 8 1500 

Atwood Center * 1037 571 1,972 754 8 1500 

Garvey Commons 423 159 455 183 6 900 

Sherburne Hall 32 24 32 24 3 225 

Total 

3,987 1,512 

Bldg 

Wick Annex 

ECC 

Education 

Miller 

Administration 

Headley 

Centennial 

PAC 

Total 

Design 

GPM 

West Leg Flow Range 

Current 

GPM 

Cumulative 

High GPM 

Cumulative 

Low GPM 

Existing 

Pipe Size 

Max 

Flow 

702 264 4,415 1,660 12 3500 

304 114 3,713 1,396 12 3500 

* 580 218 3,409 1,282 12 3500 

853 321 2,829 1,064 12 3500 

498 187 1,976 743 12 3500 

* 65 24 1,478 556 12 3500 

922 347 1,413 532 8 1500 

500 185 491 185 6 900 

4,415 1,660 

Potential for Trouble 


18

5. 51 Building

Building 51 (Business Building) 

Year Built 1968 

Renovations/Additions 1993, 2008 

Gross Square Feet 52,085 

Occupancy 495 

Usage Instruction 

Load GPM 

Cooling 

Tons EWT °F LWT °F 

Design 

Delta T 

RTU-1 68 34 44 56 12 

Total 228 114 44 56 12 

Information 

Source 

Construction 

Documents 

Estimated 

Building Occupancy Schedu 

(Fall-Spring) 

le 

Sunday Monday Tuesday Wednesday Thursd ay 

Friday 

Saturday 

Open Close Open Close Open Close Open Close Open Close Open Close Open Close 

Closed 0700 2200 0700 2200 0700 2200 0700 2200 0700 1700 1200 1700 


(Summer) 

le 

Sunday Monday Tuesday Wednesday Thursday Friday 

Saturday 


Closed 700 1700 700 1700 700 1700 700 1700 700 1700 Closed 

AHU Operating Schedule Sunday Monday Tuesday Wednesday Thursd ay 

Friday 

Saturday 

RTU-1 Start Stop Start Stop Start Stop Start Stop Start Stop Start Stop Start Stop 

No Schedule 0545 2130 0545 2130 0545 2130 0545 2130 0545 

2130 

No Schedule

5. 51 (Business) Building 

19


General Building Description 

The 51 Building contains classrooms and general use offices. Its occupancy is consistent with a university 

campus education building for normal school year use. 

HVAC System Description 

A single roof-mounted air handling unit provides air conditioning for the 

primary purpose of dehumidification. Heating systems are turned off during 

cooling season and there is no reheat provided for comfort cooling. 

The single rooftop unit (RTU) is equipped with a three-way control valve to 

adjust and control the flow of chilled water to the cooling coils. 

Base-mounted, end suction tertiary pumps boost system pressure to the 

RTU. The pumps are not equipped with variable frequency drives (VFD). 

GRAPH 1 

CHW Delta T (°F) 

30 

25 

20 

15 

10 

5 

0 

51 Building 

OAT vs. Delta T 

y = 0.2615x - 10.268 

45 50 55 60 65 70 75 80 85 90 

Outside Air Temperature (°F) 

Chilled Water Energy Use 

The trend line in Graph 1 above indicates that the three-way valve operates as designed. As the load 

increases, the difference in supply and return water temperatures (Delta T) increases. During a normal 

operating cycle, the valve bypasses up to an outside air temperature of 56–57°F, modulates between 58°F 

and 83°F, and maintains full flow through the coil above 84°F. 

20



GRAPH 2 

51 Building—September 1, 2011 

Time of Day vs. Delta T 

18 

16 

14 

12 

10 

8 

6 

4 

2 

0 

7:12 PM 12:00 AM 4:48 AM 9:36 AM 2:24 PM 7:12 PM 12:00 AM 

GRAPH 3 

80 

Building 51 

CHW Supply and Return Temperatures 


75 

70 

65 

60 

55 

50 

45 

Supply Temp, °F 

Return Temp, °F 

40 

7/31/11 

8/5/11 

8/10/11 

8/15/11 

8/20/11 

8/25/11 

8/30/11 

9/4/11 

9/9/11 

21


70 

GRAPH 4 

Building 51—September 1, 2011 


65 


60 

55 

50 

45 



40 


Cooling System Performance 

• Graphs 2, 3, and 4 above indicate that the building load commences around 2:00 AM and maintains 

the desired setpoint until 10:00 PM Monday through Friday with weekend shutdowns. It appears that 

pre-cooling occurs until approximately 7:00 AM when occupancy may begin. 

• This data is inconsistent with the operating schedule established for the building and does not appear 

to be coincidental with the AHU operating schedule. 

• These inconsistencies will likely be identified and corrected by the re-commissioning study currently 

underway. 

Building Impact on Chilled Water System 

• The three-way valve on the RTU allows colder-than-desired return chilled water temperature. 

• The tertiary pumps may be over-pressurizing the return water system as a result of the flow-through 

nature of the three-way valve. 

22



• Open South-end chilled water valves and reverse flow through building. 

• Replace the three-way cooling valve on the RTU with a two-way valve or install a shutoff valve in the 

return leg of the three-way to make it perform as a two-way. 

• Add VFD control to the tertiary pumps along with a properly located differential pressure transmitter 

to control it. 

• Install BTU chilled water meter in lower level mechanical room. 

• Balance water flow to tertiary pumps and to the RTU. 


Our study of the Business Building only includes the old part of the building; 

the new English addition is served by two DX packaged units. This portion of 

the building—and the DX system serving it—has not been addressed in this 

study. 

23

6. Administrative Services

Administration Services 


Renovations/Additions None 


Occupancy No Information Available 

Usage Administration and Offices 

Load GPM 

Cooling 


Design 

Delta T 

Information 

Source 

SF-1 307 90 44 56 12 

SF-2 191 56 44 56 12 

Total 498 146 44 56 12 

Construction 

Documents 

Construction 

Documents 

Construction 

Documents 


(Fall-Spring) 

le 


Saturday 


Closed 730 1730 730 1730 730 1730 730 1730 730 1730 Closed 


(Summer) 


Saturday 

le 


Closed 730 1730 730 1730 730 1730 730 1730 730 1730 Closed 

AHU Operating Schedule Sunday Monday Tuesday Wednesday Thursda y 

Friday 

Saturday 

SF - 1 Start Stop Start Stop Start Stop Start Stop Start Stop Start Stop Start Stop 

No Schedule 0545 1700 0545 1700 0545 1700 0545 1700 0545 1700 No Schedule 

SF - 2 Start Stop Start Stop Start Stop Start Stop Start Stop Start Stop Start Stop 

No Schedule 0430 1700 0530 1700 0530 1700 0530 1700 0530 1700 No Schedule

6. Administrative Services Building 

24



The Administrative Services Building contains administrative and general use offices. Its occupancy is 

consistent with a university campus administrative building for normal school year use. The building is 

consistently occupied during the heavy cooling months and represents one of the more significant summer air 

conditioning loads. 

Air conditioning is provided via two AHUs designed to provide winter heat and summer comfort cooling. 

Heating systems are turned off during cooling season and there is no reheat provided for comfort cooling air 

tempering. 

Both AHUs are equipped with two-way control valves that modulate in response to load change. The 

secondary distribution pumps in the chilled water plant provide system pressure. There is no tertiary booster 

in the Administrative Services Building. A return water temperature control valve is applied to maintain a 

minimum return water temperature to the chillers. 

GRAPH 1 

30 

Administrative Services Building 


y = -0.0066x + 8.7522 

25 

Delta T (°F) 

20 

15 

10 

5 

0 

45 50 55 60 65 70 75 80 85 90 



The OAT vs. Delta T graph indicates no deviation in the Delta across the range of outside air temperature. The 

application of a return water temperature control valve is having the intended impact on the system in that 

the supply and return water temperatures are nearly constant. This building appears to be functioning within 

its design parameters as it applies to the chilled water system performance. 

25


GRAPH 2 

30 

Admin. Building — September 1, 2011 


25 


20 

15 

10 

5 

0 


GRAPH 3 

80 

Administrative Services Building 



75 

70 

65 

60 

55 

50 

45 



40 

7/31/11 

8/5/11 

8/10/11 

8/15/11 

8/20/11 

8/25/11 

8/30/11 

9/4/11 

9/9/11 

26


Supply and return water temperatures appear to track well, indicating that 

the return water temperature control valve is functioning as intended. This 

graph also indicates that night and weekend setback scheduling is 

consistent and somewhat coincidental with building occupancy. 

GRAPH 4 

70 

Administrative Building — September 1, 2011 


65 


60 

55 

50 

45 



40 

7:12 PM 

12:00 AM 

4:48 AM 

9:36 AM 

2:24 PM 

7:12 PM 

12:00 AM 



the desired setpoint until 5:00 PM Monday through Friday with weekend shutdowns. It appears that 

pre-cooling occurs until approximately 7:00 AM when occupancy may begin. 

• This data is consistent with the operating schedule established for the building and does appear to be 

coincidental with the AHU operating schedule. 

27



• The two-way valves on the AHUs are performing properly and are not 

having a negative impact on the chilled water distribution system. 

• The return water temperature control valve is intended to restrict 

return water flow to the chilled water plant until it reaches a 

predetermined temperature. There is no cross-connect to the supply 

water line and no booster pump to move the water if there were. This 

valve is redundant to and, in some cases, overrides the performance 

of the individual AHU control valves. 



• Properly tune individual AHU control valves. 

• Install BTU chilled water meter in ground floor mechanical room. 

• Balance water flow to AHUs. 


28

7. Atwood Memorial Center

Atwood Memorial Center 


Renovations/Additions 1972, 1992, 2004 


Occupancy 3,000 

Usage Student Support, Ballrooms, Food Service 

Load GPM 

Cooling 


Design 

Delta T 

Information 

Source 

AHU-1 182 61 52 60 8 

Construction 

Documents 

AHU-2 177 59 52 60 8 

Construction 

Documents 

AHU-3 101 34 52 60 8 

Construction 

Documents 

AHU-4 140 70 44 56 12 

Construction 

Documents 

AHU-5 31 16 44 56 12 Construction 

Documents 

AHU-12 No Information Available 







Total 1037 518 44 56 12 Estimated 

Building Occupancy Schedule 

(Fall-Spring) 

Sunday Monday Tuesday Wednesday Thursday Friday Saturday 


1200 2400 700 2400 700 2400 700 2400 700 2400 700 2400 800 2400 


(Summer) 



Closed 700 1900 700 1900 700 1900 700 1900 700 1630 Closed 

AHU Operating Schedule Sunday Monday Tuesday Wednesday 

Thursday Friday Saturday 

AHU-1 Start Stop Start Stop Start Stop Start Stop Start Stop Start Stop Start Stop 

1100 2355 0600 2350 0600 2350 0600 2350 0600 2350 0600 2350 0700 2355 


1100 2300 0530 2300 0530 2300 0530 2300 0530 2300 0530 2300 0800 2300 


0600 2200 0600 2200 0600 2200 0600 2200 0600 2200 0600 2200 0600 2200 


1100 2300 0600 2330 0600 2330 0600 2330 0600 2330 0600 2330 0800 2100 




800 2230 0600 2330 0600 2330 0600 2330 0600 2330 0600 2230 0800 2230 


1100 2350 0600 2350 0600 2350 0600 2350 0600 2350 0600 2350 0700 2350 


1100 2300 0600 2200 0600 2200 0600 2200 0600 2200 0600 2200 0800 2200 


No Schedule 0600 1900 0600 1900 0600 1900 0600 1900 0600 1900 1130 1600 




1200 2200 830 2200 830 2200 830 2200 830 2200 830 2200 1200 2200 


1200 2200 0800 2200 0800 2200 0800 2200 0800 2330 0800 2330 1200 2300

7. Atwood Memorial Center 

29



The Atwood Memorial Center contains restaurants, ballrooms, dining areas, general meeting areas, 

recreational spaces, and a bowling alley. Its occupancy is diverse and inconsistent from day to day. Depending 

on functions and events on campus, occupancy can be as high as 3,000 and as low as 20 staff. The building is 

open year-round and sees significant use during the heavy cooling months. This building represents one of the 

most significant summer air conditioning loads on the campus. 


Air conditioning is provided via 12 AHUs designed to provide winter heat and summer comfort cooling. Heating 

systems are turned off during cooling season and there is no apparent reheat provided for comfort cooling air 

tempering. 

All AHUs are equipped with two-way control valves that modulate in response to load change. Tertiary booster 

pumps located in the lower level mechanical room provide system pressure. A return water temperature 

control valve is applied to maintain a minimum return water temperature to the chilled water plant. 

GRAPH 1 


30 

25 

20 

15 

10 

5 

0 



y = 0.2261x - 9.705 

45 50 55 60 65 70 75 80 85 90 



Graph 1 indicates deviation in the Delta across the range of outside air temperature that is consistent with the 

performance of two-way control valves on the building load. The application of the return water temperature 

control valve does not appear to be having the intended impact. 

30



30 

25 

20 

15 

10 

5 

GRAPH 2 




0 


Time of Day 

Flow (gpm) 

GRAPH 3 


OAT vs. Flow 

400 

350 

300 

250 

200 

150 

100 

50 

0 

45 50 55 60 65 70 75 80 85 90 


Atwood Memorial Center is equipped with a flow meter that provides additional insight into the performance of 

the chilled water system within the building. Graph 3 indicates a high level of volatility in flow rates but seems 

to generally trend upward as outside air temperature increases. We have not been able to verify the accuracy 

of the flow meter and actual GPM flow rates appear to be dramatically higher than indicated on this graph. 

There is also a significant concern about the velocity of the water as it enters the building. The flow rates 

required for design-day loads appear to exceed the allowable flows for the pipe size installed. 

31


GRAPH 4 

70 




65 

60 

55 

50 

45 



40 

7/31/11 

8/5/11 

8/10/11 

8/15/11 

8/20/11 

8/25/11 

8/30/11 

9/4/11 

9/9/11 

GRAPH 5 




70 


65 

60 

55 

50 

45 



40 

7:12 PM 

12:00 AM 

4:48 AM 

9:36 AM 

2:24 PM 

7:12 PM 

12:00 AM 

32



• Graphs 4 and 5 above indicate that the control valves on the various AHUs are performing properly 

according to their schedule. The full-month graph clearly demonstrates a higher-than-expected 

building load on weekends as there is deviation in temperature during only two of the weekends 

graphed. 

• Graph 5 indicates a load increase around 2:00 AM with significant fluctuation in return temperatures 

until almost 10:00 AM. The steadiness of the return water temperature indicates proper operation of 

the return water temperature control valve. It does not indicate whether space temperatures are 

satisfied or not. 


• The two-way valves on the AHUs are performing properly and are not having a negative impact on the 

chilled water distribution system. 

• The return water temperature control valve is intended to restrict return water flow to the chilled 

water plant until it reaches a predetermined temperature. There is no cross-connect to the supply 

water line. This valve is redundant to and, in some cases, overrides the performance of the individual 

AHU control valves. 


• Replace the six-inch distribution supply and return pipe from the mains into the mechanical room with 

new eight-inch pipe up to and through the tertiary pumps. 

• Increase the pipe size on the downstream side of the tertiary pumps to eight inches up to the first 

piping take off. 



• Test and reset water meter in the lower level mechanical room to display accurate flow rates. 

• Reset control parameters for pump variable frequency drives and verify performance. 


• Document all new performance data. 

33

8. Brown Hall

Brown Hall 


Renovations/Additions 2009 


Occupancy 930 

Usage Instruction and Printing 

Services 

Load GPM 

Cooling 


Design 

Delta T 

Information 

Source 

AHU-1 750 375 44 56 12 

Construction 

Documents 

AHU-2 26 16.25 44 56 12 

Estimated 

AHU-4 12.8 8 44 56 12 

Total 789 399 44 56 12 

Estimated 

Estimated 


(Fall-Spring) 

le 


Saturday 


Closed 700 2230 700 2230 700 2230 700 2230 700 1730 Closed 


(Summer) 

le 


Saturday 


Closed 700 1700 700 1700 700 1700 700 1700 700 

1700 

Closed 

AHU Operating Schedule Sunday Monday Tuesday Wednesday Thursday Friday 

Saturday 


0600 1600 0400 1700 0500 1900 0500 1900 0500 1900 0500 1700 0600 1600 


No Schedule 0600 1200 No Schedule 0600 1200 No Sched ule 0600 1200 No Schedule 



8. Brown Hall 

34

8. Brown Hall 


Brown Hall contains classrooms, faculty offices, and the campus print services department. Its occupancy is 

consistent with a university campus classroom building for normal school year use. 


Air conditioning is provided by three AHUs designed to provide winter heat and summer comfort cooling. 

Heating systems are turned off during cooling season and there is no reheat provided for comfort cooling air 

tempering. 

There are two separate entry points for chilled water supply to Brown Hall. The first entry point serves one 

AHU with a chilled water flow rate of 92 GPM and is located in the northwest mechanical room. Additional 

piping from this entry point extends into another mechanical room where it has been capped off. The second 

entry point for chilled water is in this second mechanical room and serves AHUs 1 and 2. 

AHUs 2 and 4 are equipped with two-way control valves that modulate in response to load change. Both AHUs 

are relatively small and have a correspondingly small chilled water requirement. AHU 1 is equipped with a 

three-way control valve that is having significant impact on distribution system operation. 

The secondary distribution pumps in the chilled water plant provide system pressure. There are two separate 

tertiary booster pumps in Brown Hall that are not currently used; both are bypassed and valved off in favor of 

the secondary output. 

GRAPH 1 


30 

25 

20 

15 

10 

5 

Brown Hall 


y = 0.0074x + 1.9476 

0 

45 50 55 60 65 70 75 80 85 90 


35

8. Brown Hall 


The three-way control valve on AHU 1 drives the entire building’s Delta T. The flat profile on Graph 1 across 

30°F OAT change indicates that more water is delivered than is being used. That the tertiary pumps are 

bypassed indicates that the secondary pumps via the distribution loop are providing excess capacity. These 

two parameters indicate that modifying the delivery methods to Brown Hall could have positive impact on the 

distribution system operation. 

GRAPH 2 

30 

Brown Hall — September 1, 2011 


25 


20 

15 

10 

5 

0 


36

8. Brown Hall 

GRAPH 4 


70 

65 

60 

55 

50 

45 

Brown Hall — September 1, 2011 




40 

7:12 PM 

12:00 AM 

4:48 AM 

9:36 AM 

2:24 PM 

7:12 PM 

12:00 AM 



the desired setpoint until 7:00 PM every day of the week. It appears that pre-cooling occurs until 

approximately 7:00 AM when occupancy may begin. 

• This data is not consistent with the operating schedule established for the building and does not 

appear to be coincidental with the AHU operating schedule. 


• The two-way valves on AHUs 2 and 4 appear to be performing properly and are not having a negative 

impact on the chilled water distribution system. 

• The three-way valve on AHU 1 appears to be performing properly from 

an AHU temperature control perspective but is having a negative 

impact on the distribution loop. 

• The effect of two separate supply sources into the building is unclear 

but is certainly unnecessary. The piping extended between the two 

mechanical rooms, if properly connected, would be adequate to serve 

AHU 4 from the AHU 1 & 2 mechanical room and allow the elimination 

of the AHU 4 tertiary pump entirely. 

37

8. Brown Hall 


• Cross-connect chilled water piping in mechanical rooms and eliminate small tertiary pump. 

• Replace the three-way valve on AHU 1 with a new two-way valve or insert a shutoff valve in the return 

leg of the valve. 

• A balancing contractor should be employed to measure the system supply pressure at the building 

entry point. 

• A variable frequency drive, integrated to the DDC system, should be applied to the pump along with a 

properly located, installed, and calibrated differential pressure transmitter to manage the flow of 

chilled water to the AHUs. 


• Install BTU chilled water meter in the lower level mechanical room. 



38

9. Centennial Hall

Centennial Hall 




Occupancy 746 

Usage Instruction and Bookstore 

Load GPM 

Cooling 


Design 

Delta T 

Information 

Source 

AHU-1 148 93 44 59 15 

Construction 

Documents 

AHU-2 148 93 44 59 15 

Construction 

Documents 

AHU-3 313 196 44 59 15 

AHU-4 313 196 44 59 15 

Total 922 576 44 59 15 

Construction 

Documents 

Construction 

Documents 

Construction 

Documents 


(Fall-Spring) 

le 


Saturday 


1400 2400 700 2400 700 2400 700 2400 700 2400 700 1800 1000 1800 


(Summer) 

le 


Saturday 


Closed 700 1700 700 1700 700 1700 700 1700 700 1700 Closed 


Saturday 


0810 1700 0610 2100 0610 2100 0610 2100 0610 2100 0610 2100 0810 1700 


0810 1700 0610 2100 0610 2100 0610 2100 0610 2100 0610 2100 0810 1700 


0800 1710 0600 2110 0600 2210 0600 2110 0600 2110 0600 2110 0800 1710 


0800 1710 0600 2110 0600 2210 0600 2110 0600 2110 0600 2110 0800 1710

9. Centennial Hall 

39



Centennial is the home of the G. R. Herberger College of Business. Also housed in the five-floor building will 

be academic student services such as the Advising Center, Career Services, Student Disability Services, 

Honors Program, and the Multi-Cultural Academic Center. Originally a library, Centennial Hall’s 1969 

groundbreaking marked the University’s 100th anniversary. The building was completed in 1971. 


Two AHUs and two rooftop units (RTUs) provide winter 

heat and summer comfort cooling. Heating systems are 

turned off during cooling season, and there is no 

apparent reheat provided for comfort cooling air 

tempering. All AHUs are equipped with two-way control 

valves that modulate in response to load change. A 

tertiary booster pump located in the lower level 

mechanical room provides system pressure. 

A return water temperature control valve is applied to 

maintain a minimum return water temperature to the 

chilled water plant. A system bypass valve is provided at 

the connection point to RTU-4 to continuously flow water 

back to the system, thereby assuring cold water flow to 

the coil connection points at all times. 

GRAPH 1 

30 

Centennial Building 


y = 0.1037x - 2.2646 

25 


20 

15 

10 

5 

0 

45 50 55 60 65 70 75 80 85 90 


40



Graph 1 above demonstrates the gradual increase in Delta T as outside air temperature rises. The data points 

are pretty evenly distributed across the range of temperatures, which indicates that the return water 

temperature control valve and the RTU-4 bypass valve are having limited impact on system performance. The 

graph indicates normal or near-normal two-way valve performance. 

GRAPH 2 

30 

Centennial Building—September 1, 2011 


25 


20 

15 

10 

5 

0 


41


GRAPH 3 

70 



65 


60 

55 

50 



45 

40 

7/31/11 

8/5/11 

8/10/11 

8/15/11 

8/20/11 

8/25/11 

8/30/11 

9/4/11 

9/9/11 

42


GRAPH 4 

70 





65 

60 

55 

50 

45 



40 

7:12 PM 

12:00 AM 

4:48 AM 

9:36 AM 

2:24 PM 

7:12 PM 

12:00 AM 


Graphs 2, 3, and 4 above indicate that the building load commences around 3:00 AM and maintains the 

desired setpoint until 9:00 PM every day of the week. It appears that pre-cooling occurs until approximately 

7:00 AM when occupancy may begin. 

The return water temperatures are highly inconsistent, indicating that there is a significant variation in loads 

within this building or that the controls are not functioning as intended. While load variation is possible, 

control issues are more likely. 


The two-way valves on the AHUs are performing properly and are not having a negative impact on the chilled 

water distribution system. 

The return water temperature control valve is intended to restrict return water flow to the chilled water plant 

until it reaches a predetermined temperature. The cross-connect to the supply water line is valved off, 

preventing return flow to the supply line. This valve is redundant to and, in some cases, overrides the 

performance of the individual AHU control valves. 

43





• Command the RTU-4 bypass valve closed, or manually close it and disconnect the actuator. 

• Install a BTU chilled water meter in the lower level mechanical room in place of the existing flow 

meter. 



44

10. Education Building

Education Building 




Occupancy 966 


Load GPM 

Cooling 


Design 

Delta T 

S-1 No Information Available 



Total 577 289 44 56 12 

Information 

Source 

Estimated 


(Fall-Spring) 

le 


Saturday 


Closed 700 2230 700 2230 700 2230 700 2230 700 1700 Closed 


(Summer) 

le 


Saturday 


Closed 700 2230 700 2230 700 2230 700 2230 700 1700 Closed 


Saturday 

S-1 Start Stop Start Stop Start Stop Start Stop Start Stop Start Stop Start Stop 

No Schedule 0610 2130 0610 2130 0610 2130 0610 2130 0610 2130 0800 1700 


No Schedule 0610 2130 0610 2130 0610 2130 0610 2130 0610 2130 0800 1700 


No Schedule 0610 2130 0610 2130 0610 2130 0610 2130 0610 2130 0800 1700

10. Education Building 

45



The Education Building, built in 1971, provides facilities for secondary, elementary, and special education 

programs. The Education Building also houses the community psychology program, psychology laboratories, 

communication disorders department, counselor education, and student teaching. 


Three AHUs located in the lower level mechanical room provide winter heat 

and summer comfort cooling. Heating systems are turned off during cooling 

season and there is no apparent reheat provided for comfort cooling air 

tempering. All AHUs are equipped with two-way control valves that modulate 

in response to load change. The secondary 

distribution pumps provide system pressure. 

A tertiary booster pump located in the lower 

level mechanical room has been physically 

disconnected from the loop and is not part of the system. 

A return water temperature control valve is applied to maintain a minimum 

return water temperature to the chilled water plant. 

GRAPH 1 

30 

25 



y = 0.1109x + 6.2915 

CHW Delta (°F) 

20 

15 

10 

5 

0 

45 50 55 60 65 70 75 80 85 90 


46



Graph 1 above demonstrates the gradual increase in Delta T as outside air temperature rises, indicating that 

the two-way valves are performing well. The close tolerance of the Delta T—only 6–8°F—suggests that the 

return water temperature control valve is impacting operation more significantly. The flatness of the points 

across the monitoring range also indicates that flow and load are near constant without reset for unoccupied 

operation. Night and weekend shutdown does not appear to be occurring, yet the schedules indicate it is. 

GRAPH 2 

30 

Education Building—September 1, 2011 


25 


20 

15 

10 

5 

0 


47


GRAPH 3 


70 

65 

60 

55 

50 

45 





40 

7/31/11 

8/5/11 

8/10/11 

8/15/11 

8/20/11 

8/25/11 

8/30/11 

9/4/11 

9/9/11 

GRAPH 4 


70 

65 

60 

55 

50 

45 

Education Building—September 1, 2011 




40 

7:12 PM 

12:00 AM 

4:48 AM 

9:36 AM 

2:24 PM 

7:12 PM 

12:00 AM 

48




desired setpoint until 11:00 PM every day of the week. There does not appear to be any pre-cooling as system 

response appears to be consistent with occupancy in the morning. 

This data is not consistent with the operating schedule established for the building and does not appear to be 

coincidental with the AHU operating schedule. 




The return water temperature control valve is intended to restrict return water flow to the chilled water plant 

until it reaches a predetermined temperature. There is no cross connect to the supply water line and no 

booster pump to move the water if there was. This valve is redundant to and, in some cases, overrides the 

performance of the individual AHU control valves. 


• Evaluate the control parameters for the AHUs. Determine why there is no apparent night or weekend 

setback in system control. 






49

11. Engineering & Comp. Center

Engineering and Computer Center 




Occupancy 629 


Load GPM 

Coo 

To 

ling 

ns EWT °F LWT °F 

Design 

Delta T 

AHU-1 51 32 44 59 15 

AHU-2 51 32 44 59 15 

AHU-3 38 24 44 59 15 

AHU-4 31 19 44 59 15 

AHU-5 89 56 44 59 15 

AHU-6 41 26 44 59 15 

Total 302 189 44 59 15 

Information 

Source 

Construction 

Documents 

Construction 

Documents 

Construction 

Documents 

Construction 

Documents 

Construction 

Documents 

Construction 

Documents 

Construction 

Documents 


(Fall-Spring) 

Sunday Monday Tuesday W ednesday Thursday Friday 

Saturday 


1300 2400 700 100 700 100 700 100 700 100 700 100 1200 2200 


(Summer) 


Saturday 


Closed 700 1700 700 1700 700 1700 700 1700 700 1700 Closed 


Saturday 


No Schedule 0600 2200 0600 2200 0600 2200 0600 2200 0600 1700 0700 1700 


1300 2300 0610 2300 0610 2300 0610 2300 0610 2300 0610 1700 1200 1700 






0600 2100 0615 2115 0615 2115 0615 2115 0615 2115 0615 2115 0600 2100 



11. Engineering & Computer Center 

50



The Engineering and Computing Center was built in 1958 and remodeled in 1962 and 1986. It provides 

classrooms, laboratories, and facilities for electrical and computer engineering, mathematics, mechanical and 

manufacturing engineering, and statistics. The location formerly housed the Campus Lab School. 


Four AHUs and two RTUs provide winter heat and summer comfort cooling. Heating systems are turned off 

during cooling season, and there is no apparent reheat provided for comfort cooling air tempering. All AHUs 

are equipped with two-way control valves that modulate in response to load change. A single tertiary booster 

pump located in the lower level mechanical room provides chilled water pressure for the building. 

GRAPH 1 

30 



y = 0.1065x + 1.5837 

25 


20 

15 

10 

5 

0 

45 50 55 60 65 70 75 80 85 90 



Graph 1 above demonstrates the gradual increase in Delta T as outside air temperatures rise, indicating that 

the two-way valves are performing well. The spread of data points indicates that AHU and RTU response to 

load change is good. Data points along the 0°F Delta line are indicative of night shutdown and temperature 

equalization between supply and return. The gaps or lack of data points in the 3°F to 12°F range, with 

significant data points in the 13°F to 20°F range, demonstrates that the performance of the two-way valves is 

correct and desirable. 

51


GRAPH 2 

30 




25 


20 

15 

10 

5 

0 


GRAPH 3 

160 



140 


120 

100 

80 

60 



40 

7/31/11 

8/5/11 

8/10/11 

8/15/11 

8/20/11 

8/25/11 

8/30/11 

9/4/11 

9/9/11 

52


GRAPH 4 


70 

65 

60 

55 

50 

45 

40 

7:12 PM 




12:00 AM 

4:48 AM 

9:36 AM 

2:24 PM 

7:12 PM 

12:00 AM 




• Graph 2 above indicates chilled water supply temperatures reached 150°F on two occasions and over 

120°F on numerous occasions. We believe this to be a fault in the data collection and should be 

dismissed. 


the desired setpoint until 11:00 PM throughout the week. 


• The two-way valves on the AHUs are performing properly and are not having a negative impact on the 

chilled water distribution system. 

• The return water temperature control valve is intended to restrict return water flow to the chilled 

water plant until it reaches a predetermined temperature. There is no cross-connect to the supply 

water line and no booster pump to move the water if there were. This valve is redundant to and, in 

some cases, overrides the performance of the individual AHU control valves. 

53


Chilled water enters on the north side of the basement mechanical room. A 

nearly closed balancing valve breaks system pressure significantly before the 

water enters the tertiary pump, a base mounted, end-suction, centrifugal 

booster pump. The booster pump re-pressurizes the chilled water for delivery 

to six distributed AHUs. 

A pneumatic three-way control valve connects 

cold supply chilled water and warm return water 

to the inlet of the booster pump. The shut-off 

valve on bypass leg is closed, effectively 

converting it to a two-way control valve. It is unknown what parameters are used 

to control this valve, but they appear to be unnecessary, as is the use of a booster 

pump in this application. 

The nearly closed balancing valve on the supply 

line indicates excessive system pressure at the 

entry point. The balancing valve reduces this pressure, but it is boosted again 

by the tertiary pump; this is contradictory and a significant energy waster. 

There is a flow-measuring station on the inlet pipe with a balancing tag that 

indicates Pump P-1 is balanced to deliver 37.1 GPM. This data is outdated or 

simply inaccurate since the pump is supplying adequate chilled water to all six 

AHUs — the total requirement of which is 302 GPM. 


• A balancing contractor should be instructed to measure the system supply pressure and determine if it 

is adequate to overcome the pressure drop to RTU-6, the most remote AHU. 

• If system pressure is adequate, the pump should be removed and connection to the distribution piping 

should be restored. A total building balancing, along with proper documentation, will need to be 

completed. 

• If system pressure is inadequate to overcome the pressure drop, 

the pump piping should be modified to remove the control valve 

and bypass. A variable frequency drive should be applied to the 

pump along with a properly located, installed, and calibrated 

differential pressure transmitter to manage the flow of chilled 

water to the AHUs. Total building re-balancing will be required. 

• All six AHUs are equipped with two-way electronically actuated 

DDC control valves that appear to be functioning properly. The 

retro-commissioning study being conducted should address 

calibration of these valves in routine. 

54

12. Garvey Commons






Usage Food Service 

Load GPM 

Cooling 


Design 

Delta T 

Information 

Source 

AHU-1 136 57 44 54 10 

Construction 

Documents 

AHU-2 120 50 44 54 10 

Construction 

Documents 

AHU-3 125 52 44 54 10 

Construction 

Documents 

AHU-4 4 2 44 54 10 

AHU-5 42 18 44 54 10 

Total 427 178 44 54 10 

Construction 

Documents 

Construction 

Documents 

Construction 

Documents 


(Fall-Spring) 


Saturday 

Open Close Op en Close Open Close Open Close Op en Close O pen Close O pen Close 

1030 1900 700 2000 700 2000 700 2000 700 2000 700 1900 1030 1900 


(Summer) 

le 


Saturday 


No Information Available 


Saturday 


0800 2030 0515 2200 0515 2200 0515 2200 0515 2200 0515 2030 0800 2030 


0800 2030 0515 2200 0515 2200 0515 2200 0515 2200 0515 2030 0800 2030 


0700 1930 0530 2030 0530 2030 0530 2030 0530 2030 0530 1930 0700 1930 


0200 1730 0200 1730 0200 1730 0200 1730 0200 1730 0200 1730 0200 1730 


0800 2030 0600 2200 0600 2200 0600 2200 0600 2200 0600 2030 0800 2030 

O

12. Garvey Commons 

55



Garvey Commons consists of four dining rooms seating 1300 at one time with cafeteria service. Garvey 

Commons was built in 1962 and remodeled in 1965 and 1987. 


Five AHUs provide winter heat and summer comfort cooling. Heating systems are turned off during cooling 

season, and there is no apparent reheat provided for comfort cooling air tempering. All AHUs are equipped 

with two-way control valves that modulate in response to load change. Duplex tertiary booster pumps located 

behind the kitchen space on the lower level provide chilled water pressure for the building. 

GRAPH 1 

30 

25 



y = 0.1292x - 5.5498 


20 

15 

10 

5 

0 

45 50 55 60 65 70 75 80 85 90 



Graph 1 above demonstrates a minimal range of differential with a significant number of values plotted around 

5°F. Graph 2 below substantiates this in that the single-day plot indicates load occurring 24 hours a day with 

little deviation in temperature. The AHUs are equipped with two-way valves that ought to close when the AHU 

is scheduled to be off. Delta T should approach and remain at zero during these off times. Graph 2 indicates 

this is not happening. 

56


GRAPH 2 

30 

Garvey Commons—August 26, 2011* 


25 


20 

15 

10 

5 

0 


* There is no data available for Sept. 1, 2011, so the next available design day data was used. 

GRAPH 3 

70 




65 

60 

55 

50 

45 



40 

7/31/11 

8/5/11 

8/10/11 

8/15/11 

8/20/11 

8/25/11 

8/30/11 

9/4/11 

9/9/11 

57


GRAPH 4 


70 

65 

60 

55 

50 

45 

Garvey Commons—August 26, 2011* 




40 

7:12 PM 

12:00 AM 

4:48 AM 

9:36 AM 

2:24 PM 

7:12 PM 

12:00 AM 

Graphs 3 and 4 above indicate supply water temperatures well above 

system supply temperatures. This could be a calibration issue with the 

devices used to log the data, improperly installed temperature probes, or 

actual water temperatures well above desired levels. The location of the 

temperature probes in the tunnel approaching Garvey Commons versus 

at the distribution pumps ensures that return water blending did not 

occur. 

The minimal difference in Delta T from low to high would support 

warmer-than-desired supply temperatures, but the lack of complaints 

from building occupants concerning humidity would indicate otherwise. 

This data is too inconsistent to form an accurate opinion on chilled water performance in this building. Better 

trend data and more accurate documentation are needed. 


• Graphs 2, 3, and 4 above indicate that the building load is constant 24 hours per day, supply water 

temperature notwithstanding. 

• This data is not consistent with the operating schedule established for the building, and does not 

appear to be coincidental with the AHU operating schedule. 

58



• The two-way valves on the AHUs are performing properly, and are not having a negative impact on 

the chilled water distribution system. 

• There is no return water temperature control valve applied in Garvey Commons. The two-way valves 

on the AHUs are allowed to operate as intended. 



• Install BTU chilled water meter in lower level mechanical room in place of the existing flow meter. 



59

13. Kiehle Visual Arts Center

Kiehle Visual Arts Center 




Occupancy 164 


Cooling 


Design 

Delta T 

Load GPM 


Information 

Source 

S-2 111 No Information Available 

S-3 89 No Information Available 

Total 343 171 44 56 12 

Construction 

Documents 

Construction 

Documents 

Estimated 


(Fall-Spring) 

le 


Saturday 


1200 2100 700 2300 700 2300 700 2300 700 2300 700 2000 1200 2000 


(Summer) 

le 


Saturday 


Closed 700 1700 700 1700 700 1700 700 1700 700 1700 Closed 


Saturday 


1200 2100 0630 2100 0630 2100 0630 2100 0630 2100 0630 2100 1200 2100 


1130 2100 0630 2155 0630 2155 0630 2155 0630 2155 0630 1655 1130 2100 


1100 2200 0645 2115 0645 2115 0645 2115 0645 2115 0645 1645 1100 2200

13. Kiehle Visual Arts Center 

60



Named for David L. Kiehle, president from 1875–1881, the Kiehle Visual Arts Center was built in 1952 and 

remodeled in 1974. This building provides classrooms and studio space to art students as well as a public art 

gallery. 


Three AHUs — one per floor, ground through second —provide winter heat 

and summer comfort cooling. Heating systems are turned off during cooling 

season, and there is no reheat provided for comfort cooling air tempering. 

All three AHUs are equipped with two-way 

control valves that modulate in response to 

load change. AHU-3 on the second floor is 

equipped with a bypass valve to maintain 

supply water temperature in the system when 

the AHU control valves are closed. 

A single B & G Series 80 tertiary pump located in the ground floor mechanical 

room provides system pressure. 

GRAPH 1 

30 

25 



y = 0.1998x + 2.8161 


20 

15 

10 

5 

0 

45 50 55 60 65 70 75 80 85 90 


61



Graph 1 above demonstrates the gradual increase in Delta T as outside air temperature rises. The 

preponderance of data points in the 10° to 30°F range, along with an increasing Delta T as OAT rises indicates 

very good control. The number of data points in the zero range represent the off times for AHUs. This building 

is performing well. 

GRAPH 2 

30 




25 


20 

15 

10 

5 

0 


62


GRAPH 3 

100 




90 

80 

70 

60 

50 



40 

7/31/11 

8/5/11 

8/10/11 

8/15/11 

8/20/11 

8/25/11 

8/30/11 

9/4/11 

9/9/11 

63


70 

GRAPH 4 




65 


60 

55 

50 

45 



40 

7:12 PM 

12:00 AM 

4:48 AM 

9:36 AM 

2:24 PM 

7:12 PM 

12:00 AM 



desired setpoint until 9:00 PM every day of the week. It does not appear that pre-cooling occurs prior to 

occupancy and may not be necessary. 

This data is not consistent with the operating schedule established for the building and does not appear to 

track the AHU operating schedules well. 




The bypass valve on AHU-3 is intended to maintain chilled water availability to the building while AHUs are 

commanded off. While this is a common practice, it is unnecessary and wastes pump and chiller energy. 

64



• Check and re-tune individual AHU control valves if necessary. 


• Install BTU chilled water meter in ground floor mechanical room. 



65

14. Lawrence Hall

Lawrence Hall 





Usage Housing/Student Services/Instruction 

Load GPM 

Cooling 


Design 

Delta T 

Information 

Source 

AHU-1 56 24 45 55 10 

Construction 

Documents 

AHU-2 36 15 45 55 10 

FCU 1-92 156 65 45 55 10 

Total 248 103 45 55 10 

Construction 

Documents 

Construction 

Documents 

Construction 

Documents 


(Fall-Spring) 

le 


Saturday 


Closed 800 1630 800 1630 800 1630 800 1630 800 1630 Closed 


(Summer) 


Saturday 

Open Close Open Close 

Open Close Open Close Open Close Open Close Open Close 

Closed 800 1630 800 1630 800 1630 800 1630 800 1630 Closed 


Saturday 


0600 0600 0600 0600 0600 0600 0600 


0600 0600 0600 0600 0600 0600 0600

14. Lawrence Hall 

66



The oldest structure on campus, this building was named for renowned educator and former SCSU President 

Isabel Lawrence. After standing empty for 30 years, it was renovated to house 50 pairs of international 

students and students in the foreign languages or international affairs areas of study. The Center for 

International Studies and offices of foreign language faculty occupy the lower floors. 


Two AHUs located on the ground and second floors 

provide air conditioning. There are also 92 fan coil units 

(FCUs) serving individual dorm rooms, corridors, and 

common areas. The AHUs and FCUs are designed to 

provide winter heat and summer comfort cooling. 

Heating systems are turned off during the cooling season 

and there is no reheat provided for comfort cooling air 

tempering. 

Two tertiary pumps located in the ground floor mechanical room provide system 

pressure. 

Both AHUs and all FCUs are equipped with two-way control valves that modulate in response to load change. 

GRAPH 1 


30 

25 

20 

15 

10 

5 

0 

Lawrence Hall 


y = -0.0879x + 24.499 

45 50 55 60 65 70 75 80 85 90 


67



Graph 1 above indicates a minor number of plots of below 10°F. This is a normal plot condition for a building 

that houses students. Night and weekend shut downs do not occur in residence buildings like they do in 

education buildings. 

It is unusual for the trend line to orient downward as the OAT rises. We attribute this to the ratio of FCUs to 

AHUs and the lack of outside air being introduced by the FCUs. It is also possible that over-cooling is 

occurring. This would not be unusual for a residence hall with limited DDC application. 

GRAPH 2 

30 

Lawrence Hall—September 1, 2011 


25 


20 

15 

10 

5 

0 


68


GRAPH 3 


90 

85 

80 

75 

70 

65 

60 

55 

50 

45 

40 

7/31/11 

Lawrence Hall 


8/5/11 

8/10/11 

8/15/11 

8/20/11 

8/25/11 

8/30/11 

9/4/11 

9/9/11 



GRAPH 4 


70 

65 

60 

55 

50 

45 

Lawrence Hall—September 1, 2011 




40 

7:12 PM 

12:00 AM 

4:48 AM 

9:36 AM 

2:24 PM 

7:12 PM 

12:00 AM 

69



Graphs 2, 3, and 4 above indicate that occupancy and chilled water flow are continuous, as would be 

expected. This data is consistent with the operating schedule established for the building and appears to track 

the AHU operating schedules well. 


The two-way valves on the AHUs and FCUs appear to be performing properly and are not having a negative 



• Take override control of fan coil unit chilled water control valves with the DDC system. 


• Install BTU chilled water meter in the ground floor mechanical room. 

• Balance water flow to AHUs and FCUs. 


70

15. Miller Learning Res. Center

Miller Learning Resource Center 





Usage Library/Instruction 

Load GPM 

Coolin 

Tons 

g 

EWT °F LWT °F 

Des 

Delt 

ign 

a T 

Information 

Source 

AHU-1 226 133 45 59.1 14.1 

Construction 

Documents 

AHU-2 290 172 45 59.2 14.2 

Construction 

Documents 

AHU-3 87 50 45 58.9 13.9 

Construction 

Documents 

AHU-4 49 29 45 59.3 14.3 

Construction 

Documents 

AHU-5 115 68 45 59.2 14.2 

Construction 

Documents 

AHU-6 22 13 45 59.2 14.2 

AHU-9 61 31 44 56 12 

Total 849 495 45 59.1 14.1 

Construction 

Documents 

Construction 

Documents 

Construction 

Documents 


(Fall-Spring) 



1100 200 730 200 730 200 730 200 730 200 730 1900 1000 2000 


(Summer) 


Saturday 


Closed 730 2200 730 2200 730 2200 730 2200 730 1900 Closed 

AHU Operating Schedule Sunday Monday Tuesday Wednesd ay Thursd ay Friday Saturday 


1000 2000 0630 0200 0600 0155 0600 0155 0600 0155 0630 0200 0900 1900 


1000 2000 0615 200 0615 200 0615 200 0615 200 0630 200 0900 1900 


1100 2000 0630 200 0630 200 0630 200 0630 200 0630 200 0900 1910 


1000 2000 0630 200 0630 200 0630 200 0630 200 0630 200 0900 1900 


0600 0600 0600 0600 0600 0400 0600 


No Schedule 1000 1200 No Schedule 1 000 1200 No Schedule 1000 1200 1000 1200 


0350 0350 0350 0350 0350 0350 0350 

y

15. Miller Learning Resources Center 

71



The James W. Miller Learning Resources Center opened in August of 2000. This state-of-the-art facility houses 

all materials and services usually found in a library, along with Learning Resources and Technology Services. 

The building includes hundreds of computers, a high-tech auditorium, seven electronic classrooms, 16 student 

study rooms, and a coffee shop. The building was named for a donor to the University's capital campaign. 


Seven AHUs provide winter heat and summer comfort cooling. Reheat systems are provided for 

dehumidification and comfort cooling air tempering. 

All seven AHUs are equipped with two-way control valves that modulate in response to load change. 

GRAPH 1 

30 

25 

Miller Hall 


y = 0.0986x + 12.347 


20 

15 

10 

5 

0 

45 50 55 60 65 70 75 80 85 90 




performance of two-way control valves on the building load. The application of the return water temperature 

control valve does not appear to be having the intended impact. 

The Delta T above 65°F OAT indicates that DDC programming prevents AHU shutdown as there are no 

indications of it reaching zero as expected. It is possible that this is planned and continuous AHU operation is 

necessary for proper humidity control, but there is no data to support that. The building occupancy schedule 

as well as the AHU start/stop schedules indicate normal education building schedules consistent with 

occupancy. 

72


GRAPH 2 

30 

Miller Center—September 1, 2011 


25 


20 

15 

10 

5 

0 


GRAPH 3 

70 

Miller Center 


65 


60 

55 

50 

45 



40 

7/31/11 

8/5/11 

8/10/11 

8/15/11 

8/20/11 

8/25/11 

8/30/11 

9/4/11 

9/9/11 

73


70 

GRAPH 4 

Miller Center—September 1, 2011 



65 

60 

55 

50 

45 



40 

7:12 PM 

12:00 AM 

4:48 AM 

9:36 AM 

2:24 PM 

7:12 PM 

12:00 AM 



desired setpoint until 11:00 PM throughout the week. It does not appear that pre-cooling occurs prior to 

occupancy and may not be necessary. 

This data is consistent with the operating schedule established for the building and does appear to track the 

AHU operating schedules well. 


The two-way valves on the AHUs appear to be performing properly and do not appear to be having a negative 








74

16. Performing Arts Center

Performing Arts Center 




Occupancy 251 


Load GPM 

Cooling 


Design 

Delta T 

Information 

Source 

F-1 90 45 42 54 12 

Construction 

Documents 

F-3 25 13 42 54 12 

Construction 

Documents 

F-5 24 12 42 54 12 

Construction 

Documents 

F-7 47 24 42 54 12 

Construction 

Documents 

F-10 59 30 42 54 12 

Construction 

Documents 

F-12 43 22 42 54 12 

Construction 

Documents 

F-14 123 72 42 56 14 

Construction 

Documents 

F-15 8.5 4 42 54 12 

Construction 

Documents 

F-16 9.2 5 42 54 12 

Construction 

Documents 

F-17 31 16 42 54 12 

Dual Temp System 40 20 42 54 12 

Total 500 260 42 54 12 

Construction 

Documents 

Construction 

Documents 

Construction 

Documents 


(Fall-Spring) 



800 2400 700 2400 700 2400 700 2400 700 2400 700 2400 800 2400 


(Summer) 



Closed 700 1700 700 1700 700 1700 700 1700 700 1700 Closed 

AHU Operating Schedule Sunday Monday Tuesday Wednesday Thursday Friday Saturday 

F-1 Start Stop Start Stop Start Stop Start Stop Start Stop Start Stop Start Stop 

1000 2200 0600 2200 0600 2200 0600 2200 0600 2200 0600 2200 1000 2200 


1200 1400 No Schedule 1200 1400 No Schedule 1200 1400 1500 1700 No Schedule 


No Schedule 1000 1300 No Schedule 1000 1300 No Schedule 1000 1300 1000 1400 


1000 2030 0700 2030 0700 2030 0700 2030 0700 2030 0700 2030 0700 2030 




No Schedule 1000 1400 No Schedule 1000 1400 No Schedule 1000 1400 No Schedule 




1000 1400 0600 1600 0600 1600 0600 1600 0600 1600 0600 1600 1000 1400 


0800 1600 0600 1700 0600 1700 0600 1700 0600 1700 0600 1700 0800 1600 


No Schedule 1500 1700 No Schedule 1500 1700 No Schedule 1500 1700 No Schedule 

Dual Temp System Start Stop Start Stop Start Stop Start Stop Start Stop Start Stop Start Stop 

No Schedule

16. Performing Arts Center 

75


General Building Information 

The Performing Arts Center was built in 1968. Music, theatre, film studies, and dance classrooms and offices 

are located in this building. There is also a 450-seat main theatre, studio theatre, 300-seat recital hall, 

rehearsal hall, and private practice studios. 


Ten AHUs located in two separate ground floor mechanical rooms provide winter heat and summer comfort 

cooling. Heating systems are turned off during cooling season and there is no apparent reheat provided for 

comfort cooling air tempering. All AHUs are equipped with two-way control valves that modulate in response 

to load change. System pressure is provided by the secondary distribution pumps located in the chilled water 

plant. A tertiary booster pump is located in Mechanical Room 1, but it has been disconnected and is not part of 

the distribution system. 

GRAPH 1 

30 

25 



y = 0.011x + 2.357 


20 

15 

10 

5 

0 

45 50 55 60 65 70 75 80 85 90 




performance of two-way control valves on the building load. The narrow band of Delta T is consistent with a 

pneumatic control system, as is the flat response to increases in OAT. The significant gap in the 3°F to 5°F 

range indicates a common control methodology is applied to all of the AHUs. Scheduling appears to be clockbased 

as opposed to use- and occupancy-based. 

76


GRAPH 2 

30 

Performing Arts Center—September 1, 2011 


25 


20 

15 

10 

5 

0 


70 

GRAPH 3 




65 

60 

55 

50 

45 



40 

7/31/11 

8/5/11 

8/10/11 

8/15/11 

8/20/11 

8/25/11 

8/30/11 

9/4/11 

9/9/11 

77


GRAPH 4 


70 

65 

60 

55 

50 

45 

Performing Arts Center—September 1, 2011 




40 

7:12 PM 

12:00 AM 

4:48 AM 

9:36 AM 

2:24 PM 

7:12 PM 

12:00 AM 



desired setpoint until 10 PM every day of the week. 

The return water temperatures are relatively inconsistent, indicating that there is variation in loads within this 

building or that the controls are not functioning as intended. While load variation is possible, control issues are 

more likely. 





• The Comprehensive Planning Report recommends upgrading the building in 11 to 25 years. The AHUs 

are unlikely to provide satisfactory service for that length of time given their age and condition. We 

normally would recommend upgrading controls to DDC and installing new two-way control valves on 

existing AHUs. In this case, we recommend new AHUs with VAV boxes and new controls throughout. 


• Install BTU chilled water meter in lower level mechanical room. 



78

17. Riverview

Riverview 






Load GPM 

Cooling 


Design 

Delta T 

Information 

Source 

AHU-1 76 38 44 56 12 

AHU-2 76 38 44 56 12 

Total 151 76 44 56 12 

Construction 

Documents 

Construction 

Documents 

Construction 

Documents 


(Fall-Spring) 

le 


Saturday 


Closed 700 2100 700 2100 700 2100 700 2100 700 1630 Closed 


(Summer) 

le 

Sunday Monday Tuesday Wednesday Thursda y 

Friday 

Saturday 


Closed 700 1700 700 1700 700 1700 700 1700 700 1630 Closed 


Saturday 





17. Riverview 

79

17. Riverview 


Riverview, built in 1911, houses the English department offices and classrooms along with foreign language 

laboratories. 


Two AHUs located in a renovated attic space provide winter heat and summer comfort cooling. Heating 


tempering 

Both AHUs are equipped with two-way control valves that modulate in response to load change. 

System pressure is provided by the secondary distribution pumps located in the chilled water plant. A tertiary 

booster pump is located in the lower level mechanical room, but it is being bypassed at this time. 

GRAPH 1 

30 

25 

Riverview 


y = 0.1943x - 2.3492 


20 

15 

10 

5 

0 

45 50 55 60 65 70 75 80 85 90 



Graph 1 indicates deviation in the Delta T across the range of outside air temperature that is consistent with 

the performance of two-way control valves on the building load. 

80

17. Riverview 

GRAPH 2 

30 

Riverview—September 1, 2011 

Time of Day vs Delta T 

25 


20 

15 

10 

5 

0 


GRAPH 3 

120 

Riverview 


110 


100 

90 

80 

70 

60 



50 

40 

7/31/11 

8/5/11 

8/10/11 

8/15/11 

8/20/11 

8/25/11 

8/30/11 

9/4/11 

9/9/11 

81

17. Riverview 

GRAPH 4 


85 

80 

75 

70 

65 

60 

55 

50 

45 

40 

7:12 PM 

Riverview—September 1, 2011 


12:00 AM 

4:48 AM 

9:36 AM 

2:24 PM 

7:12 PM 

12:00 AM 




Graphs 3 and 4 above indicate that there is significant chilled water heating during unoccupied, AHU-off hours. 

This is especially apparent on weekends. It appears that an external source is heating the water while it is 

dormant in the coils and connected piping. We recommend examining the heating valves on both AHUs to 

determine a possible cause. 

The graphs indicate that the building load commences around 7:00 AM and maintains the desired setpoint 

until 6:00 PM Monday through Friday with weekend shutdowns. 





• Identify the source of heat in AHUs during off-periods and correct the issue. 

• Evaluate the AHU schedule and modify it to mirror more uniformly the building’s occupancy schedules. 

• Install BTU chilled water meter in the lower level mechanical room in place of the existing flow meter. 



82

18. Stewart Hall







Load GPM 

Coo 

To 

S-1 92 39 

S-2 92 54 

ling 

ns EWT °F LWT °F 

Design 

Delta T 



S-3 128 86 No Information Available 




Total 879 354 44 56 12 

Information 

Source 

Construction 

Documents 

Construction 

Documents 

Construction 

Documents 

Construction 

Documents 

Construction 

Documents 

Construction 

Documents 

Construction 

Documents 


(Fall-Spring) 

Sunday Monday Tuesday W ednesday Thursday Friday 

Saturday 


Closed 515 2200 515 2200 515 2200 515 2200 515 1900 1230 2100 


(Summer) 


Saturday 


Closed 515 2200 515 2200 515 2200 515 2200 515 1900 Closed 


Saturday 


0800 0800 0800 0800 0800 0800 0800 


0800 0800 0800 0800 0800 0800 0800 


0700 1710 0600 2130 0600 2130 0600 2130 0600 2130 0600 2130 0700 1710 


0700 1700 0600 2145 0600 2145 0600 2145 0600 2145 0600 2145 0700 1700 


No Schedule 


No Schedule

18. Stewart Hall 

83



Named for Warren Stewart, State University Board member from 1938–1948, Stewart Hall was built in 1948 

and remodeled in 1988–1990. This building includes classrooms, offices, student media facilities, a TV studio, 

a radio station, and the 1,000-seat Kimberly Ritsche Auditorium. 


Six AHUs located in the penthouse mechanical rooms provide winter heat and summer 

comfort cooling. Heating systems are turned off during cooling season and there is no 

apparent reheat provided for comfort cooling air tempering. 

AHUs are equipped with three-way control valves that 

modulate in response to load change. 

Tertiary pumps located in Mechanical Room 19A provide 

system pressure. 

An auxiliary chiller is located on the roof to provide off-season cooling for the radio 

station equipment and systems serving that area of Stewart Hall. 

GRAPH 1 



y = 0.0767x + 8.414 

30 

25 


20 

15 

10 

5 

0 

45 50 55 60 65 70 75 80 85 90 


84



Graph 1 above demonstrates the 24/7 operation of cooling systems in Stewart Hall. There is no equalization of 

temperature between supply and return, indicating that load is scheduled continuously. AHU-1 and AHU-2 

schedules in DDC do not have a shutdown time even though the building occupancy is scheduled to end each 

day at 10:00 PM. Scheduling should be reviewed and evaluated for consistency with occupancy and required 

loads. 

Graph 1 also demonstrates a gradually increasing Delta T as OAT increases, indicating proper response to load 

conditions. The significant Delta T of less than 20°F demonstrates the control impact of the return water 

temperature control valve. 

Standard three-way valves can only achieve Delta T in this range at full load conditions when the AHU is riding 

the cooling coil curve. 

GRAPH 2 

30 

Stewart Hall—September 1, 2011 


25 


20 

15 

10 

5 

0 


85


GRAPH 3 

70 




65 

60 

55 

50 

45 



40 

7/31/11 

8/5/11 

8/10/11 

8/15/11 

8/20/11 

8/25/11 

8/30/11 

9/4/11 

9/9/11 

GRAPH 4 

Stewart Hall—September 1, 2011 



70 

65 

60 

55 

50 

45 



40 

7:12 PM 

12:00 AM 

4:48 AM 

9:36 AM 

2:24 PM 

7:12 PM 

12:00 AM 

86



Graphs 2, 3, and 4 above indicate continuous load as discussed above. The variation in return water 

temperature demonstrated in Graph 2 results from lack of load, probably during the unoccupied hours. 


The three-way valves on the AHUs are performing properly in response to their control signals but contribute 

significantly to the over-pressurization of the return loop discussed in the Distribution Loop section of this 

report. Return water temperatures in the 60–65°F range indicate that the return-to-supply valve is too far 

open far and is affecting AHU performance. It is interesting to note that the position of the valve handle 

changed between two of our site visits, a span of four weeks. The purpose of this valve and its contribution to 

building HVAC system performance needs to be reviewed. 

It is doubtful that the AHUs are achieving discharge air setpoints in this operating mode. 


• The three-way valves need to be replaced with two-way valves. 

• Properly tune individual AHU control valves upon installation. 

• Add VFD control to tertiary pumps. 


• Close or blank off supply-to-return cross-connect. 




87

19. Student Rec Center

Student Recreation Center 





Usage Athletic/Recreation 

Load GPM 

Cooling 


Design 

Delta T 

Information 

Source 

AHU-1 413 224 45 58 13 

AHU-2 103 57 45 58.3 13.3 

Total 516 281 45 58 13 

Construction 

Documents 

Construction 

Documents 

Construction 

Documents 


(Fall-Spring) 

le 


Saturday 


1200 2300 600 2300 600 2300 600 2300 600 2300 600 2300 900 1800 


(Summer) 

le 


Saturday 


Closed 900 1930 900 1930 900 1930 900 1930 700 2000 Closed 


Saturday 


1100 2300 0600 2300 0600 2300 0600 2300 0600 2300 0600 2300 0800 1800 


0700 2200 0700 2200 0700 2200 0700 2200 0700 2200 0700 2200 0700 2200

19. Student Recreation Center 

88



The Student Recreation Center (SRC), built in 2004 with student fee funds, has the largest rock-climbing wall 

in the area and over $400,000 worth of state-of-the-art fitness equipment for student and community 

recreational use. 


Two AHUs located in a penthouse mechanical room provide winter heat and summer comfort cooling. Heating 


tempering. 

AHUs are equipped with two-way control valves that modulate in response to load change. 

Delivery piping—eight-inch supply and return—is significantly oversized for the load. We believe that the large 

pipes are intended to serve Halenbeck Hall when chilled water is added to AHUs in that facility. 

Tertiary pumps located in the ground floor mechanical room provide system pressure. These pumps are 

downstream of the future load take-offs and are not intended to boost pressure beyond the needs of the SRC. 

GRAPH 1 

30 

25 

Student Rec Center 

OAT vs Delta T 

y = 0.1408x + 5.801 


20 

15 

10 

5 

0 

45 50 55 60 65 70 75 80 85 90 



Graph 1 above indicates deviation in the Delta across the range of outside air temperature that is consistent 

with the performance of two-way control valves on the building load. The consistency of Delta T with no 

indications of being below 7°F suggests that AHU operation is not scheduled while other data indicates 

response to a daily schedule. This inconsistency requires further investigation. 

89


GRAPH 2 

30 




25 


20 

15 

10 

5 

0 


GRAPH 3 


80 

75 

70 

65 

60 

55 

50 

45 

40 

7/31/11 



8/5/11 

8/10/11 

8/15/11 

8/20/11 

8/25/11 

8/30/11 

9/4/11 

9/9/11 



90


GRAPH 4 


70 

65 

60 

55 

50 

45 






40 

7:12 PM 

12:00 AM 

4:48 AM 

9:36 AM 

2:24 PM 

7:12 PM 

12:00 AM 



desired setpoint until 10:00 PM every day of the week. 





• Investigate and resolve issues with scheduling and system performance. 





91

20. Wick Science Building

Wick Science Building 




Occupancy 937 


Load GPM 

Cooling 


Design 

Delta T 

Information 

Source 

SF-1 150 63 44 54 10 

Construction 

Documents 

SF-2 160 67 44 54 10 

Construction 

Documents 

SF-3 170 71 44 54 10 

Construction 

Documents 

SF-4 150 63 44 54 10 

Construction 

Documents 

SF-5 170 71 44 54 10 

Construction 

Documents 

SF-6 150 63 44 54 10 

Construction 

Documents 

SF-7 175 73 44 54 10 

SF-8 140 58 44 54 10 

Total 1265 527 44 54 10 

Construction 

Documents 

Construction 

Documents 

Construction 

Documents 


(Fall-Spring) 



Closed 700 2200 700 2200 700 2200 700 2200 700 1700 Closed 


(Summer) 



Closed 700 1700 700 1700 700 1700 700 1700 700 1700 Closed 

AHU Operating Schedule Sunday Monday Tuesday Wednesday Thursday Friday Saturday 

SF-1 Start Stop Start Stop Start Stop Start Stop Start Stop Start Stop Start Stop 

0600 0600 0600 0600 0600 0600 0600 


0800 0800 0800 0800 0800 0800 0800 




0600 0600 0600 0600 0600 0600 0600 








0600 0600 0600 0600 0600 0600 0600

20. Wick Science Building 

92



In addition to classrooms and laboratories, this four-story structure houses the Dean’s office for the College of 

Science and Engineering, a planetarium, greenhouse, observatory, meteorology laboratory, and aquariums. 

The building, completed in 1973 as the Mathematics and Science Center, was rededicated in 2005 to honor 

former SCSU President Robert H. Wick. 


Eight AHUs located in penthouse mechanical rooms provide winter heat and summer comfort cooling. Heating 

systems remain on during the cooling season to provide reheat for humidity control and comfort cooling air 

tempering. 

AHUs have been modified and are now equipped with two-way control valves that modulate in response to 

load change. 

The distribution pumps located in the central chilled water plant provide system pressure. There are no 

tertiary pumps in the Wick Science Building. 

GRAPH 1 

30 

25 



y = 0.0822x + 6.7933 

CHW Delta T(°F) 

20 

15 

10 

5 

0 

45 50 55 60 65 70 75 80 85 90 



Graph 1 above indicates good control of chilled water to this building. The inconsistency in zero Delta T data 

points is normal for buildings with heavy exhaust requirements, especially where fume hoods are applied. The 

Delta T does remain consistently in the 9–16°F range during load periods. The number of data points on the 

zero line indicates economizer controls are working well and chilled water is not required to satisfy space 

temperatures during these conditions. 

93


GRAPH 2 

30 

Wick Science Building—September 1, 2011 


25 

CHW Delta T(°F) 

20 

15 

10 

5 

0 


94


GRAPH 3 


70 

65 

60 

55 

50 

45 





40 

7/31/11 

8/5/11 

8/10/11 

8/15/11 

8/20/11 

8/25/11 

8/30/11 

9/4/11 

9/9/11 

GRAPH 4 

70 

Wick Science Building—September 1, 2011 



65 

60 

55 

50 

45 



40 

7:12 PM 

12:00 AM 

4:48 AM 

9:36 AM 

2:24 PM 

7:12 PM 

12:00 AM 

95



The data demonstrated in graphs 2, 3, and 4 above is consistent with the data in the Delta T graph and is 

consistent with science education buildings. The higher-than-usual supply water temperature appears to be 

the result of faulty temperature probe placement that has been demonstrated in other data collection areas. A 

6–8°F error appears to be consistent with contact-style probes being placed on the surface of chilled water 

pipes. All indications are that the control system in this building is performing correctly and adequately. 


The two-way valves on the AHUs appear to be performing properly and are not having a negative impact on 

the chilled water distribution system. The proximity of this building to the central chilled water plant may 

make tertiary pumps unnecessary. Modifications to the distribution loop may alter this and result in pumps 

being added. 


• Evaluate impact of distribution system modifications on Wick chilled water supply. 


• Install BTU chilled water meter in the penthouse mechanical rooms. 



96

21. Wick Addition

Wick Science Building Addition 






Load GPM 

Cooling 


Design 

Delta T 

AHU-1 702 410 42 56 14 

Total 702 410 42 56 14 

Information 

Source 

Construction 

Documents 

Construction 

Documents 


(Fall-Spring) 

le 


Saturday 


Closed 700 2200 700 2200 700 2200 700 2200 700 1700 Closed 


(Summer) 

le 


Saturday 


Closed 700 1700 700 1700 700 1700 700 1700 700 1700 Closed 


Saturday 

AHU - 1 

Start Stop 

Start Stop Start Stop 



Start Stop Start Stop 


21. Wick Addition 

97



The addition to the Wick Science Building was completed in 2008 and has functionality similar to the main 

science building. It contains classrooms and laboratories. 


A single AHU located in the ground floor mechanical room provides winter heat and summer comfort cooling, 

and utilizes heat recovery from the exhaust air stream to satisfy part of its load. Heating systems remain on 

during the cooling season to provide reheat for humidity control and comfort cooling air tempering. 

AHUs are equipped with two-way control valves that modulate in response to load change. 

System pressure is provided by the distribution pumps located in the central chilled water plant. Tertiary 

pumps are located in the ground floor mechanical room but are not required for pressure boosting. 

GRAPH 1 

30 



y = 0.1506x - 0.8237 

25 


20 

15 

10 

5 

0 

45 50 55 60 65 70 75 80 85 90 



Graph 1 above indicates excellent control of chilled water to this building. Delta T does remain consistently in 

the 8–15°F range during load periods. The significant number of data points on the zero line indicates setback 

conditions are responding correctly to scheduled operation. 

98


GRAPH 2 

30 


August 26, 2011* 


25 


20 

15 

10 

5 

0 


* There is no data available for Sept. 1, 2011, so the next available design day data was used. 

GRAPH 3 

70 

Wick Addition Science Building 


65 


60 

55 

50 

45 



40 

7/31/11 

8/5/11 

8/10/11 

8/15/11 

8/20/11 

8/25/11 

8/30/11 

9/4/11 

9/9/11 

99


GRAPH 4 


70 

65 

60 

55 

50 

45 

40 

7:12 PM 


August 26, 2011* 


12:00 AM 

4:48 AM 

9:36 AM 

2:24 PM 

7:12 PM 

12:00 AM 




Graphs 2, 3, and 4 above are not consistent with the data indicated in the Delta T graph. The frequency of 

zero deviation in Delta T does not manifest on any of the single-day graphs. This is an indication of a bypass 

valve operating in opposition to the AHU control valve, but there was no indication of this valve type being 

applied to this building. 


The two-way valve on the AHU is performing properly and is not having a negative impact on the chilled water 

distribution system. 


• Investigate and resolve questions with scheduling and system performance. 


• Install BTU Chilled water meter in the ground floor mechanical room. 


• Review and reconfigure tertiary pump operation after distribution loop modifications are made. 


100

Exhibit U - SCSU Chilled Water Study Report - St. Cloud State ...

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