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RETROCOMMISSIONING – AUDIT REPORT

DECEMBER 2, 2013

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EXECUTIVE SUMMARY

was contracted by to complete audit phase retrocommissioning services at the . is an 81,856 ft2 building that houses college

and high school science classes, research labs, fitness center, auditorium and offices. The building was completed in 1998.

Retrocommissioning (RCx) is a collaborative process with the RCx consultant and building staff that evaluates how a building system is operated and maintained, and then identifies ways to improve overall building performance including thermal comfort, energy performance, indoor air quality and system functionality. The RCx process at the Science Center consisted of 2 phases, an audit phase and an implementation phase including verification. The scope of investigation was limited to the HVAC system.

The RCx team participated in the Focus on Energy RCx program as well as the Focus on Energy customer business incentive program. These programs provide financial rebates based on the total energy savings implemented.

Prior to beginning the audit phase, reviewed the building’s utility data. For a 1 year period in 2012, the college spent $254,000 on electric and gas utilities. Compared to other similar lab and educational buildings, the Science Center energy intensity is approximately average.

identified numerous energy efficiency opportunities during the RCx audit.

’s estimated a total savings of $52,501/year in gas and electric costs. The implementation cost was estimated to be $230,000 and the total Focus on Energy rebate is estimated to be $35,000.

Table 1: Summary of Savings

Electric Savings Gas Savings

Cost Savings

Cost Avoidance

Simple Payback

Implementation Cost

26% 46% 21% $52,501/yr 4.4 yrs ~$230,000

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TABLE OF CONTENTS

EXECUTIVE SUMMARY ....................................................................................................................................... 1

INTRODUCTION.................................................................................................................................................. 3

SCIENCE CENTER OVERVIEW ............................................................................................................................... 4

PRELIMINARY ENERGY‐USE ANALYSIS ................................................................................................................ 6

BUILDING SYSTEM DESCRIPTIONS ..................................................................................................................... 12

HVAC ................................................................................................................................................................... 12

RECOMMENDED ENERGY EFFICIENCY MEASURES .............................................................................................. 18

Overview ............................................................................................................................................................. 18 Recommended Measures .................................................................................................................................... 19

ADDITIONAL RECOMMENDATIONS ................................................................................................................... 26

Overview ............................................................................................................................................................. 26

IMPLEMENTATION PLAN ................................................................................................................................... 28

ENERGY EFFICIENCY MEASURES FOR FUTURE IMPLEMENTATION ...................................................................... 30

Overview ............................................................................................................................................................. 30 Future Measures ................................................................................................................................................. 30

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INTRODUCTION

This report summarizes the retrocommissioning process that was completed at the . ( ) was hired by to

complete an extensive building retrocommissioning (RCx) process through the Focus on Energy Retrocommissioning program. This program provides incentives to the building owner based on the total energy savings of the implemented measures. The first phase of this project included the audit portion of the RCx process only.

The project timeline is summarized below.

The following systems were evaluated during the RCx process:

Heating, Ventilation, and Air Conditioning (HVAC) Equipment and Controls

This report summarizes the findings that were identified during the study. This report is intended to provide the building manager and staff with a record of existing building operation and summarize the estimated savings from each of the measures that were identified.

As part of the RCx process, the RCx team functionally tested all major HVAC equipment, including all the AHUs, chilled water system, hot water system and terminal units. The audit phase of the project included approximately 8 visits.

Project Stage Dates Completed RCx Audit Kickoff July 2, 2013 Audit Phase July 2013 through November 2013 Implementation Phase TBD Verification Phase TBD Persistence Phase TBD


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SCIENCE CENTER OVERVIEW

is an 81,120 ft2, four story science education building located on the campus of in . The building houses classrooms, offices, laboratory facilities, laboratory support spaces, fitness center and large lecture hall. The also utilizes a number of classrooms in the facility. There are approximately 50 fume hoods throughout the facility. The building is used during the academic year as well as during the summer session. The building also hosts summer conferences.

The building was constructed in 1998. The building consists of 6 levels, including lower level, 1st, 2nd, 3rd, 4th floors and a mechanical penthouse located above the 4th floor. There is a parking ramp located on the back side of the building.

Figure 1: Aerial view of [building]

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Since the 1998 opening of the building there have been fairly few modifications to the building systems, except the following changes:

RM 402 (old room #420) hoods, supply and exhaust boxes were replaced with a new Phoenixcontrols system that replaced the original Anemostat system in approximately 2011

As part of an energy efficiency project, the AHU and exhaust fan controls were upgraded frompneumatic control to digital control.

o The exhaust fans were tied into the DDC system so that they could be scheduled offwhen the hoods were not in use.

o The AHU’s could also be scheduled more effectively using the DDC system.o EF‐21 and 22 were installed for chemical storage cabinets so that exhaust fans

associated with hoods could be shut down and not run 24/7 because they were alsopreviously connected to chemical storage cabinets.

VFD’s were added to the hot water distribution pumps.

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PRELIMINARY ENERGY‐USE ANALYSIS

Electric and gas utility data were compiled for electric and gas utility data and are shown in the tables and graphs below. The 2007 MGE walk‐through audit also included the 2007 utility consumption, which is included below for reference.

There is limited data available to benchmark the Science Center to other similar educational facilities. EPA portfolio manager does not currently have a category for college science buildings or college buildings in general. K‐12 buildings are benchmarked in the portfolio manager system, but comparing the science center to a K‐12 building is not reasonable because the science center has longer hours than K‐12 facilities and also has much more intensive use, especially with the fume hoods.

Energy Benchmarks for Science Center‐2012

Area [ft2]

Energy Use Intensity ‐

Site [kBTU/ft2/yr]

Energy Use Intensity ‐ Source

[kBTU/ft2/yr]

Energy Cost [$/yr]

Energy Cost Intensity [$/ft2/yr]

81,856 236 416 $ 254,727 $ 3.21

Energy Consumption from 2007 and 2012

Year Electric (kW‐hr)

Max Peak Demand (kW)

Natural Gas (Therms)

2012 1,767,045 417 133,000

2007 1,718,127 ‐ 102,116

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was able to do some benchmarking to buildings that we have previously worked on and also used the Labs21 benchmarking tool to benchmark the Science Center. The results of this comparison are shown in the table below.

Similar Buildings Square Footage kBtu/Sq. Ft.

Seamans Center 247,116 190.0 Avg. Building in region w/ Lab space N/A 223.0

81,856 236.2 Medical Education Research Facility 214,536 410.0 Carver Biomedical Research Building 134,628 480.0 Bowen Science Building 324,000 490.0 U of Iowa Pharmacy Building 142,968 710.0

Overall, the Science Center energy intensity would be considered average when comparing the building to other lab facilities. However, the lab use in the Science Center is intermittent and one would expect significantly lower energy intensity when comparing the building to intensive lab buildings. Based on peer buildings, good target site energy intensity would be 165 kBtu/ft2‐yr, which is a 30% reduction in the building current energy use. 100 kBtu/ft2‐yr for the Science Center would be exceptional energy use and is a 58% reduction in energy consumption.

Figure 2: Target Energy Performance Goal Based on Other Buildings and Existing Building Usage

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165

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Current Energy Use Target EnergyPerformanceS

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rgy Intensity

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Target Energy Performance


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Figure 3: Electricity Consumption History

Electric consumption shows a pattern typical of a building with electric cooling and gas heating with a significant increase in electricity consumption in the warm months. Due to the large amount of outside air brought in for hood make‐up air, the summer consumption is double the winter electric consumption due to high chiller energy consumption.

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Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

kW‐hr

Electric Consumption

2011 2012 2013

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Figure 4: Peak Demand History

Peak electric consumption is indicated in the figure above. Peak electric consumption is fairly typical, except one would not expect the peak values to plateau over so many months. The high peak values in the shoulder season indicate that the chiller plant is unable to operate efficiently at low load, or that there could have been one very hot day in each of these months that caused a spike in the kW, as the graph is indicating that maximum kW in each of the months, not an average, as indicated in the graph below.

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kW

Peak Electricity Demand

2011 2012 2013

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Figure 5: Average Peak kW by Month

15 minute electric demand information was analyzed for the period from July 2012 through July 2013. Based on the 15 minute average demand profiles, there is enormous opportunity in savings. For example, the July 2012 demand profile indicates that electric consumption is fairly constant throughout the day. This indicates that the chiller and air handlers are running 24/7 at near full capacity. This indicates opportunity for equipment scheduling.

The winter peak demand is more typical profile. However, there is opportunity to further reduce the unoccupied standby power, which is currently around 125kW.

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Figure 6: Gas Consumption History

Gas consumption also follows the traditional usage pattern, with an increase in the winter months due to space heating. Gas usage in the summer remains significant due to the reheat for the reheat boxes associated with the HVAC system air handlers. There is also some gas usage associated with domestic hot water. The summer gas usage should not be as high as indicated. One would expect summer gas usage to be about 10‐15% of the peak winter gas usage. The RCx process will further investigate how to reduce reheat energy in the facility.

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Therms

Gas Consumption

2011 2012 2013

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BUILDING SYSTEM DESCRIPTIONS

HVAC

Air Distribution System

The building is served by three indoor air handling units. All air handling units have chilled water and hot water coils, variable speed supply and return fans, steam humidification and serve variable air volume boxes. The air handlers have a combination of pneumatic and electric actuators, but are controlled entirely by the building BAS. RC Studio is utilized for the BAS front end.

Figure 7: Sample Screenshot from RC Studio BAS

AHU‐1, the unit that serves the basement and 1st floor is located in the basement mechanical room. AHU‐2 and AHU‐3 are located in the penthouse above the 4th floor. AHU‐2 serves the 2nd and 3rd floors, while AHU‐4 serves the 4th floor. AHU‐3 is different from the other air handlers, in that there is no relief air and the unit is an 89% outside air unit that is designed to provide mostly make‐up air for the numerous hoods located on the 4th floor.

Air Handler Summary

Tag Type Unit

Design Cfm

Location Serves

AHU‐1 VAV 18,120 Basement Basement and 1st floor

AHU‐2 VAV 38,250 Penthouse 2nd floor and 3rd floor

AHU‐3 VAV 41,500 Penthouse 4th floor

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There are a total of 22 exhaust fans in the building. Most of these fans serve hood exhaust. The other exhaust fans are for general bathroom exhaust and mechanical room space cooling in the warm months.

On the exhaust fan used for hood exhaust there is a make‐up box that is used to maintain a minimum exhaust plume velocity. This ensures that contaminant exhaust is removed and diluted with ambient air at a rate that avoids chemical laden air coming into contact with the building or being brought down the sides of the building with any downdrafts that occur as the wind moves around the building. The make‐up box damper is controlled by the Anemostat master controller which regulates flow based on the total exhaust flows from the associated exhaust boxes in the spaces. A schematic of this exhaust system is shown in the figure below.

Figure 8: Exhaust Fan Make Up Box Schematic

Terminal Units

The air handlers serve VAV boxes that communicate with the local zone thermostats to maintain space temperature setpoints.

There are three typical terminal unit configurations in the spaces:

Standalone pneumatic VAV boxes with no hoods Standalone pneumatic VAV boxes with hood controlled by Anemostat exhaust box and general

exhaust. Anemostat DDC supply VAV with multiple hoods. Exhaust box on each hood and 1 general

exhaust box per room controlled by Anemostat DDC system

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The majority of the VAV boxes are stand‐alone pneumatic boxes that do not communicate with the BAS. This configuration is illustrated in the figure below.

Figure 9: Stand Alone Pneumatic VAV Schematic

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For the spaces that have only one or two fume hoods in the spaces, such as Rm 312 or 314, there is a standalone pneumatic VAV supply box, with an Anemostat‐controlled exhaust box for general exhaust and the hood exhaust. The exhaust boxes are controlled such that there is a constant volume of air being exhausted from the space regardless of the sash position. Therefore, the face velocity on the hood is maintained at 100 fps and the total volume (cfm) being exhausted from the hood changes based on sash position through the hood exhaust box damper position modulation. The general exhaust will modulate its damper to maintain a constant exhaust cfm for the entire room.

The configuration for the “hybrid” system with both pneumatic supply boxes and Anemostat exhaust boxes is illustrated below.

Figure 10: Hybrid Pneumatic and Anemostat DDC System Schematic

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For hood intensive areas, the VAV boxes are part of the Anemostat hood control system. The Anemostat system is a vintage DDC system that was installed during the original construction. The front end for this system is located in room 113A. While the system is dated, it has all the features of the latest variable volume hood control systems. The system is intended to maintain space temperature, provide make‐up air for the hoods, and maintain the space at a slight negative pressure. The supply VAV boxes work in conjunction with the exhaust boxes and hood controls. The following is the sequence of operation for the components of the system:

Hood exhaust box modulates damper position to maintain a constant 100 fpm face velocity atthe hood sash. This allows the total exhaust volume to be reduced as the hood is lowered.

General exhaust box modulates damper position to maintain a fixed offset between the totalsupply air and total exhaust air to maintain the lab at slightly negative pressure.

Supply boxes modulate to maintain space temperature and supply make up air quantity tooffset the exhaust losses from hoods.

The Anemostat supply and exhaust system was replaced in Rm 402 in approximately 2011 with a Phoenix controls system. This system is tied into the RC Studio’s BAS but controlled with local Phoenix controllers. This is the only space that has been retrofitted in the facility.

Figure 11: Anemostat Supply and Exhaust System for Intensive Lab Spaces Schematic

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Heating System

Heating is provided by (2) 4400 MBH non‐condensing natural gas fired boilers located in the basement boiler room. These units serve the building reheat coils, air handler hot water coils, fin tube radiators and the domestic hot water heat exchanger.

The boiler system layout is a variable volume primary system with lead/lag pumps on variable speed drives. Fin tube radiators and cabinet unit heaters are located throughout the building in perimeter spaces. The units have standalone thermostats and are not tied into the BAS.

There is also an 837 MBH steam boiler that provides steam for the AHU humidifiers and some lab loads.

Cooling System

A 400‐ton Trane rotary screw water cooled chiller provides chilled water for the buildings air handlers. The unit capacity is large relative to the building to handle the large amount of outside air that may be needed to provide make‐up air for the large number of hoods. However, typically in the summer months the hoods will be off, and the cooling capacity is much greater than the actual demand.

The cooling tower is located on the roof. The unit has both low and high speed fan operation.

The chilled water piping configuration is a constant volume primary only setup. The lead/lag pumps for the system are located in the basement boiler room.

DOMESTIC WATER HEATING

Domestic hot water is provided to the building through a heat exchanger. The hydronic hot water system supplies 180°F water to the heat exchanger and 120°F is produced on the domestic side.

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RECOMMENDED ENERGY EFFICIENCY MEASURES

OVERVIEW

The following energy efficiency measures (EEMs) were recommended as part of the Science Center RCx energy audit. The ID#’s nomenclature is as follows:

“M” prefix are proposed measures for the Focus RCx program. “C” prefix are measures for the custom business incentive program

The total annual savings of all the measures submitted for incentives was calculated to be $52,501. The total cost of implementation is approximately $156,100 for a simple payback of 3.0 years.

The Focus on Energy RCx program maximum incentive is $0.20/ft2 or $16,371. Based on the RCx measures M1 through M5, the RCx incentive is maxed out.

Measure C1 is being submitted as a custom business incentive. This program provides incentives of $0.80/therm and $0.04/kW‐hr. The total incentive for C1 is estimated to be $19,500.

The table below summarizes the estimated savings for measures M1 through M5 and C1.

Table 2: Summary of Savings

Table 3: Recommended Measure Summary

Electric Savings Gas Savings Cost Savings Cost Avoidance Simple Payback

26% 46% 21% $52,501/yr 3.0 yrs

ID# EEM Electricity Savings (kWh/yr)

Natural Gas Savings

(Therm/yr)

Cost Savings ($/yr)

Estimated Installed Cost ($)

Payback(yrs)

M1 Schedule AHU's 1 and 2 266,568 32,806 $21,324 $100 0.1

M2 Fix HW valve leak on AHU‐2 40,779 14,716 $10,620 $1,000 0.1

M3 Fix CW valve leak on AHU‐1 4,656 794 $769 $1,000 1.0

M4 Fix AHU‐2 Mixed Air Damper Issues 8,954 ‐ $716 $1,000 1.3

M5 Modify Rm 402 VAV Control 11,460 2,012 $1,923 $3,000 1.3

C1 Pneumatic VAV Upgrade and Design Flow Mods 91,761 12,382 $17,149 $150,000 8.7

Implemented Total 424,178 62,710 $52,501 $156,100 3.0

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RECOMMENDED MEASURES

EEM #M1 – Modify Air Handler Schedules

Electricity Savings (kWh/yr)

Natural Gas Savings

(Therm/yr)

Energy Cost Savings ($/yr)

Estimated Implementation

Cost ($)

Payback (yrs)

266,568 32,806 $ 21,324 $ 100 0.1

All air handlers were set to run 24/7. It is not clear why all the air handlers were set to run 24/7. Based on conversations with the controls contractor, there were schedules established previously for the air handlers. However, there was some turnover in the facilities department and it is possible that the schedules were removed at some point.

recommends that AHU‐1 and AHU‐2 are scheduled to better match the building occupancy.

AHU‐1 can most likely be scheduled to match the fitness center hours, as it tends to be thespace used over the widest range of hours.

AHU‐2 can be scheduled to reflect general building occupancy which appears as indicated in thetable below.

AHU‐3 needs to run to provide make up air for the exhaust fans that run 24/7 for the chemicalstorage area. This includes EF‐3, 21 and22 for a total 24/7 exhaust volume of 5,035 cfm. It isrecommended that an unoccupied sequence is created for AHU‐3, such that it will maintain aconstant volume of supply air to make up for the exhaust hoods. Additionally, the anemostatboxes need to be controlled such that they remain closed during this unoccupied mode ofoperation unless they are being used to supply make‐up air for the 24/7 exhaust fans.

Figure 12: Starting Point for Schedule Modifications

AHU Season M T W R F Sat Sun Comments

AHU‐1 Academic Hours 6a‐9p 6a‐7p 7a‐6p 1p‐9p Match fitness center hours Summer Hours 7a‐7p ‐ ‐

AHU‐2 Academic Hours 6a‐8p 6a‐6p 8a‐6p ‐ Summer Hours 7a‐7p ‐ ‐

AHU‐3 Academic Hours On 24/7 Supply make‐up air for 24/7 exhaust

fans Summer Hours On 24/7

It is anticipated that the schedules will need to be adjusted slightly during implementation.

Implementing an optimal routine start for the air handlers is another way to reduce AHU runtime, as well as eliminate outside air when the units are in warm up mode.


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EEM #M2– Fix How Water Leak on AHU‐2


Natural Gas Savings

(Therm/yr)



Cost ($)

Payback (yrs)

40,779 14,716 $ 10,620 $ 1,000 0.1

Upon investigation of operation on AHU‐2, it was discovered that the hot water coil valve was consistently leaking and heating the air even when the hot water coil valve was commanded closed.

Figure 13: AHU‐2 indicating the hw valve closed but still heating over coil

This valve should be replaced with a functional 2‐way valve. As discussed in the additional measures list, there is a VFD on the hot water pump and a 3‐way valve is no longer needed, especially if a d.p. sensor is added to control the HW pump, rather than controlling the pump based on outdoor air temperature.

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Figure 14: AHU‐2 Leaky HW Valve

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EEM #M3– Fix Hot Water Leak on AHU‐2


Natural Gas Savings

(Therm/yr)



Cost ($)

Payback (yrs)

4,656 794 $769 $1,000 0.1

During investigation, it was noticed that the chilled water coil valve, when commanded closed, appeared to leak. This leak was evidenced by the large temperature difference between discharge air and mixed air.

Figure 15: AHU‐1 CW Valve Leak

This valve should be replaced or repaired. If the system is converted to a variable volume chilled water system, this valve should be replaced from a 3‐way valve to a 2‐way valve.

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EEM #M4– Fix AHU‐2 Mixed Air Damper Issues


Natural Gas Savings

(Therm/yr)



Cost ($)

Payback (yrs)

8,954 ‐ $716 $1,000 1.3

AHU‐2 mixed air damper was commanded closed, but remained 20% open. This is causing the economizer function to operate at a less than optimal rate because the mixed air temperature setpoint cannot be achieved. Based on BAS data, the economizer can only operate at 60% OA levels, not 100%

Figure 16: AHU‐2 Mixed Air Damper Control Issues

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EEM #C1– Pneumatic VAV Upgrade


Natural Gas Savings

(Therm/yr)



Cost ($)

Payback (yrs)

91,761 12,382 $17,149 $150,000 8.7

As described in the building description section, most of the VAV boxes in the building are pneumatically controlled and not connected to the building automation system. While pneumatic controlled boxes are generally reliable, pneumatic control limits the functionality of the system in regards to scheduling, temperature setbacks, occupancy sensors and other optimization strategies for VAV systems.

The proposed retrofit would remove the existing 63 standalone pneumatic boxes and replace them with DDC boxes and thermostats. The upgrade would enable the system to be optimized in the following ways:

Standby mode can be added to VAV boxes such that the box minimum flow can be reset to alower flow or zero when the space is not occupied as determined by a zone schedule or localoccupancy sensor. Additionally, the temperature setpoints can be relaxed during this standbymode

Unoccupied mode can be added for the VAV boxes that are associated with air handlers thatcurrently run 24/7 to satisfy the make‐up air requirements of the 24/7 exhaust fans

Duct static pressure reset for the air handlers can be programmed to reduce the duct staticpressure based on the box demand

Revise AHU discharge temperature reset based on feedback from the VAV boxes and zones Units that were scheduled 24/7 can now be scheduled because boxes can turn AHU's back on if

spaces go out of unoccupied temperature setback/setup range Optimal start/stop sequence can be utilized so that programmed schedules are not overly

generous to account for the worst case warm‐up period on a design hot or cold day Optimize box control utilizing the discharge air temperature sensor Demand control ventilation for auditorium space using CO2 sensor in the space Local stat override to turn on AHU if scheduled off to allow for more off time than what can be

done currently Install demand control ventilation in the auditorium space to reset VAV box minimums Peak shaving by modifying room setpoints as building kW approaches predefined threshold Close VAV hot water valves when AHU’s are off to reduce HW pump energy

In addition to the DDC VAV box retrofit, the minimum flows for the boxes should be recalculated. The original minimum flows were quite large and assumed that the hoods would be running all the time. The new minimum flows should be determined for the following operating modes: associated hood on,

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hood off and room vacant and hood off and room occupied. There is significant savings in revising the minimum flow requirements for the boxes.

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ADDITIONAL RECOMMENDATIONS

OVERVIEW

In addition to the energy efficiency measures documented above, the RCx team also identified additional issues that will improve the building performance. None of these issues by itself has a very large energy impact, but in aggregate there is significant savings in completing all these items and therefore recommends these measures are implemented.

ADDITIONAL IMPROVEMENT SUMMARY

The table below lists numerous improvements that were not listed in the report but should be considered for implementation. No energy savings calculations were performed for these measures.

Table 4: Additional Improvement Summary Table

ID# Improvement Description Estimated

ImplementationCost

A1 Return airflow station filter is plugged Clean flow straightener and potentially upgrade flow station $200

A2 Modify AHU hw valve control so that mixed air maintained at 70, not so valve goes wide open

Saves on pumping power during unoccupied period $200

A3 Replace the AHU HW 3‐way valves with 2‐ way valves

This will reduce the HW pump power consumption by allowing the drive to ramp down at night

$2,500

A4 Implement temperature reset on the cw supply temperature setpoint

This measure would reduce the chiller power consumption $500

A5 Upgrade AHU airflow stations

New airflow stations will improve the return fan control and allow sequence to be updated

$6,000

A6 Install hw system d.p. sensor Then revise control so that hw vfd maintains the dp setpoint $3,500

A7 Install RA temperature sensor on AHU‐2 This sensor will improve troubleshooting capabilities $500

A8 Troubleshoot AHU‐2 outside air dampers No outside air is being brought in this unit $1,000

A9 Troubleshoot AHU‐1 mixed air dampers Mixed air damper commanded closed but it remains 7% open $1,000


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A10 Troubleshoot AHU‐2 high filterpressure drop Currently there is a 1.5” pressure drop on unit filters $500

A11 Troubleshoot AHU‐3 face andbypass issues

Face damper commanded open and only 50% open, face commanded closed and only 80% closed. Bypass commanded open and only 60% open.

$1,500

A12 Close exhaust valve dampers when air handlers are off

Closing dampers will reduce heat loss due to stack effect, especially in the winter

$1,300

A13 Schedule pond fountain to go off at night There is an existing timer in the control panel for this unit $200

A14 Replace AHU‐3 CW thermometer Thermometer is broken $200

A15 Troubleshoot AHU‐1 economizer damper

Economizer damper commanded closed but remained 5% open

$500

A16 Replace AHU‐1 HW thermometer Thermometer is broken $200

A17 Troubleshoot AHU‐2 economizerdamper

Economizer damper commanded closed but remained 3% open

$1,200

Total $21,000

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IMPLEMENTATION PLAN

The information below is intended to assist in formulating a plan to implement the recommendations outlined in this report. Due to the building complexity and various control systems, implementation of the measures is more complicated than a conventional building.

Phase 1:

Project Time Frame: 12/20‐1/20

Facilities Projects

Participants: EC facilities staff,

AHU‐2 Hot Water Valve Repair AHU‐1 Chilled Water Valve Repair AHU‐2 Mixed Air Damper Other miscellaneous damper issues

Anemostat Recommissioning

Participants: Anemostat TAB technician, Anemostat Controls Tech, facilities staff,

Recalibrate flow stations, dampers, thermostats and other devices Replace faulty transducers Review system programming Modify programming as necessary

Rm. 402 Phoenix Recommissioning

Participants: Masters Phoenix Controls Tech, TAB technician, facilities staff,

Recalibrate flow stations, thermostats and other devices Install space occupancy sensor Modify programming so that minimum flow values change based on exhaust fan status and

room occupancy condition




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Phase 2: Design and Bidding


Design Services for Controls Upgrade

Recalculate minimum flows for all VAV boxes. Calculation to determine minimum flows forVAV boxes when associated exhaust fans are on and off, as well as standby flow whenexhaust fan is off and room is vacant.

Write design narrative for VAV pneumatic to DDC conversion including the followingelements

o Equipment schedule for box and coil sizeo Box sequences of operationo Graphics requirements including reporting and trendingo Points listo Alarm requirementso Occupancy sensor locationso AHU temperature and pressure reset sequenceso Meter screen updateso Peak limiting sequenceso Define project alternates potentially including the following:

CW pump VFD and CW AHU valve mods HW diff pressure sensor install Stack modification to eliminate need for rain sensor

EC to Bid Project

VAV box installation contract Controls contract

o QCS is preferredo Other controls contractors could be used but it would add some complexity to the user

interface

Phase 2: Implementation


Installation Services

Complete upgrades as outlined in the bid package

Commissioning Services

Complete commissioning on all implemented measures

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ENERGY EFFICIENCY MEASURES FOR FUTURE IMPLEMENTATION

OVERVIEW

A number of measures were identified but not recommended for implementation at this time. For these measures, the simple payback was significantly longer than the payback for the recommended measures. In most cases the simple payback was greater than 10 years and it did not make sense to investment money in these improvements until all the other low cost measures are completed.

FUTURE MEASURES

Convert Chilled Water Systems to Variable Volume

The existing chilled water system consists of the chilled water loop and the condenser water loop. Both of these systems are constant volume systems. Each AHU has a 3‐way chilled water valve that maintains a constant flow of chilled water regardless of the amount of water needed by the coil.

The condenser water flow is also maintained by a constant flow pump.

This system could be modified to a variable volume primary flow chilled water system. The following changes would be required:

Install VFD’s for the pumps and upgrade motors as necessary Add bypass valve in cw system not maintain min flow Switch AHU cw coil valves from 3‐way to 2‐way valves Install d.p. sensor used to control cw pump speed

Figure 17: Minimum Flows Possible for Chilled Water System

System Pumps Current Flow Minimum Req’dFlow

Chilled Water P‐1,2 770 gpm 417 gpm

Condenser Water P‐3,4 1,200 gpm 425 gpm

The estimated cost savings for this measure is approximately $2,300/yr. However, the cost for this measure would likely exceed $30,000.

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Modify AHU‐3 Configuration

AHU‐3 was designed originally to be a 90% outside air unit. Only 1 room has return air back to AHU‐3. The original design intent was that fume hoods run 24/7, as typically done in a lab building to meet code requirements. The make‐up air for the hoods is provided by AHU‐3 and therefore must run 24/7 as well. However, EC is now using the hoods intermittingly, and shutting the units down when there are no chemicals in the hoods. When the exhaust fans associated with the hoods are off, there is no way to return air back to AHU‐3 from the lab spaces. Therefore, AHU‐3 must continue to be used as a nearly 100% make‐up air unit.

Ideally, it would be best to have return air pulled from the lab rooms when they are used as traditional classrooms with all the hoods off. AHU‐3 outside air percentage could then be reduced as the exhaust fans are shut down that serve the fume hoods.

However, this would require extensive duct work modification to the AHU and the rooms throughout the 4th floor. The controls would also be quite complex and further increase the project cost.

Based on the extensive modifications necessary it was determined that this measure is not feasible.

Implement Heat Recovery for AHU‐3

Airside heat recovery is often used in buildings with high exhaust or outside air requirements, such as labs. A heat exchanger is utilized to heat or cool the make‐up air using the already conditioned exhaust stream. Because the exhaust air is potentially contaminated with chemical exhaust, a run around loop or heat pipe system is typically used to avoid cross contamination of the air streams.

If incorporated into the original design, these heat recovery systems have reasonable payback periods and work quite well. However, in a retrofit application there are tremendous costs involved. Specifically, all the hood exhaust needs to be brought back to the same central location.

In the Science Center most fume hoods run a fraction of the time, so the overall savings from a heat recovery system is greatly reduced.

Based on the above information, modifying the AHU‐3 system to include heat recovery is not feasible.

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Replace Existing Boilers with Condensing Boilers

The existing boilers are non‐condensing boilers that are approximately 80% efficient. The modern modulating burner condensing boilers have efficiencies of over 95% when the supply water temperatures are less than 120°F. There are significant gas savings associated with a condensing boilers when they are operated in the condensing range.

At the Science Center, there are a number of system modifications that would be needed to achieve condensing operation including the following:

VAV reheat coils would need to be sized for 120° or less entering water temperature. They arecurrently sized for entering water temperature of 180°F.

Domestic hot water would need a stand‐alone water heater, and not be tied into the hydronicsystem

Additionally, the perimeter heat requires 180°F water. Therefore, the proposed condensing boilers would need to be operated outside the condensing range when the outside air temperature is less than 30°F to effectively heat.

Based on all the modifications that are needed, installing condensing boilers at this time is not feasible.

Install Pony Chiller

The existing chiller is a 400 ton unit that is sized based on the large amount of outside air required to be cooled for fume hood make up on a design day. However, most of the time, the actual cooling loads are a fraction of the rated capacity. However, this chiller plant part load performance is not very good because it is a constant volume system.

Installing a pony chiller system in conjunction with adding variable speed pumps to the system would enable the system to have much better part load performance, such as during unoccupied hours, or when the majority of the exhaust fans that serve fume hoods are off when lab classes are not in session.

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Modify Exhaust Stacks

The existing exhaust stacks were designed with the assumption that the exhaust fans run 24/7, and therefore were designed without any means to avoid rain and snow from falling down the stack when the units are off. After the exhaust fans were initially scheduled off, there were issues with rain accumulating in the ductwork and fan housing. A series of drains was added to the duct work, but there remained issues with water accumulating in the ductwork.

Based on these issues, a rain water sensor was added that turns on the exhaust fans if they are scheduled off and the sensor detects rain.

While the extra runtime is not very significant, it was reported by building occupants that the apparent random operation of the exhaust fans and hoods is a nuisance.

One solution would be to refabricate the exhaust ducts to allow self‐draining of the stack and eliminate the need for the rain sensor. The figure below illustrates some solutions to this issue.

Figure 18: Alternate Stack Designs

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Figure 19: Existing Exhaust Stacks

At this time, did not recommend the implementation of this item due to the longer payback of this measure compared to the other measures.


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