Continuous Commissioning® Assessment Report

For

Board of Regents Building (Bldg. 455)

By

Chenggang Liu

David E. Claridge, Ph.D., P.E.

Homer L. Bruner, Jr., CEM

Contact:

David E. Claridge (979-845-1280) Homer L. Bruner, Jr. (979-862-7185)

August, 2004

Table of Contents 1. Introduction...................................................................................................................................1 2. Continuous Commissioning Measures ........................................................................................2 3. HVAC Control System .................................................................................................................5

I. Existing Control Scheme .........................................................................................................5 II. New Control Scheme ...............................................................................................................6

4. Energy Consumption .....................................................................................................................6 5. Recommendation............................................................................................................................7 Appendix A: Simulation Results .....................................................................................................8 Appendix B: Temperature trend data for 2nd floor suites .........................................................11 Appendix C: AHU Measurements.................................................................................................13 Appendix D: Thermostat Verification ..........................................................................................15 Appendix E: The estimated cost for the work in the recommendation (Parts List).................16

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1. Introduction The Board of Regents Building is a two-story building with a total conditioned area of

21,000 ft2 and was constructed in 1972 as a part of Memorial Student Center (MSC) complex. The first floor consists of a foyer, reception area, conference room, dining room, and kitchen. The second floor consists of 12 suites where the Regents and guests stay during meetings and special events. Each suite has a seating room, bedroom, and a bathroom. The entire Board of Regents Building contains elaborate wallpaper (some made of silk), paintings, sculptures, rugs, and furniture, which require special care to ensure they are kept in good condition.

The Board of Regents Building is served by two air-handling units (AHUs), AHU-1 andAHU-2. AHU-1 serves the first floor and AHU-2 serves the second floor. AHU-1, as shown in figure 2, is single duct constant volume unit with cooling only and a preheat coil and a precool coil for the mixed air. It then has zone reheats. AHU-2, shown in figure 3, is similar to AHU-1 with the exception that there are no pre-treat coils for mixed air. Both units have direct digital control (DDC) through the energy management control system (EMCS).

Figure 1: Board of Regents Building on TAMU Main Campus

2

SupplyFan

CC 5

6RA

Filter

OA

1

2

3 4

RH

TPH

PC

T

Damper EMCS

Zone Reheat Coil

To Zones, typical of 8

T & RH

Figure 2: AHU-1 diagram

Figure 3: AHU-2 diagram

The AHUs are served by one constant speed chilled water pump and one constant speed

hot water pump, which are located in the pump room of the MSC main building. Both of the on/off switches for the pumps are DDC controlled.

There are three general exhaust fans for the building. One is for the kitchen, one is for the conference room, and one is for the bathrooms in the suites and toilets on the first floor. Major Continuous Commissioning® (CC®) activities started on 06/01/04 and ended 07/30/04. 2. Continuous Commissioning Measures

• The building’s cooling and heating energy consumption was simulated for the existing

status of the HVAC system using AirModel. The table below shows the simulated energy consumption for each AHU and the total consumption. The total annual cooling and heating energy costs are $45,502. See Appendix A for detailed simulation results.

Existing Annual energy consumption and cost

CHW (MMBtu)

HW (MMBtu)

CHW (cost in $)

HW (cost in $)

AHU-1 1,560 1,008 $ 1,7612 $ 8,013 AHU-2 1,155 860 $ 13,040 $ 6,837 Total 2,715 1,868 $ 30,652 $ 14,850

Note: $11.29/MMBtu for chilled water, $7.95/MMBtu for hot water.

SupplyFan

CC 5

6RA

Filter

OA

1

2

3

To Zones, typical of 24

4

RH

TDamper

EMCS

RH

T & RH

Zone Reheat Coil

3

• The building cooling and heating energy consumption was then simulated for the new

control programs and the proposed recommendations to the HVAC system using AirModel. The table below shows the simulated energy consumption for each AHU and the total consumption according to the new programs and the recommendations on page 6. The proposed cooling and heating energy costs are $13,083. The total potential annual cooling and heating energy savings are $ 32,419. It is 71% savings on the existing energy costs. See appendix A for detailed simulation results.

Proposed Annual energy consumption and cost

CHW (MMBtu)

HW (MMBtu)

CHW (cost in $)

HW (cost in $)

AHU-1 375 273 $ 4,233 $ 2,170 AHU-2 372 312 $ 4,200 $ 2,480 Total 747 585 $ 8,433 $ 4,650 Annual Savings 1,968 1,283 $ 22,219 $ 10,200

Note: $11.29/MMBtu for chilled water, $7.95/MMBtu for hot water.

• The control programs were modified. The building cooling and heating energy consumption was simulated to see the energy savings achievements by running the new program. The table below is the simulation results. The new annual cooling and heating energy costs for running the new control program are $40,980. The total savings for running the new program are $ 4,522. It is 10% on the existing cost. Therefore, 61% savings which is $27,897 will be achieved if the retrofits according to the recommendations are done.

Annual energy consumption and cost for new control programs

CHW (MMBtu)

HW (MMBtu)

CHW (cost in $)

HW (cost in $)

AHU-1 1,372 855 $ 15,490 $ 6,797 AHU-2 1,091 802 $ 12,317 $ 6,376 Total 2,463 1,657 $ 27,807 $ 13,173 Annual Savings 252 211 $ 2,845 $ 1,677

• Trend data was collected for four suites on the 2nd floor in order to determine if the

supply airflow could be decreased. For two suites, the lights and televisions were left off and for the other two suites, the lights and televisions were left on to simulate a load in the rooms. The following table shows the average room and supply air temperature readings for the trend data. From the results, it is possible to reduce the supply airflow during unoccupied periods because the supply air temperature for the unoccupied zones is much higher than the discharge air temperature of 57°F from the AHU-2. This indicates that the reheats are being used when not required. See appendix B for details.

4

Suite Room

Room temperature (°F)

supply air temperature (°F)

Delta T between room and supply air temperature (°F)

delta T across reheat Note

sitting room 70.5 59 11.5 3 275 bedroom 71.5 63 8.5 7 lighting on

sitting room 71 68 3 12 277 bedroom 70 67 3 11 lighting off

sitting room 69 60 9 4 278 bedroom 69 58.5 10.5 2.5 lighting on

sitting room 71 64 7 8 284 bedroom 73 65 8 9 lighting off

• Two temperature data loggers were place on AHU-1 to monitor the discharge air

temperature. The average temperature for the two loggers was approximately 70°F. This indicates that the zone reheat was on during this time frame, where the building was also unoccupied. Similar to the trend data for the second floor AHU-2, this shows that the air flow for this unit could be decreased during unoccupied periods.

• Exhaust fan #3 on the roof, which serves the conference room, has a design flow rate of 3,350 cfm. This fan could be removed since the conference room is now a no smoking area.

• Exhaust fan #2, which serves the kitchen and dining room, has a design flow rate of 7,700 cfm, 4,000 cfm for the kitchen and 3,700 cfm for the dining room. The dining room is exhausted by pulling dining room air to the kitchen via transfer ducts on the wall. These ducts are capped off, so dining room air is being returned back to the AHU-1 through the dining room doors and the hallway. Therefore, exhaust fan #2 can be adjusted to a lesser a capacity of 4,000 cfm to serve the kitchen only. In order to facilitate return air from the dining room, transfer ducts need to be installed on the wall above the ceiling between the dining room and hallway.

• For the kitchen exhaust fan, there is no on/off switch, so the exhaust runs continuously, even when not needed.

• On the kitchen exterior wall, there are louvers which are missing a set of dampers. These louvers need a set of dampers, which will open when the kitchen exhaust fan is off and closed when the exhaust fan is on.

• Exhaust fan #1 serves the first floor restrooms and the bathrooms for the suites on the second floor. This fan has a design capacity of 3,000 cfm. Based on ASHRAE standards of 50 cfm per bathroom for the suites, this airflow could be reduced to 1,000 cfm (600 cfm for the 12 suites and 400 cfm for all the first floor restrooms).

• The two AHUs were measured for airflows, relative humidity, and temperatures and compared with EMCS readings and design data. See appendix C for detail information of the measurements results.

• An ultrasonic flowmeter was installed on the chilled water supply for the Board of Regents to measure the chilled water usage from June 29 to July 2. A maximum usage of 230gpm was measured. The pump capacity is 480 gpm. The building control valve and AHUs control valves were fully open.

• For the strainer on the precool coil for AHU-1, a pressure drop of 9 psi was measured even after it was back flushed. This indicates that the strainer is stopped up and restricting flow. This results in a high discharge temperature of the precool coil of 67°F, with a design of 62°F. This strainer and its isolation valve need to be replaced.

5

• All exhaust fans were checked and measured for airflow rate. The air intake of the building was measured. The building was positive as design.

Outside air intake (CFM) Air exhaust (CFM) remarks Design Measured Design Measured AHU-1 12,640 7,700 0 0 AHU-2 2,500 3,650 0 0 EF-1 0 0 3,000 1,500 EF-2 0 0 7,700 3,900 EF-3 0 0 3,350 1,555 total 15,140 11,350 14,050 6,955 • All of the thermostats were checked and calibrated as necessary. See appendix C for

details. • Others

• Checked mechanics on AHUs. • Changed filters. • Cleaned coils and outside air inlet. • Replaced fan belts as needed.

3. HVAC Control System

I. Existing Control Scheme

(1) Chilled water and hot water pumps: • Both pumps are constant speed and have a manual on/off control. • The building chilled water and hot water control valves are pneumatic control and are

in the process of being converted to DDC control.

(2) AHU-1 control: • The precool and preheat control valves are modulated to maintain the pretreat

temperature set point at 2°F higher than the discharge air temperature of the AHU. • The control valve of the main cooling coil is modulated to maintain the discharge air

temperature at the set point. The set point is calculated according to the maximum zone relative humidity as shown in the following table.

Max. Zone RH 50 60 Tdis,sp (°F) 60 48

• The outside air damper has the ability to modulate but is not controlled in the control

program. • The zone reheat control valves are modulated by terminal equipment controllers (TECs)

in order to maintain the zone temperature at its set point. (3) AHU-2 control: • The control valve of the cooling coil is modulated to maintain the discharge air

temperature at the set point of 56°F. • The outside air damper has the ability to modulate but is not controlled in the control

program.

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• The zone reheat control valves are modulated by TECs in order to maintain the zone temperature at its set point.

(4) The issues of the existing control scheme: • For AHU-1, it is incorrect to have the preheat set point 2°F higher than the discharge

temperature when in use. • For AHU-1, the chilled water control valve needs to be modulated to maintain the space

relative humidity and the discharge temperature, instead of just controlling relative humidity.

• For AHU-2, the discharge temperature set point needs to be reset based on the cooling and heating load instead of a constant set point of 56°F.

II. New Control Scheme

(1) Chilled water and hot water pumps • The chilled water pump operations were not altered.

(2) AHU-1 control: • For the precool coil, the discharge temperature was reset to be 58-60°F corresponding

to outside air temperatures of 90-70°F. • The preheat temperature setpoint was changed from 2°F above discharge set point to

45°F. • The chilled water control valve for the main cooling coil is modulated to maintain the

discharge air temperature or space relative humidity at its set point. The discharge air temperature setpoint was reset based on outside air temperature as shown below.

When the space relative humidity is above its high limit of 60%, the relative humidity

control loop takes over the discharge air temperature control loop to maintain the relative humidity at its setpoint.

(3) AHU-2: • The discharge air temperature set point was reset based on outside air temperature as

seen below instead of being set at a constant set point of 56°F.

Toa (ºF) 40 50 60 70 80 90 Tdis (°F) 62 61 59 57 56 55

4. Energy Consumption

There is no consumption data available. The consumption will be calculated if a magnetic flow meter and temperature sensor is installed on the hot water and chilled water supply lines.

The estimated cost of work in the recommendation based on the quote from REC is $102,485. The corrected cost for this work is $34,045, if some work is done by Physical Plant. The savings from this work is $27,897. Therefore, the payback is one year and three months.

Toa (ºF) 40 50 60 70 80 90 Tdis (°F) 62 61 59 57 56 55

7

5. Recommendation For chilled water and hot water control and pumps

1) Install VFD for chilled water and hot water pumps. Then remove the building chilled water bypass and replace all 3-way control valves with 2-way control valves on AHU-1 and -2.

2) Install magnetic flow meters on hot water and chilled water supply lines. 3) After 1) and 2), perform water balance and calculate building DP set point according to

flow rate for hot water and chilled water. For first floor AHU-1

4) Remove existing exhaust fan and cap existing ductwork for the conference room (exhaust fan #3).

5) Install three 18” x 12” transition ducts with fire dampers on the wall above the ceiling between the conference room and the hallway for return air.

6) Disconnect exhaust ducting from existing registers to convert to return air registers. 7) Zone #8, the kitchen on the first floor, is pneumatic control and should be changed to

DDC control. 8) Install a user on/off switch in the kitchen for the kitchen exhaust fan and an on/off proof

tied to EMCS. 9) Install relief air damper for kitchen in the relief opening and interlock with the kitchen

exhaust. The damper should close when the kitchen exhaust is on and open when the exhaust is off.

10) Install three 18” x 12” transition ducts with fire dampers on the wall above the ceiling between the dining room and the hallway for return air of 3,700 cfm.

11) Adjust exhaust fan flow rate for kitchen (exhaust fan #2) from 7,700 cfm design to 4,000 cfm.

12) After 4), 5), 6), 10), and 11), adjust outside air damper for an outside airflow rate of 5,000 cfm.

13) Install a VFD to vary the supply cfm during occupied and unoccupied periods. The VFD will be modulated to maintain the zone temperature set point.

14) If a VFD is installed, install an air flow meter on the outside air duct and connect to EMCS system. Then the outside air damper for AHU-1 can be modulated to maintain an outside airflow rate of 5,000 cfm.

For second floor AHU-2

15) Adjust exhaust fan #1, which serves the first floor restrooms and the bathrooms for the second floor suites, from 3,000 cfm to 1,000 cfm.

16) Then adjust outside air damper for an outside airflow rate of 1,200 cfm. 17) Install a VFD to vary the supply cfm during occupied and unoccupied periods. The VFD

will be modulated to maintain the zone temperature set point. 18) If a VFD is installed, install an air flow meter on the outside air duct and connect to

EMCS system. Then the outside air damper for AHU-2 can be modulated to maintain a certain flow rate of outside air.

8

Appendix A: Simulation Results

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Appendix A: Simulation Results (continued)

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Appendix A: Simulation Results (continued)

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Appendix B: Temperature trend data for 2nd floor suites

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Appendix B: Temperature trend data for 2nd floor suites (continued).

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Appendix C: AHU Measurements

AHU No. Date Time Toa Person BOR-1

Schematic of AHU

Air Side Position No. 1 2 3 4 5 6

Design 12,640 17,420 CFM Measure 5,450 7,700 13,150 EMCS 69 87 68 59 Temp.

Measure 69.5 87.6 66.8 59.2 EMCS 1.25" S.P

Measure -0.81 0.79 R.H 72 70

Duct Size

OA/SA (%) SA (CFM/sq.ft) Area Served (sq.ft)

Measure Design Measure Design Ratio

59% 72.6 1.3 1.7 10500

VFD (Hz) Filter Belt Other Checks

n/a

Chilled Water Side Ps(psi) Pr (psi) Ts (F) Tr(F)

Hot Water Side Ps (psi) Pr (psi) Ts (F) Tr (F)

Note : 1. Outside air damper is not hooked up. 2. Sdrainers of preheat, precool, and main cool coils need to be cleaned. 3.

SupplyFan

CC 5

6RA

Filter

OA

1

2

3 4

RH

TPH

PC

T

Damper EMCS

Zone Reheat Coil

To Zones, typical of 8

T & RH

14

Appendix C: AHU Measurements (continued)

AHU No. Date Time Toa Person BOR-2

Schematic of AHU

Air Side Position No. 1 2 3 4 5 6

Design 2,500 14,300 CFM Measure 9,250 3,650 12,900 EMCS 70.6 73.6 56 Temp.

Measure 71.7 71.9 56.6 EMCS .75" S.P

Measure -0.25 -1.23 R.H 63%

Duct Size

OA/SA (%) SA (CFM/sq.ft) Area Served (sq.ft) Measure Design Measure Design Ratio

28% 17.5 1.2 1.4 10500

VFD (Hz) Filter Belt Other Checks

n/a

Chilled Water Side Ps(psi) Pr (psi) Ts (F) Tr(F)

Hot Water Side Ps (psi) Pr (psi) Ts (F) Tr (F)

Note :

SupplyFan

CC 5

6RA

Filter

OA

1

2

3 4

RH

TPH

PC

T

Damper EMCS

Zone Reheat Coil

To Zones, typical of 8

T & RH

15

Appendix D: Thermostat Verification Board of Regents 1st floor thermostat verification Room TEC Address TEC

Temp (°F) TEC RH (%) Measured

Temp (°F) Measured RH (%)

Foyer Zone #1 71.25 52.5 72.7 55.2 Dining Rm Zone #2 70.00 52.0 71.6 57.4 Dining Rm Zone #3 71.00 49.0 73.1 55.2 Reception Zone #4 71.32 58.19 71.1 58.0 Reception Zone #5 71.40 55.62 71.1 58.4 Confer. Rm Zone #6 68.00 56.0 68.8 61.4 Confer. Rm Zone #7 69.00 57.0 70.2 58.4 Board of Regents 2nd floor suites thermostat verification Measured

Discharge Temp (°F)

TEC Discharge Temp (°F)

Measured Room Temp (°F)

TEC Room Temp (°F)

Sitting Area 58.9 58.0 67.0 68.25 Rm 273 Bedroom 62.2 64.0 70.2 71.25 Sitting Area 59.0 59.5 67.3 68.75 Rm 274 Bedroom 65.2 60.0 68.4 70.00 Sitting Area 68.1 69.0 69.9 70.25 Rm 275 Bedroom 60.4 60.0 69.9 71.50 Sitting Area 58.7 58.0 67.0 68.25 Rm 276 Bedroom 59.1 58.0 67.5 68.50 Sitting Area 83.8 84.0 72.0 73.00 Rm 277 Bedroom 60.6 60.0 70.0 69.75 Sitting Area 57.6 57.0 70.1 70.75 Rm 278 Bedroom 77.1 80.0 74.9 74.50 Sitting Area 59.4 58.5 67.4 68.50 Rm 279 Bedroom 60.2 61.0 67.1 68.50 Sitting Area 70.4 72.0 70.4 70.00 Rm 280 Bedroom 66.0 66.5 70.4 71.25 Sitting Area 60.7 61.0 68.3 69.25 Rm 281 Bedroom 65.3 64.5 69.8 71.00 Sitting Area 56.8 56.0 66.8 67.50 Rm 282 Bedroom 65.4 67.0 69.7 70.25 Sitting Area 67.9 69.5 71.4 72.00 Rm 283 Bedroom 63.0 64.5 71.1 72.00 Sitting Area 64.7 64.5 70.5 71.25 Rm 284 Bedroom 62.3 60.0 71.6 73.00

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Appendix E: The estimated cost for the work in the recommendation (Parts List)

Area Served Item Quantity REC Quote corrected

cost

Chilled water pump VFD, Enclosed (NEMA 1), 460 volt for 10 HP motor size 1 $7,610.00 $2,500.00

Hot water pump VFD, Enclosed (NEMA 1), 460 volt for 5 HP motor size 1 $6,610.00 $2,000.00

Chilled water Magnetic flow meter 1 $9,850.00 $2,500.00 Hot water Magnetic flow meter 1 $9,000.00 $2,000.00

1st Floor between conference room and hallway

Transition duct, 3" deep, square to round, 12" x 18" 3

1st Floor between conference room and hallway

Fire/smoke combination damper, louver type, 18" x 12" 3 $3,250.00 $1,000.00

1st Floor between dining room and hallway

Transition duct, 3" deep, square to round, 12" x 18" 3

1st Floor between dining room and hallway

Fire/smoke combination damper, louver type, 18" x 12" 3 $3,250.00 $1,000.00

AHU-1 VFD, Enclosed (NEMA 1), 460 volt for 10 HP motor size 1 $6,550.00 $3,000.00

AHU-2 VFD, Enclosed (NEMA 1), 460 volt for 10 HP motor size 1 $6,550.00 $3,000.00

AHU-1 VFD Air flow meter 1 $6,575.00 $2,500.00 AHU-2 VFD Air flow meter 1 $6,575.00 $2,500.00 1st Floor Kitchen motorized damper & on/off switch $2,995.00 $2,995.00

AHU-1&2

Electronic control valves, replace 3-way control valves with 2-way on AHU-1 and 2 $17,450.00 $5,000.00

Chilled water

Remove ChW bypass, replace 3-way control valves with 2-way on AHU-1 and 2

$1,200.00 $1,200.00

AHU-1, conference room Remove exhaust fan #3 and cap existing ductwork

$950.00 $500.00

AHU-1, conference room

Disconnect exhaust ducting from existing registers to convert to return air registers, 13 flexible duct connections and box removal

$750.00 $750.00

Zone #8, 1st floor kitchen Change pneumatic control to DDC control $2,820.00 $600.00

1st floor kitchen Adjust exhaust fan #2 flow rate $3,500.00 $500.00 2nd floor Adjust exhaust fan #1 flow rate $3,500.00 $500.00 Balancing system $3,500.00 Total $102,485.00 $34,045.00