Attachment_3_-_B_-_Proposed_HVAC_Sequence_of_Operation.pdf

Northwest Oregon District Office HVAC System Improvements SOO TOC Proposed HVAC Control Sequences of Operation

Northwest Oregon District Office HVAC System Improvements

Proposed HVAC Control Sequences of Operation (SOO)

Table of Contents

A. General

B. Zone Group Assignments

C. Trim and Respond Setpoint Reset Logic

D. Occupied-Unoccupied Modes

E. Heating System

F. Air Handling Units AHU-1 and AHU-2

G. Air Handling Unit AHU-3

H. Variable Air Volume (VAV) Terminal Units

I. Booster Heating Coils

J. Exhaust Fans

K. Cabinet Unit Heaters

L. FC-1 / AC-1 and FC-2 / AC-2

M. Temperature Monitoring

N. Carbon Dioxide Monitoring

O. Power Monitoring ...................................................................... Error! Bookmark not defined.

P. Renewable Energy Monitoring .................................................. Error! Bookmark not defined.

Q. Natural Gas Usage Monitoring .................................................. Error! Bookmark not defined.

R. Input/Output Point Lists

HVAC System Improvements SOO Page 1 Proposed HVAC Control Sequences of Operation

A. General: Provide sequences of operation for the Northwest Oregon District Office HVAC systems as specified below. Please note that most of the sequences specified here are based on ASHRAE Guideline 36-2021 “High-Performance Sequences of Operation for HVAC Systems”.

B. Zone Group Assignments: Zone group assignments shall be as shown below.

ZONE GROUP ASSIGNMENTS

ZONE GROUP AHU

TAG

TERMINAL UNIT

TAGS

MISC.

EQUIPMENT

TAGS

DEFAULT SCHEDULE

First Floor General AHU-3 BHC-301 thru BHC-306 EF-3, EF-4 &

EF-5

WD: 6:00 AM to 6:00 PM WE: Off HOL: Off

First Floor Office & Conference

AHU-1 TU-101 thru TU-103 - WD: 6:00 AM to 6:00 PM WE: Off HOL: Off

Second Floor South AHU-1 TU-201 thru TU-207, TU-209A thru TU-213B, TU-229 & TU-230

EF-1 WD: 6:00 AM to 6:00 PM WE: Off HOL: Off

Second Floor North AHU-2 TU-208, TU-214 thru

TU-228, TU-231 & TU-

EF-2 WD: 6:00 AM to 6:00 PM WE: Off HOL: Off

Third Floor South AHU-1 TU-301 thru TU-305 EF-1 WD: 6:00 AM to 6:00 PM WE: Off HOL: Off

Third Floor North AHU-2 TU-306 thru TU-315 EF-2 WD: 6:00 AM to 6:00 PM WE: Off HOL: Off

IT/Telecom Rooms FC-1 &

FC-2

- AC-1 & AC-2 -

South Stairwell CUH-1 - - - North Stairwell CUH-2 - - -

C. Trim and Respond Setpoint Reset Logic:

1. General: The following setpoints shall be reset by trim and respond logic.

a. Heating hot water supply temperature.

b. AHU-1 and AHU-2 supply air duct static pressure.

c. AHU-1 and AHU-2 supply air temperature.

The trim and respond logic shall reduce (or increase) the setpoint at a fixed rate until a downstream zone is no longer satisfied and generates a request. When a sufficient number of requests are present, the setpoint shall be increased (or reduced) in response. The importance of each zone’s requests can be adjusted to ensure that critical zones are always satisfied. When a sufficient number of requests no longer exist, the setpoint shall resume

HVAC System Improvements SOO Page 2 Proposed HVAC Control Sequences of Operation decreasing (or increasing) at its fixed rate. A running total of the requests generated by each zone shall be kept in order to identify the zones that are driving the reset logic.

2. Requests: Requests are calls generated by the VAV terminal units and heating coils to reset the setpoints listed above. These requests are sent upstream to the systems that serve the VAV terminal units and heating coils that generated the request. For each VAV terminal unit and heating coil, and for each type of setpoint request, provide the following software points:

a. Importance Multiplier: Each Importance Multiplier shall initially be set to a default of one (1) (adjustable).

b. Request Hours Accumulator: Every 5 minutes (adjustable), add 5 divided by 60 times the current number of requests to the Request Hours Accumulator.

c. Run Hours Total: The number of hours each VAV terminal unit or heating coil has been operating in any mode other than Unoccupied Mode.

d. Cumulative Percent Request Hours: The VAV terminal unit or heating coil Request Hours divided by the VAV terminal unit or heating coil Run Hours since the last reset, expressed as a percentage.

See “Air Handling Unit AHU-3”, “Variable Air Volume (VAV) Terminal Units”, and “Booster Heating Coils” below for the logic to generate setpoint reset requests at the zone level. The number of requests from the zone level logic shall be multiplied times the Importance Multiplier before being sent upstream to the system that serves the VAV terminal unit or heating coil that generated the request. See “Heating System” and “Air Handling Units AHU-1 and AHU-2” below for the logic to handle setpoint reset requests at the system level.

3. Reset to Zero: The Request Hours Accumulator and Run Hours Total shall be reset to zero as follows:

a. Reset automatically for an individual VAV terminal unit or heating coil when the Run-Hours Total exceeds 400 hours.

b. Reset manually by a global operator command. This command shall simultaneously reset the Request Hours Accumulator point for all VAV terminal units or heating coils served by their associated upstream systems.

4. Rogue Zones: If the Cumulative Percent Request Hours exceed 70% for any VAV terminal unit or heating coil, a maintenance alarm condition shall be reported at the operator workstation. Manually setting the Importance Multiplier to zero (0) shall cause the trim and respond logic to ignore requests from the rogue zone.

D. Occupied-Unoccupied Modes: Occupied-unoccupied modes shall be controlled by user-adjustable schedules with optimal start/stop algorithms as described below. Schedules shall be as listed in Zone Group Assignments above. Coordinate finalized occupied/unoccupied schedules for each Zone Group with the BLM site manager, accounting for seasonal use, holidays, special events, etc. in the finalized schedules.

HVAC System Improvements SOO Page 3 Proposed HVAC Control Sequences of Operation

All zones in each Zone Group shall be in the same operating mode. If one zone in the Zone Group is placed in any operating mode other than Unoccupied Mode due to being overridden (Unoccupied Bypass Mode) or by scheduled occupancy, all zones in that Zone Group shall enter that mode.

1. Optimal Start: The DDC system shall adaptively determine the length of time required to bring each zone from the unoccupied setpoint temperature to the occupied setpoint temperature. System operation shall be delayed as long as possible before starting, such that the temperature in the most demanding zone reaches occupied setpoint just as the occupied period begins.

a. Morning Warmup: If any of the zone air temperatures are below the occupied heating setpoint when optimal start begins, morning warmup shall be initiated by the optimal start program.

1) AHU-1 and AHU-2:

a) Minimum and maximum outside air dampers shall remain closed.

b) Return air dampers shall remain open.

c) Exhaust air dampers shall remain closed.

d) Supply air fans and return air fans shall be energized. Return air fan speed shall be controlled such that the return air fan flowrate matches the supply air fan flowrate.

e) Zone reheat coil valves and dampers shall modulate as necessary to bring each zone temperature up to occupied setpoint temperature.

f) When all zone temperatures reach occupied heating setpoints at the end of the unoccupied period, the systems shall continue operation in normal occupied mode.

2) AHU-3:

a) Minimum and maximum outside air dampers shall be opened.

b) Return air damper shall remain open.

c) Exhaust air damper shall remain closed.

d) Supply air fan, return air fan, and EF-3 shall be energized.

e) AHU-3 heating coil valve shall modulate as necessary to maintain 75 degrees F (adjustable) supply air temperature. If the Warehouse room temperature reaches setpoint before the morning warmup cycle ends, control of the heating coil shall be returned to the Warehouse room temperature sensor.

HVAC System Improvements SOO Page 4 Proposed HVAC Control Sequences of Operation

f) Booster heating coil valves shall modulate as necessary to bring each zone temperature up to occupied setpoint temperature.

g) When all zone temperatures reach occupied heating setpoints at the end of the unoccupied period, the system shall continue operation in normal occupied mode.

b. Morning Precool: If any of the zone air temperatures are above the occupied cooling setpoint when optimal start begins, morning precool shall be initiated by the optimal start program.

1) AHU-1 and AHU-2:

a) Minimum and maximum outside air dampers shall remain closed.

b) Return air dampers shall remain open.

c) Exhaust air dampers shall remain closed.

d) Supply air fans and return air fans shall be energized. Return air fan speed shall be controlled such that the return air fan flowrate matches the supply air fan flowrate.

e) Cooling shall be sequenced as necessary.

f) When all zone temperatures reach occupied cooling setpoint temperature at the end of the unoccupied period, the systems shall continue operation in normal occupied mode.

2) AHU-3:

a) Minimum and maximum outside air dampers shall be opened.

b) Supply air fan, return air fan, and EF-3 shall be energized.

c) Return air damper, exhaust air damper, and heating coil valve shall modulate as necessary to maintain supply air temperature at 55 degrees F (adjustable).

d) When all zone temperatures reach occupied cooling setpoint temperature at the end of the unoccupied period, the system shall continue operation in normal occupied mode.

2. Optimal Stop: The DDC system shall adaptively determine how early heating or cooling can be disabled in each zone before the beginning of the unoccupied period such that the indoor temperature is allowed to drift ±3 degrees F (adjustable) from occupied heating and cooling setpoint temperatures. Only heating or cooling shall be disabled; supply air fans, return air fans, and exhaust fans shall continue to operate, and the outside air dampers shall remain open until the beginning of the unoccupied period.

HVAC System Improvements SOO Page 5 Proposed HVAC Control Sequences of Operation

3. Occupied Mode:

a. AHU-1 and AHU-2:

1) Minimum and maximum outside air dampers shall be opened.

2) Return air dampers shall be opened (or shall be under the control of the economizer)

3) Exhaust air dampers shall be closed (or shall be under the control of the economizer).

4) Supply air fans, return air fans, EF-1, and EF-2 shall be energized.

5) Zone temperature sensors shall control space temperatures at their normal setpoints (74 degrees F with a 2 degree F offset; 76 degrees F cooling, 72 degrees F heating, adjustable).

b. AHU-3:

1) Minimum and maximum outside air dampers shall be opened.

2) Return air damper shall be opened (or shall be under the control of the economizer).

3) Exhaust air damper shall be closed (or shall be under the control of the economizer).

4) Supply air fan, return air fan, and EF-3 shall be energized.

5) Zone temperature sensors shall control space temperatures at their normal setpoints (74 degrees F with a 4 degree F offset; 78 degrees F cooling, 70 degrees F heating, adjustable).

c. Domestic Hot Water:

1) RHWP-1 operation shall be enabled. RHWP-1 shall cycle on and off as necessary to maintain recirculating hot water temperature at 110 degrees F.

2) If RHWP-1 fails to operate when it is commanded on, a maintenance alarm condition shall be reported at the operator workstation.

4. Unoccupied Mode:

a. AHU-1 and AHU-2:

1) Minimum and maximum outside air dampers shall be closed.

2) Return air dampers shall be opened.

3) Exhaust air dampers shall be closed.

HVAC System Improvements SOO Page 6 Proposed HVAC Control Sequences of Operation

4) Supply air fans, return air fans, EF-1, and EF-2 shall be de-energized.

5) Supply air fans and return air fans shall cycle on and off on calls for heating or cooling from any of the zone temperature sensors. Return air fan speed shall be controlled such that the return air fan flowrate matches the supply air fan flowrate.

6) The economizers shall be enabled if cooling is required and conditions are suitable for economizer operation (outside air temperature is less than return air temperature).

7) Zone temperature sensors shall control space temperatures at cooling setup/heating setback setpoints (74 degrees F with a 6 degree F offset; 80 degrees F cooling, 68 degrees F heating, adjustable).

b. AHU-3:

1) Minimum and maximum outside air dampers shall be closed.

2) Return air damper shall be opened.

3) Exhaust air damper shall be closed.

4) Supply air fan, return air fan, and EF-3 shall be de-energized.

5) Minimum and maximum outside air dampers shall be cycled open and closed, supply air fan and return air fan shall cycle on and off, and EF-3 shall cycle on and off on calls for heating or cooling from any of the zone temperature sensors.

6) The economizer shall be enabled if cooling is required and conditions are suitable for economizer operation (outside air temperature is less than return air temperature).

7) Zone temperature sensors shall control space temperatures at cooling setup/heating setback setpoints (74 degrees F with an 8 degree F offset; 82 degrees F cooling, 66 degrees F heating, adjustable).

c. Domestic Hot Water:

1) RHWP-1 operation shall be disabled.

5. Unoccupied Bypass Mode: Operation of the override button on any of the zone temperature sensors during unoccupied mode shall cause the associated air handling unit and all zones in the affected Zone Group to operate in occupied mode for the duration of the bypass timer time setting (3 hours, adjustable). For unoccupied mode bypass times of greater than 3 hours, the input of a manual command at the operator workstation shall cause the associated air handling unit to operate in occupied mode continuously until reset manually or until the start of the next unoccupied period.

HVAC System Improvements SOO Page 7 Proposed HVAC Control Sequences of Operation

E. Heating System: Heating system operation shall be enabled by the DDC system and the heating hot water supply temperature setpoint shall be calculated by the DDC system. Boiler control (boiler staging and capacity control, lead-lag boiler rotation, lag boiler start on lead boiler failure, and boiler pump control) shall be accomplished with the boiler manufacturer’s internal controls, using the heating hot water supply setpoint calculated by the DDC system as input.

1. Heating System Enable/Disable:

a. Requests: Requests are calls generated by the heating coil valves to enable the heating system. See “Air Handling Unit AHU-3”, “Variable Air Volume (VAV) Terminal Units”, and “Booster Heating Coils” below for the logic to generate enable/disable requests at the zone level.

b. Heating System Enable: Heating system operation shall be enabled after the system has been disabled for at least 15 minutes (adjustable), and the outside air temperature is below 70 degrees F (adjustable) and the number of heating hot water system enable requests R is greater than the number of ignored requests I, with ignored requests initially set to zero (0) (adjustable).

c. Heating System Disable: Heating system operation shall be disabled after the system has been enabled for at least 15 minutes (adjustable), and the outside air temperature rises above 71 degrees F (adjustable) or the number of heating hot water system enable requests R is less than or equal to the number of ignored requests I, with ignored requests initially set to zero (0) (adjustable).

2. Boiler Staging: Boilers B-1 and B-2 shall be fired sequentially in response to heating system load changes to maintain heating supply water temperature at setpoint. As heating demand increases, the lead boiler shall be fired and shall modulate upward from low fire to 100 percent capacity as necessary to maintain boiler supply water temperature at the heating hot water supply temperature setpoint. Upon further increase in heating demand, the lag boiler shall be fired and both boilers shall modulate from 50 percent capacity upward to 100 percent capacity as necessary to maintain boiler supply water temperature at the heating hot water supply temperature setpoint.

3. Heating Hot Water Supply Temperature Setpoint Reset: The heating hot water supply temperature setpoint shall be reset by trim and respond logic using the parameters shown below (all adjustable).

TRIM AND RESPOND PARAMETERS

Variable Value Device HW Boilers

SP0 160 degrees F SPmin 90 degrees F SPmax 160 degrees F

Td 10 minutes T 5 minutes I 2 R Heating hot water supply temperature reset requests

HVAC System Improvements SOO Page 8 Proposed HVAC Control Sequences of Operation

TRIM AND RESPOND PARAMETERS

Variable Value SPtrim -2 degrees F SPres +3 degrees F

SPres-max +7 degrees F

The trim and respond logic shall reset the heating hot water supply temperature setpoint within the minimum and maximum heating hot water supply temperature limits, SPmin and SPmax. When the heating system is off, the setpoint shall be the initial setpoint SP0.

The reset logic shall be active any time the heating system is enabled, starting with a delay time Td after the initial heating system enable command. When the reset logic is active, if the number of requests R is less than or equal to the number of ignored requests I, the setpoint shall be changed by the trim amount SPtrim after every time step T. If the number of requests R is more than the number of ignored requests I, the reset logic shall respond by changing the setpoint by the respond amount SPres times the number of requests R minus the number of ignored requests I, but no more than the maximum response per time step SPres-max. In other words, for every time step T:

a. If R is less than or equal to I, change the heating hot water supply temperature setpoint by SPtrim.

b. If R is greater than I, change the heating hot water supply temperature setpoint by (R

- I) x SPres, but no more than SPres-max.

4. Boiler Rotation: Boiler staging sequencing (lead boiler vs. lag boiler) shall be rotated weekly (adjustable) to equalize run time between boilers.

5. Boiler Failure: If the lead boiler fails to operate when boiler operation is enabled, the lag boiler shall be enabled. Upon failure of either (or both) of the boilers to operate, a critical alarm condition shall be reported at the operator workstation for each failed boiler.

6. Boiler High Temperature: Individual boilers shall have automatic reset high limit thermostats that will lock out individual boilers when boiler water temperature rises above 170 degrees F (adjustable). When boiler water temperature falls below 150 degrees F, individual boilers shall be automatically re-enabled.

7. Boiler Lockout and Alarm: Operation of the boilers shall be locked out and a critical boiler alarm condition shall be reported at the operator workstation if any of the following conditions occur:

a. Boiler Water Level Falls below Low Water Cutoff Sensor: After cause of the low water condition has been corrected, the low water cutoff sensor must be manually reset.

b. Supply Water Temperature Rises above 180 Degrees F (adjustable): After the cause of the over temperature condition has been corrected, the manual reset high limit thermostat must be manually reset.

c. Failure to Fire: Boiler ignition failure or flame failure.

HVAC System Improvements SOO Page 9 Proposed HVAC Control Sequences of Operation

d. Blocked Intake or Vent: Blockage of either the boiler combustion air intake pipe or the boiler vent pipe.

e. High or Low Gas Pressure: Boiler inlet gas pressure is outside normal limits (4 inches water column to 14 inches water column, adjustable). After the cause of the high or low gas pressure has been corrected, the gas pressure switches must be manually reset.

f. EPO (emergency power off) Switch Activation: Activation of the EPO switch shall disable the boilers, and an emergency power off critical alarm condition shall be reported at the operator workstation.

8. Boiler Circulating Pumps BP-1A, BP-1B, BP-2A, and BP-2B:

a. Boiler On: Boiler circulating pumps shall be energized when their associated boiler is called upon to fire.

b. Boiler Off: Boiler circulating pumps shall be de-energized 10 minutes (adjustable) after their associated boiler stops firing.

c. Boiler Pump Failure: If a boiler circulating pump fails to operate when its associated boiler operation is enabled, a critical alarm condition shall be reported at the operator workstation.

9. Hot Water Circulating Pumps HWP-1 and HWP-2:

a. Heating System Enabled: Lead hot water circulating pump shall be energized.

b. Heating System Disabled: Lead hot water circulating pump shall be de-energized.

c. Pump Sequence Rotation: Hot water circulating pump lead-lag sequencing shall be rotated weekly (adjustable) to equalize run time between the pumps.

d. Hot Water Pump Failure: If the lead hot water circulating pump fails to operate when pump operation is enabled, the lag pump shall be energized and a maintenance alarm condition shall be reported at the operator workstation.

10. AHU-3 Heating Coil Pump HWP-3:

a. Heating System Enabled: Heating coil pump shall be energized.

b. Heating System Disabled: Heating coil pump shall be de-energized.

c. Heating Coil Pump Failure: If the heating coil pump fails to operate when pump operation is enabled, a maintenance alarm condition shall be reported at the operator workstation.

F. Air Handling Units AHU-1 and AHU-2:

1. Supply Air Fan Control:

HVAC System Improvements SOO Page 10 Proposed HVAC Control Sequences of Operation

a. Supply Air Fan Operation: Supply air fan start/stop operation shall be controlled as described in Occupied-Unoccupied Modes above. Supply air fan VFD shall start in low speed and shall ramp up to controlled speed. Supply air flowrate in cubic feet per minute shall be measured with airflow measuring stations located at both supply air fan inlet bells. Supply air fan speed shall be controlled by the supply air duct static pressure sensor in response to the VAV terminal unit damper positions. Above the supply air duct static pressure sensor setpoint, the supply air fan variable frequency drive shall decrease the supply air fan speed. Below the supply air duct static pressure sensor setpoint, the supply air fan variable frequency drive shall increase the supply air fan speed.

b. Supply Air Fan Pressure Setpoint Reset: The supply air duct static pressure setpoint shall be reset by trim and respond logic using the parameters shown below (all adjustable).

TRIM AND RESPOND PARAMETERS

Variable Value Device Supply Air Fan

SP0 0.5 in. H2O SPmin 0.1 in. H2O SPmax 1.5 in. H2O

Td 10 minutes T 2 minutes I 2 R VAV terminal static pressure reset requests SPtrim -0.05 in. H2O SPres +0.06 in. H2O

SPres-max +0.13 in. H2O

The trim and respond logic shall reset the supply air duct static pressure setpoint within the minimum and maximum supply air duct static pressure setpoint limits, SPmin and SPmax. When the associated supply air fan is off, the setpoint shall be the initial setpoint SP0. The reset logic shall be active any time the associated supply air fan is on, starting with a delay time Td after the initial supply air fan start command. When the reset logic is active, if the number of requests R is less than or equal to the number of ignored requests I, the setpoint shall be changed by the trim amount SPtrim after every time step T. If the number of requests R is more than the number of ignored requests I, the reset logic shall respond by changing the setpoint by the respond amount SPres times the number of requests R minus the number of ignored requests I, but no more than the maximum response per time step SPres-max. In other words, for every time step T:

1) If R is less than or equal to I, change the supply air duct static pressure setpoint by SPtrim.

2) If R is greater than I, change the supply air duct static pressure setpoint by (R

- I) x SPres, but no more than SPres-max.

HVAC System Improvements SOO Page 11 Proposed HVAC Control Sequences of Operation

c. Supply Air Duct Overpressurization: If the supply air duct pressure sensor detects a duct overpressurization condition (3.0 inches static pressure, adjustable), the supply air fan operation shall be disabled, and a critical alarm condition shall be reported at the operator workstation.

d. Supply Air Fan Status: If the supply air fan fails to operate when supply air fan operation is enabled, a critical alarm condition shall be reported at the operator workstation.

2. Return Air Fan Control:

a. Return Air Fan Operation: Return air fan start/stop operation shall be controlled as described in Occupied-Unoccupied Modes above. Return air fan VFD shall start in low speed and shall ramp up to controlled speed. Return air flowrate in cubic feet per minute shall be measured with airflow measuring stations located at both return air fan inlet bells. Return air fan speed shall be controlled by the measured difference between the supply air flowrate and the return air flowrate (2,450 CFM for AHU-1 and 3,000 CFM for AHU-2, adjustable) to maintain minimum ventilation air and constant building pressurization during occupied mode.

b. Return Air Fan Status: If the return air fan fails to operate when return air fan operation is enabled, a critical alarm condition shall be reported at the operator workstation.

3. Supply Air Temperature Control:

a. Supply Air Temperature Control Loop: The supply air temperature control loop shall be enabled when the supply air fan operation is proven on and shall be disabled with the loop output set to deadband (minimum economizer) otherwise. The ventilation dampers and DX cooling coils shall operate in sequence to maintain the supply air temperature at setpoint.

b. Supply Air Temperature Setpoint Reset:

1) During Occupied and Unoccupied Modes, the supply air temperature setpoint shall be reset from SPmin when the outside air temperature is 70 degrees F (adjustable) and above, proportionally up to T-max when the outdoor air temperature is 60 degrees F (adjustable) and below. T-max shall be reset within the range of SPmin to SPmax by trim and respond logic using the parameters shown below (all adjustable).

TRIM AND RESPOND PARAMETERS

Variable Value Device AHU/CU

SP0 65 degrees F SPmin 55 degrees F SPmax 65 degrees F

Td 10 minutes T 2 minutes I 2

HVAC System Improvements SOO Page 12 Proposed HVAC Control Sequences of Operation

TRIM AND RESPOND PARAMETERS

Variable Value

R VAV terminal supply air temperature reset requests

SPtrim +0.2 degrees F SPres -0.3 degrees F

SPres-max -1.0 degrees F

When the associated supply air fan is off, T-max shall be the initial setpoint SP0. The reset logic shall be active any time the associated supply air fan is on, starting with a delay time Td after the initial supply air fan start command.

When the reset logic is active, if the number of requests R is less than or equal to the number of ignored requests I, T-max shall be changed by the trim amount SPtrim after every time step T. If the number of requests R is more than the number of ignored requests I, the reset logic shall respond by changing T-max by the respond amount SPres times the number of requests R minus the number of ignored requests I, but no more than the maximum response per time step SPres-max. In other words, for every time step T:

a) If R is less than or equal to I, change T-max by SPtrim.

b) If R is greater than I, change T-max by (R - I) x SPres, but no more than SPres-max.

2) During Morning Precool, the supply air temperature setpoint shall be SPmin.

3) During Morning Warmup, the supply air temperature setpoint shall be 95 degrees F (adjustable). Although there are no heating coils in AHU-1 and AHU-2, raising the setpoint during morning warmup will effectively lock out the economizers and cooling coils.

c. Condensing Unit Interlocks: Condensing unit (CU-1 and CU-2) operation shall be interlocked with the associated supply air fan; the condensing unit shall be enabled only if the associated air handling unit supply air fan is running.

d. Staging Sequence for Existing Condensing Units: Staging sequence of AHU-1 or AHU-2 components on a rise in supply air temperature above the supply air temperature setpoint shall be as follows:

1) Economizer Enabled (outside air temperature is less than return air temperature):

a) Economizer shall provide first stage of cooling.

b) The first DX cooling stage shall be energized and hot gas bypass shall be enabled for low load suction pressure/temperature control.

c) The second DX cooling stage shall be energized.

HVAC System Improvements SOO Page 13 Proposed HVAC Control Sequences of Operation

2) Economizer Disabled (outside air temperature is greater than return air temperature):

a) The first DX cooling stage shall be energized and hot gas bypass shall be enabled for low load suction pressure/temperature control.

b) The second DX cooling stage shall be energized.

e. Staging Sequence for Bid Option A Condensing Units: Staging sequence of AHU-1 or AHU-2 components on a rise in supply air temperature above the supply air temperature setpoint shall be as follows:

1) Economizer Enabled (outside air temperature is less than return air temperature):

a) Economizer shall provide first stage of cooling.

b) DX cooling stages shall be energized proportionally in steps, up to a maximum of 36 steps.

2) Economizer Disabled (outside air temperature is greater than return air temperature):

a) DX cooling stages shall be energized proportionally in steps, up to a maximum of 36 steps.

f. Staging sequences of AHU-1 or AHU-2 components on a drop in supply air temperature below the supply air temperature setpoint shall be the reverse of the sequences above.

4. Ventilation Damper Control:

a. Ventilation Damper Operation: Ventilation damper open/closed operation shall be controlled as described in Occupied-Unoccupied Modes above.

b. Minimum Outside Air Control: Minimum and maximum outside air dampers shall be fully open during all occupied hours for ventilation. Minimum outside air quantity at all VAV operating points shall be controlled by the measured difference between the supply air flowrate and the return air flowrate (2,450 CFM for AHU-1 and 3,000 CFM for AHU-2, adjustable).

c. Economizer Cycle: Economizer cycle shall be differential dry-bulb type and shall be enabled any time that the outside air temperature is less than the return air temperature. If the outside air temperature is greater than the return air temperature, the economizer cycle shall be disabled.

1) Economizer Enabled: When the economizer is enabled, the exhaust air damper shall be opened and the return air damper shall be closed. As the outdoor air temperature drops, the exhaust air damper shall modulate closed

HVAC System Improvements SOO Page 14 Proposed HVAC Control Sequences of Operation and the return air damper shall modulate open under the control of the economizer to maintain supply air temperature at setpoint.

2) Economizer Disabled: When the economizer is disabled, the exhaust air damper shall be closed and the return air damper shall be opened.

5. Alarms:

a. Cooling Supply Air Temperature Out of Range: If all AHU-1 or AHU-2 stages of cooling have been commanded on and the supply air temperature fails to drop to the supply air temperature setpoint within 10 minutes (adjustable), a maintenance alarm condition shall be reported at the operator workstation.

b. Dirty Air Filter: If the AHU-1 or AHU-2 air filter pressure drop exceeds 1.0 inch water column (adjustable), a maintenance alarm condition shall be reported at the operator workstation.

c. VFD Fault: If either the supply air fan or return air fan VFD registers an internal fault, a maintenance alarm condition shall be reported at the operator workstation.

d. Freeze Protection: When any 1-foot section of the freezestat detects a mixed air low temperature condition (35 degrees F, adjustable) upstream of the cooling coil, the associated supply air fan and return fan shall be disabled, the outside air dampers and exhaust air dampers shall be closed, and a critical alarm condition shall be reported at the operator workstation.

e. Duct Smoke Detection: In the event of actuation of either the supply air or the return air duct smoke detectors, the associated supply air fan, return air fan, and exhaust fan operation shall be disabled; the associated supply air and return air smoke dampers shall be closed; the associated outside air damper and exhaust air damper shall be closed; and a critical alarm condition shall be reported at the operator workstation and at the fire alarm control panel. The closing time for the supply air and return air smoke dampers shall be sufficient for the supply air and return air fans to spin down before the supply air and return air smoke dampers are fully closed.

G. Air Handling Unit AHU-3:

1. Supply Air Fan Control:

a. Supply Air Fan Operation: Supply air fan start/stop operation shall be controlled as described in Occupied-Unoccupied Modes above. Supply air fan VFD shall start in low speed and shall ramp up to controlled speed. Supply air fan speed shall be constant.

b. Supply Air Fan Status: If the supply air fan fails to operate when supply air fan operation is enabled, a critical alarm condition shall be reported at the operator workstation.

2. Return Air Fan Control:

HVAC System Improvements SOO Page 15 Proposed HVAC Control Sequences of Operation

a. Return Air Fan Operation: Return air fan start/stop operation shall be controlled as described in Occupied-Unoccupied Modes above. Return air fan VFD shall start in low speed and shall ramp up to controlled speed. Return air fan speed shall be constant.

b. Return Air Fan Status: If the return air fan fails to operate when return air fan operation is enabled, a critical alarm condition shall be reported at the operator workstation.

3. Room Air Temperature Control Operation:

a. The heating coil control valve and ventilation air dampers shall operate in sequence to maintain the Warehouse room air temperature at its setpoint. Limited zone temperature setpoint adjustment (±3 degrees F, adjustable) shall be available at the Warehouse room temperature sensor.

b. Staging sequence of AHU-3 components on a rise in Warehouse room temperature above the Warehouse room temperature setpoint shall be as follows:

1) The heating coil valve shall modulate closed.

2) The exhaust air damper shall modulate open and the return air damper shall modulate closed under the control of the economizer cycle.

3) Economizer Enabled (outside air temperature is less than return air temperature):

a) Economizer shall provide first stage of cooling.

4) Economizer Disabled (outside air temperature is greater than return air temperature):

a) AHU-3 ventilation air shall provide as much cooling as possible.

c. Staging sequence of AHU-3 components on a drop in Warehouse room temperature below the Warehouse room temperature setpoint shall be the reverse of the sequence above.

4. Ventilation Damper Control:

a. Ventilation Damper Operation: Ventilation damper open/closed operation shall be controlled as described in Occupied-Unoccupied Modes above.

b. Minimum Outside Air Control: Minimum and maximum outside air dampers shall be fully open during all occupied hours for ventilation. Minimum outside air quantity shall be controlled by the difference between the supply air flowrate and the return air flowrate (7,265 CFM) and shall be set by the balancer during the balancing process.

HVAC System Improvements SOO Page 16 Proposed HVAC Control Sequences of Operation

c. Economizer Cycle: Economizer cycle shall be differential dry-bulb type and shall be enabled any time that the outside air temperature is less than the return air temperature. If the outside air temperature is greater than the return air temperature, the economizer cycle shall be disabled.

1) Economizer Enabled: When the economizer is enabled, the exhaust air damper shall be opened and the return air damper shall be closed. As the outdoor air temperature drops, the exhaust air damper shall modulate closed and the return air damper shall modulate open under the control of the economizer to maintain supply air temperature at setpoint.

2) Economizer Disabled: When the economizer is disabled, the exhaust air damper shall be closed and the return air damper shall be opened.

5. Alarms:

a. Low Space Temperature: If the Warehouse room temperature falls below 55 degrees F (adjustable), a maintenance alarm condition shall be reported at the operator workstation.

b. Heating Supply Air Temperature Out of Range: If the AHU-3 heating control valve has been commanded fully open and the supply air temperature fails to rise to the supply air temperature setpoint within 10 minutes (adjustable), a maintenance alarm condition shall be reported at the operator workstation.

c. Dirty Air Filter: If the AHU-3 air filter pressure drop exceeds 1.0 inch water column (adjustable), a maintenance alarm condition shall be reported at the operator workstation.

d. VFD Fault: If either the supply air fan or return air fan VFD registers an internal fault, a maintenance alarm condition shall be reported at the operator workstation.

e. Duct Smoke Detection: In the event of actuation of either the supply air or the return air duct smoke detectors, the associated supply air fan, return air fan, and exhaust fan operation shall be disabled; the associated outside air damper and exhaust air damper shall be closed; and a critical alarm condition shall be reported at the operator workstation and at the fire alarm control panel.

f. Freeze Protection: When any 1-foot section of the freezestat detects a low temperature condition (35 degrees F, adjustable) downstream of the heating coil, the supply air fan and return fan shall be disabled, the outside air dampers and exhaust air dampers shall be closed, and a critical alarm condition shall be reported at the operator workstation.

6. Heating Hot Water Supply Temperature Reset Requests:

a. If the AHU-3 heating coil control valve position is greater than 95%, send 1 request until the reheat coil control valve position is less than 85%.

b. If the AHU-3 heating coil control valve position is less than 95%, send 0 requests.

HVAC System Improvements SOO Page 17 Proposed HVAC Control Sequences of Operation

7. Heating Hot Water System Enable Requests:

a. If the AHU-3 heating coil control valve position is greater than 95%, send 1 request until the reheat coil control valve position is less than 10%.

b. If the AHU-3 heating coil control valve position is less than 95%, send 0 requests.

8. Time-Based Alarm and Request Suppression: A time delay period shall be calculated and applied after any change in the Warehouse zone temperature setpoint based on the difference between the zone temperature at the time of the setpoint change and the new setpoint. This time delay shall suppress any alarms or requests during the calculated period after a change in setpoint to avoid nuisance alarms. The default time delay periods for each type of alarm or request shall be as follows:

a. Zone Temperature Alarms: 10 minutes per degree F of difference, but no longer than 120 minutes.

b. Zone Temperature Cooling Requests: 5 minutes per degree F of difference, but no longer than 30 minutes.

c. Zone Temperature Heating Requests: 5 minutes per degree F of difference, but no longer than 30 minutes.

H. Variable Air Volume (VAV) Terminal Units:

1. VAV Control Loops:

a. Two separate control loops, the Cooling Loop and the Heating Loop, shall operate to maintain space temperature at setpoint in each zone. (Note: These loops may always remain active if provisions are made to minimize integral windup. The loops shall only use proportional + integral logic or other technology with similar performance;

proportional-only control is not acceptable.)

1) The Heating Loop shall be enabled whenever the space temperature is below the current zone heating setpoint temperature and disabled when space temperature is above the current zone heating setpoint temperature and the loop output is zero for 30 seconds (adjustable).

2) The Cooling Loop shall be enabled whenever the space temperature is above the current zone cooling setpoint temperature and disabled when space temperature is below the current zone cooling setpoint temperature and the loop output is zero for 30 seconds (adjustable).

b. The Cooling Loop shall maintain the space temperature at the active cooling setpoint. The output of the loop shall be a software point ranging from 0% (no cooling) to 100% (full cooling).

c. The Heating Loop shall maintain the space temperature at the active heating setpoint.

The output of the loop shall be a software point ranging from 0% (no heating) to 100% (full heating).

HVAC System Improvements SOO Page 18 Proposed HVAC Control Sequences of Operation

d. The VAV terminal unit damper shall be modulated by a control loop to maintain the measured airflow at the active setpoint.

2. VAV Zone State:

a. Cooling: When the output of the space Cooling Loop is nonzero and the output of the Heating Loop is equal to zero.

b. Deadband: When not in either heating or cooling zone state.

c. Heating: When the output of the space Heating Loop is nonzero and the output of the Cooling Loop is equal to zero.

3. Zone Temperature Control: Variable air volume terminal units shall be controlled in response to their individual zone temperature sensors to maintain space temperatures at their respective setpoints. Limited zone temperature setpoint adjustment (±3 degrees F, adjustable) shall be available at each zone temperature sensor.

a. Cooling: When the Zone State is Cooling, the Cooling Loop shall maintain space temperature at the cooling setpoint by modulating the active airflow setpoint from the minimum airflow endpoint setting up to the cooling maximum airflow endpoint setting. The reheat coil shall be disabled unless the VAV terminal unit discharge air temperature is below its minimum setpoint.

b. Deadband: When the Zone State is Deadband, the active airflow setpoint shall be the minimum airflow endpoint setting. The reheat coil shall be disabled unless the VAV terminal unit discharge air temperature is below its minimum setpoint.

c. Heating: When the Zone State is Heating, the Heating Loop shall maintain space temperature at the heating setpoint as follows:

1) From 0% to 50%, the heating loop output shall modulate the VAV terminal unit discharge air temperature setpoint from the current air handling unit supply air temperature setpoint up to a maximum of 20 degrees F (adjustable) above space temperature setpoint. The active airflow setpoint shall be the minimum airflow endpoint setting.

2) From 51% to 100%, if the VAV terminal unit discharge air temperature is greater than space temperature plus 5 degrees F (adjustable), then the heating loop output shall modulate the active airflow setpoint from the minimum airflow endpoint setting to the heating maximum airflow endpoint setting.

3) The reheat coil control valve shall be modulated to maintain the VAV terminal unit discharge air temperature at setpoint; directly controlling the reheat coil control valve from the zone temperature control loop is not acceptable.

4) In Occupied Mode, the reheat coil control valve shall be modulated to maintain a VAV terminal unit discharge air temperature no lower than 50 degrees F.

HVAC System Improvements SOO Page 19 Proposed HVAC Control Sequences of Operation

4. Alarms: If any of the following conditions occur, maintenance alarm conditions shall be reported at the operator workstation.

a. Low Space Temperature: If any of the zone space temperatures fall below 55 degrees F (adjustable).

b. Zone Heating Temperature Out of Range: If a VAV terminal reheat coil valve has been commanded 100% open and the zone temperature fails to rise to the zone temperature setpoint within 10 minutes (adjustable).

c. Zone Cooling Temperature Out of Range: If a VAV terminal unit damper has been commanded 100% open and the zone temperature fails to drop to the zone temperature setpoint within 10 minutes (adjustable).

5. VAV System Requests:

a. Supply Air Temperature Reset Requests:

1) If the zone space temperature exceeds the zone cooling setpoint by 5 degrees F for 2 minutes (adjustable) and occurs after the suppression period due to setpoint change, send 3 requests.

2) If the zone temperature exceeds the zone’s cooling setpoint by 3 degrees F for 2 minutes (adjustable) and occurs after the suppression period due to setpoint change, send 2 requests.

3) If the zone Cooling Loop output is greater than 95%, send 1 request until the Cooling Loop output is less than 85%.

4) If the zone Cooling Loop output is less than 95%, send 0 requests.

b. Supply Air Duct Static Pressure Reset Requests:

1) If the measured VAV terminal unit airflow is less than 50% of setpoint while the airflow setpoint is greater than zero and the damper position is greater than 95% for 1 minute, send 3 requests.

2) If the measured VAV terminal unit airflow is less than 70% of setpoint while the airflow setpoint is greater than zero and the damper position is greater than 95% for 1 minute, send 2 requests.

3) If the VAV terminal unit damper position is greater than 95%, send 1 request until the damper position is less than 85%.

4) If the VAV terminal unit damper position is less than 95%, send 0 requests.

c. Heating Hot Water Supply Temperature Reset Requests:

1) If the VAV terminal unit discharge air temperature is 30 degrees F less than setpoint for 5 minutes (adjustable), send 3 requests.

HVAC System Improvements SOO Page 20 Proposed HVAC Control Sequences of Operation

2) If the VAV terminal unit discharge air temperature is 15 degrees F less than setpoint for 5 minutes (adjustable), send 2 requests.

3) If the reheat coil control valve position is greater than 95%, send 1 request until the reheat coil control valve position is less than 85%.

4) If the reheat coil control valve position is less than 95%, send 0 requests.

d. Heating Hot Water System Enable Requests:

1) If the reheat coil control valve position is greater than 95%, send 1 request until the reheat coil control valve position is less than 10%.

2) If the reheat coil control valve position is less than 95%, send 0 requests.

6. Time-Based Alarm and Request Suppression: A time delay period shall be calculated and applied after any change in zone temperature setpoint based on the difference between the zone temperature at the time of the setpoint change and the new setpoint. This time delay shall suppress any alarms or requests during the calculated period after a change in setpoint to avoid nuisance alarms. The default time delay periods for each type of alarm or request shall be as follows:

a. Zone Temperature Alarms: 10 minutes per degree F of difference, but no longer than 120 minutes.

b. Zone Temperature Cooling Requests: 5 minutes per degree F of difference, but no longer than 30 minutes.

c. Zone Temperature Heating Requests: 5 minutes per degree F of difference, but no longer than 30 minutes.

I. Booster Heating Coils:

1. Zone Temperature Control: Booster heating coils shall be controlled in response to their individual zone temperature sensors to maintain space temperatures at their respective setpoints. Limited zone temperature setpoint adjustment (±3 degrees F, adjustable) shall be available at each zone temperature sensor.

a. Zone Temperature above Setpoint: The booster heating coil valve shall modulate closed.

b. Zone Temperature below Setpoint: The booster heating coil valve shall modulate open.

2. Alarms: If any of the following conditions occur, maintenance alarm conditions shall be reported at the operator workstation.

a. Low Space Temperature: If any of the zone space temperatures fall below 55 degrees F (adjustable).

HVAC System Improvements SOO Page 21 Proposed HVAC Control Sequences of Operation

b. Zone Heating Temperature Out of Range: If a booster heating coil valve has been commanded 100% open and the zone temperature fails to rise to the zone temperature setpoint within 10 minutes (adjustable).

3. Heating Hot Water Supply Temperature Reset Requests:

a. If the booster heating coil control valve position is greater than 95%, send 1 request until the reheat coil control valve position is less than 85%.

b. If the booster heating coil control valve position is less than 95%, send 0 requests.

4. Heating Hot Water System Enable Requests:

a. If the booster heating coil control valve position is greater than 95%, send 1 request until the reheat coil control valve position is less than 10%.

b. If the booster heating coil control valve position is less than 95%, send 0 requests.

5. Time-Based Alarm and Request Suppression: A time delay period shall be calculated and applied after any change in zone temperature setpoint based on the difference between the zone temperature at the time of the setpoint change and the new setpoint. This time delay shall suppress any alarms or requests during the calculated period after a change in setpoint to avoid nuisance alarms. The default time delay periods for each type of alarm or request shall be as follows:

a. Zone Temperature Alarms: 10 minutes per degree F of difference, but no longer than 120 minutes.

b. Zone Temperature Heating Requests: 5 minutes per degree F of difference, but no longer than 30 minutes.

J. Exhaust Fans:

1. EF-1 and EF-2:

a. Exhaust fan operation shall be controlled as described in Occupied-Unoccupied Modes above. EF-1 operation shall be interlocked with the operation of AHU-1 and EF-2 operation shall be interlocked with the operation of AHU-2. Exhaust fan operation shall be interlocked such that the exhaust fan shall be energized only when its associated isolation damper has been proven open.

b. If an exhaust fan fails to operate when exhaust fan operation is enabled, a maintenance alarm condition shall be reported at the operator workstation.

2. EF-3:

a. Exhaust fan operation shall be controlled as described in Occupied-Unoccupied Modes above. EF-3 operation shall be interlocked with the operation of AHU-3.

Exhaust fan operation shall be interlocked such that the exhaust fan shall be energized only when its isolation damper has been proven open.

HVAC System…