M-6 Narrative.pdf

HVAC Alternative #M-6 Narrative

General Description of Alternative: Existing building chiller plant with the new cooling towers and pumps, existing hot water boilers and new pumps, all new hot water and chilled water piping and insulation, new variable volume air handling units located in existing mechanical rooms, new dedicated energy recovery air handling systems.

System Components:

1. Air Side Systems

a. Variable Air Volume Air Handling Systems – General Requirements

• All new air handling systems serving the occupied areas shall be factory constructed custom central station air handling units located in existing mechanical fan room areas throughout the facility. Units shall be broken down into sections to allow for entry into the building areas and then reconstructed in-place with factory witness of re-assembly.

• All new air handling units will be factory custom built type units, with the following general components:

1) Economizer damper section to operate dampers for enthalpy economizer control.

2) Provide separate duct connections for minimum outdoor air from dedicated heat recovery makeup air unit (described in separate section below). The volume of outdoor air will be measured at each air handling unit by air flow measuring stations, that in turn will control the supply of outdoor air required for the occupant load.

3) Return/relief fan section.

4) 30% MERV 8 prefilter/85% MERV 13 final filter section.

5) Chilled water coil section.

6) Supply Fan Section with centrifugal fans.

7) Discharge air section.

8) Ultraviolet lights in all air handlers.

• All air handling units to deliver 55 F. supply air (summer) with reset of discharge temperatures in winter (up to 60 F.) based on space zone temperatures.

• All air handlers shall be ducted with pre-conditioned outdoor air at a capacity required for minimum outdoor air requirements for people plus an additional amount necessary for pressurization of the building. This pre-conditioned outdoor air shall be supplied by the dedicated energy recovery units identified in the section below. This air shall be ducted from the ERU’s in the mechanical rooms to each air handler.

• All air handlers shall be ducted for full outdoor and relief air to existing or new louvers on the mechanical floors for full enthalpy controlled economizer. The outdoor air dampers shall be fully closed when economizer operation is not possible. The relief damper shall modulate to maintain space pressures based on average of the floor served.

• Provide the following air handling systems:

1) B-1: 25,000 CFM – Located in 2nd floor mechanical room. Serving basement.

2) B-2: 25,000 CFM – Located in 2nd floor mechanical room. Serving basement.

3) G-1: 25,000 CFM – Located in 2nd floor mechanical room. Serving ground floor.

4) G-2: 25,000 CFM – Located in 2nd floor mechanical room. Serving ground floor.

5) G-3: 25,000 CFM – Located in 2nd floor mechanical room. Serving ground floor.

6) G-4: 25,000 CFM – Located in 2nd floor mechanical room. Serving ground floor.

7) 1-1: 25,000 CFM – Located in 2nd floor mechanical room. Serving first floor.

8) 1-2: 25,000 CFM – Located in 2nd floor mechanical room. Serving first floor.

9) 1-3: 25,000 CFM – Located in 2nd floor mechanical room. Serving first floor.

10) 1-4: 25,000 CFM – Located in 2nd floor mechanical room. Serving first floor.

11) 1-5: 25,000 CFM – Located in 2nd floor mechanical room. Serving first floor.

12) 2-1: 15,000 CFM – Located in 2nd floor mechanical room. Serving second floor.

13) 2-2: 15,000 CFM – Located in 2nd floor mechanical room. Serving second floor.

14) 3-1: 22,500 CFM – Located in Penthouse mechanical room. Serving third floor.

15) 3-2: 22,500 CFM – Located in Penthouse mechanical room. Serving third floor.

16) 3-3: 22,500 CFM – Located in Penthouse mechanical room. Serving third floor.

17) 4-1: 22,500 CFM – Located in Penthouse mechanical room. Serving fourth floor.

18) 4-2: 22,500 CFM – Located in Penthouse mechanical room. Serving fourth floor.

19) 4-3: 22,500 CFM – Located in Penthouse mechanical room. Serving fourth floor.

20) 5-1: 22,500 CFM – Located in Penthouse mechanical room. Serving fifth floor.

21) 5-2: 22,500 CFM – Located in Penthouse mechanical room. Serving fifth floor.

22) 5-3: 22,500 CFM – Located in Penthouse mechanical room. Serving fifth floor.

23) 6-1: 22,500 CFM – Located in Penthouse mechanical room. Serving sixth floor.

24) 6-2: 22,500 CFM – Located in Penthouse mechanical room. Serving sixth floor.

25) 6-3: 22,500 CFM – Located in Penthouse mechanical room. Serving sixth floor.

Note: Air handling unit locations are based on conceptual information and may be located to an alternative mechanical room location depending upon the space available in the existing mechanical rooms.

b. Special Area Air Handling Systems All special area air handling units will be factory built type units, with the following general components:

1) Economizer damper section to operate dampers for enthalpy economizer control.

2) A separate duct connection for minimum outdoor air from a dedicated heat recovery makeup air unit (described in section c. below). The volume of outdoor air will be measured at each air handling unit by air flow measuring stations, that in turn will control the supply of outdoor air required for the occupant load.

3) Return/relief fan section (where required).

4) 30% MERV 8 prefilter/85% MERV 13 final filter section.

5) Chilled water coil section.

6) Hot water coil section (where required).

7) Supply Fan Section with centrifugal fans.

8) Discharge air section (where required).

9) Ultraviolet lights in all air handlers.

• Kitchen/Cafeteria: The Kitchen/Cafeteria shall be provided with a separate variable air volume air handling unit G-5, with capability of providing of up to 100% outdoor air when kitchen hoods are in use. The unit shall be sized to achieve approximately 18,000 CFM. The unit shall be a variable volume air handling unit. The unit shall control the position of outdoor air and return/relief air dampers, supply and return fans based on space pressure relative to adjoining spaces to provide the required makeup air and to maintain a slight negative condition. The unit shall be a packaged air handling unit with supply and return fans, chilled water cooling and hot water heating coils, located in the 2nd floor mechanical room.

• Mail Room: An air handling unit B-3 shall be provided for the mail room. This unit shall be the sole source of air to and from this space and will have hot water heating and chilled water cooling coils. The unit shall be sized to achieve approximately 3,000 CFM.

The unit shall be a variable volume air handling unit. The unit may be located in the 2nd floor mechanical room (or at the mail room) with duct distribution to and from the room. The mail room shall be provided with an emergency exhaust system to purge the space upon command from the occupants. Outdoor air from a louver shall be ducted directly to the mail room air heat pump for 100% outdoor air capability for economizer and makeup air.

• Loading Dock: Provide a separate air handling unit G-7 for the temperature control of the loading dock area and to provide 100% makeup air for the exhaust systems. The unit may be located in the loading dock area and shall be provided with supply fan, hot water heating and chilled water cooling coils. The unit shall be sized to achieve 5,000 CFM.

The unit shall be a variable air volume air handling unit. The exhaust of the loading dock shall be provided by exhaust duct inlets located to one side of the space near the floor to remove carbon monoxide/dioxide concentrations. The exhaust system shall be ducted to a fan on 2nd floor in the mechanical room. Exhaust shall be energized through an automatic sensor system located in the loading dock area.

• Main Lobby/Entrance: An air handling unit 1-6 shall be provided for the main lobby/entrance vestibule. This unit shall be located in the 2nd floor mechanical room.

The unit shall be sized to achieve 7,500 CFM. The unit shall be a variable air volume air handling unit. This unit shall have supply and return fans, hot water heating and chilled water cooling coils and shall have the capability of operating up to 100% outdoor air to maintain a positive pressure in the lobby/entrance relative to the rest of the building.

• Auditorium: An air handling unit G-6 shall be provided to serve the Auditorium areas.

This unit may be located in the 2nd floor mechanical room. The unit shall be sized to achieve approximately 10,000 CFM. The unit shall be a variable volume air handling unit.

The unit shall be provided with outdoor air from the energy recovery systems and will adjust the amount of outdoor air based on carbon dioxide sensors located in the space to adjust the amount of outdoor air based on actual occupancy loads.

• Elevator Equipment Room: Provide a fan coil unit 7-1 for this room. The unit shall be located in the penthouse mechanical room. The unit shall be sized to achieve approximately 3,000 CFM. The unit shall be constant volume fan coil unit. The unit shall be provided with chilled water cooling coil and full economizer capability. The room shall be provided with electric unit heater for winter heating needs.

• Fire Command Centers, Building Control System (BAS) Control Rooms, Security Monitoring Rooms, Voice/Data Rooms, Computer Rooms: Dedicated 24/7 packaged four pipe fan coil systems with cooling systems using the building dedicated “house” condenser water system as a source for heat of rejection. Redundant units will be provided where required by PS100 standards.

c. Dedicated Outdoor Air/Energy Recovery Systems – General Requirements

• Exhaust from toilet rooms, janitors closets, loading dock and general exhaust for the kitchens/break rooms and other areas will be collected and routed through total energy recovery air handling systems (recovery of energy from grease producing exhaust systems cannot be achieved due to the grease contamination and fire potential). The energy recovery units will be located in the mechanical rooms located on 2nd and the 7th floor penthouse mechanical rooms.

• Estimated amount of continuous exhaust is = approximately 40,000 CFM.

• Estimated minimum outdoor air requirements are based on the amount required for makeup air to supply the occupants and makeup for the volume of air exhausted (40,000) + the amount required for building pressurization (approximately 40,000). Total required makeup air for the facility = 80,000 CFM.

• The heat recovery units shall be mounted inside the existing mechanical rooms and consist of the following:

1) Supply and exhaust fans.

2) Intake and Exhaust louvers and dampers.

3) Total energy heat wheel.

4) Chilled water coil.

5) Hot water Reheat coil.

6) 30% MERV 8 prefilter/85% MERV 13 final filter section.

7) Unit capable of recovering 80% of the energy from the air being exhausted and transferring this heat energy to the incoming makeup air.

8) Ultraviolet lights in all air handlers.

• All energy recovery units to deliver 55 F. supply air (summer) with reset of discharge temperatures in winter (up to 60 F.) based on space zone temperatures.

• All energy recovery units shall be ducted for to existing or new louvers on the mechanical floors with motorized dampers.

• Provide the following energy recovery systems:

1) ERU-1: 17,500 CFM – Located in 2nd floor mechanical room.

2) ERU-2: 17,500 CFM – Located in 2nd floor mechanical room.

3) ERU-3: 17,500 CFM – Located in 2nd floor mechanical room.

4) ERU-4: 17,500 CFM – Located in 2nd floor mechanical room.

5) ERU-5: 15,000 CFM – Located in 7th floor mechanical room.

6) ERU-6: 15,000 CFM – Located in 7th floor mechanical room.

7) ERU-7: 15,000 CFM – Located in 7th floor mechanical room.

• Intake and exhaust ductwork from the seven ERU’s will be connected to the existing louvers on each of the two floors. Provide motorized dampers at these connections.

• Exhaust from the basement through 1st floor sources will be ducted directly to the inlets of the four ERU’s evenly split between each unit.

• Exhaust from the 2nd floor through 6th floor sources will be ducted directly the inlets of the three ERU’s in the 7th floor, evenly split between each unit.

• Makeup air from each of the four (4) ERU’s in the 2nd floor mechanical room will be ducted directly to the inlets of the fourteen (14) air handling units in these rooms for minimum outdoor air requirements. Makeup from the three (3) ERU’s in the 7th floor mechanical room will be ducted directly to the inlets of the twelve (12) air handling units in these rooms.

d. General HVAC Systems

• All bathrooms, locker room and janitor rooms will be exhausted at a rate of 10 air changes per hour.

• All break/small kitchen areas on floor x floor locations will be exhausted at a rate to maintain a slight negative condition to adjoining areas.

• Ductwork from shafts serving multiple floors shall be provided with combination smoke/fire dampers at penetrations on to a floor served.

• Areas served by the air handling systems shall be provided with variable air volume boxes for zone control. Perimeter zones shall be fan powered type vav boxes with reheat coils.

Interior areas will be variable air volume boxes with hot water reheat coils.

• Interior conference rooms, training rooms, classrooms, seminar rooms or other rooms with larger occupancy will be provided with VAV boxes with reheat coils and a space carbon dioxide level sensor to enable the VAV box to supply up to 100% air flow for increased outdoor air capabilities when the room(s) are fully occupied.

• Air distribution shall be through overhead vaned type diffusers. Perimeter zones will be provided with linear slot type air diffusers along the exterior window walls.

• Return air from spaces shall be through ceiling return air plenum.

• Perimeter Heating: All perimeter walls with windows and walls exposed to outdoors with a heating load of greater than 400 btuh/lineal foot of exposed wall shall be provided with perimeter hot water finned tube radiation. Hot water will be supplied at a maximum water temperature of 140 F. at -19 F. peak winter condition. Where heating load is under 400 btuh/linear foot for these same locations, overhead slot type diffusers shall be provided in lieu of finned tube radiation under the windows.

• Thermostatic Zones

1) Interior – open office areas: One zone for similar occupancies up to 1500 sq. ft.

maximum.

2) Interior – private offices: One zone per three offices.

3) Interior – larger conference rooms: One zone per conference room.

4) Perimeter offices – No more than 300 sq. ft. per zone along a common exposure.

5) Perimeter conference rooms: One zone per conference room.

6) Perimeter – corner rooms/offices: One corner room per zone.

2. Chiller Plant, Dedicated 24/7 Chilled Water Systems and Cooling Towers

• Total current capacity of the hilled water system will be = approximately 950 tons.

• The three existing McQuay model PEH-087K centrifugal chillers located in the basement chiller room shall remain. These chillers are approximately 12 years old.

• The existing piping installed in 1998 connecting to the chillers and mains shall remain.

• The existing primary and secondary pumps connected to the three chillers installed in 1998 shall be removed and replaced with new pumps.

• Remove all original building chilled water piping outside of this chiller room. Distribute new chilled water supply and return water piping to new air handling units and fan coil units in locations described in “Air Systems”. All coils shall be provided with modulating two way valves.

• The existing Evapco cooling towers and condenser water pumps were installed in 1998. The estimated life expectancy of cooling towers range from 20 to 30 years depending upon maintenance. Remove these cooling towers and pumps. Replace with three new nominal cooling towers and pumps of same size and capacity. These cooling towers shall be provided with new piping down to the chiller room and reconnected to the existing chillers and new condenser pumps.

• Route 12” to 14” condenser water supply from the sump of tower and a 10” to 12” condenser water return from the condenser water pump(s) in the chiller room up to the cooling towers. Route in the current pipe shaft location at the north side of the building.

Dedicated Condenser Water System

• Provide a dedicated 24/7 condenser water system to supply continuous water to air conditioning systems serving building fire command/building automation/security type communication rooms, voice/data rooms and computer rooms with dedicated packaged DX AC equipment. Provide two evaporative fluid coolers (one redundant) on the roof area above the 6th floor. Each evaporative fluid cooler shall be sized for approximately 100 tons of cooling capacity. The evaporative fluid coolers will be provided with finned coils for 100% “free cooling” capability in the winter (below 40 F. ambient conditions) and to minimize any potential for water freezing. The fluid cooler fans shall be controlled with variable speed drives. One of the coolers will be redundant.

• Route domestic water for fill of the fluid cooler sump for coil spray.

• Provide two condenser water pumps (one redundant) in the Penthouse mechanical room.

The pumps shall deliver approximately 300 gpm at 75 ft. of head. The pumps shall be based mounted centrifugal. The condenser water system shall be filled with a nominal 40% propylene glycol solution.

• Route the condenser water piping from the 24/7 fluid cooler(s) to these pumps and then provide a circulating loop at each floor connecting to the 24/7 AC systems. The condenser water supply and return temperatures shall be based on a 10 F. temperature differential, typically 90 F. supply and 100 F. return during peak summer ambient conditions.

3. Boiler Plant

• Total current capacity required hot water capacity of the plant = approximately 15,000,000 btu

• The three existing Cleaver Brooks model CB-200-270-125 hot water boilers located in the basement boiler room shall remain and be reused. These boilers are approximately 13 years old.

• The two remaining backup hot water boilers (one gas fired, one electric) shall be removed, including their respective pumps.

• The existing steam boiler and accessories shall be removed.

• The existing piping installed in 1997 connecting to the three boilers shall remain.

• The existing primary and secondary pumps connected to the three boilers installed in 1997 shall be removed and replaced.

• The boiler systems shall serve hot water needs of the building.

• The circulating hot water systems shall be filled with a 40% solution of propylene glycol.

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