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Mechanical Description and Scope

PART 1 - DESIGN CRITERIA

1.1 Codes, Standards and Regulations

A. International Code (2015)

B. International Fuel and Gas Code (2015)

C. International Mechanical Code (2015)

D. International Code (2015)

E. State Energy Conservation Office (SECO)

F. American Society of Heating, and Engineers (ASHRAE) Standard 90.1-2013

G. ASHRAE Standard 62.1-2013

H. National Fire Protection Association (NFPA) 54: National Fuel Gas Code

I. NFPA 90A: Standard for the Installation of Air-Conditioning and Ventilating Systems

J. NFPA 90B: Standard for the Installation of Warm Air Heating and Air-Conditioning Systems

K. NFPA 92: Standard for Smoke Control Systems

L. NFPA 92A: Standard for Smoke-Control Systems Utilizing Barriers and Pressure Differences

M. Energy Policy Act (EPAct) 2005

1.2 Indoor & Outdoor Design Conditions

A. ASHRAE Weather Station: Austin Camp Mabry, TX, USA (WMO #722544) Construction Documents – February 9, 2018 31

B. Summer Outdoor Conditions (Cooling)

1. Dry Bulb Temperature = 97.9˚F (ASHRAE Fundamentals 2013 – 1% Cooling Day)

2. Wet Bulb Temperature = 74.4˚F (ASHRAE Fundamentals 2013 – 1% Cooling Day)

C. Dehumidification Outdoor Conditions

1. Dry Bulb Temperature = 81˚F (ASHRAE Fundamentals 2013 – 0.4% Dehumidification Day)

2. Wet Bulb Temperature = 77.5˚F (ASHRAE Fundamentals 2013 – 0.4% Dehumidification Day)

D. Evaporation Outdoor Conditions

1. Wet Bulb Temperature = 78.5˚F (ASHRAE Fundamentals 2013 – 0.4% Evaporation Day)

2. Mean Coincident Dry Bulb Temperature = 89˚F (ASHRAE Fundamentals 2013 – 0.4% Evaporation Day)

E. Winter Outdoor Conditions

1. Dry Bulb Temperature = 28.4˚F (ASHRAE Fundamentals 2013 – 99.6% Heating Day)

F. Indoor Design Conditions

1. Office, Conference , Restrooms, Meeting Rooms, Telephone Rooms, Break Rooms, Corridors, Administration Support Areas, Fitness Center, and :

a. Dry Bulb Temperature

1) Cooling = 75˚F ± 2˚F

2) Heating = 70˚F ± 2˚F Construction Documents – February 9, 2018 32

b. Relative

1) Cooling = max 60%

2) Heating = No requirement

2. Telecommunications Rooms (Office Building)

a. Dry Bulb Temperature = 76˚F ± 2˚F (year round)

b. Relative Humidity = max 60%

3. Mechanical and Electrical Rooms (Office Building)

a. Dry Bulb Temperature = 85˚F maximum

b. Relative Humidity = No requirement

4. Machine ( and Office Building)

a. Dry Bulb Temperature = 76˚F

b. Relative Humidity = No requirement

5. Central Utility Plant (CUP) Mechanical

a. Dry Bulb Temperature = 95˚F maximum; 60˚F minimum

b. Relative Humidity = No requirement

6. CUP

a. Dry Bulb Temperature = 95˚F

b. Relative Humidity = Non-condensing

Construction Documents – February 9, 2018 33

1.3 INTERNAL HEAT GAINS

A. Electrical Gains

1. loads will be based on 100 percent of the final loads as determined by the lighting designers. An allowance will be made for the percentage of heat gain directly to the return air stream based on fixture type. Current goals for lighting based on ASHRAE 90.1-2013 are:

a. Enclosed Offices: 1.11 watts per square foot

b. Open Plan Offices: 0.98 watts per square foot

c. Conference Rooms: 1.25 watts per square foot

d. Storage: 0.63 watts per square foot

e. Copy/Print Rooms: 0.72 watts per square foot

f. Training Rooms: 1.24 watts per square foot

g. Fitness Center: 0.72 watts per square foot

h. Corridors & Restrooms: 1.0 watts per square foot

i. Breakrooms: 0.73 watts per square foot

j. Mechanical and Electrical Rooms: 0.95 watts per square foot

2. Office, conference rooms, training rooms and IT & computer equipment loads will be based on 100 percent of the estimated loads as described below. Equipment loads will be diversified at the air handling unit level. Current estimated loads are:

a. Offices: 1.5 watts per square foot

b. Open Office Areas: 1.5 watts per square foot

c. Conference Rooms: 1.0 watts per square foot

Construction Documents – February 9, 2018 34

d. Training Rooms: 1.0 watts per square foot

e. IT / Computer Rooms: 10 watts per square foot

B. Occupancy Gains

1. The occupancy heat rejection will be based on 2013 ASHRAE handbook of Fundamentals, Chapter 18 for Moderately Active Office Work for:

a. Sensible = 250 Btuh per person

b. Latent = 200 Btuh per person

2. The number of occupants in each space will be based on the actual occupant density listed in the facility program for sizing equipment. Energy models will be based on schedules determined with the help of the users.

a. Diversity = 90 percent occupancy equipment sizing.

C. Infiltration Gains

1. The building heat loss calculations will include an load based on 1.5 cfm of infiltration air per linear foot of exterior with per level, and 1.0 cfm of infiltration air per linear foot of wall without windows per floor level.

a. The following infiltration rates will be used for :

1) 200 cfm per for exterior main doors

2) 5 cfm per square foot for exterior overhead doors

D. Gains

1. Performance criteria for building envelope construction materials will be in accordance with the data provided by the Architect. Wall, , and fenestration performance criteria will meet or exceed those indicated in Chapter 5 of ASHRAE 90.1-2013.

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1.4 VENTILATION REQUIREMENTS

A. Offices, Conference rooms, Administrative areas, and Training Rooms

1. Offices, conference rooms, administrative areas, and training rooms will be provided with outdoor air ventilation rates based on ASHRAE Standard 62.1- 2013. The total air supplied will meet the maximum cooling load.

2. The control for air handling system outside air ventilation rates will use a carbon dioxide based demand ventilation control strategy to reduce the total supply of outside air during periods of reduced occupancy in the densely occupied spaces within the building such as conference rooms, training rooms, etc. Carbon dioxide and outdoor levels will be monitored in the zones and will vary the ventilation rates to track a carbon dioxide offset consistent with ASHRAE 62.1- 2013 recommendations. Integrated airflow monitoring systems will provide an additional level of safety assurance for demand control ventilation.

B. Electrical Rooms

1. Electrical rooms (with transformers) will be ventilated using supply air from the building systems utilizing single VAV boxes without reheat coils.

C. Restrooms and Janitor Rooms

1. Restrooms will be exhausted at a minimum rate of 75 cfm per plumbing fixture. Restrooms will be supplied with air conditioning to maintain design conditions. Janitor rooms will be exhausted at a rate of 2 cfm per square foot, and no less than 100 cfm.

D. Outdoor Air Intake

1. Outdoor air intake for air handling units will be minimum 40 feet above grade and will be a minimum of 25 feet away from exhaust or plumbing vent discharge.

E.

1. The crawl space will be ventilated with a dedicated single duct VAV box served from the building air handling system and will have an interlocked exhaust to draw air out of the crawl space and will discharge at the roof of the dining area. The VAV box will be enabled upon the crawl space relative humidity rising above 60% RH. When the supply VAV box is enabled, the interlocked exhaust fan will be energized.

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F. Pressure Relationships

1. Pressure relationships will be maintained by offsets between supply and exhaust airflow rates:

a. Breakroom: Negative

b. Fitness Center: Negative

c. Restrooms, Janitor Rooms: Negative

d. Grab-n-Go: Negative

e. Building: Positive to ambient areas

G. Noise Design Criteria

1. Sound attenuation equipment will be provided based on programmatic need of the space. Maximum room noise criteria levels will be in accordance with ASHRAE Handbook Applications – 2015 Chapter 48. Noise criteria levels are exclusive for HVAC equipment only and do not include background noise of additional equipment or occupants. Input from an acoustical consultant may be required.

a. Typical Occupancy Max. Noise Criteria

1) Private Offices: 30

2) Conference/Meeting rooms: 30

3) Training Rooms: 30

4) Telephone rooms: 25

5) Open-plan offices: 40

6) Corridors and lobbies: 40

Construction Documents – February 9, 2018 37

1.5 PIPE SIZING CRITERIA

A. , condenser water, and heating hot water will be sized for a maximum pressure drop of 3.0 feet/100 feet or a maximum fluid velocity of 7.5 fps, whichever is more restrictive. Design flow rates and pipe diameters will not yield a velocity less than 3.5 fps. All pipe sizing will be in accordance with ASHRAE 90.1- 2013. All major control will be sized for a maximum 5 psig pressure drop at design flow rate.

1.6 DUCT SIZING CRITERIA

A. Supply, return and exhaust air ductwork will be sized based upon the following criteria.

1. Supply Ductwork Sizing (Between AHU and Terminal Units) will be the more stringent of the following:

a. A Maximum pressure drop of 1.5 inches per 100 feet

b. Maximum velocity of 2,000 feet per minute

2. Supply Ductwork Sizing (Between Terminal Unit and Diffuser/Register/) will be the more stringent of the following:

a. A Maximum pressure drop of 0.08 inches per 100 feet

b. Maximum velocity of 1,000 feet per minute

3. Return Ductwork Sizing

a. Maximum pressure drop of 0.1 inch per 100 feet when less than 8,000 cfm

b. Maximum velocity of 1,500 feet per minute when greater than 8,000 cfm

4. Exhaust Ductwork Sizing

a. Maximum pressure drop of 0.06 inch per 100 feet

b. Maximum velocity of 1,500 feet per minute

Construction Documents – February 9, 2018 38

PART 2 - HVAC SYSTEMS DESCRIPTIONS

2.1 HEATING HOT WATER SYSTEM (Office Building Only)

A. Heating hot water will be generated in the office building from natural gas-fired, high efficiency, condensing type hydronic sized for N+1 redundancy. Heating hot water will be distributed throughout the building at 140°F with a 40°F delta-T. The heating hot water system will be a primary/secondary system with small inline circulation pumps provided for each individual . The secondary heating hot water pumps will be horizontal split case, double suction, centrifugal type.

B. Heating hot water piping 2-1/2” and larger will be distributed through ASTM A53 black steel Schedule 40 piping with welded fittings. Heating hot water piping 2” and smaller will be Type L copper with brazed joints. Heating hot water piping and fittings will be insulated with mineral fiber or calcium silicate insulation with ASTM C 921, Type II jacketing.

C. The boiler vents will be individually routed to the exterior wall of the boiler room. Combustion intake air will be drawn in through a single with manifold duct and individual connections to each boiler.

2.2 CHILLED WATER SYSTEM (CUP and Office Building)

A. Chilled water will be generated in new Central Utility Plant (CUP) located on the first level of the parking garage. The chilled water system will be comprised of variable primary chilled water pumping system and centrifugal . The CUP is designed with an ultimate buildout capacity to serve the latest master planned chilled water demand. However, only equipment required to serve the first office building will be installed under this phase. The chilled water system will be designed to allow for chillers, pumps, and other major equipment to be installed while the existing system is in operation.

B. The phase one and final buildout installation will allow for an N+1 equipment redundancy, including chilled water pumps and centrifugal chillers.

C. Chilled water will be supplied from the CUP at 40˚F with a return water temperature of 54 ˚F. Under winter design conditions, the supply water temperature will be reset in conjunction with the building chilled water reset schedule, maintaining a minimum 2 degree F difference between CUP and Building chilled water supply temperature.

D. Three (3) 1,000 ton centrifugal chillers will be required to meet the firm capacity of the fully built out master plan. To meet the N+1 redundancy requirements the final buildout will be provided with four (4) chillers. Each will be provided with an associated chilled water pump, condenser water pump, and cell. To meet the Construction Documents – February 9, 2018 39

capacity and redundancy requirements of the first two (2) chillers will be installed.

E. The chillers will be provided with a centrifugal type with variable speed low voltage motor and packaged controls. The variable speed drive will be provided by the chiller manufacturer and mounted on the chiller. The chillers will utilize R-1233zd(e) or R-134a as the . Final chiller selection will be optimized based on the expected full load and part load operational performance of the building. Chiller performance will be verified to conform with the allowable tolerances if AHRI 550.

F. The chilled water pumps will be centrifugal impeller type vertical inline pumps, conforming to the applicable requirements of the Hydraulic Institute. Each pump will be provided with a dedicated, wall mounted variable speed drive, located adjacent to the pump. Final pump head pressure will be determined using a hydraulic model of the planned routing and equipment/device pressures of the chilled water piping and system

G. As an alternate, a Thermal Energy Storage (TES) system is being included in the project. The system will consist of an above ground insulated pre-stressed concrete tank with upper and lower diffusers and associated distribution piping. The TES system will operate with three modes of operation, charging, discharging, and bypass. Charging will occur during “off peak” time of day rates, while discharging will occur during “on peak” time of day rates. Tank bypass will occur when the tank is fully discharged or charged. A total of two TES tanks will be required to meet the demand of the final campus build out. Day one will consist of one tank with provisions to tie in the second tank to the existing distribution system. A dedicated pumping system will be provided for the TES tanks to provide distribution to the campus chilled water system.

H. New chilled water primary supply and return loop piping will be distributed from the CUP to the future phase buildings. Valved and capped connection points for future extension to the future phase buildings will be located in the crawl space in the office building.. The chilled water supply and return piping risers will be anchored midway up the chase, with the appropriate guides placed on the upstream and downstream sides of the anchors, to account for expansion and contraction of the system.

I. New chilled water supply and return connections for the office building will be provided from the CUP chilled water mains to the office building mechanical room through the below-grade conditioned walk-way. The route for the underground piping will avoid piping under the footprint of the building. Two chilled water plate-and-frame heat exchangers in an N+1 configuration will be located within the office building mechanical room to decouple the secondary building loop from the primary CUP loop. A control in the primary chilled water loop return on the cold side of the building heat exchangers will be modulated to maintain a return temperature of 54˚F back to the CUP. Chilled water on the hot side of the heat exchangers will be provided to the office building at 42˚F at a 14˚F Delta-T. The difference in building chilled water supply temperature and CUP chilled water supply temperature is to account for the inefficiency of the heat exchange at the plate-and-frame heat exchangers. The Construction Documents – February 9, 2018 40

building chilled water supply temperature will be reset up to 45˚F as the outdoor air temperature falls from 50˚F down to 30˚F.

J. The office building chilled water loop will be provided with two centrifugal chilled water pumps sized and selected for N+1 redundancy. Variable frequency drives will be provided on all pumps. The pumps will be horizontal split case, double suction type. The pumps will operate during the office building’s occupied hours to serve the office building equipment.

K. Permanent chemical storage onsite for the chilled water system will not be provided. However, provisions to manually inject chemicals into the chilled water system will be provided.

2.3 CONDENSER WATER SYSTEM (CUP only)

A. The condenser water system will consist of open type evaporative cooling towers, condenser water pumps, side stream filtration, and chemical treatment system.

B. The cooling tower cells and condenser water pumps will be sized for N+1 configuration, aligning with the redundancy requirements of the associated chilled water system components.

C. The cooling towers will be FM approved, factory fabricated induced draft counterflow cooling tower. The cooling tower basin and casing will be constructed of type 304 stainless steel to minimize corrosion. Each cooling tower will be provided with propeller type adjustable pitch fan blades, belt drive, motor located out of the air stream, variable frequency drive, cellular inlet with filter screens, high efficiency PVC fill, drift eliminators, and distribution nozzles capable of reducing he design flow rate of the cell by 50%. The cold basin outlet will be a depressed sump outlet with filter screen and vortex breaker. An equalization line will be provided between cells to allow consistent draw down across the cells.

D. The cooling towers will be located north of the parking garage, on structural steel dunnage. The cooling towers will be elevated on steel dunnage to a height required to maintain acceptable maintenance clearances and to maintain the Net Positive Suction Head required of the condenser water pumps.

E. Each cooling tower will be designed for an outside air wet bulb temperature of 78 ˚F. The cooling towers will have an expected entering and leaving water temperatures of 95˚F and 85˚F, respectively.

F. An automatic fill valve, with bypass from the make-up water system to the basin shall control water level in the basin based on level sensor readings.

Construction Documents – February 9, 2018 41

G. The condenser water pumps will be centrifugal impeller type vertical inline pumps, conforming to the applicable requirements of the Hydraulic Institute. Each pump will be provided with a dedicated, wall mounted variable speed drive, located adjacent to the pump. Final pump head pressure will be determined using a hydraulic model of the planned routing and equipment/device pressures of the chilled water piping and system

H. A side stream filtration system will be provided for the condenser water system. The side stream filtration system will be a packaged high efficiency microsand filtration system, including stainless steel filter vessel(s), centrifugal pump, and controls. The filtration system will be sized for 5% of the total condenser water system flow rate.

I. Chemical water treatment equipment and products shall be provided based on local vendor arrangements and specific local water quality. The water treatment system will include corrosion and biofilm coupon racks, two (2) weeks of chemical storage, chemical injection pumps for each product, associated piping and appurtenances, chemical controllers, and other equipment as required for the water treatment program. The chemical treatment program will be designed to maintain a minimum Cycles of Concentration of 5.

2.4 AIR DISTRIBUTION SYSTEMS

A. Building areas will be served from two (2) factory fabricated, modular, custom, (VAV) air handling units (AHUs). The AHUs will be located in the mechanical penthouse. The AHUs will consist of return fan-wall (array), outdoor air intake, mixing section, pre-filter (MERV 8), final filter (MERV 13), chilled water coils, supply fan-wall (array), and discharge plenum section.

B. Outdoor air for the building will be pre-conditioned through one (1) dedicated outdoor air handling unit (OAHU) located in the penthouse. The OAHU will consist of a filter section (MERV 8), heating hot water coils, chilled water coils, supply fan-wall (array), and discharge plenum. Pre-Conditioned outdoor air will be supplied to the two (2) AHU’s through branch ductwork.

C. The AHU distribution systems will be a single duct VAV. The AHUs will meet the minimum outside air dictated by ASHRAE Standard 62.1-2013 and IMC. The single duct VAV boxes in the building interior zones will vary the amount of supply air with return air when space conditions are met. Each VAV box along the building perimeter zone, or on the top floor, will be parallel fan-powered with heating hot water re-heat coils to mix primary air with plenum air to maintain space temperature. Return air sound boots will be provided to transfer return our out of rooms with that extend to structure.

D. VAV Box Zoning

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1. Each perimeter exposure will be served by dedicated parallel fan-powered VAV boxes with slot diffusers along the exterior walls/windows. Corner offices will be served by dedicated parallel fan-powered VAV boxes. The perimeter zones will serve an area within 15 linear feet of the exterior wall. Interior VAV boxes serving an open office area will serve a maximum of 1500 square feet. VAV boxes serving private offices will serve a maximum of 3 private offices.

E. CoLo Server Room

1. The CoLo Server Room in the office building will be provided with free standing computer room air conditioning (CRAC) units in an N+1 configuration. The CRAC units will have primary chilled water coils with backup direct expansion (DX) coils. The associated condenser units will be located on the roof of the connector between the office building and the parking garage. The CRACs will have stand-alone controls with an interface to the system (BAS). The CRAC units will operate 24/7 and will be on emergency backup power.

F. Main Normal Power and Emergency Power Electrical Rooms

1. The main normal and emergency power electrical rooms on the first floor will be served by single duct VAV boxes.

G. Small IT/Data

1. The small IT/Data Closets in the office tower will be served by variable refrigerant flow (VRF) ductless minisplit system units for 24/7 operation.

2. The small IT/Data Closets in the parking garage will be served by individual ductless mini-split systems for 24/7 cooling.

H. Small electrical rooms with transformers will be served by single duct VAV boxes.

I. The first level mechanical room in the office building will be conditioned with a floor mounted, vertical, chilled water .

J. The first level plumbing room will be served by a single duct VAV box without reheat.

K. The first level fire pump room will be served by a heating hot water unit heater to prevent freezing.

L. The elevator machine room in the office tower penthouse will be provided with VRF ductless minisplit system units on emergency power for continuous 24/7 cooling.

M. The CUP will be provided with a chilled water fan coil unit(s) to provide cooling to the areas where pumps and chillers are located. A dedicated chilled water fan coil unit will also serve the electrical room.

Construction Documents – February 9, 2018 43

2.5 BUILDING PRESSURIZATION

A. The BAS will continuously monitor building pressurization via building static pressure sensors located on each of the four exposures of the building. The BAS will modulate the AHU minimum outside air dampers open (from the minimum position), return air dampers closed and relief air dampers open as required to maintain building pressurization setpoint of 0.05”w.c. (adjustable). A fan CFM offset will be maintained between the supply and return air fans.

2.6 MISCELLANEOUS FAN SYSTEMS

A. Stairwell Shaft Pressurization

1. The stairwells will be served by pressurization fans located in the mechanical penthouse to supply outdoor air, through duct risers installed in vertical shafts adjacent to the stairwells, directly into the stairwell at insertion points on every third floor. The fans and associated distribution systems will be designed in accordance with IBC 2015 and NFPA 92. The fans will be UL listed for smoke control application.

B. Elevator Shaft Pressurization

1. Elevator shaft pressurization is NOT required by IBC 2015 for this project since there are rated elevator lobby enclosures on all .

C. Ventilation

1. The penthouse mechanical room within the office building will be ventilated by providing relief air from the building.

D. CUP Refrigerant Purge Exhaust System

1. The CUP will be provided with a dedicated exhaust fan to purge any refrigerant that has been detected within the space by the refrigerant leak detection system. The system will have exhaust intakes that are within 12” of the floor near the chillers. The refrigerant leak detection system will interface with the building automation system along with horns/strobes at the exit doors for the CUP in accordance with IMC 2015 and ASHRAE Standard 15.

E. Office Building General Exhaust System

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1. All exhaust from restrooms, locker rooms, copy rooms, etc. for the office building will be tied together and routed to a single utility set fan located in the penthouse. The exhaust will be discharged through a louver in the penthouse wall.

F. Grab-N-Go

1. The hood for the range in the Grab-N-Go will be served by a combination upblast exhaust fan and filtered makeup air unit located on the dining area rooftop. The makeup air for the will be heated using natural gas.

G. Fire Pump Room

1. The fire pump room will be provided with a heating hot water unit heater to prevent freezing.

2.7 BUILDING AUTOMATION SYSTEM (BAS)

A. The controls system for the office building, parking garage and CUP will be comprised of a Tridium Niagara Framework as the supervisor server with JACE controllers as the combination gateway/router devices integrating the BAS subsystem, and all associated controllers, with the Niagara Framework. The main BAS panel and servers for the office building, parking garage and CUP will be located in the Telecom Equipment Room in the office building near the batch panel. The HVAC systems throughout the CUP and the office building will be provided with modular direct digital controls (DDC). All controls systems in these facilities will be BACNet protocol.

B. Standalone modules will control air handlers, make-up air units, pumps, exhaust fans, single duct VAV boxes, parallel fan powered boxes and other equipment. A common data highway will link modular controllers. Valve and actuators will be electrically operated.

C. Each DDC controller will have a minimum of 20 percent spare points of each type at each panel.

D. All control panels and controllers will operate on emergency power, as will all DDC system primary controllers, PC and communications equipment monitoring life safety and critical points. This equipment will be provided with UPS.

E. Temperature sensors for fan powered or single duct VAV boxes will be DDC and wall- mounted at 48” from finished floor to the top of the temperature sensor.

2.8 SYSTEM MAINTENANCE AND OPERATION CONSIDERATIONS

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A. All of the mechanical, HVAC, and BAS systems will be operated and maintained in accordance with ASHRAE Standard 180. The design specifications will require operations and maintenance manuals which will be reviewed by the designer to ensure compliance with ASHRAE Standard 180.

PART 3 - HVAC SYSTEM COMPARISON

3.1 Office Building:

A. During the Programming phase, multiple mechanical systems were discussed for the office building. In lieu of the VAV air handling systems discussed in the OPR, other systems such as chilled beams and were discussed. A list of deviations was included at the end of the Mechanical portion of the Programming Document. One of the deviations was that Jacobs would be proceeding with the VAV Air Handling System indicated in the OPR in lieu of evaluating three different systems. This also included a minimum energy savings target of 5% below the ASHRAE 90.1- 2013 baseline in lieu of what was called for in the OPR. For the purposes of meeting the requirements of the TFC AE Guidelines, below is a discussion of the advantages and disadvantages of the proposed system from the OPR as well as two Alternative system types for the office building:

1. Proposed System: VAV Air Handling System with Fan Powered and Single Duct VAV boxes

a. Advantages:

1) System described in OPR

2) TFC Maintenance Staff is versed in these systems

3) Lowest Capital Cost of the three options

4) Flexible with respect to reworking the floor level air distribution for future tenant improvements

5) Proven system in the HVAC industry

6) Most of TFC buildings utilize this type of system

b. Disadvantages:

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1) Ductwork takes up significant room in above space

2) Highest fan horsepower of the three systems

2. Alternate System #1: Displacement Ventilation

a. Advantages:

1) Cooling is not required for the entire volume of space. Warm air can stratify above 6-8 feet where there are no occupants

2) Slight energy savings above the VAV air handling system

3) Still utilizes VAV air handling units and VAV boxes similar to the “Proposed” System so maintenance staff has some familiarity.

b. Disadvantages:

1) System not described in OPR

2) Maintenance staff not familiar with the air distribution devices for this system type

3) Limited flexibility in reworking for future tenant improvements since displacement ventilation diffusers and are a part of the in the spaces

3. Alternate System #2: Active Chilled Beams with Dedicated OA Unit(s)

a. Advantages:

1) Slightly better energy savings than the Proposed and Alternate #1 systems

2) Smaller sized ductwork throughout the building that VAV air handling or displacement ventilation system

3) Smaller chase sizes due to smaller ductwork

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4) Less equipment above ceiling in the spaces

5) Potential reduction in Penthouse mechanical space

b. Disadvantages:

1) System not described in OPR

2) Maintenance staff not familiar with this system type

3) Limited flexibility when reworked for future tenant improvements. This was the greatest concern indicated from TFC personnel in the Sustainability and Energy Use Criteria meetings held during the programming phase.

4) Potential condensate issues if not controlled properly

5) Separate high temperature chilled water loop would be required (including redundant heat exchangers, redundant pumps, air separation, , controls, etc.) Mechanical room space in basement or 1st floor and more chase space for risers.

6) The chilled beams take up significant area in the ceiling grid and are a challenge to coordinate with lighting

7) Substantially more piping which offsets the smaller ductwork

8) Overall greater capital and maintenance cost of all three systems

9) More pieces of equipment to maintain than VAV air handling systems and Displacement Ventilation systems

B. We recommend the installation of the “Proposed” system described above due to its proven track record as a maintainable and energy efficient system, its lower capital cost, and its flexibility for future tenant improvements. The TFC staff is also skilled in the maintenance and reworking of the Proposed system. With the Proposed system we will be able to achieve in the range of 5 to 8% energy savings below ASHRAE 90.1- 2013 baseline as defined in the programming document. This has been confirmed with a preliminary energy modeling.

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C. With the installation of the “Proposed” system, there would be adequate above ceiling space, and mechanical room equipment space to installed one of the Alternate systems in the future.

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