army reserve center newport, rhode island alexander hosko mechanical option

Army Reserve CenterNewport, Rhode Island

Alexander HoskoMechanical Option

General Building InformationExisting Mechanical Systems

Design ObjectivesVariable Refrigerant Flow System

Ground Couple Heat Pump SystemSystem ComparisonStructural BreadthAcoustical Breadth

Questions

Presentation Outline

Alexander HoskoMechanical OptionSpring 2011


Location: Newport, Rhode IslandSize: 59,000 square feet Levels: 2 levelsCost: $17 millionConstruction Time: January 2009 – September 2011Delivery Method: Design-Bid-Build

General Building Information

General Building InformationExisting Mechanical SystemsDesign ObjectivesVariable Refrigerant Flow SystemGround Couple Heat Pump SystemSystem ComparisonStructural BreadthAcoustical BreadthQuestions



General Building Information

1st Floor 2nd Floor




Existing Mechanical Systems

Waterside

To cool the building:-2 air-cooled rotary screw packaged water chillers

-40 and 52 tons

To heat the building:-2 natural gas boilers

-each 960 MBH

Controls

- Direct Digital Control (DDC) by Johnson Controls

Airside

- 1 constant volume air handling unit (AHU)- 2100 CFM

- 2 variable air volume air handling units- 3700 CFM and 13200 CFM

- Unit ventilators- 8 total between 400 and 1600 CFM





1st Floor 2nd Floor

AHU-1





1st Floor 2nd Floor

AHU-1

AHU-2





1st Floor 2nd Floor

AHU-1

AHU-2

AHU-3





1st Floor 2nd Floor

AHU-1

AHU-2

AHU-3

UV





1st Floor 2nd Floor

AHU-1

AHU-2

AHU-3

UV

UH AND DSS





Total Energy Use: 1, 227 mmBtu / yr

Cost of Energy Use: $27, 384 / year

First Cost: $301,410

LEED: 36 – 42 Points = Silver or Gold




Design Objectives

- Reduce Aspect Ratios of Ducts- Reduce Total Cost of Ductwork- Reduce Energy Required for Supply Fans

- Reduce Total Energy Consumption

- Maintain Current LEED Silver or Gold Rating or Improve Upon




Variable Refrigerant Flow System

- Condenser (rooftop) connected to multiple indoor evaporators

- DOAS to handle outside air and latent load requirements

- VRF to handle remaining sensible load

Summary



Presentation Outline- Simultaneous heating and cooling – allows for Heat Recovery

- Max COP of 5.68 compared to 2.90 for chiller

- Rooftop Condensing Units lead to saved mechanical space (replace boilers)

- Pipes take up less space than ductwork- Leads to reduced building height / cost in some cases


Benefits





Total Energy Use: 1018 mmBtu / yr


First Cost: $283,105

LEED: 43 – 49 Points = Gold




Ground Couple Heat Pump

Summary

- Uses Earth as a heat source / sink- Send fluid through pipes in ground to heat or cool fluid- Takes advantage of 50 – 60 °F constant ground temperature- Heat exchanger to bring heat into / out of system

Benefits

- DOAS to handle latent loads and outside air

- Boilers to meet heating when GCHP is not enough

- Less ductwork

- Save energy




Ground Couple Heat Pump

Types

Vertical -Pipes are placed downward into ground

- Two small diameter tubes / borehole- Boreholes 50 feet to 600 feet deep- Boreholes 20 feet apart to prevent thermal interference

Horizontal-Pipes are placed about 4 feet deep-Single or multiple pipe / trench

- If multiple, further distance because of thermal interference Vertical Horizontal




Vertical Ground Couple Heat Pump

Advantages- Smaller amount of land required- More constant thermal properties of soil- More efficient than horizontal GCHP- Smallest amount of pumping / piping energy

Disadvantages

- Cost- Difficult to find experienced contractors





Vertical GCHP Pipe Length Required

- Method of Ingersoll and Zobel- Based on heat transfer from cylinder buried in earth

For Cooling:

For Heating:

Variables are determined based on:

-Loads for the Building-Average Heat Transfer to the Ground-Thermal Resistance of the Ground and Pipe-Ground Temperature-Proximity of Adjacent Bores-Liquid Temperature at Heat Pump Inlet / Outlet-Power Input at Design Cooling / Heating Loads





Vertical GCHP Pipe Length Required

Using Equation Above:

Total Length for Cooling: 15,424 feetTotal Length for Heating: 23,048 feet

Use the greater of two values:

23,048 feet

3 Boreholes / Loop600 Feet Deep

20 Feet between Borehole




Total Energy Use: 878 mmBtu / yr


First Cost: $502, 086

LEED: 46 – 52 Points = Gold to Platinum





System Comparison

ANNUAL ENERGY USE (mmBtu/yr) FIRST COST ANNUAL ENERGY COSTMECHANICAL

SPACE SAVED (FT)VAV 1,227 $301,410.00 $27,384.00 -VRF 1018 $283,105.00 $27,784.00 800

GSHP 878 $502,086.00 $23,733.00 -

SYSTEM COMPARISON

- GCHP uses least energy and has least cost of energy - Simple payback of 54 years – unfeasible

- VRF is the best choice overall- Save mechanical space- Uses less energy than existing VAV- Lowest first cost




System Comparison

Factors Effecting Cost

- Extra maintenance cost not included with VRF- $40,000 / year (at least) if extra personnel required- One time cost if training required



GSHP 878 $502,086.00 $23,733.00 -

SYSTEM COMPARISON

- Extra cost of controls for VRF

- Boilers oversized for existing VAV- Sized at 66% of total capacity (each)- If changed, total cost would be $292,193

- Prices for VRF determined by Daiken VRV Specs- Converted from euros to dollars- Used RS Means for installation costs- May be slightly higher due to less familiar system- May be more expensive to purchase units in U.S.




System Comparison

- Natural gas ranges from $ 4.00 / mmBtu to $12.00 / mmBtu- Currently $4.00 / mmBtu

- Cost of VRF energy use is more expensive even though it uses less energy because it uses all electricity- Electricity is expensive relative to natural gas- 12.7% electricity in region is generated by natural gas




System Comparison

If natural gas doubles….- electricity goes up 12.7%- natural gas goes up 100%



GSHP 878 $502,086.00 $26,779.00 -

SYSTEM COMPARISON

If natural gas triples….- electricity goes up 27.0%- natural gas goes up 200%



GSHP 878 $502,086.00 $30,207.00 -

SYSTEM COMPARISON


- VRF uses $464 / year less than VAV - VRF uses $1,306 / year less than VAV



System Comparison

Aspect Ratio Problem

- The Aspect Ratio of the ducts will still be high on the first floor- Greatly reduced on second floor

VRF AREA SERVED CFM (MAX)AHU-1 1ST FLOOR AND SPACES PREVIOUSLY ON UVS 9200AHU-2 SECOND FLOOR 4600AHU-3 ASSEMBLY 3000

VAV AREA SERVED CFM (MAX)AHU-1 FIRST FLOOR OFFICES 3700AHU-2 SECOND FLOOR 13200AHU-3 ASSEMBLY 2100UV-1 CLASSROOM 625UV-2 CLASSROOM 440UV-3 CLASSROOM 440UV-4 SOUTH SUPPLY OFFICES 606UV-5 WEST SUPPLY OFFICES 650UV-6 WEAPONS SIMULATOR 975UV-7 SIPRNET CAFÉ 1575UV-8 MAILROOM SUITE 375

AHU-1

AHU-2

AHU-3

UV

UH AND DSS

General Building InformationExisting Mechanical SystemsDesign ObjectivesVariable Refrigerant Flow Systemground couple heat pump SystemSystem ComparisonStructural BreadthAcoustical BreadthQuestions



System Comparison

Achieving Design Objectives?

- Aspect Ratio- Improved on second floor- The same on first floor but not worse

- LEED- VRF will achieve LEED Gold- GCHP will achieve LEED Gold or Platinum

- Energy Improvement- VRF will use 83% of existing VAV- GCHP will use72% of existing VAV

General Building InformationExisting Mechanical SystemsDesign ObjectivesVariable Refrigerant Flow Systemground couple heat pump SystemSystem ComparisonStructural BreadthAcoustical BreadthQuestions



Structural Breadth

- With VRF System, will need to place condensing VRV units on the roof changing the structural requirements

- Mass of each unit according to specifications:

TAG MANUFACTURER MODEL MASS (LB)VRV-1 DAIKIN REYQ96PYDN 732VRV-2 DAIKIN REYQ120PYDN 732VRV-3 DAIKIN REYQ168PYDN 1036VRV-4 DAIKIN REYQ168PYDN 1036VRV-5 DAIKIN REYQ72PYDN 732VRV-6 DAIKIN REYQ96PYDN 732




Structural Breadth

VRV UNITS 3STANDING SEAM METAL ROOF 2INSULATION 3APPROXIMATE DECK SELF WEIGHT 3TOTAL 11

TOTAL DEAD LOAD (psf)- Addition of VRV units leads to dead load of 11psf as shown below:

- Total load 61 psf when 20 psf live load and 30 psf snow load are included




Structural Breadth

- Thus, need to use the following to support additional load:

- Vulcraft 1.5B20 roof deck- 28K8 joists - W10x54 girders




Acoustical Breadth

- Daikin VRV Units will be placed as shown on right- Space below units is office space

- Max noise level of 40 – 45 dBA in office space

- Max noise level on roof will occur at point X or next to VRV - 3 or VRV - 4




Acoustical Breadth

TAG MODEL dBAVRV-1 REYQ96PYDN 58VRV-2 REYQ120PYDN 60VRV-3 REYQ168PYDN 61VRV-4 REYQ168PYDN 61VRV-5 REYQ72PYDN 58VRV-6 REYQ96PYDN 58

DIAKIN VRV UNITS

- Decibels produced by each unit shown in table below:

I1 / I2 = (d2 / d1)2

I1 = intensity at point 1d1 = distance from source to intensity 1I2 = intensity at point 2d2 = distance from source to intensity 2

Use following equation to determine sound intensity from each VRV Unit at point X:




Acoustical Breadth

- Decibel addition (as shown below) allows dB to be added to find sound at point X

- Sound at X is 53 dB- Less than sound at VRV – 3 and VRV – 4 (both at 61 dBA)

- Transmission loss through roof is 35 dBA- Thus, total sound from VRV Units is 26 dBA which is below

40-45 dBA and will not be a problem in the office





Questions?

-The Pennsylvania State University Architectural Engineer Faculty and Staff

-Thesis Advisor: Dr. Stephen Treado

-Michael Baker Corporation: Specifically Duncan Penney and Doug Barker

-U.S. Army Corps of Engineers

-Family and Friends for their support

army reserve center newport, rhode island alexander hosko mechanical option

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