HVAC FInal Report

7/31/2019 HVAC FInal Report

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Project Building Analysis

Final Report #3


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TABLE OF CONTENTS

EXECUTIVE SUMMARY ........................................................................................ Page 3

BUILDING DESCPRITION ...................................................................................... Page 4DESIGN CONDITIONS ............................................................................................ Page 8

Inside Air Temperatures .................................................................................... Page 8Supply Air Temperatures ................................................................................... Page 9

THERMAL ANALYSIS .......................................................................................... Page 10

Determination of Heating and Cooling Loads ................................................. Page 10

Determination of Building Airflows ................................................................ Page 17Determination of Duct System......................................................................... Page 23

Determination of System Load ........................................................................ Page 29Comparison to eQUEST Computer Modeling ................................................. Page 30

SUMMARY OF RESULTS ..................................................................................... Page 30

REFERENCES ......................................................................................................... Page 33

APPENDIX I ............................................................................................................ Page 34

APPENDIX II ........................................................................................................... Page 36APPENDIX III .......................................................................................................... Page 40

TABLE OF FIGURESFigure 1. Building Plan View ..................................................................................... Page 5

Figure 2. South Facing Wall ....................................................................................... Page 5

Figure 3. North Facing Wall ....................................................................................... Page 6

Figure 4. Ceiling and Roof Diagram........................................................................... Page 6Figure 5. Wall Detail (Top View) ............................................................................... Page 7

Figure 6. Wall Detail (Side View) .............................................................................. Page 7

Figure 7. South Wall Detail (Side View) .................................................................... Page 7Figure 8. Wall Representative Section ...................................................................... Page 10

Figure 9. Ceiling Representative Section.................................................................. Page 11

Figure 10. Window Geometry .................................................................................. Page 13


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TABLE OF TABLES

Table 1. Thermal Resistances ..................................................................................... Page 8

Table 2. Heat Gain for Winter .................................................................................... Page 9Table 3. Total Winter Thermal Loads ......................................................................... Page 9

Table 4. Conductive Thermal Loads ......................................................................... Page 10Table 5. Window Thermal Loads ............................................................................. Page 11

Table 6. Occupancy Chart......................................................................................... Page 12

Table 7. Equipment Chart ......................................................................................... Page 12

Table 8. Internal Thermal Loads ............................................................................... Page 13Table 9. Total Summer Thermal Loads .................................................................... Page 14

Table 10. Absolute Temperatures ............................................................................. Page 15Table 11. Average Wall Pressure Coefficient........................................................... Page 16Table 12. Wind Pressure ............................................................................................ Page16

Table 13. Total Pressure Difference ......................................................................... Page 16

Table 14. Infiltration Flow Rates for Components ................................................... Page 16

Table 15. Infiltration Flow Rates .............................................................................. Page 17Table 16. ASHRAE 62.1 Required Outside Airflow Rate ....................................... Page 17

Table 17. Building Required Outside Airflow Rate ................................................. Page 17

Table 18. Supply Airflow Rates ................................................................................ Page 18Table 19. Controlling Ratio ...................................................................................... Page 19

Table 20. Building Airflows ..................................................................................... Page 19

Table 21. Percentage of Supply Airflow Contributing to Infiltration ....................... Page 19

Table 22. Duct Size ................................................................................................... Page 21Table 23. Fitting Type............................................................................................... Page 22

Table 24. Pressure Drop Values................................................................................ Page 22

Table 25. Supply Duct Pressure Drop ....................................................................... Page 23Table 26. Supply Duct Fitting Loss Coefficient ....................................................... Page 23

Table 27. Supply Duct Damper Angles .................................................................... Page 24

Table 28. Return Duct Pressure Drop ....................................................................... Page 24


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condensation produced in the air-handling unit was calculated to be 10.2 lbm/hr. The system-

heating load was calculated to be 19,555 Btu/hr (1.6 tons).

The building was analyzed using an energy analysis computer program, called eQUEST. The

energy simulation program provided the LS-D: Building Monthly Loads Summary and SS-D:Building HVAC Load Summary reports. The LS-D report provided a maximum heating laod of

8,283 Btu/hr, which is lower, then the calculated 19,555 Btu/hr. The SS-D report provided a

maximum cooling load of 236,754 Btu/hr, which is slightly lower, then the calculated 276,777

Btu/hr.

BUILDING DESCIPTION

The commercial building type is a conventional wood frame structure built on a concrete slab.

It is divided into four sections, three 1600 square foot rooms for a health club, a coffee house,

and a bookstore, and a 1000 square foot machinery room. The plan view of the building is

shown below, Figure 1.

Figure 1. Plan View (not to scale, doors and windows not shown)

hi k b i k h


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The back (north) side of the building has two doors located on either side of the machinery room,

as shown in Figure 3, below. The door type used for these doors is foam insulated steel slabswith metal slab in a steel frame.

Figure 3. North Facing Wall

In this report, to simplify calculations the roof is considered negligible. The roof has a

continuous ridge vent located at the top, shown in Figure 4 so the air in the attic is assumed to beequivalent to the outside temperature.


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Figure 5. Wall Detail (top view) Figure 6. Wall Detail (side view)


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DESIGN CONDITIONS

Inside Air Temperatures

The winter thermal load calculations are based on the worse case scenario, where the outsidetemperature is a constant heating dry bulb design temperature, which was found on Table 4-7B

in the HVAC textbook for Portland, OR, and there are no internal thermal loads. The inside

temperature of the building during the winter is set at 70oF. The design temperature for this

building is 22oF based on the heating dry bulb at 99.6%.

The summer load calculations are based on an hour-by-hour time series. The hourlytemperatures were found by where, Tdesign is the cooling dry bulb design temperature, % is the percentage of daily range, and

daily range is the range of the dry bulb. The cooling dry bulb design temperature and range of

the dry bulb were found on the same table as the heating dry bulb design table. The cooling dry

bulb design temperature is 99oF at 0.4% and the range of dry bulb is 21.6

oF. Table 7-2 in the

HVAC textbook shows the percentage of daily range for each hour. The inside temperature of

the building during the summer is set at 74oF.

The sol air temperature, needed to calculate the conductive thermal loads of the outer shellcomponents is calculated by * where, Ta is the outside temperature, Et is the total solar radiation incident on the surface,

is

the surface color parameter, and is the long wave radiation term. The surface colorparameter is 0.15 for light colored surfaces and 0.30 for dark colored surfaces. The long wave

radiation term is -7oF for horizontal surfaces and 0

oF for vertical surfaces. To find the total solar


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The diffuse irradiance is calculated by

for vertical surfaces

for surfaces other then verticalwhere, C is the sky diffuse coefficient, Y is the ratio, and is the tilt angle. The sky diffusecoefficient used was 0.138, found on Table 7 of the 2005 ASHRAE handouts. The ratio is

calculated by for for where, is the solar angle.

The ground reflective irradiance was calculated by *where, g is the ground reflectance.

The total irradiance was then calculated by .Supply Air Temperature

The supply airflow rates required for the building are based on the supply air temperatures. The

supply air temperature used during the winter was 140oF with low humidity and during the

summer was 50oF at 85% relative humidity.

The enthalpies and humidity ratios for the supply air conditions were found as follows. The

equation to solve for enthalpy is

where, T is the temperature, hda is the enthalpy of dry air, is the humidity ratio, and hwv is theenthalpy of water vapor. The enthalpy of dry air was found by . Theenthalpy of water vapor was found by The humidity


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where, supply is the supply humidity ratio, int is the internal mass flow rate, and supply is thesupply mass flow rate. This equation will be used later in the report.

THERMAL ANALYSIS

Determination Of Heating and Cooling Loads

The first step in determining thermal loads on the building is to estimate the thermal resistancesof all shell components. This includes each exterior wall, ceiling, doors, and windows.

The total thermal resistance was calculated following the equation: where, Rout is the air resistance of moving air, Rcomponent is the thermal resistance of a

representative section of the component, and Rin is the air resistance of still air. The thermal

resistance was calculated for both winter and summer based on the different air resistance valuesfor moving air.

The thermal resistance of the wall is calculated based on a detailed representative section, asshown in Figure 8 below.


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where, Atotal is the total area of the wall, Astud is the total area of the studs, Rstud is the thermalresistance of the studs, Ainsualtion is the total area of the insulation, R insuluation is the thermal

resistance of the insulation, Aspacer is the total area of the spacers, and the Rspacer is the thermal

resistance of the spacers. An example calculation is shown in Appendix II.

The thermal resistance of the ceiling is found similarly to the walls. The representative section

of the ceiling being analyzed is shown below, Figure 9.

Figure 9. Representative Section of the ceiling.

The equation for the thermal resistance of the ceiling is as follows.

where, Rinsulation is the resistance of 12 loose insulation, Rtruss is the resistance of southerncypress softwood, and Rgypsum is the resistance of 5/8 gypsum wallboard.


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*

where, A is the area, T is the temperature difference between the outside and inside, and R is

the thermal resistance. The slab/foundation heat loss was calculated by * where, P is the perimeter, FP is the heat loss coefficient, and T is the temperature differencebetween the outside and inside. The total thermal loads acting on the walls, ceiling, windows,

doors, and foundation/slab of are shown on Table 2 below.

Table 2. Heat Gain for winterComponent Rwinter (ft

2*h*oF/Btu) A (ft2) Tin (oF) Tout (

oF) Heat Loss (Btu/h)

North Wall 14.5 1159.5 70 22 3842

East Wall 15.4 400 70 22 1247

West Wall 15.4 400 70 22 1247

South Wall 16.7 592.5 70 22 1700

Ceiling 35.8 4800 70 22 6434

Windows 1.5 572.25 70 22 17854

North Doors 2.7 40.5 70 22 719

South Doors 6.3 60.75 70 22 467

Perimeter (ft) FP (Btu/ft2*h*oF) Tin (

oF) Tout (oF) Heat Loss (Btu/h)

Slab/Foundation 320 0.49 70 22 7526

From the table above, the total thermal loads acting on each business was calculated by addingthe appropriate components. These values are shown on Table 3 below.

Table 3. Total Winter Thermal LoadsThermal Loads (Btu/h)

Health Club 14173

Coffee House 12692

Book Store 14173


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Table 4. Conductive Thermal Loads calculated in Btu/hTime North Wall East Wall South Wall West Wall North Roof South Roof

1 -131 -8 -16 -8 1243 3972 -562 -44 -61 -44 907 297

3 -949 -77 -110 -77 431 144

4 -1294 -104 -146 -104 33 11

5 -1560 -123 -170 -123 16 5

6 -1551 -101 -181 -101 112 33

7 -379 163 -149 163 625 143

8 635 516 -72 516 1905 484

9 977 765 64 765 3803 1132

10 1532 879 303 879 6000 2012

11 2522 886 601 886 8188 2980

12 3730 812 894 812 10221 3922

13 4930 697 1132 697 11945 4730

14 5951 709 1283 709 13195 5310

15 6675 878 1326 878 13872 5596

16 7023 1091 1258 1091 13923 5557

17 6983 1251 1087 1251 13330 5195

18 6740 1304 858 1304 12120 4542

19 6607 1201 657 1201 10351 3666

20 5719 886 483 886 8104 2687

21 3844 499 330 499 5740 1811

22 2245 249 210 249 3824 1187

23 1204 122 117 122 2546 793

24 453 45 43 45 1748 550

The RTS, representative solar values were found on table 7-31 (non-solar) and table 7-32 (solar)

of the HVAC textbook, based on the flooring and window percentage. The following steps were

conducted on each room rather then the entire wall. Similarly to the CTS the representative solarvalues were multiplied by the corresponding radiant heat gain calculated by

* where, Aunshaded is the area of the window not shaded, (SHGC)angle is the incidence angle value,


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The incidence angle and hemispherical diffuse values were found on table 7-4 in the HVAC

textbook for clear glass. The sum of radiant heat gain per hour was calculated and added to theconductive heat gain calculated by

* where, U is the thermal transmittance, A is the area of the window, and T is the temperature

difference. The thermal transmittance is found the equation

. The thermal load through

the window as then calculated by

.The calculated thermal loads through the window for each business is shown on Table 5 below.

Table 5. Thermal Loads through the Window calculated in Btu/hTime Health Club Coffee House Book Store

1 1117 1170 470

2 778 825 276

3 510 550 129

4 303 338 -5

5 164 195 -87

6 587 632 777

7 1300 1367 1883

8 2203 2296 3100

9 3228 3347 4403

10 4307 4452 5653

11 5615 5794 7192

12 7262 7491 9293

13 8158 8410 9859

14 8073 8312 8886


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Table 6. The Occupancy ChartHealth Club Coffee House Book Store

Workers Customers Workers Customers Workers CustomersTime # of People # of People # of People # of People # of People # of People

1 0 0 0 0 0 0

2 0 0 0 0 0 0

3 0 0 0 0 0 0

4 0 0 0 0 0 0

5 0 0 2 0 0 0

6 0 0 2 15 0 0

7 0 0 2 20 0 0

8 0 0 2 20 0 0

9 0 0 2 15 2 010 0 0 2 10 2 4

11 0 0 2 10 2 5

12 0 0 2 0 2 5

1 0 0 0 0 2 6

2 0 0 0 0 2 4

3 2 0 0 0 2 3

4 2 8 0 0 2 2

5 2 18 0 0 2 2

6 2 18 0 0 2 5

7 2 18 0 0 2 68 2 18 0 0 2 7

9 2 8 0 0 2 8

10 2 0 0 0 2 3

11 0 0 0 0 2 0

12 0 0 0 0 0 0

Table 7. The Equipment ChartHealth Club

Equipment ON/Off

Personal Computer (Btu/h) 187.55 When Workers are Present

Monitor (Btu/h) 187.55 When Workers are Present

Task Light (Btu/h) 57.97 When Workers are Present

Laser Printer (Btu/h) 1091 2 When Workers are Present


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From the occupancy table, the thermal loads were calculated based on the heat gains per person

by activity given on table 7-14 in HVAC textbook. The table gives values of total heat, sensible

heat, and latent heat in Btu/h/person and the percent sensible heat in radiant. The total heat,sensible heat, and latent heat were each multiplied to the number of people present in the room

for each hour. Then adding the sensible heat and latent heat you calculate the convective heatgain. The radiant heat gain was found by multiplying the percent sensible heat in radiant by the

sensible radiant for each hour. The equipment thermal loads were calculated in a similar manor

to the human thermal load. Most of the equipment power was found on tables 7-18 to 7-24 in the

HVAC textbook, the rest were looked up online. Table 7-26 in the textbook provides possibleequipment that can be split into radiant and convective parts. The sum of the radiant human and

equipment loads for each hour was solved before using the RTS method to find the total radiantheat gain per hour. The total heat gain of internal loads for each business are found by

.The calculated total internal loads calculated for each business is shown on table 8 below.

Table 8. Internal thermal loads calculated in Btu/h.

Time Health Club Coffee House Book Store1 2541 915 712

2 2396 265 525

3 2296 -255 423

4 2202 814 345

5 2104 12193 302

6 2033 15024 262

7 1984 16940 239

8 1936 17683 216

9 1912 18812 996310 1910 21756 11438

11 1887 15511 11958

12 1839 16384 12100


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Table 9. Total Summer Thermal Loads

Time Health Club (Btu/h) Coffee House (Btu/h) Book Store (Btu/h) Total Thermal Loads (Btu/h)1 3838 1609 1362 6809

2 2985 915 612 4511

3 2224 265 -30 2458

4 1600 -255 -565 781

5 1189 814 -864 1139

6 1557 16763 -24 18295

7 3064 19594 1902 24560

8 5078 21510 4255 30843

9 7220 22253 16445 45918

10 9725 23382 20598 5370611 12644 26326 24293 63264

12 15826 15511 28119 59456

13 17999 16384 30383 64767

14 18912 17222 29920 66053

15 19930 17499 29713 67143

16 60358 16969 28700 106027

17 65639 13789 25258 104686

18 66331 13697 25746 105775

19 64528 11485 23410 99423

20 62179 9065 20897 9214121 51825 6693 18665 77184

22 9781 4777 15304 29861

23 6256 3391 13089 22735

24 4863 2382 2364 9608

DETERMINIATION OF BUILDING AIRFLOWS

The building airflows are shown on Figure 11, below. The outside air and recirculated air entersthe air-handling unit (AHU). The supply air exits the air-handling unit then disperses into each

business. The return air divides into recirculated air and exhaust air.


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*

where, Pb is the absolute outside pressure, h is the vertical distance from the neutral pressurelevel, To is the outside absolute temperature, and Ti is the inside absolute temperature. The

absolute outside pressure used was 14.696 psi for 1 atmosphere. The vertical distance from the

neutral pressure level was found by dividing the building height into two feet increments, asshown on Figure 12, below. The neutral pressure level was at the height of 5 feet.

Figure 12. The vertical distance from the neutral pressure level

The absolute temperatures used are shown on Table 10 below.


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was 11.06 m/s. The average wall pressure coefficient was found on chapter 16, Figure 6, of the

2005 ASHRAE fundamentals handout. The pressure coefficient is located based off of the wind

angle, which can be found on the wind data chart. The average wall pressure coefficients usedare shown on Table 11 below.

Table 11. Average Wall Pressure Coefficient for each wallSummer Winter

Cp (west) 0.1 Cp (east) 0.5

Cp (north) 0.4 Cp (south) -0.4

Cp (east) -0.6 Cp (west) -0.1

Cp (south) -0.5 Cp (north) -0.6

The wind pressure is calculated in so a unit conversion is need to convert to inches ofH2O. The wind pressures calculated are shown on Table 12 below.

Table 12. The calculated Wind PressureSummer Wind Pressure (in of H2O) Winter Wind Pressure (in of H2O)

West 0.017 East 0.162

North 0.067 South -0.130

East -0.100 West -0.032

South -0.084 North -0.194Ceiling -0.084 Ceiling -0.162

The building pressurization is approximately 0.001 inches of H2O because of the HVAC systemused. The stack pressure, wind pressure, and building pressurization were added together for

each wall component and the wind pressure and building pressurization were added together for

the ceiling total. A sample calculation to find the total pressure difference can be found onAppendix II, Sample Calculation 2. Table 13 below, shows the total pressure difference for each

component.

Table 13. The total pressure differenceSummer (inches of H20) Winter (inches of H20)

North 0 063 -0 176


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The calculated infiltration flow rates for each business and the building are shown on Table 15

below.

Table 15. Infiltration Flow RatesSummer (cfm) Winter (cfm)

Heath Club 336 198

Coffee House 312 182

Book Store 376 270

Building 1024 649

The next step in determining the building airflows is to calculate the required outside air tomaintain the indoor air quality in a building. The ASHRAE standard 62.1-2004 minimum

ventilation rates are found on Table 5-9 of the HVAC textbook for different occupancy facilities.The minimum outdoor air ventilation rate was found by where, the people outdoor air rate and area outdoor air rate are found on Table 5-9. The area of

each business is 1600 ft2

and the maximum amount of people is 20 for the health club, 22 for thecoffee house, and 10 for the bookstore. The people outdoor air rate and area outdoor air rate

were found for health club/weight room, bars/cocktail lounges, and sales. Table 16 below shows

the calculated outdoor air rate for each business.

Table 16. The ASHRAE 62.1 required calculated outdoor air.Required Outdoor Air (cfm)

Health Club 496

Coffee House 453

Book Store 267

The building also came with a required outdoor air rate for each business. The required outdoor

air rate for the Health Club was 50 cfm/person, for the Coffee House 25 cfm/person, and for the

Book Store 10 cfm/person. The total building outdoor air for each business is located on Table17 below.

Table 17 The building required outdoor air


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where wv is the mass water vapor. The mass water vapor during the summer was solved usingthe equation

where, QL is the latent heat gain and hfg is the latent heat of vaporization. The latent heat gainswere found on Table 7-14 for people and Table 7-18 for equipment. Both tables were located in

the HVAC textbook. The latent heat of vaporization was found on Table 2-1 in the HVACtextbook under evaporative specific enthalpy at a certain temperature. The average human

temperature used was 98oF and the equipment was estimated to be 200

oF for the coffee maker

and espresso machine and 100oF for the dishwasher. The latent heat of vaporization used was

1059.32 Btu/lb for humans and 1048.03 Btu/lb for equipment.

The winter mass water vapor was calculated following the where, Q is the winter thermal flow rate and hfg is the evaporative specific enthalpy. Theevaporative specific enthalpy was found on Table 2-1 in the HVAC textbook at the buildings

winter room temperature. The value found was 1053.68 Btu/lb.

The internal enthalpy during the summer was calculated by the equation . The latent heat of vaporization for workers and customers are thesame value. During the winter the internal enthalpy is equal to the evaporative specific enthalpy

at room temperature.

By rearranging the energy balance equation, the supply mass flow rate is found by the equationbelow. ()


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The controlling ratio calculated for each business is shown on Table 19 below.

Table 19. Controlling RatioControlling Ratio

Health Club 0.25

Coffee House 0.41

Book Store 0.22

Building 0.28

The supply airflows were adjusted for each business, to set the controlling ratio equal for each

room. The controlling ratio was set to 0.22, the lowest controlling ratio calculated. In order toprevent over ventilation the outside airflow must remain the same, so the supply airflow was

adjusted.

The exhaust airflow, recirculated airflow, and return airflow were the last values calculated. Theexhaust airflow rate was calculated by

where, the local exhaust airflow is 150 cfm from the three restroom exhaust fans. Therecirculated airflow was from the following equation. The return air was calculated by the equation below. The building airflows are shown on Table 20 below.

Table 20. The Building AirflowsSupply Airflow (cfm) Outside Air Requirement (cfm) Exhaust Airflow (cfm) Recirculated Air (cfm) Return Airflow (cfm)Health Club 4545 1000 850 3545 4395

Coffee House 2500 550 400 1950 2350

Book Store 1214 267 117 947 1064


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Determination Of Duct System

The next step in the thermal analysis was to determine the air duct routing and fittings. The topand side view of the supply and return air ducts are show on figures 13, 14, 15, and 16,

respectively. It should be noted the following figures are not to scale.

Figure 13. Top View of the Supply Air Duct Routing


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Figure 16. Side View of the Return Air Duct Routing

The air ducts are color-coded based on the dimensions, shown on Table 22 below.

Table 22. Duct SizeSupply Duct

Height (in) 12

Width (in) 44

Height (in) 10

Width (in) 37

Height (in) 8

Width (in) 22

Height (in) 9

Width (in) 33

Height (in) 7Width (in) 18

Height (in) 6

Width (in) 18

Height (in) 5


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is a rectangular duct so Table 9-1, in the HVAC textbook, was used to find the equivalent

rectangular duct dimensions. The fittings used in the duct are shown on Table 23, below. The

fitting information was found on Table 9-4, in the HVAC textbook, and on Chapter 21 of the2009 AHSRAE Fundamentals Handbook.

Table 23. Fitting TypeFitting Name

3-1 Elbow, Smooth Radius, Without Vanes

5-35 Cross, 90 degrees, Recatgular, Diverging

4-2 Transition, Rectangular, two sides parallel, symmetrical

SR5-15 Bullhead Tee Without Vanes, Diverging

5-28 Tee, Diverging, Rectangular Main and Tap

6-2 Damper, Butterfly, Rectangular

Next, the pressure drops in the ducts were calculated. The equation used was ( ) where, is the air density at 70

oF, g is gravity, h is the duct height in the building, V is the air

velocity traveling through the duct, and L1-2 is the frictional losses. The velocity and friction losswas found on Figure 9-2 in the HVAC textbook based on the flow rate and the previously

selected duct diameter. The frictional losses in straight pipes were found by the following

equation. The frictional losses in the fittings were found by where, c is the fitting loss coefficient and V is the air velocity at the entrance of the fitting. The

fitting loss coefficient were found on Table 9-4, in the HVAC textbook, and on Chapter 21 of the2009 ASHRAE Fundamentals Handbook for the specific fitting used. The needed values are

shown on Table 24.


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The supply duct pressure drops calculated from the air-handling unit to each vent without the

balancing dampers are shown on Table 25, below.

Table 25. Supply Duct Pressure DropHealth Club

AHU -> 1 (in H2O) 1.261

AHU -> 2 (in H2O) 1.261

AHU -> 3 (in H2O) 1.722

AHU -> 4 (in H2O) 1.722

Coffee House

AHU -> 5 (in H2O) 0.525

AHU -> 6 (in H2O) 0.525

AHU -> 7 (in H2O) 0.620AHU -> 8 (in H2O) 0.620

Book Store

AHU -> 9 (in H2O) 1.415

AHU -> 10 (in H2O) 1.415

AHU -> 11 (in H2O) 2.110

AHU -> 12 (in H2O) 2.110

The balancing dampers were added at each air vent in order to control the amount of airflow into

each room. Adding the frictional losses from the fully open damper to the largest calculated our

wanted pressure drop. The fitting loss coefficient for the other dampers were calculated by

*where, Pneeded is the wanted pressure drop, Pcalculated is the pressure drop calculated, and V is

the air velocity through the air vents. The fitting loss coefficients calculated are shown on Table

26, below.Table 26. Supply Duct Fitting Loss Coefficient

Health Club

AHU > 1 0 982


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Table 27. Supply Duct Damper AnglesHealth Club

AHU -> 1 17.50

AHU -> 2 17.50AHU -> 3 11.40

AHU -> 4 11.40

Coffee House

AHU -> 5 27.90

AHU -> 6 27.90

AHU -> 7 27.09

AHU -> 8 27.09

Book Store

AHU -> 9 17.64

AHU -> 10 17.64

AHU -> 11 0.000

AHU -> 12 0.000

The return duct pressure drops were calculated from the return fan to each air vent, from thereturn fan to the exhaust fan, and from the return fan to the air-handling unit. The calculated

pressure drops without balancing dampers are shown on Table 28, below.

Table 28. Return Duct Pressure Drops

HC -> Return Fan (in H2O) 0.3868

CH -> Return Fan (in H2O) 0.9635

BS -> Return Fan (in H2O) 0.5068

Return Fan -> Exhaust Fan (in H2O) 0.1869

Return Fan -> AHU (in H2O) 0.6965

Following the previous steps a damper was placed next to the air vent in each store. The fitting

loss coefficient and angles calculated are shown on Tables 29 and 30 respectively.

Table 29. Return Duct Fitting Loss CoefficientHC -> Return Fan 0.2704

CH -> Return Fan 0.0800


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*

*

* * *where, Q is the flow rate, D is the diameter, N is the speed in RPM, P is the pressure drop, and

is the air density. The diameter and air density do not change. A new lower speed was

originally guessed in order to calculate the new pressure and flow rate. The flow rate at thecalculated pressure of 0.9876 inches of H2O was found by interpolating. Once the equations

were set up in excel the new speed was varied until the desired flow rate and pressure drop were

found. The fan needs to run at a speed of 977.2 RPM in order to produce 7809 cfm at a pressuredrop of 0.9876 inches of H2O. The fan characteristics are shown on Figure 17, below.

Figure 17. Return Fan Characteristics

The exhaust fan had a calculated flow rate of 1367 cfm and a pressure drop of 0.2158 inches of

H O F h b i 13 125 i h if l i li bl h Th

0.000

0.200

0.400

0.600

0.800

1.000

1.200

1.400

1.600

1.800

2.000

5800 6800 7800 8800 9800

PressureDro

p(inofH2O)

Flowrate (CFM)

Speed = 1034 RPM

Speed = 977.2 RPM


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The air-handling unit was not chosen. This is because a custom air-handling unit will be built to

meet the requirements needed to supply the appropriate amount of air to the building. The air-handling unit needs to produce a flow rate of 8259 cfm at a pressure drop of 2.1138 inches of

H2O.

DETERMINATION OF SYSTEM LOADS

The next step in the thermal analysis was to determine the air-handling unit system loads. A

detailed diagram of the air-handling unit is shown below, Figure 19.

Figure 19. Detailed Air-Handling Unit Diagram

In order to calculate the system loads in the air-handling unit the mass flow rates, humidity ratio,

and enthalpies were calculated. The mass flow rate was found by the following equation. The densities used were 0.072 lbm/ft3 for the outside air at 90oF and 0.074 lbm/ft3 for

recirculated air at 74oF. The supply mass flow rate is equal to the outside air and recirculated air

added together. The mass flow rates calculated are shown on Table 31, below.

Table 31. Mass Flow Rates in lbm/hrSummer Winter

Outside Air 7859 279

R i l t d Ai 28755 900


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where,

is the power input to the fan, and hcondensate is the saturated liquid enthalpy at 50

oF and

140o

F found in Table 2-1 in the HVAC textbook. The power was found for the return fan byP=VI. On the specification sheet provided for the 7H483 square centrifugal in-line blower the

voltage and current can be found. The voltage and current used was 208 V and 9.2 ampsrespectively. The power used is 6525 Btu/hr. During the summer the enthalpies calculated were

31.5 Btu/lbm for outside air, 25.5 Btu/lbm for recirculated air, 19.0 Btu/lbm for supply air, and

18.1 Btu/lbm for condensation. The system-cooling load calculated was 23 tons (276777 Btu/hr).

The system-heating load could be calculated following the steps above, but to be conservative

the winter thermal loads calculated above was used. The system-heating load was 41041 Btu/hr(3.4 tons).

COMPARISON TO eQUEST COMPUTER MODELING

Finally a thermal energy simulation was performed on the building. The program used for thesimulation was eQUEST. The building information given through out this report was used to set

up the simulation. Once the simulation was completed the LS-D: Building Month Loads

Summary and the SS-D: Building HVAC Load Summary were viewed. The reports are locatedin Appendix III. The LS-D report only provides static loads with no ventilation and the SS-D

report includes ventilation on the thermal loads.

The maximum heating load provided on the LS-D report is 8,283 Btu/hr. This was compared to

the system-heating load calculated, which was 41,041 Btu/hr. The value provided was

significantly lower then the calculated heating load. The main reason this was found could be

due to input error in the simulation program. However, the maximum cooling load, located onthe SS-D report, was 236,754 Btu/hr. This value is closer to our calculated heating load, which

was 276,777 Btu/hr.


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The total thermal loads acting on each business as well as the building during the summer is

shown on Figure 20 below.

Figure 20. The Total Summer Thermal Loads based on a 24-hour profile.

From the chart, the Health Club produces the highest heat gain. This makes sense due to theamount of equipment used during business hours. The Coffee Houses maximum heat gain isaround 11:00 AM due to the business hours. This makes since because the conductive heat gain

through the walls peak around mid-day and the business is open till 11:00 AM. The Book

Stores heat gain curve is gradual. This makes sense because the Book Store is open from 10:00

AM10:00 PM with a steady amount of internal thermal loads.

The infiltration and building airflow rates were calculated for the building and each business.The infiltration airflow rates were calculated for both summer and winter and are shown on

Table 33, below.

-10000

10000

30000

50000

70000

90000

110000

0 5 10 15 20 25

Heat

Gain(Btu/h)

LST

Heath Club

Coffee House

Book Store

Building Total


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infiltration airflow rates were compared to the supply airflow rates and found to be negligible.

This means infiltration does not need to be accounted for in our building airflow rates.

The building ductwork and fan selections were selected. The supply pressure drop from the air-

handling unit to each air vent was set at 2.1138 inches of water, with dampers place next to eachvent, at a flow rate of 8,259 cfm. The angle each damper needs to be set at is shown on Table 35,

below.

Table 35. Supply Duct Damper AnglesHealth Club

AHU -> 1 17.50

AHU -> 2 17.50AHU -> 3 11.40

AHU -> 4 11.40

Coffee House

AHU -> 5 27.90

AHU -> 6 27.90

AHU -> 7 27.09

AHU -> 8 27.09

Book Store

AHU -> 9 17.64

AHU -> 10 17.64AHU -> 11 0.000

AHU -> 12 0.000

The return pressure drop from the return fan to each air vent was set at 0.9876 inches of water,with the dampers placed next to each vent, at a flow rate of 7,809 cfm. The angle each damper

needs to be set at is shown on Table 36, below.

Table 36. Return Duct Damper Angles

HC -> Return Fan 7.62CH -> Return Fan 0.00

BS -> Return Fan 9.46

Th f d i 24 i h if l i li bl i d f 977 2


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loads are lower then the calculated loads. This error could be due to human input error, when

modeling the building.

REFERENCES

2005 ASHRAE Handbook- Fundamentals Handouts

2009 ASHRAE HandbookFundamentals (SI Edition)

Crowe, Clayton, Donald Elger, Barbara Williams, and John Roberson.Engineering Fluid

Mechanics. 9th. Wiley, 2009. 92-97. Print.

Howell, Ronald H., Harry J. Sauer, and William J. Coad. Principles of Heating, Ventilating, and

Air Conditioning. Atlanta, GA: American Society of Heating, Refrigerating and Air-

Conditioning Engineers, 2005. Print.


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Appendix I


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Table 1. Values Needed for Calculations

Sol Air Temperature Calculations

0.15 Dark Surface 0 Vertical SurfaceA (Btu/h*ft

2) 346 Table 7 in Chapter 31 of 2005 ASHRAE Fundamentals

B 0.186 Table 7 in Chapter 31 of 2005 ASHRAE Fundamentals

C 0.138 Table 7 in Chapter 31 of 2005 ASHRAE Fundamentals

(degree) 20.6 Table 7 in Chapter 31 of 2005 ASHRAE Fundamentals

ET (min) -6.2 Table 7 in Chapter 31 of 2005 ASHRAE FundamentalsCN 0.99

g 0.2 Table 10 in Chapter 31 of 2005 ASHRAE

Fundamentals

Enthalpy Calculations

air(140oF) (slug/ft

3) 0.00206 Table A.3 in Fluid Mechanics Textbook

air(50oF) (slug/ft

3) 0.00242 Table A.3 in Fluid Mechanics Textbook

Psat(140

o

F) (psi) 2.8926 Table 2-1 in HVAC TextbookPsat(50oF) (psi) 0.17811 Table 2-1 in HVAC Textbook

hfg(74oF) (psi) 1053.68 Table 2-1 in HVAC Textbook



Thermal Resistance Calculations

Rplywood 0.62 Table 5-15 in HVAC textbook

Rgypsum 0.56 Table 5-15 in HVAC textbook

Rstud = Rspacer = Rtruss 1.1 Table 5-15 in HVAC textbookRwall insulation 21 Table 5-15 in HVAC textbook

Rout, winter 0.17 Table 5-12 in HVAC textbook


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Appendix II


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Sample Calculation 1

Find: thermal resistance for the east wall

Given: Rplywood = 0.62 (ft2*h*oF/Btu)

Rgypsum = 0.56 (ft2*h*oF/Btu)

Rstud/spacer = 1.1 (ft2*h*

oF/Btu)

Rwallinsulation = 21 (ft2*h*

oF/Btu)

Rout,summer = 0.25 (ft2*h*oF/Btu)

Rout,winter = 0.17 (ft2

*h*o

F/Btu)Rin = 0.68 (ft

2*h*

oF/Btu)

Atotal= (40+1.5)X(16+1.5) = 726.25 in2 = 5.04 ft2

Astud= 1.5X41.5 = 62.25 in2 = 0.432 ft2

Aspacer= 1.5X14.5 = 21.75 in2

= 0.151 ft2

Ainsulation= 14.5X38.5 = 588.25 in2

= 3.877 ft2

Finding Rparallel:

Finding Rwall:


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Sample Calculation 2

Find: Total Pressure Difference

Given: Pb = 14.696 psiTo = 549.67

oR

Ti = 533.67oR

h1 = 4

= 0.00224 slug/ft3

V = 8.49 m/s

Cp = 0.1Pp = 0.001 in of H2

O

Finding Ps: * *

Finding Pw: *

Finding P:


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SAMPLE CALCULATION 3

Find: Supply Airflow Rate

Given: Tsupply = 50oF supply = 85 %

= 0.00242 slug/ft3

Psat = 0.17811 psi

P (1atm) = 14.696 psi

Troom = 74oF

Q = 66331 Btu/hr

Finding hsupply:

* * Finding hroom values:

Finding : ()


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Appendix III


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41

HVAC Project DOE-2.2-47h2 5/01/2012 13:44:18 BDL RUN 3

REPORT- LS-D Building Monthly Loads Summary WEATHER FILE- Portland OR TMY2

---------------------------------------------------------------------------------------------------------------------------------

- - - - - - - - C O O L I N G - - - - - - - - - - - - - - - - H E A T I N G - - - - - - - - - - - E L E C - - -

MAXIMUM MAXIMUM ELEC- MAXIMUM

COOLING TIME DRY- WET- COOLING HEATING TIME DRY- WET- HEATING TRICAL ELEC

ENERGY OF MAX BULB BULB LOAD ENERGY OF MAX BULB BULB LOAD ENERGY LOAD

MONTH (MBTU) DY HR TEMP TEMP (KBTU/HR) (MBTU) DY HR TEMP TEMP (KBTU/HR) (KWH) (KW)

JAN 19.12405 6 14 47.F 42.F 42.865 -0.635 27 6 20.F 17.F -8.283 729. 1.349

FEB 17.53141 20 16 58.F 51.F 44.040 -0.525 15 6 28.F 28.F -6.294 658. 1.349

MAR 20.14322 18 16 70.F 52.F 46.821 -0.478 11 6 32.F 32.F -5.464 729. 1.349

APR 20.09656 20 15 77.F 60.F 47.724 -0.341 30 5 34.F 34.F -4.278 705. 1.349

MAY 22.45200 20 16 87.F 61.F 50.274 -0.140 2 5 44.F 42.F -2.136 729. 1.349

JUN 23.16181 25 15 90.F 67.F 51.861 -0.023 3 5 49.F 46.F -0.788 705. 1.349

JUL 25.21755 23 16 90.F 69.F 52.437 0.000 13 4 52.F 50.F -0.037 729. 1.349

AUG 25.90529 14 16 92.F 63.F 53.684 0.000 0 0 0.F 0.F 0.000 729. 1.349

SEP 24.29659 9 16 92.F 67.F 53.867 -0.002 22 5 45.F 45.F -0.545 705. 1.349

OCT 23.12724 6 15 77.F 59.F 51.237 -0.065 20 5 34.F 34.F -1.996 729. 1.349

NOV 20.72382 1 14 64.F 55.F 47.909 -0.154 30 6 31.F 31.F -3.236 705. 1.349

DEC 19.92703 2 21 55.F 52.F 43.385 -0.376 26 6 32.F 30.F -4.229 729. 1.349--------- ---------- --------- ---------- -------- -------

TOTAL 261.707 -2.739 8581.

MAX 53.867 -8.283 1.349


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42

HVAC Project DOE-2.2-47h2 5/01/2012 13:44:18 BDL RUN 3

REPORT- SS-D Building HVAC Load Summary WEATHER FILE- Portland OR TMY2

---------------------------------------------------------------------------------------------------------------------------------

- - - - - - - - C O O L I N G - - - - - - - - - - - - - - - - H E A T I N G - - - - - - - - - - - E L E C - - -

MAXIMUM MAXIMUM ELEC- MAXIMUM

COOLING TIME DRY- WET- COOLING HEATING TIME DRY- WET- HEATING TRICAL ELEC

ENERGY OF MAX BULB BULB LOAD ENERGY OF MAX BULB BULB LOAD ENERGY LOAD

MONTH (MBTU) DY HR TEMP TEMP (KBTU/HR) (MBTU) DY HR TEMP TEMP (KBTU/HR) (KWH) (KW)

JAN 0.55643 18 15 56.F 51.F 39.127 -116.269 26 23 20.F 17.F -390.024 2597. 8.003

FEB 1.17070 21 16 60.F 48.F 63.625 -88.218 1 6 29.F 29.F -324.268 2403. 9.368

MAR 6.06866 19 16 70.F 55.F 104.511 -84.430 12 6 32.F 31.F -302.880 3008. 11.050

APR 11.11841 21 14 73.F 64.F 192.307 -73.140 30 6 34.F 34.F -283.999 3254. 16.521

MAY 31.70915 21 14 76.F 63.F 180.895 -61.494 25 6 43.F 41.F -222.872 4653. 16.334

JUN 54.54934 25 17 92.F 67.F 222.171 -52.241 29 6 49.F 47.F -185.684 5998. 21.484

JUL 72.95649 23 17 90.F 69.F 236.754 -48.001 14 6 54.F 51.F -163.785 7170. 22.005

AUG 78.33167 3 19 83.F 68.F 221.836 -42.261 21 6 51.F 49.F -170.710 7584. 21.414

SEP 62.64047 9 16 91.F 68.F 227.226 -50.172 22 6 45.F 45.F -208.670 6439. 21.588

OCT 25.25869 12 17 71.F 62.F 172.900 -69.073 23 6 34.F 34.F -279.807 4242. 15.133

NOV 3.78992 1 14 63.F 56.F 113.238 -79.726 30 6 31.F 31.F -305.775 2762. 11.482

DEC 3.23061 13 15 61.F 58.F 123.523 -102.420 31 23 30.F 25.F -319.470 2797. 12.017--------- ---------- --------- ---------- -------- -------

TOTAL 351.380 -867.443 52906.

MAX 236.754 -390.024 22.005

MAXIMUM DAILY INTEGRATED COOLING LOAD (DES DAY ) 0.000 (KBTU)

MAXIMUM DAILY INTEGRATED COOLING LOAD (WTH FILE) 0.000 (KBTU)

HVAC FInal Report

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