11

21032103--454 Ventilation and Air Conditioning454 Ventilation and Air Conditioning

Cooling LoadCooling Load CalculationsCalculations

byby

Assist. Prof. Dr. Tul Assist. Prof. Dr. Tul ManewattanaManewattana.. ChulalongkornChulalongkorn UniversityUniversity

Bangkok, THAILANDBangkok, THAILAND

November 2010November 2010

22

Principles of Cooling LoadPrinciples of Cooling Load

33

Principles of Cooling LoadPrinciples of Cooling Load

44

Principles of Cooling LoadPrinciples of Cooling Load

55

Principles of Cooling LoadPrinciples of Cooling Load

66

Principles of Cooling LoadPrinciples of Cooling Load

77

Principles of Cooling LoadPrinciples of Cooling Load

88

Outdoor Design ConditionOutdoor Design Condition

99

Outdoor Design ConditionOutdoor Design Condition

1010

Outdoor Design ConditionOutdoor Design Condition

1111

Outdoor Design ConditionsOutdoor Design Conditions

1212

Indoor Design ConditionIndoor Design Condition

1313

Indoor Design ConditionIndoor Design Condition

1414

Components of Cooling LoadComponents of Cooling Load

1) External Load

2) Internal Load

3) Outdoor Air Load

1.1) Roofs

1.2) Wall

1.3) Glass (Windows)

1.4) Ceiling

1.5) Floor

1.6) Partition

2.1) People

2.2) Lights

2.3) Power

2.4) Appliances

1515

Lighting Heat GainLighting Heat Gain

1616

LightingLighting

Radiant-CL

41% Conv.59% Radiant

Heat Gain

Conv-CL

Total-CL

Sum

NS-RTS

Watt & Usage

Profile

1717

Cooling Load from LightsCooling Load from Lights

1818

Convective/Radiant SplitConvective/Radiant Split

1919

NonsolarNonsolar RTS ValuesRTS Values

2020

NonsolarNonsolar RTSRTS

2121

Cooling Load from LightsCooling Load from Lights

2222

Calculation ExampleCalculation Example

2323

Example of CalculationsExample of Calculations

2424

Plenum Heat BalancePlenum Heat Balance

2525

Approximate Watt/Approximate Watt/Sq.mSq.m

2626

Lighting Efficiency CompareLighting Efficiency Compare

2727

Wall Heat GainWall Heat Gain

2828

WallWallLocation &

Outside Design Conditions

Radiant-CL

37% Conv.63% Radiant

Heat GainHeat InputSol-air Temp

Conv-CL

Total-CL

Sum

Wall CTS

NS-RTS

2929

Solar Irradiance on WSolar Irradiance on W--WallWall

3030

Solar AngleSolar Angle

3131

Solar EquationsSolar Equations

3232

Solar Irradiance DataSolar Irradiance Data

3333

Earth OrbitEarth Orbit

3434

DeclinationDeclination

3535

WW--Wall Cooling LoadWall Cooling Load

3636

WW--Wall TimeWall Time--delay Effectdelay Effect

3737

SolSol--Air TemperatureAir Temperature

3838

SolSol--Air TemperatureAir Temperature

3939

SolSol--air Temperatureair Temperature

4040

Wall CTSWall CTS

4141

Wall CTSWall CTS

4242

UU--ValueValue

4343

Film Coefficient of AirFilm Coefficient of Air

4444

Air GapAir Gap

4545

KK--ValueValue

4646

UU--ValueValue

4747

UU--ValueValue

4848

UU--ValueValue

4949

Energy Efficient WallEnergy Efficient Wall

5050

Roof Heat GainRoof Heat Gain

5151

RoofRoofLocation &

Outside Design Conditions

Radiant-CL

16% Conv.84% Radiant

Heat GainHeat InputSol-air Temp

Conv-CL

Total-CL

Sum

Roof CTS

NS-RTS

5252

Roof CTSRoof CTS

5353

UU--ValueValue

5454

UU--ValueValue

5555

RR--Value of AtticsValue of Attics

5656

Partition/Floor/Ceiling Heat GainPartition/Floor/Ceiling Heat Gain

5757

Ceiling/Floor/PartitionCeiling/Floor/Partition

Radiant-CL

37% Conv.63% Radiant

Heat Gain

Conv-CL

Total-CL

Sum

NS-RTS

Heat Input CTS

5858

Partition/Ceiling/FloorPartition/Ceiling/Floor

5959

UU--ValueValue

6060

Temperature for Temperature for Adjacent Adjacent UncondUncond--RoomRoom

6161

Temperature forTemperature for Adjacent Adjacent UncondUncond--RoomRoom

6262

WINDOW HEAT GAINWINDOW HEAT GAIN

1) Window Conduction Heat Gain1) Window Conduction Heat Gain

2) Window Solar Heat Gain2) Window Solar Heat Gain

6363

WindowWindow--Solar #1Solar #1Location &

Outside Design Conditions

Radiant-CL

37% Conv.63% Radiant

Beam Heat Gain

Conv-CL

Total-CL

Sum

NS-RTS

Diffuse Heat Gain

100% Radiant

Heat Input - Solar Irradiance

(Direct, Diffuse, Reflect)

S-RTS

No Blinds or

Overhang

6464

WindowWindow--ConductionConductionOutside Design Conditions

Radiant-CL

37% Conv.63% Radiant

Heat GainOutside Air Temp

Conv-CL

Total-CL

Sum

NS-RTS

6565

WW--Window Heat GainWindow Heat Gain

6666

WW--Window CLWindow CL

6767

Beam Solar TimeBeam Solar Time--delay Effectdelay Effect

6868

Diff. Solar TimeDiff. Solar Time--delay Effectdelay Effect

6969

WW--Window CL ComponentsWindow CL Components

7070

Solar RTS ValuesSolar RTS Values

7171

SHGCSHGC

7272

UU--Factors for GlassFactors for Glass

7373

Insulating Glass Unit (IGU)Insulating Glass Unit (IGU)

7474

WindowWindow--Solar #2Solar #2Location &

Outside Design Conditions

Radiant-CL

37% Conv.63% Radiant

Beam Heat Gain x IAC

Conv-CL

Total-CL

Sum

NS-RTS

Diffuse Heat Gain x IAC

Heat Input - Solar Irradiance

(Direct, Diffuse, Reflect)

With Blinds No

Overhang

7575

WindowWindow--Solar #3Solar #3Location &

Outside Design Conditions

Radiant-CL

37% Conv.63% Radiant

Beam Heat Gain x IAC

Conv-CL

Total-CL

Sum

NS-RTS

Diffuse Heat Gain x IAC

Heat Input - Solar Irradiance

(Direct, Diffuse, Reflect)

With Blinds and

Overhang

Shading Fraction & EAC

7676

Venetian Blinds Venetian Blinds Shading Coefficients (IAC)Shading Coefficients (IAC)

7777

Venetian BlindsVenetian Blinds

7878

Draperies IACDraperies IAC

7979

DraperiesDraperies

8080

External ShadingExternal Shading

8181

External ShadingExternal Shading

8282

External ShadingExternal Shading

8383

People Heat GainPeople Heat Gain

8484

PeoplePeople

Radiant-CL

40-63% Conv.60-27% Radiant

Sensible

Heat Gain

Conv-CL

Total-CL

Sum

NS-RTS

Latent Heat Gain

Heat Gain Per Person &

Usage Profile

8585

People Heat GainPeople Heat Gain

8686

Occupant Density (PTT Bld.)Occupant Density (PTT Bld.)

8787

Motor Heat GainMotor Heat Gain (Power)(Power)

8888

Motor Heat GainMotor Heat Gain

8989

Appliances Heat GainAppliances Heat Gain

9090

EquipmentsEquipments

Radiant-CL

80-20% Conv.20-80% Radiant

Sensible

Heat Gain

Conv-CL

Total-CL

Sum

NS-RTS

Latent Heat Gain

Heat Gain Per Equipment & Usage Profile

Exhaust

Hood

9191

Heat Gain from EquipmentsHeat Gain from Equipments

9292

Hood Load FactorHood Load Factor

9393

Office Equipment Load FactorOffice Equipment Load Factor

9494

Actual Load FactorActual Load Factor

9595

Ventilation/Infiltration Heat GainVentilation/Infiltration Heat Gain

9696

Outside AirOutside Air

Sensible

Heat Gain

Total-CL

Sum

Latent Heat Gain

CFM, Design Conditions & Usage Profile

9797

Outdoor Air LoadOutdoor Air Load

9898

Ventilation CFM: Ventilation CFM: ASHRAE Standard 62ASHRAE Standard 62--20072007

9999

Example: Calculation of Ventilation Example: Calculation of Ventilation RateRate

100100

MiscellaneousMiscellaneous

101101

Duct Heat GainDuct Heat Gain

102102

Duct Leak LossDuct Leak Loss

103103

Duct Leakage ClassDuct Leakage Class

104104

Duct Heat Gain & Leak LossDuct Heat Gain & Leak Loss

Duct Heat Gain in % of RSHDuct Heat Gain in % of RSH --Supply Duct 1.5% (Typical Value)Supply Duct 1.5% (Typical Value) --Return Duct 1.5% (Typical Value)Return Duct 1.5% (Typical Value)

Duct Leakage in % of Total Air SupplyDuct Leakage in % of Total Air Supply --Supply Duct 3% (Typical Value)Supply Duct 3% (Typical Value) --Return Duct 0% (Typical Value)Return Duct 0% (Typical Value)

Note that these value are only approximated.Note that these value are only approximated.

105105

Effect of Internal MassEffect of Internal Mass

106106

Room Temperature VariationRoom Temperature Variation

107107

Diversity Factor & Block LoadDiversity Factor & Block Load