Cooling Load Calculation Designed for 12th April /17.00, 25.5 0C And 50% Relative Humidity Room Dimension: 6.3*3.69*2.77 m3 In figure; W for Window & D for door Window Dimension: 0.88*1.36 m2 Door Dimension: 1.14*2.12 m2 Open space, North Side W West Side Unconditioned Room at 30 0C Unconditioned Room at 30 0C D East Side W Partition walls (West, East & North Wall) : with 127 mm thickness brick and 25 mm plaster on both sides. Roof: Type 6 (No insulation) 150 mm l.w.concrete without suspended ceiling Floor: Type 6 (No insulation) 150 mm l.w.concrete South Wall: Type D with 127 mm thickness brick and 25 mm plaster on both sides. Door: 2.42 m2 area ; 40 mm thickness hardwood. South ( Sunlit Wall ) W W Window: 1.2 m2 area on north & south side.5 mm thickness glass; light construction. Air Exchange Rate: 1.0/hour Lights: 4 fluorescent light of 25 watt Occupants: 4 occupants (Approximately 15 hours) using 4 computer (Approximately 5 hours in a day) Heat Conduction Through Surfaces: 1) Conduction through shaded or partition surfaces Q=U.A.TD 2) Conduction through sunlit surfaces Q=U.A.CLTD U→ Overall Heat Conductance A→ Surface Area TD→ Temperature Difference CLTD→ Cooling Load Temperature Difference Overall Heat Conductance, U: ROOF: From table -12(a) For type 6 Code numbers of layers→ A0,E2,E3,C15,E0 RTotal=0.059+0.099+0.050+0.880+0.121 [ From table -16] =1.209 URoof=1/RTotal=0.827 ( Construction of roof and floor is same so Ufloor=Uroof=1.827) South Wall (Sunlit) : From table -14 For type D Code numbers of layers→ A0,A2,C4,E1,E0 RTotal=0.059+0.0 (No Insulation) +0.175+2*0.034+0.121 [ From table -16] =0.423 USouth-wall=1/RTotal=2.364 West, East and North Walls (Partition wall) : RTotal=Ri+R1+R2+R3+RO =E0+ R1+R2+R3+A0 R1=R3→ Resistance for Plaster R2→ Resistance for brick From table -16 For Brick: C4→ K=0.727; R2=L/K=0.127/0.727=0.175 For Plaster: E1→ K=0.7277; R1=R3=L/K=0.025/0.7277=0.034 So, RTotal=0.121+0.034+0.175+0.034+0.059 [ From table -16] =0.423 UPartition-wall=1/RTotal=2.364 Door: R=Ri+Rd+Ro =E0+Rd+A0 From Table -17 For Hard-Wood (Oak) ; K=0.16 → Rd=L/K=0.040/0.16=0.25 So, R=0.121+0.25+0.059 UDoor=1/R=2.33 Window: From Table-17 Conductivity of cellular glass is 0.050w/mk So, R=L/K=0.005/0.05=0.1 RTotal=Ri+Rw+Ro =Eo+Rw+Ao =0.121+0.1+0.059 =0.28 UWindow=1/RTotal=3.57 Conduction Heat Transfer Through Partition/Shaded Walls/Surfaces: Item Description U A TD Q=A.U.TD i)Partition Wall East Side 2.364 17.451 4.5 185.644 ii)Partition Wall West Side 2.364 17.451 4.5 185.644 iii)Shaded Wall North Side 2.364 5.411 7.5 95.937 iv)2Window North Side 3.57 2.3936 7.5 64.089 v)Door North Side 2.33 2.4168 7.5 42.234 Vi)Floor Bottom Side 0.827 23.247 4.5 86.514 ∑=660 W CLTD For Sunlit Walls: CLTDC=[(CLTD+LM)*K+(25.5-Ti)+(Toavg-29.4)]*f ------(i) Here, CLTDC=Corrected Cooling Load Temperature Difference LM=Correction for latitude and month K=Color adjustment factor; 0.5 for light color & 1.0 for dark color. f=Attic fan factor; 1 for no attic fan/duct &0.75 for +ve ventilation From Table-9 Toutside-maximum=330C Daily range=110C So, Toavg=33-11/2=27.50C CLTD For Roof: Table 12(b) → CLTD=350C Table-13→ LM=0.0 K=1 & f=1 So from equation (i) CLTDC=33.10C CLTD For South Wall: Table 15 → CLTD=150C Table-13→ LM=-1.6 K=0.5 (For light color) & f=1 So from equation (i) CLTDC=4.80C Conduction Heat Transfer From Sunlit Roof Or Walls: Item Description U A CLTDC Q=U.A.CLTDC i)Roof Type-6 0.827 23.247 33.1 636.356 ii)South Wall Type-D 2.364 7.8277 4.8 88.822 iii)2 Windows South Wall 3.57 2.3936 7 59.82 ∑=785.0 W Solar Heat Gain Through Glasses: Q=A.SC.SHGFmax.CLF Where, A=Heat transfer area SC=Shading Co-efficient SHGFmax =Maximum solar heat gain factor CLF=Cooling load factor North Side Glass (2 Glasses, Shaded): So, Q=(1.2*0.95*126*0.75)*2=215.46 Watt [SC→Table-21, SHGFmax →Table-18(b),CLF→Table-19] South Side Glass (2 Glasses, Sunlit): So, Q=(1.2*0.95*237*0.43)*2=232.35 Watt [SC→Table-21, SHGFmax →Table-18(a),CLF→Table-19] So, Total Heat Gain Due To Glasses = (215.46+232.35)Watt=447.81Watt Cooling Load For Air Exchange: Sensible Heat Gain =ρcpὺ(To-Ti) ρcp=1200 J/m3k ὺ=6.3*3.69*2.77/3600=0.0179 m3/s To=330C (Table-9), Ti=25.50C So, Sensible Heat Gain =ρcpὺ(To-Ti)=1200*0.0179*(33-25.5)=161.1 Watt Latent Heat Gain=ρhfgὺ(ω0- ωi)=3010*1000*0.0179*(0.021-0.010)=619.61 Watt [ ρhfg =3010*1000 J/m3, Ti,dry_bulb=25.50C, RH=50%; So, From psychometric chart ωi =0.010 kg/kg ;To_dry_bulb=330C, To_wet_bulb=270C, ω0=0.0215 kg/kg ] Heat Gain Due To Occupants: QS=75*4=300 Watt; QL=55*4=220 Watt [From table-28] Heat Gain Due To Equipment: QS=P*CLF=200*1*4=800 Watt [ P=Wattage of each computer, Number of computer =4] Heat Gain Due To Lights: QS=PL*BF*D*CLF Where, PL =Wattage of light=25 Watt*4=100 Watt [ No of light is 4] BF=Balast factor=1 for incandescent light =1.2 for fluorescent light D=Diversity factor for not all lights being on=1 (Let all time on) CFL=Cooling load factor=0.85 for light So, QS=PL*BF*D*CLF=100*1.2*1*0.85=102 Watt Item QS QL i)Conduction heat gain through partition/shaded walls/surfaces ii) Conduction heat gain through sunlit wall/roof iii)Solar heat gain through glasses 660 iv)Heat gain due to air exchange 161.1 619.61 v)Heat gain due to occupants 300 220 vi)Heat gain due to equipments 800 vii)Heat gain due to lights 102 QTotal 785 447.81 ∑All= 4095.52 Watt So, QTotal=4095.52 Watt=4.0955 Kilowatt=4.0995/3.517 =1.164 Ton of refrigerator So, 1.5 Ton refrigerator is required for my room. (Room No. 5005; Dr. M. A. Rashid Hall; BUET) Calculating a Home's Cooling Load 1. Determine the dimensions of the room or home that needs cooling. For a room, you can do this with a measuring tape. ... 2. For a room, multiply its length by its width to get the square footage. 3. Multiply the square footage by 20. This is the measure of the BTU cooling load of the space. Selecting the Right Air Conditioning Unit for Your Needs Now that you know how many BTUs are needed, it is time to select from the myriad possibilities for air conditioning systems. Our heating and cooling service technicians are happy to provide you with recommendations for units that we know to be reliable and energy efficient. Another way to research is to use consumer review publications and websites. When looking for a new air conditioning system, be sure to choose one with the highest SEER (Seasonal Energy Efficiency Ratio) rating that fits into your budget. The higher the SEER rating, the less electricity the system will consume in cooling the space. Carrier Factory Authorized Dealer We are proud to serve as your factory authorized dealers for the Carrier Corporation. In order to achieve this honor, each one of our service team members has surpassed Carrier’s intense requirements for skill, knowledge and customer service on all types of HVAC related issues. We offer a 100 percent customer satisfaction guarantee on all maintenance, repairs and installations of Carrier products. Our company maintains a full supply line of Carrier factory authorized replacement parts and new heating and cooling products. At Berkeley Heating & Air Conditioning, we have helped home and small business owners in the Hanahan, SC, community achieve and maintain indoor comfort for many years. By helping you estimate the necessary cooling capacity, you can be an informed consumer when a new air conditioner is needed. Give us a call any time for more information.