We have seen the basic concept of HVAC in our previous post "Heating ventilating and air conditioning (HVAC)".

Let us consider how we will calculate the cooling load calculation for HVAC system .Before starting the calculation of cooling load, I will suggest looking previous post "Heating ventilating and air conditioning (HVAC)" for better understanding the concept of cooling load calculations, So let us start.

In following table, we will come to know that how we may proceed to calculate the cooling load for our selected site.

 Sr. NO. Load sources Calculating equation 1 Window & Glass Areas q= (GLF)A 2 Doors q=U d A (CLTD) 3 Above grade exterior wall q=U W A (CLTD) 4 Partitions for unconditioned space q=U P A  Δ t 5 Infiltration q = 1.1QΔt Where, Q = ACH * Room volume / 60 6 Roofs and ceiling q=U f A (CLTD) 7 Floors those are exposed q=U f A (CLTD) 8 Internal Loads , such as    People Lights Appliances Let for one person 230 BTU/Hr Total Cooling Load = L F * Summation of sensible cooling load for individual components

Where,

Δ t = Difference between temperature of air of inside and outside (0F)

Q= Volumetric air flow rate (CFM)

A= Area of surface in ft2

U= U factor for suitable construction (Btu/h. ft2. 0F)

ACH = air changes / hour, 1/h

CLTD = Cooling load temperature difference, °F

GLF = glass load factor, Btu/h· ft2

We will determine cooling load room by room in order to calculate the proper air distribution

### Living Room

#### Infiltration-

Q = ACH * Room volume / 60
Q = (0.5 x 3840)/60
Q =32
q = 1.1QΔt
q = 1.1 x 32 x (96-75)
q = 740 Btu/h

#### Occupant –

As we have mentioned above that one person 230 BTU/Hr
q = 230 x 4 = 920 Btu/h

#### Appliances-

As we have mentioned above that 50% load of kitchen appliance will be taken in living room, hence
q = 0.5 x 1600
q = 800 Btu/h

### Kitchen-

#### Infiltration-

Q = ACH * Room volume / 60
Q = (0.5 x 1920)/60
Q =16
q = 1.1QΔt
q = 1.1 x 16 x (96-75)
q = 370 Btu/h

#### Occupant –

As we know that there is no occupant
q = 0

#### Appliances-

As we have mentioned above that 25% load of utility appliance will be taken in kitchen room, hence
q = 0.5 x 1600 + 1600/4
q = 1200 Btu/h

We will find complete cooling load calculation for living room and kitchen separately with the help of following mentioned table

#### For Living room

 Description Area (Ft2) GLF  (Btu/h· ft2) Factor-U (Btu/h. ft2. 0F) CLTD (°F) Cooling Load  (Btu/h) West Wall 91 0.06 24 131 Partition 192 0.07 12 161 Roof 480 0.05 48 1152 West door 21 0.32 24 161 West glass 35 44 1540 Shaded glass 13 19 247

#### For Kitchen

 Description Area  (Ft2) GLF  (Btu/h· ft2) Factor-U (Btu/h. ft2. 0F) CLTD (°F) Cooling Load  (Btu/h) East Wall 135 0.06 24 194 Roof 240 0.05 48 576 East Glass 14 44 616 Shaded glass 11 19 209

GLF, CLTD are values taken from HVAC design data. These are standard value based on the outdoor design temperature.

Cooling load, we have calculated by using formula that we have mentioned above for each cases.

 Description Roof, Door & wall People Glass Appliances Infiltration Living room 1605 920 1787 800 740 Kitchen 770 825 1200 370 Storage & utility 1404 1200 443 Bed room#1 559 544 278 Bed room#2 686 548 278 Master Bed room with bath 1682 816 813 Bath room 540 276 295 Final /Total 7246 920 5096 3200 3217

Total cooling load = 7246 + 920 +5096 + 3200 + 3217
Total cooling load = 19679 Btu/h
We have to also consider duct losses which will be 10 % or 1967.9
Duct losses = 1968

Summation of sensible cooling load for individual components =
19679 + 1968 = 21647 Btu/h
Total Cooling Load = L F * Summation of sensible cooling load for individual components
For a medium construction house L F will be 1.15
Total Cooling Load = 1.15 x 21647 =24894 Btu/h

#### Total Cooling Load = 24894 Btu/h

This blog is basically based on the process for calculating the cooling load calculations for HVAC system .

I will suggest looking my previous post "Heating ventilating and air conditioning (HVAC)"
for better understanding of calculations as all assumptions have been taken in previous post.