I am a little worried that our classroom will be too hot lat

I am a little worried that our classroom will be too hot late in the spring and want to know now, so proper steps can be taken to make sure the room is comfortable. You can help by performing the energy balance of a full classroom. We have about 36 people in our class (including the instructor). The building is cooling by air conditioning units that provide 4 kW pf cooling capacity. Each person dissipates about 350 kJ/h. There are about 30 light bulbs in the room, each with a rating of about 40 W. The rate of heat transfer through the walls and windows to the room will probably be around 16,000 kJ/h on an average spring day. Determine the total number of air conditioning units needed to maintain the room at 22 degreeC.

Solution

The Heat Input from 36 people

Q_p=36*(350 /3600) =3.5 KW

Heat Transfer through the walls

Q_w=(16000/3600)=4.44 KW

Heat transfer from light bulbs

Q_b=30*40 =1200 Watts =1.2 KW

So the total heat Input

Q=3.5+4.44+1.2 =9.14 KW

The Heat removal comes from Air conditioning units at 4 KW for each.So Number of air conditioning units needed to maintain temperature at 22^oC is

N =9.14/4 =2.286 = 3 units (approx)