I am designing a HVAC system for a location off the coast of Nigeria.

Along with the AHU there is chiller system which I am trying to size.

To calculate the cooling load can I simply use the volume airflow multiplied by the density of air and the delta T? Or do I have to use the equation:

Qc = ma(ho – hs)

My problem with the later method is whilst I have the db and wb of the outside conditions i only have the db of the supply conditions so pinning down the process line of the psychrometric chart is difficult.

Would an acceptable solution be to estimate the %RH for the supply conditions?

Any advice would be appreciated.