You need to look at the Input/Output reference guide for Zone

The cooling/heating "loads" are the following two variables:

HVAC,Average,Zone Air System Sensible Heating Rate [W]
HVAC,Average,Zone Air System Sensible Cooling Rate [W]

You'll note that we're talking here about sensible cooling.

If you want to get total cooling, you need to look at the HVAC system. If you don't have a specific HVAC system designed in your model, you should put a ZoneHVACIdealLoadsSystem and report the following variables (especially the last one which is the sum of the first two):

HVAC,Average,Zone Ideal Loads Zone Sensible Cooling Rate [W]
HVAC,Average,Zone Ideal Loads Zone Latent Cooling Rate [W]
HVAC,Average,Zone Ideal Loads Zone Total Cooling Rate [W]

If this is for sizing purposes, it's worth also noting is that you should really use the Sizing:Zone objects for this. You'll get a epluszsz.csv file where you'll have a row for each zone where you have a Sizing:Zone, and that specifies the load (see output description)

Hi Julian,

I have problem for calculating heating and cooling load. I am using AFN for natural ventilation and my model does not have an HVAC system. I have read the inputOutput Reference for EP. It says "the Ideal Loads Air System is usually the sole conditioning component: the user does not need to specify air loops, water loops, etc. All that is needed for the ideal system are zone controls, zone equipment configurations, and the ideal loads system component." I tried adding different objects, but either I got the "severe" error and the simulation terminated Or I had some warnings and it did not calculate the loads. Can you please list all the objects I need to successfully calculate heating and cooling load? Your help is much appreciated. Sam