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That relationship is only valid when the outdoor air is warmer and more humid than the zone air which only happens in the afternoons of Jul 14 and Aug 3 for this simulation with Copenhagen IWEC weather. The qualifier "When the economizer is not active . . . " should be expanded to "When the outdoor air and the supply air both require sensible and latent cooling these values are related by the following equation:" but that's rather confusing.

The missing link here is free cooling (sensible and/or latent) which is not currently reported as a separate value. The goal of the current outputs was to show what the real load components are

• Zone Ideal Loads Zone Total Cooling Energy = the cooling delivered to the zone (both mechanical and free)
• Zone Ideal Loads Outdoor Air Total Cooling Energy = the cooling load required to condition outdoor air (only accumulates when this is positive, free cooling is excluded here)
• Zone Ideal Loads Supply Air Total Cooling Energy = supply air mechanical cooling required (includes the net outdoor air load)

The reporting currently separates out the Outdoor Air Sensible/Latent Cooling/Heating values independently, and then adds them together for the totals. So this balance can get even more confusing when the outdoor air is warmer and drier than the zone. If anyone is interested in the exact algorithm, see the code here.

Perhaps it would help to add new output variables for Zone Ideal Loads Outdoor Air Free Sensible Cooling, etc