[Bldg-sim] Calculation ventiltion loads in estimating annual heating/cooling loads

[Jin Minming]

Dear All,

I want to calculate annual heating/cooling loads in a building. But I am not sure how to handle ventilation loads. The main problem is how to specify the temperature for ventilaiton air.  

To my knowledge, different software uses various methods to consider the effects of ventiliton loads: 
In ESP-R, the temperature for ventialtion air can be constant or ambient. 
In DOE2.1, the thermal loads do not include the effects of ventilation.
In EnergyPlus, the ventilaiton loads will be added by considering ventilaiton air with ambient temperature. 

If the calculaiton of ventilation loads is using ambient temperature, then there is no differences between infiltration and ventilaiton. But in actual most of HVAC systems, ventilaiton air will be heated or cooled to a certain temperature (possible close to indoor air temprature) and then import it to indoor space. The thermal loads due to infiltration belong to space loads, while the ventilation loads belong to coil loads.  Hence, it sounds not to be fair using ambient temperaure to calculate ventilaiton loads. 

Do you think which is a better way to calculate ventilaiton loads using ambient or possilbe indoor temperature in order to estimate annual heating/cooling loads? or Annual heating/cooling loads itself should not include the influences of ventilation (like in DOE2.1e) as ventilation loads vary a lot in different types of HVAC systems? Then annual heating/cooling loads itself may not be a very good concept at all. 

Thanks,

Jim