HB Energy IdealAir HVAC input / cooling energy


I am doing a thermal comfort calculation of a simple shoebox kind of model. I have the following input for my HVAC.

Especially the IdealAir is improtant here. Because when I have the supply air temperature at 18°C (as in the picture), the results come out as shown below, where the cooling turns off in the middle of the day where it is needed the most. (Note that the shown results are a random selection)

However, when I set the IdealAir to NoLimit for its energy consumption (and thus noEconomizer either), all of a sudden this exact same day has a cooling energy use.

Has anyone experienced something similar?

In addition, when I change the NoLimit from the cooling availability to 5 kW (which is way higher than the maximum needed cooling energy in a single hour in the results), and I keep the NoEconomizer, the maximum cooling energy remains under 1 kW. And the operative temperatures are even higher then when I do not use the NoEconomizer input in the IdealAir system.

I came to understand that the 0 W for cooling energy comes from that the IdealAir system only uses outdoor air to cool when the set inlet temperature is above the outdoor air temperature. But it does not explain the difference between NoLimit and 5 kW inputs. Or why the maximum cooling capacity is never met when I set it manually.

As I keep working and trying out things, I keep getting closer. I found out that the previous mismatches were due to the DDY only taking the outdoor temperature. Changing this to a more strict DDY got me to a more reasonable situation. However, the cooling energy still seems to turn off in the middle of the day when it’s needed. By increasing the cooling limit, the cooling energy needed for the same hours change from 0 to maximum between 2 simulations. I’m still stuck on why this happens and can’t figure it out.

If I find out what’s wrong I will update again. Otherwise, input or just suggestions in which way to look would be greatly appreciated.