I understand that the Additional Air Changes section is providing fresh air at a fixed ACH based on the selected outside conditions.
I'm curious as to why when I set the Fixed Temperature Air section to the same temperature and RH as the outside conditions, and same ACH rate they come out with different results e.g. the additional air changes comes out with a much higher room temp.
There's obviously a difference in how this is calculated, so could anyone confirm the difference between these (even when the air temp and RH for the fixed temp air is the same as the outdoor air max conditions).
In instances like this, the capabilities of the current software (ie OpenBuildings Energy Simulator) really come to their own, and offer much more insight into results and calculation methodologies than was ever available in Hevacomp.
In Hevacomp this is largely limited to the manuals, which do give a thorough breakdown of the formulae used, as below:
However the same Summer calculation is available in Energy Sim, and you can easily interrogate the results and drill into every variable as you need, to see what is affecting results. Info on this can be found below:
How to view Calculation Formulae - OpenBuildings | AECOsim | Speedikon Wiki - OpenBuildings | AECOsim | Speedikon - Bentley Communities
So, if you like, we can log a Service Request to obtain the specific Hevacomp project you are looking at, or what might be more beneficial to you is that you could import your model into Energy Sim, and interrogate the results as you require there. Just let us know what approach is preferable to you and we will help further.
Shane Regan | Principle Building Performance Support Engineer
Answer Verified By: Shane Regan