Hi, I commonly use Hevacomp to calculate the maximum internal temperature for ventilated and non-ventilated enclosures as well calculating required cooling loads.
I am currently modelling a pump station (approximately 3m long x 2m wide x 2m high) in a metal enclosure and appear to have some conflicting information between summer method and AIRAH Gain.
What I am finding is:
Can anyone please explain why there is such a significant difference between the maximum temperature calculated using the Summer Temperature method and the AIRAH gain method (when the internal temperature is adjusted until the Total Load is zero)? Zip file attached if needed.
Thanks
Pump Station Hevacomp.zip
Hi TimMethods used by the calculations are designed to calculate comfort conditions for occupied buildings that consider air conditioning. As you move outside of this into extreme conditions, variances in the calculation methods would be greatly exaggerated.Regards,
Duncan Brown
Thanks Duncan.
So with this point in mind, is one of these methods more appropriate for this situation or are both exaggerated?
Cheers,
Tim
Hi Tim,
The design engineer would need to make the decision as to which calculation is most appropriate, however please note that the Summertime calculation's purpose is to find the peak temperature, while the AIRAH Gain (and CIBSE Gain) calculation is more designed to calculate Air Flow rates necessary to maintain room design conditions. With this in mind Summertime would give you more of a worst-case-scenario for peak temperature.
Shane Regan | Principle Building Performance Support EngineerHevacomp to OpenBuildings - A complete guide for every user | Bentley Communities
Thanks Shane,
Just to clarify, Our buildings are usually of typical size and construction. Much like small commercial or residential buildings (ie. I didn't consider this to be an extreme scenario)
In summary, would we best to use:
Hi Tim - That sounds reasonable to me, but I should state again that the conditions of the project were extreme, and would be pushing the tolerance of the calculation.Regards,