Outdoor Variation Profile

[mlmJonathan]

HI

I am trying to understand what the outside air variation profile is used for.

Currently we have a building where I am running the overheating analysis. We are using a MVHR system in, there are no openable windows because of noise. When I have the outside air variation profile set to off in apache rooms fail, but when I have it set on they pass.

The MVHR system have heat exchangers on so I have set the air to external & offset @ 2 degrees.

I would appreciate your help on this one it has me in a pickle.

[Complex Potential]

If you are talking about the system tab, the system outside air supply controls the amount of fresh air being added. If you have this set to off continuously you will see no fresh air in summer conditions (unless you have separately defined the fresh air in the aux vent tab).

The system outside air links to the apache systems definitions which will use the external + offset that you have set up whereas the aux vent tab will not. Otherwise they work in very similar ways.

CP

[mlmJonathan]

Thanks CP

So i have auxillary ventilation set up, to external air with offset. If i have this set up does that mean in the "systems" tab i leave the outside variation profile turned off continuously, or in effect will be doubling up on the fresh air load in the summer ?

or am i understanding it wrong ?

[Complex Potential]

Correct. You can use either method but using both would be doubling up.