IES-VE User Forum

I need to model overheating in a project with the scenario:

• When outside air gets above 24degC it needs to be cooled down centrally in ahu to 24degC at a certain design flowrate of 10l/s/person.the central AHU supplying this air will supply it to few rooms at once.need to check if rooms still overheat.

I have tried to do it in profiles to ‘enable controller when outside temp reaches 24degC’
Where do I put this profile next?
• If I do it in ‘room condition tab’ do I just input this profile but that may be assuming a system within the room dealing with that at all times, rather than in an AHU centrally.
• If I do it in ‘auxillary ventilaiton’ in ‘air exchange tab’ there seems to be no room for temperature settings. The profile thats there to me seems to be vent flowrate profile. the 'adjacent condition temperature profile doesn't have the option for putting new user deifned profiles but NCM defined templates only.

I’m sure question like that has been asked before. Could you reply how do I go about it please. Possibly with some screenshots of this solution.

It's probably easiest to do what you want via the Air Exchanges tab using an Auxiliary Ventilation. Set and apply a template specifically for the rooms that the AHU will serve and then add an aux vent into the air exchange set at 10l/s/person max flow with whatever variation profile you want but then change the Adjacent Condition to "temperature from profile" and then apply a custom absolute profile that you create in the profile database manager with the formula:

if(to>24,to,24)

This basically says; if the outside air (variable "to") is warmer than 24C then set the supply temperature to the outside temperature, otherwise cool to 24.

Set that as the continuous profile for all times of the day/week and then it should bring the air in correctly.

You can check the aux vent gain in vista once it has run and check if it corresponds to the expected cooling effect you would expect to see based on the flow rate and room temperature at an instant in time when you know the AHU should be in cooling mode.

CP