IES-VE User Forum

I am a little stuck with this,
I have a 4 story building with an atrium running down through the middle of it. This makes it perfect for natural ventilation but i have no idea how to go about setting it up in IES.
I made an attempt at it but im not sure was i doing it right. Here is what i done:
I kept the heating to FCU's and turned cooling to 'off continuosly'. I then went to air exchanges and switched it to natural ventilation with 5 ac/hr. I assigned the profile to the various rooms and re-calculated the loads again. The results showed the cooling dropped just over 10kW but the heating increased from 274kW to 665kW
Is this right?????
I would appreciate it if anyone could find the time to come up with an answer.
Regards
John

Hi John
I am new to IES and am not an engineer so my experience may me of little use? BUt i recently modelled a central atrium in a 7 storey building attempting to do a similar thing. To simplify things I just looked at the ground floor and atrium in isolation and got some reasonable results. I had cooling set to off continuously as well. Window profiles were set to open during the day when oustide temp was above 18 degrees and below 26 which reflected the remperature band I propsed. The atrium wasn't enclosed so i could only apply an external window opening profile. The other thing I did was put a louvred glass box over the atrium to help with convection. This had the same window profile as the ground floor. Without doing CFD I can't be sure but my results seemed to look ok.

The other thing that would explain the increased heat load is that maybe infiltration is happening at night? I had this issue with night purging. There was a massive heat load every morning. Maybe an openging profile would be a better option than changing infiltration rates?

Not sure if that's helpful? Sorry If I have missed the point!

Anthony

Hi,

Those seem like good ideas to me, if you're applying the Natural ventilation as an Air Exchange then have a look at the variation profile to check that it's not on continuously as that could have a large impact on heating load.

If you grab a room in Vista and take a look at some charts of Heating load and Natural vent gain you should quickly see the times that the heating load is being impacted by this air exchange.

For the Natural ventilation study I'd be inclined to go suggest you go with Anthony's idea of using MacroFlo to control the opening of windows and get a realistic idea of the effect of the natural ventilation from airflow.

Phil