Hi there,
I'm looking to create an operational profile that varies with respect to internal/external temperature difference, for a naturally ventilated atrium.
This is useful since the natural ventilation rate varies with respect to the external temperature, with the smaller the different between internal and external, the higher the required flow rate (i.e. when it is hot outside) and then I would like to purge the space with a high ventilation rate when it reaches 23 degrees.
Could somebody please let me know whether this is possible in IES?
Many thanks
Dynamic external temperature dependent window profile
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Complex Potential
- VE Expert
- Posts: 467
- Joined: Wed Jan 09, 2013 11:57 am
- Location: Bristol, UK
Re: Dynamic external temperature dependent window profile
That is certainly possible yes, although it is more at the experienced user end of the spectrum. I'm sure we can help you out if you give us more detail.
Re: Dynamic external temperature dependent window profile
Great, thank you.
When Tin-Tex < 6 the vent rate needs to be 10l/s/p
when between 6 and 9, the vent rate would be 7l/s/p
when above 9 then the vent rate would be 2l/s/p
when Tin is above 23 then the vent rate needs to be 30l/s/p
I currently have a large 4 floor atrium with glazed east and west faces, and adiabatic equivalent walls on the north and south side
There are louvres on both east and west faces at varying heights and a roof space which has louvres lining its walls.
Each floor is 4.5m high.
I would like to vary the number of louvres that open, as well as the extent to which they open depending on the above profile in order to achieve the required ventilation rates.
What other information would be useful in order for you to help me with this problem?
Many thanks
When Tin-Tex < 6 the vent rate needs to be 10l/s/p
when between 6 and 9, the vent rate would be 7l/s/p
when above 9 then the vent rate would be 2l/s/p
when Tin is above 23 then the vent rate needs to be 30l/s/p
I currently have a large 4 floor atrium with glazed east and west faces, and adiabatic equivalent walls on the north and south side
There are louvres on both east and west faces at varying heights and a roof space which has louvres lining its walls.
Each floor is 4.5m high.
I would like to vary the number of louvres that open, as well as the extent to which they open depending on the above profile in order to achieve the required ventilation rates.
What other information would be useful in order for you to help me with this problem?
Many thanks
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RossThompson87
- VE Professor
- Posts: 202
- Joined: Mon Feb 13, 2012 8:56 am
Re: Dynamic external temperature dependent window profile
Hi,
Off the top of my head you could set up a modulating formula like this:
IF(ta-to<6,(10/30),IF(AND(ta-to>6,ta-to<9),(7/30),IF(ta-to>9,(2/30),IF(ta>23,1))))
If you apply this to a ventilation rate of 30l/s/person it should step up and down to give the right flow rate. You can do this with an air exchange and its nothing to do with the Macroflo module.
It is well worth checking how it works in vista after a simulation, it is rare to get these things right first time.
An easier approach if you aren't too familiar with that sort of programming would be to set up four separate air exchanges.
One at 10 l/s/p with a profile like "ta-to<6"
One at 7 l/s/p with a profile "AND(ta-to>6,ta-to<9)"
............
Just make sure only one of them triggers at the same time otherwise you are being optimistic.
Hope this helps
Ross
Off the top of my head you could set up a modulating formula like this:
IF(ta-to<6,(10/30),IF(AND(ta-to>6,ta-to<9),(7/30),IF(ta-to>9,(2/30),IF(ta>23,1))))
If you apply this to a ventilation rate of 30l/s/person it should step up and down to give the right flow rate. You can do this with an air exchange and its nothing to do with the Macroflo module.
It is well worth checking how it works in vista after a simulation, it is rare to get these things right first time.
An easier approach if you aren't too familiar with that sort of programming would be to set up four separate air exchanges.
One at 10 l/s/p with a profile like "ta-to<6"
One at 7 l/s/p with a profile "AND(ta-to>6,ta-to<9)"
............
Just make sure only one of them triggers at the same time otherwise you are being optimistic.
Hope this helps
Ross
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Complex Potential
- VE Expert
- Posts: 467
- Joined: Wed Jan 09, 2013 11:57 am
- Location: Bristol, UK
Re: Dynamic external temperature dependent window profile
Just to add to what Ross has said, please keep in mind that louvres or window openings are defined by their free area, not their flow rate. You set an opening size and then the model will work out the flow dynamically at all points of the year dependent upon wind speed, direction etc.
As Ross said, if you want to set a specific flow rate, do it as an air exchange.
If you want to use IES to size a louvre then you will need to iterate through free areas until you get a peak/average flow rate you want although I personally hate doing this because you are then effectively underwriting a loure manufacturer's product for them.
As Ross said, if you want to set a specific flow rate, do it as an air exchange.
If you want to use IES to size a louvre then you will need to iterate through free areas until you get a peak/average flow rate you want although I personally hate doing this because you are then effectively underwriting a loure manufacturer's product for them.