model natural ventilation - formula

[JulesAA]

Hi,

I try to model natural ventilation for a simple building. I use MacroFlo and want the windows to open when
1) to>25C
2) ta>to
3) to>16C

My question is:

In the "degree of opening" tab I can use the profile (from ApPro) with the formula (ta>25) & (ta>to) & (to>12) (i.e. modulating)?? if so, this will simply open and close the window when all the conditions are met?

or

I have to use a profile that gives a percentage number (i.e. absolute) as an outcome? like the (int(100*(ta/25)) provided in the User Guide?


Ideally, could anyone please give me the final formula I should use for the three conditions I mentioned above?

Thank you in advance.

[PCully]

Hi,

Create a modulating formula profile and apply as the degree of opening profile. You should also switch the opening threshold to be zero so it won't interfere as you want your profile to do all the work.

This will then modulate your window between the max equivalent area described by your opening type and closed as the conditions are met or not.

MacroFlo will also use any fraction between 0 and 1 to partially open the window so for example a ramp profile or similar will have the opening and closing more gradual rather than instantaneously

Phil

[JulesAA]

Thank you Phil!

One specification..

If I want the windows to open only when the building is occupied (i.e. 0:00-8:00 and 17:00-24:00) is this profile correct? (assuming the windows open instantaneously)

0:00 | 0
7:00 | 0
7:00 | (ta>25) & (ta>to) & (to>12)
8:00 | (ta>25) & (ta>to) & (to>12)
8:00 | 0
17:00 | 0
17:00 | (ta>25) & (ta>to) & (to>12)
24:00 | (ta>25) & (ta>to) & (to>12)
24:00 | 0

or

0:00 | 0
7:00 | (ta>25) & (ta>to) & (to>12)
8:00 | 0
17:00 | (ta>25) & (ta>to) & (to>12)
24:00 | 0

??

or none of them?

[Complex Potential]

So the building is occupied through the night from 5pm until 8am the following morning? A bit odd, but ok.....

0:00 | (ta>25) & (ta>to) & (to>12)
8:00 | (ta>25) & (ta>to) & (to>12)
8:00 | 0
17:00 | 0
17:00 | (ta>25) & (ta>to) & (to>12)
24:00 | (ta>25) & (ta>to) & (to>12)

I think the above should do it.