Hi all,
Has anyone come out with a proper profile formula set up for the opening of windows in macroflow?
When expecting the building to run mainly on natural ventilation. The project is in a hot clime, climate zone 1 (ASHRAE 90.1), 28C daily mean temperature, 26C design temperature. I’m thinking on having a formula that opens the windows when the outdoor temperature is between 10C - 33C and indoor temperature >26C, any views or suggestions about this.
Profile formula set up
Re: Profile formula set up
Hi Jose,
This is exactly the kind of control you would be looking to specify in MacroFlo by creating a formula profile and then assigning as the variation profile.
In ApPro create the new modulating profile and enter a formula during the building operational hours, this can use the AND operator and be based on both internal room air temp and the external dry bulb for example. Have a look in the Profiles Database User Guide (Help >> User Guides >> Thermal category) and you will see the variables you can us and some example formula profiles with clear applications in VE.
Then in MacroFlo set up your new opening type, set opening threshold temp to 0 (as we are overriding this control with a more detailed formula profile) and apply the new profile as the opening profile.
Run the simulation and then have a look at results and you can see your window opening and closing as the air temps vary. You may initially find that the open and close control is too sudden and you can then tweak your control formula further to put in a deadband or by using a ramp so there is a little proportion applied to the opening and closing and it will balance out somewhat.
Getting to grips with the formula profile options in VE is very important as it is one of the most flexible areas across the whole software and opens up all sorts of complicated control strategies which you can use to mirror the real life operation of your buildings into your models. As always if anyone has any experiences with MacroFlo nat vent they'd be interested to share or sample profiles for different standard strategies then I'm sure new users would find it useful and interesting
Phil
This is exactly the kind of control you would be looking to specify in MacroFlo by creating a formula profile and then assigning as the variation profile.
In ApPro create the new modulating profile and enter a formula during the building operational hours, this can use the AND operator and be based on both internal room air temp and the external dry bulb for example. Have a look in the Profiles Database User Guide (Help >> User Guides >> Thermal category) and you will see the variables you can us and some example formula profiles with clear applications in VE.
Then in MacroFlo set up your new opening type, set opening threshold temp to 0 (as we are overriding this control with a more detailed formula profile) and apply the new profile as the opening profile.
Run the simulation and then have a look at results and you can see your window opening and closing as the air temps vary. You may initially find that the open and close control is too sudden and you can then tweak your control formula further to put in a deadband or by using a ramp so there is a little proportion applied to the opening and closing and it will balance out somewhat.
Getting to grips with the formula profile options in VE is very important as it is one of the most flexible areas across the whole software and opens up all sorts of complicated control strategies which you can use to mirror the real life operation of your buildings into your models. As always if anyone has any experiences with MacroFlo nat vent they'd be interested to share or sample profiles for different standard strategies then I'm sure new users would find it useful and interesting
Phil
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Wasted Energy
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Re: Profile formula set up
Phil
I've got some formulae set up in profiles to control the opening of windows dependent upon internal and external conditions using some proportional control - and this works fine, (I used the wizard - very easy).
But the scenario here is a block of residential apartments, and what I'm trying to model is what would happen during the working week, and in particular what would happen during that part of the day when the majority of the residences are unoccupied (because folk are at work).
What I'd like to be able to model is that windows are open or closed from 09:00 to 18:00 dependent upon what happens between 08:00 to 09:00. In other words if internal/external conditions are such that windows will open between 08:00 and 09:00 then they will stay open until 18:00 (because the residents will leave them open), otherwise they will not open between 09:00 and 18:00, even if the internal/external conditions would otherwise dictate they should, because there will be no-one present to open them.
At the moment I have the formulae opening/closing the windows during the working day but using a fractional multiplier - but this is not ideal as it means all windows will open/close to some fraction depending on internal/external conditions - which is not what is going to happen, but is as close as I have so been able to get to the ideal.
Any ideas? Or am I trying to model human behaviour using physical variables, and that's never going to be possible?
W
I've got some formulae set up in profiles to control the opening of windows dependent upon internal and external conditions using some proportional control - and this works fine, (I used the wizard - very easy).
But the scenario here is a block of residential apartments, and what I'm trying to model is what would happen during the working week, and in particular what would happen during that part of the day when the majority of the residences are unoccupied (because folk are at work).
What I'd like to be able to model is that windows are open or closed from 09:00 to 18:00 dependent upon what happens between 08:00 to 09:00. In other words if internal/external conditions are such that windows will open between 08:00 and 09:00 then they will stay open until 18:00 (because the residents will leave them open), otherwise they will not open between 09:00 and 18:00, even if the internal/external conditions would otherwise dictate they should, because there will be no-one present to open them.
At the moment I have the formulae opening/closing the windows during the working day but using a fractional multiplier - but this is not ideal as it means all windows will open/close to some fraction depending on internal/external conditions - which is not what is going to happen, but is as close as I have so been able to get to the ideal.
Any ideas? Or am I trying to model human behaviour using physical variables, and that's never going to be possible?
W
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Complex Potential
- VE Expert
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- Joined: Wed Jan 09, 2013 11:57 am
- Location: Bristol, UK
Re: Profile formula set up
Hi Wasted
Sorry to be the bearer of bad news but I don't think there is a way to do what you want. Time is not a variable that can be referenced in IES.
Sorry to be the bearer of bad news but I don't think there is a way to do what you want. Time is not a variable that can be referenced in IES.
-
Wasted Energy
- VE Graduate
- Posts: 93
- Joined: Thu Sep 10, 2015 5:58 am
- Location: UK NW
Re: Profile formula set up
Complex
What I ended up using was the toav24 variable in the formula gt(toav24,16,4).
This opens the windows (subject to 4K ramp) if the mean air temp of the previous 24 hours is greater than 16 deg C.
Seems to work okay, and is probably as close as possible to modelling human behaviour, and it sort of dovetails with the TM 52 methodology. What it doesn't do is allow for any diversity between occupant behaviour. But this might be modelled by applying a different formula to alternate windows.
W
What I ended up using was the toav24 variable in the formula gt(toav24,16,4).
This opens the windows (subject to 4K ramp) if the mean air temp of the previous 24 hours is greater than 16 deg C.
Seems to work okay, and is probably as close as possible to modelling human behaviour, and it sort of dovetails with the TM 52 methodology. What it doesn't do is allow for any diversity between occupant behaviour. But this might be modelled by applying a different formula to alternate windows.
W