I have run an Apache/MacroFlo simulation and am not sure how to interpret the results. I am able to select "Volume flow in" and "Volume flow out" variables and visualize them with red and blue arrows on the 3D model. I also see that I'm able to adjust the time for which the data is being displayed.
My questions:
1. Why am I getting values for most openings that show flow in AND out of the opening? I would think that I'm looking at results for a given instance and that air is flow EITHER in or out of the opening.
2. Is there a way to display the "net" flow for a given instance. For example, if I want to show that Space "101" is receiving X cfm from the south window and it's leaving via two windows on the north side at Y and Z cfms, respectively.
3. What's the best way to determine the number of air changes per hour (ach) of outside air for a given space?
I have looked through the user guides (which haven't offered much guidance so far)..
Thanks in advance.
MacroFlo - flow in AND out?
MacroFlo - flow in AND out?
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Greg
Greg
Re: MacroFlo - flow in AND out?
I think it is correct, that the flow is both in and out, else you would have to turn up the inlet or exhaust fans, unless you have multiple windows facing opposite directions, however i still think that some of the air would go out through the window again.
They have probably made the both in and out, in case some people have different sized windows and facing in different directions. One case could be you have 3x larger windows that can open to the south compared to the ones facing north, and there is an open door between the 2 rooms. Due to wind pressure on the south facing windows, a lot of the air comes in this way and goes out of the north facing windows. However if someone was to close the door, you would still get air in through the windows (at a reduced speed), and this air have to go out somewhere, which have to be either the cracks, or the same window.
Hope this could help you a little.
They have probably made the both in and out, in case some people have different sized windows and facing in different directions. One case could be you have 3x larger windows that can open to the south compared to the ones facing north, and there is an open door between the 2 rooms. Due to wind pressure on the south facing windows, a lot of the air comes in this way and goes out of the north facing windows. However if someone was to close the door, you would still get air in through the windows (at a reduced speed), and this air have to go out somewhere, which have to be either the cracks, or the same window.
Hope this could help you a little.
Re: MacroFlo - flow in AND out?
Thanks for the response.. It doesn't exactly answer or confirm my questions, but it seems like you are on the same level of uncertainty.
Anyone from IES out there?
Anyone from IES out there?
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Greg
Greg
Re: MacroFlo - flow in AND out?
I have a similar problem.
I wish to show the ACH and also heat losses due to infiltration/ventilation which I have modelled with Macroflo. I have a model set up of a terraced house where in MacroFlo air flows into and out of the loft space from the exterior (it is highly ventilated. There is also air flowing between the main house and the loft through cracks around a loft hatch.
To calculate the ACH for the whole house at a given moment in time, presumably you could select all rooms, select combine rooms in Vista, output your Macroflo external ventilation in l/s, convert this to m^3 per hour, and divide by the total volume of your building?
(EnerGwhizz - thats how you could do ACH i think? The documentation states- MacroFlo ext vent: The sum of MacroFlo-calculated air flows entering the room from the external environment.)
And presumably you can also look at the overall Macroflo external vent gain, to see how much heat is lost by this flow of air.
However, the problem occurs when you wish to know the ACH and the losses of just a portion of the building (i.e. I do not wish to include the loft because it will have a much increased ACH and is continuously gaining and losing heat that will distort the figure, but is completely unoccupied - it is essentially outside the ventilation envelope and should be excluded from an ACH figure).
At this point, I thought, perhaps I could use the Macroflo internal ventilation flow with just the loft selected. But this only gives flow into the loft not out of it into the building. I can't use the Macroflo internal ventilation flow on the other other side of the opening because of course this room is connected by open doors to all the others, and so you cannot distinguish the portion flowing in from the loft hatch.
You can drill down to the specific opening and see flow in and out. But at this level you cannot see the heat gains. So basically I can find no way of enquiring as to the gains flowing into the main building via ventilation in the loft. In this case its not too much of a problem as 99% of the air is flowing out through the loft, but I have exactly the same problem for the space under the suspended ground floor which is modelled similarly.
Does anyone have a way of extracting the information I require?
I wish to show the ACH and also heat losses due to infiltration/ventilation which I have modelled with Macroflo. I have a model set up of a terraced house where in MacroFlo air flows into and out of the loft space from the exterior (it is highly ventilated. There is also air flowing between the main house and the loft through cracks around a loft hatch.
To calculate the ACH for the whole house at a given moment in time, presumably you could select all rooms, select combine rooms in Vista, output your Macroflo external ventilation in l/s, convert this to m^3 per hour, and divide by the total volume of your building?
(EnerGwhizz - thats how you could do ACH i think? The documentation states- MacroFlo ext vent: The sum of MacroFlo-calculated air flows entering the room from the external environment.)
And presumably you can also look at the overall Macroflo external vent gain, to see how much heat is lost by this flow of air.
However, the problem occurs when you wish to know the ACH and the losses of just a portion of the building (i.e. I do not wish to include the loft because it will have a much increased ACH and is continuously gaining and losing heat that will distort the figure, but is completely unoccupied - it is essentially outside the ventilation envelope and should be excluded from an ACH figure).
At this point, I thought, perhaps I could use the Macroflo internal ventilation flow with just the loft selected. But this only gives flow into the loft not out of it into the building. I can't use the Macroflo internal ventilation flow on the other other side of the opening because of course this room is connected by open doors to all the others, and so you cannot distinguish the portion flowing in from the loft hatch.
You can drill down to the specific opening and see flow in and out. But at this level you cannot see the heat gains. So basically I can find no way of enquiring as to the gains flowing into the main building via ventilation in the loft. In this case its not too much of a problem as 99% of the air is flowing out through the loft, but I have exactly the same problem for the space under the suspended ground floor which is modelled similarly.
Does anyone have a way of extracting the information I require?