[esp-r] Re: on night ventilation

[Achim Geissler]

Dear Koji Takemasa

below some thoughts inline.

Best
Achim

On Nov 8, 2012, at 1:16 AM, 武政 孝治 <koji_takemasa at me.com> wrote:

> Hi.
> 
> I have calculated the natural room temperature using night ventilation.
> The size of a model is shown below. 
> Height : 3m   Width : 4m   Depth : 5m
> The air change rate of this model is 0.5 ac/h. 
> The south window area used for ventilation is 3.5 m2 and the north window area is 1 m 2.
> I attach the elevational view and sectional view of a model which were used for calculation. 
> 
> I calculated in the following procedures. 
> 
> (1)  I considered a three kinds model. 
> 
> A) The model which has not set up night ventilation.
> B) The model which set up night ventilation.  
> C) The model which  not be used it , although night  ventilation was set up.
> 
> I set up in the following procedures about B) and C).
> 
> (1) I chose network flow (menu) and defined Nodes, Components, and Connections. 
> And Link nodes and zones was chosen. 
> 
> (2) I chose network flow from Controls. 
> sensor details chose dry bulb temparature and flow actuator chose single flow connection. 
> 
> (3) I chose 1 day type by period data, and it defined B as follows. 
> This my definition assumed that outdoor air temperature opened a window at 18 to 27 degrees at night. 
> 
> a 1 0.00 outside ambient > low /default/mid/hi 18.00 22.00 27.00 0.00 1.00 0.00
> b 2 6.00 outside ambient > low /default/mid/hi 18.00 22.00 27.00 0.00 0.00 0.00
> c 3 22.00 outside ambient > low /default/mid/hi 18.00 22.00 27.00 0.00 1.00 0.00
> 
It's been a while since I have used these controllers, but have you made sure that what you think is supposed to happen actually happens? What is your "default" setting (you have three temperatures that give you four ranges, but you only have three set points for the component / connection)? I find the logic in these controllers not quite easy to understand at times.

So you want the window to open, when the ambient is above 22.0 degC and below 27.0 degC?

> The definition of C) is shown below. 
> 
> a 1 0.00 outside ambient > low /default/mid/hi 18.00 22.00 27.00 0.00 0.00 0.00
> b 2 6.00 outside ambient > low /default/mid/hi 18.00 22.00 27.00 0.00 0.00 0.00
> c 3 22.00 outside ambient > low /default/mid/hi 18.00 22.00 27.00 0.00 0.00 0.00
> 
> (4) Annual natural room temperature was calculated. ( esp-r 11.11 GTK)
> 
> The room temperature graph in January and August is attached. 
> 
> *The followings are my questions. 
> (a) The room temperature should become equal in January because the window is not opened , but it differs. 
For the model without air flow network, what is your air change rate (via .opr)? Also, I expect you have some kind of "cracks" defined in the air flow network to allow it to work numerically with closed windows. So, your model with air flow network will have a (very) small air change even with closed windows, most likely.

> The room temperature of B) and C) is equal, it differs from A). 
Is this a question? It would seem to suggest that the window is not opened due to control, then both cases B and C are, actually, the same. The difference to A may be due to the above issues.

> 
> (b) I think that the room temperature of B in August  is right, there is an unusual value in the room temperature of C. 
You mean the "caving in" of the C-curve? Have you looked at the data with a smaller time step output? At which time step setting are you simulating? Do you get "not converged" messages during the run? Have you analysed the exact hour in which the cave-in happens? Is it between 23:30 and 00:30, i.e. at day change?

> 
> 
> Best regards,
> 
> Koji Takemasa ( Dr. eng. )
> 
> <model.pdf>
> <graph.pdf>_______________________________________________
> esp-r mailing list
> esp-r at lists.strath.ac.uk
> http://lists.strath.ac.uk/mailman/listinfo/esp-r

achim.geissler at intergga.ch