I did not join in earlier, because I do not know what you are after.
Now, it seems to me that you are trying to model an IT equipment room with a raised floor, and is not exposed to outdoor environment.
In general, in EPlus, the thermal dynamic boundary is the building envelope. The building is in an air tank. When air enters the building, the amount of heat that comes with the inlet air is registered. The same amount of air at the zone temperature is relieved to the OD air tank. The heat transferred is simply lost, as it is not significant to change the environment. This applies to the OA mixer, infiltration and ventilation objects, not using AFN or EMS..
However, user may make life to be complicated trying to recover heat from the relief air and feed it back to the OA inlet. I maintained that the HE should be connected to chimney, etc. and not the return air relieved amount.
When you mount a window AC unit to a zone, EPlus does not actually insert the unit in the wall. Only the circulating air is considered. The power used by the fan can be included or excluded in the simulation. It is not necessary to leave an empty space for the unit. If the unit is large, it would be split and mount outside or on the roof top.
For the IT box, if it is very large and separately controlled, it is like a refrigerated room in reversal The condition should be specified in more detail.
For example, the heat generated by a lighting fixture may be split into parts. The visible and heat in the zone is one part, the heat which can be removed by the plenum is another part. A fraction can be declared in the Lighting object so that only part of the lighting power is added to the zone heat balance calculation.
The IT box can be declare as a equipment with heating source. The size of the box is not important. However, if you have a cooling system circulating inside the box, the temperature of the box surface may not be the same as that of the zone. If the user do not want to simulate the system inside the box, the equipment may have positive or negative heat contribution to the zone. Because the box is not declared, there is no reporting of the box surface temperature.
If you declare the box as a separate zone with the metel box as the wall and add another AHU to control its temperature, then the IT box is another zone. The heat generated is exchanged with the environment, resulting in a box temperature which can have a set point value. If this is set different from the room, there will be some heat flow across the box.
In a tropical country where there is no heating requirement, I actually reverse the normal equipment cooling process of drawing the cooled room air into the box and exhaust from the top. The cooled dry air is fed int from the top and hot equipment air exhaust into the r
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Now, it seems to me that you are trying to model an IT equipment room with a raised floor, and is not exposed to outdoor environment.
In general, in EPlus, the thermal dynamic boundary is the building envelope. The building is in an air tank. When air enters the building, the amount of heat that comes with the inlet air is registered. The same amount of air at the zone temperature is relieved to the OD air tank. The heat transferred is simply lost, as it is not significant to change the environment. This applies to the OA mixer, infiltration and ventilation objects, not using AFN or EMS..
However, user may make life to be complicated trying to recover heat from the relief air and feed it back to the OA inlet. I maintained that the HE should be connected to chimney, etc. and not the return air relieved amount.
When you mount a window AC unit to a zone, EPlus does not actually insert the unit in the wall. Only the circulating air is considered. The power used by the fan can be included or excluded in the simulation. It is not necessary to leave an empty space for the unit. If the unit is large, it would be split and mount outside or on the roof top.
For the IT box, if it is very large and separately controlled, it is like a refrigerated room in reversal The condition should be specified in more detail.
For example, the heat generated by a lighting fixture may be split into parts. The visible and heat in the zone is one part, the heat which can be removed by the plenum is another part. A fraction can be declared in the Lighting object so that only part of the lighting power is added to the zone heat balance calculation.
The IT box can be declare as a equipment with heating source. The size of the box is not important. However, if you have a cooling system circulating inside the box, the temperature of the box surface may not be the same as that of the zone. If the user do not want to simulate the system inside the box, the equipment may have positive or negative heat contribution to the zone. Because the box is not declared, there is no reporting of the box surface temperature.
If you declare the box as a separate zone with the metel box as the wall and add another AHU to control its temperature, then the IT box is another zone. The heat generated is exchanged with the environment, resulting in a box temperature which can have a set point value. If this is set different from the room, there will be some heat flow across the box.
In a tropical country where there is no heating requirement, I actually reverse the normal equipment cooling process of drawing the cooled room air into the box and exhaust from the top. The cooled dry air is fed int from the top and hot equipment air exhaust into the r
Hi, Jean
I've checked the Zone object, and I saw only the Volume field, but not the area field. Besides, there are floor area and ceiling height as well. So, how do I consider some significant areas (e.g. big IT boxes that generate heat) which can result in heat transfer inside a building envelope? Should I go with the internal mass approach like Jeremiah suggested above?
Best,
Long
Long
On Tue, Jul 24, 2012 at 12:11 AM, Jean marais <jeannieboef@xxxxxxxxx> wrote:
Draw the empty space. Export the idf. Search the idf for the Zone object of the zone in question. Compare the fields to the description thereof in the io ref. documentaion. You will see that there are two fields which you may use to override the automatic calculation of both Area and Volume, namely Area and Volume. Fill these fields with the appropriate figures.
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Long T. Phan" <ltb.phan@...> wrote:
>
> Hi, Jeremiah
>
> It's me again. Let's say I have something big attached to the interior wall
> like an air conditioner, so it occupies a large surface area of the wall.
> Do I need to draw the model geometry of that AC for later calculation of
> its surface temperature or just ignore it and focus on the wall geometry
> only? I see some tutorial video on youtube, they consider partition like
> cubical in an office space.
>
> Best Regards,
> Long
>> On Mon, Jul 23, 2012 at 4:05 PM, Long T. Phan <ltb.phan@...> wrote:> > jeremiah@...> wrote:
>
> > Thank you Jeremiah.
> >
> > Long
> >
> >
> > On Mon, Jul 23, 2012 at 3:25 PM, CleanTech Analytics <
> >
> >> **> >> *Jeremiah D. Crossett*
> >>
> >>
> >> The internal items can be accounted for later as internal mass. You do
> >> not want to specify anything other than the external shell and internal
> >> zone boundary's.
> >> Also you will not want to save as sketchup format whatsoever (even tho
> >> it will ask you to do so) save only in open studio or export IDF. Many use
> >> open studio/sketchup for creation of IDF and use IDF editor from there.
> >>
> >> Have fun-
> >>
> >>
> >> *CleanTech Analytics*
> >> *503-688-8951*
> >> *www.cleantechanalytics.com* <http://www.cleantechanalytics.com>> >> On Mon, Jul 23, 2012 at 12:20 PM, Long Phan <ltb.phan@...> wrote:
> >>
> >>
> >> *
> >>
> >> This document may contain valuable information proprietary to CleanTech
> >> Analytics which is private and confidential. It may not be shared, copied,
> >> stored or transmitted in any form without the prior written consent of
> >> CleanTech Analytics
> >> *
> >>
> >>
> >>
> >>
> >>> **
> >>>
> >>>
> >>> Hi Group,
> >>>
> >>> I'm a new user in EnergyPlus. I am trying to learn this software. My
> >>> question is when creating a office building geometry in Google Sketchup for
> >>> EPlus, do I need to draw stuff inside the office like furniture, tables,
> >>> chairs, etc., in order to accurately simulate the office energy use? Or
> >>> just simply an empty envelope and then specify loads later?
> >>>
> >>> Thanks for your help,
> >>> Long
> >>>
> >>>
> >>
> >>
> >
> >
>
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