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Daylight harvesting on a floor of building model in eQUEST

asked 2015-01-12 04:14:59 -0500

Ashok Dhayal gravatar image

updated 2015-01-14 05:06:18 -0500

I have a three floor building model in eQUEST. To reduce lighting energy consumption of building, I have daylight set to "ON" for the second floor of the building and I got following results when I use Jaipur, India weather file (.BIN)

eQuest Results

  1. lighting energy consumption decreases which makes sense
  2. Why does HVAC (cooling) and fan energy consumption increase?

Moreover, I am getting proper energy consumption reduction when I use weather file of Atlanta for same building model.

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Which weather file are you using?

Julien Marrec gravatar image Julien Marrec  ( 2015-01-12 06:28:33 -0500 )edit

Jaipur, India (composite climate)

Ashok Dhayal gravatar image Ashok Dhayal  ( 2015-01-12 07:06:36 -0500 )edit

Did you figure this out? I'd be interested to hear the outcome.

adam gravatar image adam  ( 2015-01-20 10:48:17 -0500 )edit

@adam: thank you for interest, i will share for sure if i get any solution.

Ashok Dhayal gravatar image Ashok Dhayal  ( 2015-01-20 23:57:18 -0500 )edit

3 Answers

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answered 2015-02-02 02:47:42 -0500

updated 2015-02-03 02:29:03 -0500

It seems that the problem is clear: he modified the TMY weather file. In there, he replaced the solar radiation with the 2014 values from a local weather station he has access too.

So the solar radiation doesn't match at all the rest of the weather conditions, and explains why the results don't make physical sense.

I suggest you simply use the 2014 TMY weather file - without any edits - if you are looking for projections of energy usage.

On the other hand, if you are trying to compare the output from your eQuest model to what actually happened in 2014 (for PV production for example), I suggest you either create, or purchase* an Actual Meteorological Year (AMY) weather file. Please refer to this thread for more information.

*Note: For a moderate cost it'll save you the time and you'll avoid this kind of potential mistakes

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answered 2015-01-12 08:05:09 -0500

updated 2015-01-23 10:57:11 -0500

This is a very peculiar behaviour in this model.

After looking at the .inp, I couldn't see anything immediately that was the cause.

I noticed that the model with daylighting had significantly higher autosized system cooling capacities than the model with no daylighting. This was on all floors, not just the floor with daylighting. You may want to try specifying the cooling capacity of each system in the daylighting model, with the autosized capacities from the non-daylighting model.

It could also be related to the windows - many of the windows on the third floor are specified using the "Simplified" specification method. I don't fully understand why, but I've been told that eQuest doesn't properly handle the angle of incidence of solar radiation to the window when they are "Simplified", and so it may not be giving you the correct solar gains in those third floor spaces. What this means is that when you turn on the daylighting calculation, it may be giving you too much solar gains in those spaces when it does the daylight calculation, resulting in higher cooling loads. You might try a window from the glass library and see if that makes a difference.

One other comment, Ashok, that isn't related to this problem, but I wanted to let you know - when you use the VRF curves provided by Daikin and import them into the eQuest, one of the heating curves doesn't import properly - the line is too long and eQuest truncates the exponent.

The curve "VRV Heating EIR-F-EWB/ODB AC" imports with coefficient number 4 as 7.145853, but it should be 0.07145853 in the model. Again, not a problem for you since you aren't using that particular curve, but could be a problem down the line. :)

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Dear Benjamin, Thank you for response, solar heat gain through envelope of the building is already there in both cases(i.e without daylight and with daylight). Without daylight case: there is no use of daylight illuminance and building lighting is set "ON" ; With daylight case: building lighting is set "OFF" using daylight sensor wherever daylight illuminance is reachable. Therefore, In my view HVAC cooling consumption should not increase.

Ashok Dhayal gravatar image Ashok Dhayal  ( 2015-01-12 22:29:27 -0500 )edit

@Benjamin: I think I'm still puzzled as well. I did look at Ashok's inp, and found out that the conduction load from windows and walls are the culprits, but I don't see a physical reason for that... Are you suggesting that eQuest changes algorithm when you select daylight and that's what is giving you the difference?

Julien Marrec gravatar image Julien Marrec  ( 2015-01-14 07:21:46 -0500 )edit

How can I see the .inp file? Would help to make a more informed answer :)

Benjamin gravatar image Benjamin  ( 2015-01-16 23:47:17 -0500 )edit

@Benjamin: please write me your email address, I will send INP file

Ashok Dhayal gravatar image Ashok Dhayal  ( 2015-01-17 03:07:40 -0500 )edit

Apparently @Ashok Dhayal reported that using the 2014 ISHRAE weather file, instead of 2013 as previously, seems to produce results one could expect (a diminution in pretty much everything). Maybe a weather guru like @Joe Huang would be able to explain what's going on exactly.

Julien Marrec gravatar image Julien Marrec  ( 2015-01-27 02:37:43 -0500 )edit

answered 2015-01-30 18:25:34 -0500

Joe Huang gravatar image

I would need more specifics on the weather files to be able to tell whether they are the cause for the change. Julien's comment says that the runs were done using the 2014 ISHRAE and 2013 ISHRAE weather files for Jaipur. As far as I know, there have been only two versions of ISHRAE weather files - the first set in 2009 and a second set in 2014. I helped in recalculating the solar radiation for the first set, and was responsible for producing the second set. The solar in the first set were calculated "blind", but for the second set I had a more refined approach and was also able to calibrate the results against satellite-derived solar from NREL. Therefore, I'm more comfortable with the solar on the second (2014) set. I'm not sure what was meant by the 2013 ISHRAE weather file.

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@Joe Huang: I got thrown off by the name of the file @Ashok Dhayal sent me: IND_Jaipur_ISHRAE_20131.BIN. I read the end too quickly and thought it was from 2013. Ashok, can you explain exactly where you got both files (the "old" version and the new 2014 version)?

Julien Marrec gravatar image Julien Marrec  ( 2015-02-02 02:25:37 -0500 )edit

@Julien Marrec I got these files in CD by ISHRAE, Solar radiation of ISHRAE 2013 weather file is edited by me.

Ashok Dhayal gravatar image Ashok Dhayal  ( 2015-02-02 02:48:41 -0500 )edit

It sounds that Ashok is using the two versions of ISHRAE weather files that I know of, i.e., ISHRAE1 done circa 2009 and ISHRAE2 released in 2014. However, it would still be nice to have that confirmed before I do any digging. Ideally, Ashok, could you just send me at the two weather filesyou're using?

Joe Huang gravatar image Joe Huang  ( 2015-02-02 14:45:27 -0500 )edit

@Joe Huang: Please check your email

Ashok Dhayal gravatar image Ashok Dhayal  ( 2015-02-02 22:52:29 -0500 )edit

@Ashok Dhayal: Have you made sure to tell @Joe Huang whether you sent the original ISHRAE file or the one you modified to replace solar radiation by your own values?

Julien Marrec gravatar image Julien Marrec  ( 2015-02-03 02:30:39 -0500 )edit

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Asked: 2015-01-12 04:14:59 -0500

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Last updated: Feb 03 '15