Dear All,
I am doing envelope analysis of a rectangular building in eQuest. The
building have identical parameters for all perimeter zones. The simulation
is being done for New Delhi climate zone. The results shows that the total
solar heat gain through glazing is more in east zone compare to west zone.
In the result of that the total load and energy consumption in east zone is
higher than in west zone.
To verify the results, I analyzed the total horizontal and beam radiation
incident on east and west facade. Here, the issue was started. In the
eQuest, there always high incident solar radiation in east surface compare
to west surface. However, the incident solar radiation on east and west
surface in energy plus and TRNSYS have different trend from the eQuest.
Here I am attaching graph showing variation of incident solar radiation in
east and west facade with energy plus and TRNSYS.
Any guidance, suggestions will be appreciated.
1. Variation in eQuest and TRNSYS. (Blue and green is for eQuest and;
Magenta and brown for TRNSYS)
[image: Inline image 1]
2. eQuest and Energy Plus
[image: Inline image 1]
Regards,
Mayank Bhatnagar
Energy Analyst
Mayank,
compare them with direct normal, diffused, global radiations, trend in E+
and equest are reverse, one has more on east other has more on west,
important would be to see what does the radiation data say?
jyotirmay
Are you using the same hourly weather data in eQuest, TRNSYS and
EnergyPlus? The radiation can vary significantly.
Dear Dru,
Yes, I am using the same weather file for all simulation tools. eQuest used
bin format, which I have already checked with weather file (epw format).
The bin file only have total horizontal radiation and Normal direct
radiation, the diffuse radiation is being calculated by eQuest itself (as
per Joe huang's mail: previously asked for a query on eQuest users). TRNSYS
and E+ used epw format.
The variation are found in radiation falling on east and west surface of
the building.
Regards,
Mayank
Dear Jeff,
I converted same epw file into bin format using eQ_WthProc (DOE weather
converter tool). Additionally, eQuest also have hourly output for global
data (total horizontal radiation, direct normal radiation) which are also
compared and found identical with the epw weather file.
Regards,
Mayank
Continue with the last mail........
The incident radiation falling on the east and west surface are outputs of
the simulation tools.
Regards,
Mayank
Try checking the date and time set on the programs. One could be using summertime hours ?
Peter Simmonds, Ph.D., ASHRAE Fellow and DL
Mobile US: +1-310-383-9911
Mobile HKG: +852-9845-4902
Mobile UK: +44 7711 926317
FYI:
You also didn't say that you're using the EPW weather file in EQUEST, only that EQUEST is using .BIN format (or binary). Is EQUEST using TMY2 or TMY3?
Jeff
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Jeff S. Haberl, Ph.D.,P.E.inactive,FASHRAE,FIBPSA,......jhaberl at tamu.edu
Professor........................................................................Office Ph: 979-845-6507
Department of Architecture............................................Lab Ph:979-845-6065
Energy Systems Laboratory...........................................FAX: 979-862-2457
Texas A&M University...................................................77843-3581
College Station, Texas, USA, 77843..............................URL:www.esl.tamu.edu
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Mayank,
compare them with direct normal, diffused, global radiations, trend in E+
and equest are reverse, one has more on east other has more on west,
important would be to see what does the radiation data say?
jyotirmay
Are you using the same weather file in all three programs? The weather files contain the
global horizontal and direct normal radiation (beam looking directly at the sun). The
different simulation programs take these and calculate the incident solar on each surface
using similar algorithms. However, when you compare radiation on different orientations
where you set the clock, i.e., Time-Zone and Longitude, is very critical.
You should first figure out whether the weather files for the three programs come from the
same source data (you can convert from the EPW to a BIN if you're not sure (see
http://doe2.com/index_Wth.html#eQ_WthProc ). If the weather files are different, then
all bets are off, and the differences are due to the weather data and not the three programs.
If they are the same weather data, you should check if you're inputting the same
longitude and time-zone. Since India is at GMT +5.5, but eQUEST accepts only integer
time-zones, you'll likely see a half-hour difference in the hourly profile of radiation,
which seems consistent with the first page of your spreadsheet where the eQUEST beam
radiation looks a half-hour late. The comparison of the TRNSYS to the eQUEST curves
(confusing because nothing is labeled) suggests they may be off by several hours.
Joe
Joe Huang
White Box Technologies, Inc.
346 Rheem Blvd., Suite 205A
Moraga CA 94556
yjhuang at whiteboxtechnologies.com
http://weather.whiteboxtechnologies.com for simulation-ready weather data
(o) (925)388-0265
(c) (510)928-2683
"building energy simulations at your fingertips"
Dear Joe,
Thanks for your response and interest in this issue. I have done some more
analysis and would appreciate your inputs.
I am using the same weather file for both energy plus and eQuest. As eQuest
uses BIN format I converted the same epw format file using eQ_wthProc tool
(EPW to BIN converter). I have attached a spreadsheet (New
Delhi_ISHRAE_2014EPW.xlsx) that compares Total global Horizontal radiation
and direct normal radiation for EPW file (by converting it into CSV format)
and eQuest hourly outputs (as it reads BIN file). Since both the global
horizontal and direct normal radiations are identical, conversion from epw
to bin seems correct. Additionally, as you know, eQuest doesn't take
diffused radiation from the weather file, it calculates itself.
Since I am using the same source file for both eQuest and Eplus simulations
I would expect similar trend in solar radiation data for both East and West
facades. However, for Delhi I found variation in solar radiation output for
east and west facade. I have attached results spreadsheet (eQUest and
energy plus_Miami and Delhi_v1.xlsx) for your reference.
Interestingly, when I performed a similar analysis for "Miami epw and bin
file", I got fairly consistent results (refer graph below, the results are
for June 6 to June 9)
[image: Inline image 1] [image: Inline image 2]
[image: Inline image 3]
[image: Inline image 5]
I would like to understand the inconsistency in results for the Delhi case
in particular.
Regards,
Mayank
Dear Joe,
Thanks for your response and interest in this issue. I have done some more
analysis and would appreciate your inputs.
I am using the same weather file for both energy plus and eQuest. As eQuest
uses BIN format I converted the same epw format file using eQ_wthProc tool
(EPW to BIN converter). I have attached a spreadsheet (New
Delhi_ISHRAE_2014EPW.xlsx) that compares Total global Horizontal radiation
and direct normal radiation for EPW file (by converting it into CSV format)
and eQuest hourly outputs (as it reads BIN file). Since both the global
horizontal and direct normal radiations are identical, conversion from epw
to bin seems correct. Additionally, as you know, eQuest doesn't take
diffused radiation from the weather file, it calculates itself.
Since I am using the same source file for both eQuest and Eplus simulations
I would expect similar trend in solar radiation data for both East and West
facades. However, for Delhi I found variation in solar radiation output for
east and west facade. I have attached results spreadsheet (eQUest and
energy plus_Miami and Delhi_v1.xlsx) for your reference.
Interestingly, when I performed a similar analysis for "Miami epw and bin
file", I got fairly consistent results (refer graph below, the results are
for June 6 to June 9)
[image: Inline image 1] [image: Inline image 2]
[image: Inline image 3]
[image: Inline image 5]
I would like to understand the inconsistency in results for the Delhi case
in particular.
Regards,
Mayank
I've been corresponding with Mayank offline and have determined that the cause for the
difference is due entirely to the 30 minute difference between the GMT 5.50 time zone for
India, and the GMT 5.0 integer time zone input into eQUEST.
I'm summarizing the e-mail exchange with Mayank below for those who may be curious as to
the cause and solution for this discrepancy in solar radiation on different orientations.
Joe Huang
White Box Technologies, Inc.
346 Rheem Blvd., Suite 205A
Moraga CA 94556
yjhuang at whiteboxtechnologies.com
http://weather.whiteboxtechnologies.com for simulation-ready weather data
(o) (925)388-0265
(c) (510)928-2683
"building energy simulations at your fingertips"
That's what I said I the beginning. Well done Joe
Peter Simmonds, Ph.D., ASHRAE Fellow and DL
Mobile US: +1-310-383-9911
Mobile HKG: +852-9845-4902
Mobile UK: +44 7711 926317
Congratulations, Sherlock; you have solved the mystery very handily!
James V Dirkes II, PE, BEMP, LEED AP
www.buildingperformanceteam.com
Energy Analysis, Commissioning & Training Services
1631 Acacia Drive, Grand Rapids, MI 49504 USA
616 450 8653
I've been corresponding with Mayank offline and have determined that the cause for the
difference is due entirely to the 30 minute difference between the GMT 5.50 time zone for
India, and the GMT 5.0 integer time zone input into eQUEST.
I'm summarizing the e-mail exchange with Mayank below for those who may be curious as to
the cause and solution for this discrepancy in solar radiation on different orientations.
Joe Huang
White Box Technologies, Inc.
346 Rheem Blvd., Suite 205A
Moraga CA 94556
yjhuang at whiteboxtechnologies.com
http://weather.whiteboxtechnologies.com for simulation-ready weather data
(o) (925)388-0265
(c) (510)928-2683
"building energy simulations at your fingertips"