[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [EnergyPlus_Support] Re: Design Day V.S. Schedule
There is a logged error in some IP conversions of table
units (not sure if this is one). Will be fixed in the next
release.
but if you find more, please let me know.
I will try to snag your file.
At 01:03 PM 7/14/2011, Qianmin Zhang wrote:
Dr. Li,
Thanks a lot. These additional objects come from openstudio template...
I'll read your results carefully.
From my result variable, ZONE 6:Zone Window Heat Gain[W](Hourly) is
2959.68 at 07/31 13:00:00, which match the value of my hand
calculation.
But, just in result table(html), WINDOW HEAT GAIN [Btu/h] max is 1380.75
for one skylight of 26ft2, which is about 1/3 of my hand calculation
zone 6 has two skylight,
I'm working on unit conversion now, and will run a simulation without
unit conversion to check the number.
Regards,
Qianmin
On Thu, Jul 14, 2011 at 11:24 AM, YuanLu Li
<yli006@xxxxxxxxxxx>
wrote:
-
- You have 500 unused material and constructions in your IDF. The
attached IDF has been sorted and report variables added and deleted.
-
- See whether the result in the csv files are reasonable.
- Dr. Li
-
- To:
EnergyPlus_Support@xxxxxxxxxxxxxxx
- From: zqianmin@xxxxxxxxx
- Date: Thu, 14 Jul 2011 10:08:48 -0700
- Subject: Re: [EnergyPlus_Support] Re: Design Day V.S.
Schedule
-
- I choose " Run simulation for weather file run
periods"
- Here is the equation used to calculated window solar
incident:
- window_transmitted_hg = tau_D * E_D + tau_diff * E_diff
- tau_D is the transmittance of the window to direct (beam)
radiation
- E_D is the incident direct (beam) radiation flux
- tau_diff is the transmittance of the window to diffuse
radiation
- E_diff is the incident diffuse radiation flux
- From my calculation @ 20:00
- surface azimuth angle: 0
-
latitude: 38.7
-
declination: 20.64
-
solar time: 36
-
tilt: 18.97
- incidence angle:
1.588(rad)
- cos(incidence angle): 0.9998
-
SC: 0.64
- transmittance of the window to direct radiation: 0.557
- transmittance of the window to diffuse radiation: 0.511
-
incident direct (beam) radiation flux: 284 Btu/hr-sq.ft
-
incident diffuse (beam) radiation flux: 39 Btu/hr-sq.ft
- transmitted heat gain=0.557 x 284.97 + 0.511 x 39.94 = 179.17
Btu/hr-sq.ft (565 watt/meter square)
- window with 26sq.ft = 26 x 179= 4658 Btu/hr
- 1 Btu/hr·ft2 = 3.154W/m2
- Above are my hand calculation
- I'm not sure how energyplus calculate incident solar irradiance on
window. Attached is my idf file.
- I really appreciate your time, thanks.
- Qianmin
- On Thu, Jul 14, 2011 at 5:08 AM, YuanLu Li
<yli006@xxxxxxxxxxx>
wrote:
-
- Cannot comment without knowing what is included in your hand
calculation, and whether you were using DesignDay sizing or weather file
run. What is the listed solar direct normal value and
Global diffused horizontal value used. What solar altutude angle
did you use?
-
- The location and roof tilt do not cover all the necessary
conditions. You need to calculate the angle between the skilight
normal and the solar beam at the time of calculation.
-
- The maximum solar radiation intensity must not exceed 1400 watt/meter
square. It is only around 1000 watt/meter square measured in
Kuching, East Malaysia.
- Because you are using IP units, it is not easy to compare the result
with the weather file input conditions.
-
- Dr. Li
-
- To:
EnergyPlus_Support@xxxxxxxxxxxxxxx
- From: zqianmin@xxxxxxxxx
- Date: Wed, 13 Jul 2011 14:41:00 -0700
- Subject: Re: [EnergyPlus_Support] Re: Design Day V.S.
Schedule
-
- I have a skylight in my modeling, the simulation result shows this
skylight has following maximum value
- window transmitted solar of 1142.11Btu/h,
- window transmitted beam solar of 858Btu/h
- window transmitted diffuse solar of 284btu/h
- window heat gain of 1382.65btu/h
- this skylight window has a
- u-factor of 0.35,
- SHGC of 0.55,
- Visible transmittance of 0.71,
- 23ft^2,
- latitude of 38.7
- longitude of -121.6 (Sacramental CA)
- tilt angle is 18.97degree
- hand calculating with radiant time series method give me following
results:
- window transmitted heat gains of 3360btu/h, which two times bigger
than energyplus result.
- I looked at the engineering reference, but still don't know why the
value from energyplus are so small, about one third of hand calculating
results.
- Any one could give me some help? Thanks a lot.
- Qianmin
- On Wed, Jul 13, 2011 at 5:19 AM, YuanLu Li
<yli006@xxxxxxxxxxx>
wrote:
-
- With DesignDay sizing, the beam intensity can be controlled by
changing the skyclearance number. (0.0 to 1.1)
-
- The diffused components will adjust itself according the rules in the
manual, when the incoming beam value is changed.
-
- However, you should know that the set values are for the whole
day. The temperature profile and the RH values may be set using
schedules.
-
- You can make it rain for the whole day, and not by the hours.
When it rain, the sky temperature becomes close to the outdoor air
temperture for the whole day.
- =====================
- If a building is comfortable for the worst condition, it should be
good for the other time as well. I do use the weather
file to verity the conditions in the Summer and Winter transition
periods.
-
- Dr. Li
-
- To:
EnergyPlus_Support@xxxxxxxxxxxxxxx
- From:
jeannieboef@xxxxxxxxx
- Date: Wed, 13 Jul 2011 06:32:08 +0000
- Subject: [EnergyPlus_Support] Re: Design Day V.S. Schedule
-
- When specifying the Design Day, I specify quite a few variables that
will "override" the normal weather file variables for specified
date e.g. wind velocity is set to a constant. What I don't see are
options for radiation (4 kinds). Does e+ pull any hourly variables from
the weather file for set date, that are not specified in the Design Day
object?
- I have thus far assumed this to be the case.
- --- In
EnergyPlus_Support@xxxxxxxxxxxxxxx, YuanLu Li <yli006@...>
wrote:
- >
- >
- > Hi, QiangMin Table is useful to get an overall view of the
result. Meters, etc. are useful only for those who are interested in
preparing 'Green' reports. Solar loading on the building is a daily
cyclic property. It cannot be separated into hourly value from the daily,
monthly averaged values.
- >
- > This is why I am not very interested in the reports and annual
simulation, when trying to design a comfortable building with natural
ventilation. By the way, there will not be any monthly results in the
table, if you do not do an annual simulation.========================= I
high lighted some fields in the DesignDay object in the other mail. For
your building, because the roof overhang is shielding the windows, you
may not get any solar beam to beam through windows except in the morning
and afternoon periods, when the sun altitude angle is low. If you plot
this variable, you will see two peaks during one day, on the windows
facing South. The North facing windows will see these during the Summer.
I used March 21, June 21, September 21, December 21 in the four DesignDay
object for the four seasons. If you want to have special schedules, you
can use CustomDay1, SUmmerDesignDay, CustomDay2, WinterDesignDay for
them. The maximum temperature occured on July 21 2 pm, because it is an
diffused heat transfer effect from the ground and cloud to the
environment outdoor air. This is a statistical value. The OA temperature
etc. can be selected from the stat file, or the epw weather file for the
location. These controls the convection heat balance on the exterior
surfaces. Do not forget to turn on the skyclearance to unity in Winter.
This controls the solar beam into the windows and change the MRT in the
room. Blinds inside the window will reduce the solar heating, but not as
afficient as the external one. Interior window temperature may not be the
window glass temperature. The rate tells you how strong is the sun, the
energy gives you the total heat transmitted. You can sum this on the
spread sheet to get the monthly solar beam heating component. In building
design, the annual value is not very useful. When you rotate the
building, the window area and orientation are the controlling factor. In
order to reduce the two peaks, you add vertical fins on two sides of the
windows. Changing the glass position would also help. (recessed and bay
window.) With natural ventilation, an open window can work like a fin and
reduces the beam into the room.=================All surface temperature
are reported. You can find these in the .rdd file. Use timestep to list
and plot them. You can reduce the number of variables displayed using the
.rvi file to selected from the .eso file, provided the variables are
requested in the IDF. The advancedOutput directory under the exampleFiles
directory has an exercise to show you the use of .rvi to get hourly,
daily, monthly listing.=========================The heating and cooling
load is calculated by summing all the zone surfaces and obtain a heat
balanced condition. The internal heat is added, and then get a mean
temperature. If this temperature is higher than the set point, a volume
of air is exchanged with the cooled air, until the set point is met. Then
the air change will still go on, if the fan is on, but the temperature of
the cooled air would be different, because the cooling coil condition is
changed. The values are in the sensible heat gain or loss variables for a
survace or a zone. How the heat transferred through the material is
calculated using CTF is described in the Engineering
Manual.=======================Hope the above will be helpful to you. Dr.
Li
- > To:
EnergyPlus_Support@xxxxxxxxxxxxxxx
- > From: zqianmin@...
- > Date: Tue, 12 Jul 2011 16:51:40 -0700
- > Subject: Re: [EnergyPlus_Support] Design Day V.S. Schedule
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- > Thank you so much for your help!
- > I have a question about the report output. I want to take a look
at the solar heat gain through all the fenestration, and heat gain
through walls in different orientations to understand how energyplus
calculate the cooling load. But I couldn't find these in my summary
report. I selected all summary and monthly in output:Table: summary
reports.
- >
- > Regards,Qianmin
- >
- > On Tue, Jul 12, 2011 at 1:52 PM, YuanLu Li <yli006@...>
wrote:
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- > Hi, QiangMin
- >
- > ==================SizingPeriod:DesignDay,
- > SACRAMENTO Ann Clg .4% Condns DB=>MWB, !- Name
- > 38.4, !- Maximum Dry-Bulb Temperature {C}
- > 18.6, !- Daily Dry-Bulb Temperature Range {deltaC}
- >
- > 20.6, !- Humidity Indicating Conditions at Maximum Dry-Bulb
- > 101229., !- Barometric Pressure {Pa}
- > 2.4, !- Wind Speed {m/s}
- > 260, !- Wind Direction {deg}
- >
- > 1.00, !- Sky Clearness
- > 0, !- Rain Indicator
- > 0, !- Snow Indicator
- > 21, !- Day of Month
- >
- > 7, !- Month
- > SummerDesignDay, !- Day Type
- > 0, !- Daylight Saving Time Indicator
- >
- > WetBulb; !- Humidity Indicating Type
- >
- > There are more fields below this line in the later version of
EPlus.
- > For temperature profile, comfort typw, RH, etc.
- >
- >
- > ======================SummerDesignDay and WinterDesignDay are
the name of the schedules which you would like to use with the Sizing
object. (day types 9 and 10) Because the weekdays, etc. are related to
the real situations, EPlus provided four extra conditions for you to do
the simulation. In your schdules, if you wanted to use a week day to do
the simulation, simply replace SummerDesignDay with, say, Monday.
- > The Day of Month and Month specify the solar angle or earth tilt
angle. The Daylight saving time adjust the local time, as the solar noon
and local time noon is changed by one hour. You may change these to other
days and define special schedules and call them CustomDay1 and CustomDay2
(daytypes 11 and 12).
- > You can use as many DesignDay object as you want. However, you
may need to use unique names. The data fields can be identical. When you
use the annual simulation or short runPeriod simulation, the actual
weather file conditions are used.
- > When you use the Designday sizing simulation, the 24 hour period
is repeated until the midnight conditions are the same. When you use the
weather file simulation, the conditions of the previous day is carried
forward to the next day at midnight.
- > Sizing is controlled by what you think the system should be and
is fixed. You have used sizing multiplier of 1.2, which means you want
the system to be larger. You can also make it smaller and veriy with the
PLR listing for the whole year.
- > The schedule can be changed according to occupancy and can have
many different conditions for the whole year. Therefore you have
National, Xmas, Easter holidays, etc.By default,I think Saturday is in
the Holidays group. You can list all the schedules to verify as in my
attached IDF. I have removed all your unused material and
constructions.
- > School holidays can be scheduled as a period with allDays with
holiday values.==========================
- > RunPeriod,
- > Annual, !- Name
- > 1, !- Begin Month
- >
- > 1, !- Begin Day of Month
- > 12, !- End Month
- > 31, !- End Day of Month
- > UseWeatherFile, !- Day of Week for Start Day
- >
- > Yes, !- Use Weather File Holidays and Special Days
- > Yes, !- Use Weather File Daylight Saving Period
- > No, !- Apply Weekend Holiday Rule
- > Yes, !- Use Weather File Rain Indicators
- >
- > Yes, !- Use Weather File Snow Indicators
- > 1.0000; !- Number of Times Runperiod to be Repeated
- > =======================
- > If you use short period for simulation, the first day result may
not be accurate, therefore, the repeat field is provided for you to run
the simulation a few time and use the second or third group results.
- > You can shift the week days along by specifying a different day,
say Monday, as day of week for start day of the weather file.
- > Dr. Li
- >
- > To:
EnergyPlus_Support@xxxxxxxxxxxxxxx
- >
- > From: zqianmin@...
- > Date: Tue, 12 Jul 2011 13:01:50 -0700
- > Subject: [EnergyPlus_Support] Design Day V.S. Schedule
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >
- >