Reports/Files
Produced by the Weather Converter[LINK]
Minimally, two outputs are produced for every weather
converter run: an audit / log file and a statistical report
file. The audit / log file shows details of the processing
(including any errors) as well as the statistical report. The
statistical report produced from the weather conversion
process is a short, but complete, picture of the weather data
on the file. A single file (.stat extension) is produced of
the “statistics” about the data file. A feature of the weather
converter is to look in several design condition files for
possible design conditions for the location from the stored
design condition files (source: ASHRAE Handbook of
Fundamentals, 2001). If found (WMO (World Meteorological
Organization) id is used for matching), these will be shown in
the report as well as included in the output data files (EPW
and CSV, as applicable). In addition, the Köppen
classification scheme is used to characterize the climate
based on the data file’s contents. Other statistics are given
as well to help you visualize the data.
In the “reporting” section of the file, each line contains
“tab-delimited” elements. This will allow you to easily place
the data into a spreadsheet program for further refinement but
the tabs are not as intrusive for “normal viewing” as
commas.
As an example, the initial portion of an audit file is
shown (illustrating the error reporting):
-Input File Type = WY2, with FileName = D:\DevTests\Release\WeatherData\04772.wy2
-Out of Range Data items will NOT be corrected.
Warning ** Dew Point = 5.00°C > Dry Bulb = 4.90°C on date = 5/ 1 at hour = 4
Warning ** Dew Point = 4.80°C > Dry Bulb = 4.40°C on date = 5/ 1 at hour = 5
Warning ** Dew Point = 4.70°C > Dry Bulb = 3.80°C on date = 5/ 1 at hour = 6
Warning ** Suspected missing data line after processing 365 days
Month = 0 Day = 0 Hour = 0
Processing continues but may be in error
Warning ** Suspected Blank line after processing 365 days
** Remaining records, if any, will be ignored
Warning ** Missing Data Found on Source Weather Data File
** Missing (and corrected) Aerosol Optical Depth, Number of items = 8760
Warning ** Out of Range Data Found on Weather Data File
** Out of Range Dew Point Temperatures > Dry Bulb Temperatures, Number of items = 3
- Start Date/End Date for Weather Source
Start Date = Jan 1; End Date = Dec 31
- Actual Data Years for Monthly Data**
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
1966 1980 1964 1964 1968 1970 1977 1981 1979 1969 1974 1960
- ** Not all weather data sources represent contiguous years.
- ** Monthly data values may come from different years.
- Data Sources should be checked for relevancy to these statistics.
Average Delta DB Change = 0.76°C ; Std Dev = 0.73°C
Average Delta DP Change = 0.62°C ; Std Dev = 0.69°C
Average Delta Relative Humidity Change = 3.50% ; Std Dev = 3.63%
Average Delta Wind Speed Change = 0.93m/s ; Std Dev = 0.88m/s
Hourly Dry Bulb temperature change trigger = minimum of 11.07°C and 10.°C
11.07°C = calculated trigger based on mean change in dry-bulb temperature and standard deviation shown above
10.°C = trigger set by user
-Output File Type = epw, with FileName = D:\DevTests\Release\WeatherData\Out\CAN\_Ottawa-International\_Airport\_CWEC.epw
-Output File Type = csv, with FileName = D:\DevTests\Release\WeatherData\Out\CAN\_Ottawa-International\_Airport\_CWEC.csv
As will be seen in comparison with a “statistical” report
shown following, the audit file may contain some details about
the data that the statistical report does not (such as the
data years for the weather data). Some basic statistics are
shown first:
Statistics for USA_CA_San.Francisco.Intl.AP.724940_TMY3
Location -- San Francisco Intl Ap CA USA
{N 37° 37'} {W 122° 24'} {GMT -8.0 Hours}
Elevation -- 2m above sea level
Standard Pressure at Elevation -- 101301Pa
Data Source -- TMY3
WMO Station 724940
- Displaying Design Conditions from "Climate Design Data 2009 ASHRAE Handbook"
- ASHRAE design conditions are carefully generated from a period of record
- (typically 30 years) to be representative of that location and to be suitable
- for use in heating/cooling load calculations.
Design Stat ColdestMonth DB996 DB990 DP996 HR_DP996 DB_DP996 DP990 HR_DP990 DB_DP990 WS004c DB_WS004c WS010c DB_WS010c WS_DB996 WD_DB996
Units {} {°C} {°C} {°C} {} {°C} {°C} {} {°C} {m/s} {°C} {m/s} {°C} {m/s} {deg}
Heating 1 3.8 4.9 -3.7 2.8 10.7 -1.2 3.4 11.2 12.9 12.1 11.6 12.2 2.2 150
Design Stat HottestMonth DBR DB004 WB_DB004 DB010 WB_DB010 DB020 WB_DB020 WB004 DB_WB004 WB010 DB_WB010 WB020 DB_WB020 WS_DB004 WD_DB004 DP004 HR_DP004 DB_DP004 DP010 HR_DP010 DB_DP010 DP020 HR_DP020 DB_DP020 EN004 DB_EN004 EN010 DB_EN010 EN020 DB_EN020 \#Hrs_8-4_&_DB-12.8/20.6
Units {} {°C} {°C} {°C} {°C} {°C} {°C} {°C} {°C} {°C} {°C} {°C} {°C} {°C} {m/s} {deg} {°C} {} {°C} {°C} {} {°C} {°C} {} {°C} {kJ/kg} {°C} {kJ/kg} {°C} {kJ/kg} {°C} {}
Cooling 8 8.5 28.3 17.2 25.7 16.7 23.6 16.2 18.6 25.7 17.8 23.9 17 22.4 5.9 310 16.1 11.5 19.9 15.3 10.9 19.2 14.7 10.4 18.7 52.4 25.8 49.8 23.8 47.6 22.4 2038
Design Stat WS010 WS025 WS050 WBmax DBmin_mean DBmax_mean DBmin_stddev DBmax_stddev DBmin05years DBmax05years DBmin10years DBmax10years DBmin20years DBmax20years DBmin50years DBmax50years
Units {m/s} {m/s} {m/s} {°C} {°C} {°C} {°C} {°C} {°C} {°C} {°C} {°C} {°C} {°C} {°C} {°C}
Extremes 12.8 11.5 10.6 22.3 1.8 34.6 1.5 2.3 0.8 36.2 -0.1 37.5 -0.9 38.8 -1.9 40.5
- Displaying Monthly Design Conditions "Climate Design Data 2009 ASHRAE Handbook"
- Monthly Optical Sky Depth Beam (taub) and Diffuse (taud)
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
taub (beam) 0.316 0.326 0.334 0.362 0.368 0.353 0.371 0.365 0.352 0.335 0.320 0.318
taud (diffuse) 2.608 2.528 2.525 2.345 2.360 2.496 2.395 2.435 2.518 2.545 2.611 2.538
taub = Clear Sky Optical Depth for Beam Irradiance
taud = Clear Sky Optical Depth for Diffuse Irradiance
- Monthly Solar Irradiance Wh/m<sup>2</sup> (noon on 21st of month)
ib (beam) 879 910 933 918 912 923 903 904 901 887 866 846
id (diffuse) 79 93 100 124 123 108 118 112 99 90 78 80
ib = Clear Sky Noon Beam Normal Irradiance on 21st Day
id = Clear Sky Noon Diffuse Horizontal Irradiance on 21st Day
- Monthly Drybulb and Mean Coincident Wetbulb Temperatures°C
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Drybulb 0.4% 17.8 21.1 23.3 26.9 28.3 31.5 29.4 29.2 31.1 29.5 22.7 17.5
Coincident Wetbulb 0.4% 12.1 13.9 14.4 16.2 17.3 17.7 18.4 18.2 18.0 16.5 14.0 12.9
Drybulb 2.0% 15.8 17.9 19.8 22.5 23.7 25.6 25.3 25.0 27.1 25.5 20.0 16.2
Coincident Wetbulb 2.0% 12.1 12.7 13.4 14.4 15.8 16.7 17.3 17.5 17.1 15.6 13.5 13.0
Drybulb 5.0% 14.6 16.2 17.6 19.5 21.1 22.3 22.7 22.9 23.9 22.6 18.2 15.2
Coincident Wetbulb 5.0% 11.8 12.6 13.0 13.6 15.1 15.8 16.5 16.8 16.6 15.2 13.4 12.5
Drybulb 10.% 13.5 15.0 16.2 17.5 19.1 20.6 21.2 21.5 21.8 20.5 16.8 14.2
Coincident Wetbulb 10.% 11.2 12.1 12.5 12.9 14.1 15.1 15.9 16.2 16.1 14.9 13.3 11.7
Drybulb 0.4% = 0.4% Monthly Design Drybulb Temperature
Coincident Wetbulb 0.4% = 0.4% Monthly Mean Coincident Wetbulb Temperature
Drybulb 2.0% = 2.0% Monthly Design Drybulb Temperature
Coincident Wetbulb 2.0% = 2.0% Monthly Mean Coincident Wetbulb Temperature
Drybulb 5.0% = 5.0% Monthly Design Drybulb Temperature
Coincident Wetbulb 5.0% = 5.0% Monthly Mean Coincident Wetbulb Temperature
Drybulb 10.% = 10.% Monthly Design Drybulb Temperature
Coincident Wetbulb 10.% = 10.% Monthly Mean Coincident Wetbulb Temperature
Or, if the weather converter must calculate the design
stats:
-EnergyPlus Weather Converter V7.1.0.010
Statistics for FaroCST
Location -- Faro - PRT
{N 37° 2'} {E 7° 55'} {GMT +0.0 Hours}
Elevation -- 100m above sea level
Standard Pressure at Elevation -- 100129Pa
Data Source -- Custom-085790
WMO Station 085790
- Displaying Design Conditions calculated from this weather file.
- The following design temperature statistics are calculated based on THIS weather file ONLY
- and may not be representative of a long-term period of record normally used for
- design temperatures. Also, note that dew point temperatures are listed where
- wet-bulb temperatures are normally presented.
Design Stat Coldest Month HDB 99.6% HDB 99%
Units {} {C} {C}
Heating 3 5.6 6.0
Design Stat Hottest Month CDB .4% CDB 1% CDB 2% CDP .4% CDP 1% CDP 2%
Units {} {C} {C} {C} {C} {C} {C}
Cooling 8 33.3 32.5 31.8 22.6 22.0 21.7
Design Stat Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Units {m/s} {m/s} {m/s} {m/s} {m/s} {m/s} {m/s} {m/s} {m/s} {m/s} {m/s} {m/s}
Max WS 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
- Heating/Cooling Degree Days/Hours calculated from this weather file are later in this report.
These are followed by groupings of Monthly temperature
data.
The program calculated “undisturbed” ground
temperatures:
- Monthly Calculated "undisturbed" Ground Temperatures**°C
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
0.5 m 9.8 9.5 10.1 11.5 13.4 15.1 16.3 16.7 16.0 14.6 12.8 11.0
2.0 m 11.0 10.4 10.6 11.4 12.6 14.0 15.1 15.7 15.6 14.8 13.5 12.1
4.0 m 12.0 11.4 11.3 11.6 12.4 13.3 14.2 14.8 14.9 14.5 13.8 12.8
- **These ground temperatures should NOT BE USED in the GroundTemperatures object to compute building floor losses.
- The temperatures for 0.5 m depth can be used for GroundTemperatures:Surface.
- The temperatures for 4.0 m depth can be used for GroundTemperatures:Deep.
- Calculations use a standard soil diffusivity of 2.3225760E-03 {m**2/day}
As noted in the above statistics calculation, the "undisturbed" ground temperatures calculated by the weather converter should not be used in building losses but are appropriate to be used in the GroundTemperatures:Surface and GroundTemperatures:Deep objects. The reasoning (for building losses) is that these values are too extreme for the soil under a conditioned building. For best results, use the Slab or Basement program described in this document to calculate custom monthly average ground temperatures (see the Ground Heat Transfer section). This is especially important for residential applications and very small buildings. If one of these ground temperature preprocessors is not used, for typical commercial buildings in the USA, a reasonable default value is 2C less than the average indoor space temperature.
Heating/cooling degree days from the weather file are shown. Long term heating/cooling degree days are shown earlier if available from ASHRAE HOF for the location/WMO.
- Monthly Heating/Cooling Degree Days/Hours
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
HDD 10C 52 3 7 1 0 0 0 0 0 0 1 36
HDD 18C 290 188 223 173 130 100 73 59 54 92 169 273
CDD 10C 10 39 32 68 118 142 188 189 200 157 72 10
CDD 18C 0 0 0 0 0 3 14 0 14 1 0 0
CDH 20C 0 9 0 45 93 136 330 223 410 129 0 0
CDH 23C 0 0 0 5 13 41 167 50 169 13 0 0
CDH 27C 0 0 0 0 0 0 61 5 59 0 0 0
- 1227 annual cooling degree-days (10°C baseline)
- 100 annual heating degree-days (10°C baseline)
- 32 annual cooling degree-days (18°C baseline)
- 1825 annual heating degree-days (18°C baseline)
In the preceding display for degree-days, users more familiar with degree days to a Fahrenheit temperature base, may wish to multiply the degree day or degree hour values by 9/5.
And then the Köppen, ASHRAE and typical/extreme period calculations:
- Climate type "Cfb" (Köppen classification)**
- Marine west coastal (warm summer, mild winter, rain all year, lat. 35-60°N)
* - **Note that the Köppen classification shown here is derived algorithmically from the source weather data.*
* - It may not be indicative of the long term climate for this location.*
- Climate type "3C" (ASHRAE Standards 90.1-2004 and 90.2-2004 Climate Zone)**
- Warm - Marine, Probable Köppen classification = Cs, Dry Summer Subtropical (Mediterranean)
* - **Note that the ASHRAE classification shown here is derived algorithmically from the source weather data.*
* - It may not be indicative of the long term climate for this location.*
- Typical/Extreme Period Determination
- Summer is Jul:Sep
Extreme Summer Week (nearest maximum temperature for summer)
Extreme Hot Week Period selected: Sep 23:Sep 29, Maximum Temp = 35.10°C, Deviation = |16.393|°C
Typical Summer Week (nearest average temperature for summer)
Typical Week Period selected: Aug 19:Aug 25, Average Temp = 16.27°C, Deviation = | 0.032|°C
- Winter is Jan:Mar
Extreme Winter Week (nearest minimum temperature for winter)
Extreme Cold Week Period selected: Jan 22:Jan 28, Minimum Temp = -0.40°C, Deviation = | 8.532|°C
Typical Winter Week (nearest average temperature for winter)
Typical Week Period selected: Mar 5:Mar 11, Average Temp = 10.19°C, Deviation = | 0.417|°C
- Autumn is Oct:Dec
Typical Autumn Week (nearest average temperature for autumn)
Typical Week Period selected: Nov 12:Nov 18, Average Temp = 12.19°C, Deviation = | 0.990|°C
- Spring is Apr:Jun
Typical Spring Week (nearest average temperature for spring)
Typical Week Period selected: May 13:May 19, Average Temp = 13.59°C, Deviation = | 0.018|°C
As this data is all tab-delimited, putting in a spreadsheet
and displaying is not difficult:
WeatherSpreadsheet
Figure 12. Monthly Dry Bulb Data in SpreadSheet (for
graphing)
Using the WMO field (or determining it from the WBAN
field), the Weather Converter performs table look up in the
Design Condition files to see if there are recorded design
conditions for the subject location. If this location is
found, then design day objects are produced on the resultant
design day object (ddy extension) file - ready for inclusion
into an EnergyPlus input data file. If no design conditions
are located, then the design day object file will still
include a location object for inclusion with EnergyPlus.
However, statistics using the weather file are displayed to
the statistics file - these “can” be used to create your own
design day definitions but you should read the warning that is
issued and take care if your weather file is only a “single
instance” weather data representation.
The location objects as well as the design condition
objects are constrained by the data source. Some data sources
do not have elevation information - thus, a location object
from such a source will have an elevation of 0.0. Likewise,
the time zone of some locations may not be available from the
source data nor other data resources that the weather
converter uses. A time zone will be estimated from the
standard meridian of the location (determined by the
longitude) but it may not be accurate. A user needs to be
aware of these limitations when taking the design day files
from the weather converter.
Note that you can always include a “def” file with this
data to assure accuracy regardless of input format
limitations.
An excerpt of a design day output is shown in the following
(actual design day objects have been deleted for brevity).
Note that with the 2009 ASHRAE HOF climate conditions, a
possible DaylightSavingPeriod object may be included.
! The following Location and Design Day data are produced as possible from the indicated data source.
! Wind Speeds follow the indicated design conditions rather than traditional values (6.7 m/s heating, 3.35 m/s cooling)
! No special attempts at re-creating or determining missing data parts (e.g. Wind speed or direction)
! are done. Therefore, you should look at the data and fill in any incorrect values as you desire.
Site:Location,
Chicago Ohare Intl Ap_IL_USA Design_Conditions, !- Location Name
41.98, !- Latitude {N+ S-}
-87.92, !- Longitude {W- E+}
-6.00, !- Time Zone Relative to GMT {GMT+/-}
201.00; !- Elevation {m}
! WMO = 725300 Time Zone = NAC: (GMT-06:00) Central Time (US & Canada)
! Data Source = ASHRAE 2009 Annual Design Conditions
RunPeriodControl:DaylightSavingTime,
2nd Sunday in March, !- StartDate
2nd Sunday in November; !- EndDate
! Using Design Conditions from "Climate Design Data 2009 ASHRAE Handbook"
! Chicago Ohare Intl Ap_IL_USA Extreme Annual Wind Speeds, 1% = 11.1m/s, 2.5% = 9.4m/s, 5% = 8.6m/s
! Chicago Ohare Intl Ap_IL_USA Extreme Annual Temperatures, Max Drybulb = -23.7°C Min Drybulb = 35.9°C
! Chicago Ohare Intl Ap_IL_USA Annual Heating Design Conditions Wind Speed = 4.9m/s Wind Dir = 270
! Chicago Ohare Intl Ap Annual Cooling Design Conditions Wind Speed = 5.2m/s Wind Dir = 230
! Coldest Month = January
! Chicago Ohare Intl Ap IL USA Annual Heating 99.6%, MaxDB = -20°C
! Chicago Ohare Intl Ap IL USA Annual Heating 99%, MaxDB = -16.6°C
! Chicago Ohare Intl Ap IL USA Annual Cooling (DB = >MWB) 1%, MaxDB = 31.6°C MWB = 23°C
! Chicago Ohare Intl Ap IL USA Annual Humidification 99.6% Design Conditions DP = >MCDB, DP = -25.7°C
! Chicago Ohare Intl Ap IL USA Annual Humidification 99% Design Conditions DP = >MCDB, DP = -22.1°C
! Chicago Ohare Intl Ap IL USA Annual Heating Wind 99.6% Design Conditions WS = >MCDB, WS = 12.4m/s
! Chicago Ohare Intl Ap IL USA Annual Heating Wind 99% Design Conditions WS = >MCDB, WS = 11.4m/s
! Hottest Month = July
! Chicago Ohare Intl Ap IL USA Annual Cooling (DB = >MWB) .4%, MaxDB = 33.3°C MWB = 23.7°C
! Chicago Ohare Intl Ap IL USA Annual Heating Design Conditions Wind Speed = 4.9m/s Wind Dir = 270
! Chicago Ohare Intl Ap IL USA Annual Cooling (DB = >MWB) 2%, MaxDB = 30.1°C MWB = 22.1°C
! Chicago Ohare Intl Ap IL USA Annual Cooling (WB = >MDB) .4%, MDB = 31.2°C WB = 25.5°C
! Chicago Ohare Intl Ap IL USA Annual Cooling (WB = >MDB) 1%, MDB = 29.6°C WB = 24.5°C
! Chicago Ohare Intl Ap IL USA Annual Cooling (WB = >MDB) 2%, MDB = 28.1°C WB = 23.5°C
! Chicago Ohare Intl Ap IL USA Annual Cooling (DP = >MDB) .4%, MDB = 28.9°C DP = 23.8°C HR = 0.0192
! Chicago Ohare Intl Ap IL USA Annual Cooling (DP = >MDB) 1%, MDB = 27.7°C DP = 22.9°C HR = 0.0180
! Chicago Ohare Intl Ap IL USA Annual Cooling (DP = >MDB) 2%, MDB = 26.5°C DP = 21.9°C HR = 0.0170
! Chicago Ohare Intl Ap IL USA Annual Cooling (Enthalpy = >MDB) .4%, MDB = 31.4°C Enthalpy = 79.2kJ/kg
! Chicago Ohare Intl Ap IL USA Annual Cooling (Enthalpy = >MDB) 1%, MDB = 29.6°C Enthalpy = 75.1kJ/kg
! Chicago Ohare Intl Ap IL USA Annual Cooling (Enthalpy = >MDB) 2%, MDB = 28.2°C Enthalpy = 70.9kJ/kg
Design day “definitions” originate in the ASHRAE Handbook
of Fundamentals. Prior to 1997, these conditions were
described for winter and summer (heating and cooling). They
were based on seasonal percentages.
EnergyPlus uses the design day object values and creates an
entire day of weather data - this is described more fully in
the Input Output Reference under the
DesignDay object. The weather converter
program assigns “SummerDesignDay” and “WinterDesignDay” day
types by default - these day types influence “scheduling” of
various elements. How to use these effectively is described
during the DesignDay and
Schedule objects discussions in the Input
Output Reference.
Beginning in 1997, and continuing (the latest version was
published in 2009), the design condition data is based on
annual percentages. In addition, only locations with long-term
hourly observations data (on which to form the basis) are
included.
[From
ASHRAE Handbook of Fundamentals, 2009]:[LINK]
Design data based on dry-bulb temperature represent peak
occurrences of the sensible component of ambient outdoor
conditions. Design values based on wet-bulb temperature are
related to the enthalpy of the outdoor air. Conditions based
on dew point relate to the peaks of the humidity ratio. The
designer, engineer, or other user must decide which set(s) of
conditions and probability of occurrence apply to the design
situation under consideration.
The 99.6% and 99% Heating conditions are often used in the
sizing of heating equipment.
The 0.4, 1.0, and 2.0% dry-bulb temperatures and mean
coincident wet-bulb temperatures (i.e., DB = >MWB) often
represent conditions on hot, mostly sunny days. These are
often used in sizing cooling equipment such as chillers or
air-conditioning units.
Design conditions based on wet-bulb temperatures (i.e., WB
= >MDB) represent extremes of the total sensible plus
latent heat of outdoor air. This information is useful for
cooling towers, evaporative coolers, and fresh air ventilation
system design.
Design conditions based on dew-point temperatures (i.e., DP
= >MDB) are directly related to extremes of humidity ratio,
which represent peak moisture loads from the weather. Extreme
dew-point conditions may occur on days with moderate dry-bulb
temperatures, resulting in high relative humidity. These
values are especially useful for humidity control
applications, such as desiccant cooling and dehumidification,
cooling-based dehumidification, and fresh-air ventilation
systems. The values are also used as a check point when
analyzing the behavior of cooling systems at part-load
conditions, particularly when such systems are used for
humidity control as a secondary function. Humidity ratio
values are calculated from the corresponding dew-point
temperature and the standard pressure at the location’s
elevation.
The enthalpy design conditions (i.e. Enthalpy = > MDB)
gives the annual enthalpy for the cooling season; this is used
for calculating cooling loads caused by infiltration and/or
ventilation into buildings. Enthalpy represents the total heat
content of air (the sum of its sensible and latent energies).
Cooling loads can be easily calculated knowing the conditions
of both the outdoor ambient and the building’s interior
air.
Reports/Files Produced by the Weather Converter[LINK]
Minimally, two outputs are produced for every weather converter run: an audit / log file and a statistical report file. The audit / log file shows details of the processing (including any errors) as well as the statistical report. The statistical report produced from the weather conversion process is a short, but complete, picture of the weather data on the file. A single file (.stat extension) is produced of the “statistics” about the data file. A feature of the weather converter is to look in several design condition files for possible design conditions for the location from the stored design condition files (source: ASHRAE Handbook of Fundamentals, 2001). If found (WMO (World Meteorological Organization) id is used for matching), these will be shown in the report as well as included in the output data files (EPW and CSV, as applicable). In addition, the Köppen classification scheme is used to characterize the climate based on the data file’s contents. Other statistics are given as well to help you visualize the data.
In the “reporting” section of the file, each line contains “tab-delimited” elements. This will allow you to easily place the data into a spreadsheet program for further refinement but the tabs are not as intrusive for “normal viewing” as commas.
Audit / Log File[LINK]
As an example, the initial portion of an audit file is shown (illustrating the error reporting):
Statistical Report File[LINK]
As will be seen in comparison with a “statistical” report shown following, the audit file may contain some details about the data that the statistical report does not (such as the data years for the weather data). Some basic statistics are shown first:
Or, if the weather converter must calculate the design stats:
These are followed by groupings of Monthly temperature data.
The program calculated “undisturbed” ground temperatures:
As this data is all tab-delimited, putting in a spreadsheet and displaying is not difficult:
Figure 12. Monthly Dry Bulb Data in SpreadSheet (for graphing)
And these can be easily used to produce graphs:
Design Day Calculations Output[LINK]
Using the WMO field (or determining it from the WBAN field), the Weather Converter performs table look up in the Design Condition files to see if there are recorded design conditions for the subject location. If this location is found, then design day objects are produced on the resultant design day object (ddy extension) file - ready for inclusion into an EnergyPlus input data file. If no design conditions are located, then the design day object file will still include a location object for inclusion with EnergyPlus. However, statistics using the weather file are displayed to the statistics file - these “can” be used to create your own design day definitions but you should read the warning that is issued and take care if your weather file is only a “single instance” weather data representation.
The location objects as well as the design condition objects are constrained by the data source. Some data sources do not have elevation information - thus, a location object from such a source will have an elevation of 0.0. Likewise, the time zone of some locations may not be available from the source data nor other data resources that the weather converter uses. A time zone will be estimated from the standard meridian of the location (determined by the longitude) but it may not be accurate. A user needs to be aware of these limitations when taking the design day files from the weather converter.
Note that you can always include a “def” file with this data to assure accuracy regardless of input format limitations.
An excerpt of a design day output is shown in the following (actual design day objects have been deleted for brevity). Note that with the 2009 ASHRAE HOF climate conditions, a possible DaylightSavingPeriod object may be included.
Design day “definitions” originate in the ASHRAE Handbook of Fundamentals. Prior to 1997, these conditions were described for winter and summer (heating and cooling). They were based on seasonal percentages.
EnergyPlus uses the design day object values and creates an entire day of weather data - this is described more fully in the Input Output Reference under the DesignDay object. The weather converter program assigns “SummerDesignDay” and “WinterDesignDay” day types by default - these day types influence “scheduling” of various elements. How to use these effectively is described during the DesignDay and Schedule objects discussions in the Input Output Reference.
Beginning in 1997, and continuing (the latest version was published in 2009), the design condition data is based on annual percentages. In addition, only locations with long-term hourly observations data (on which to form the basis) are included.
[From ASHRAE Handbook of Fundamentals, 2009]:[LINK]
Design data based on dry-bulb temperature represent peak occurrences of the sensible component of ambient outdoor conditions. Design values based on wet-bulb temperature are related to the enthalpy of the outdoor air. Conditions based on dew point relate to the peaks of the humidity ratio. The designer, engineer, or other user must decide which set(s) of conditions and probability of occurrence apply to the design situation under consideration.
The 99.6% and 99% Heating conditions are often used in the sizing of heating equipment.
The 0.4, 1.0, and 2.0% dry-bulb temperatures and mean coincident wet-bulb temperatures (i.e., DB = >MWB) often represent conditions on hot, mostly sunny days. These are often used in sizing cooling equipment such as chillers or air-conditioning units.
Design conditions based on wet-bulb temperatures (i.e., WB = >MDB) represent extremes of the total sensible plus latent heat of outdoor air. This information is useful for cooling towers, evaporative coolers, and fresh air ventilation system design.
Design conditions based on dew-point temperatures (i.e., DP = >MDB) are directly related to extremes of humidity ratio, which represent peak moisture loads from the weather. Extreme dew-point conditions may occur on days with moderate dry-bulb temperatures, resulting in high relative humidity. These values are especially useful for humidity control applications, such as desiccant cooling and dehumidification, cooling-based dehumidification, and fresh-air ventilation systems. The values are also used as a check point when analyzing the behavior of cooling systems at part-load conditions, particularly when such systems are used for humidity control as a secondary function. Humidity ratio values are calculated from the corresponding dew-point temperature and the standard pressure at the location’s elevation.
The enthalpy design conditions (i.e. Enthalpy = > MDB) gives the annual enthalpy for the cooling season; this is used for calculating cooling loads caused by infiltration and/or ventilation into buildings. Enthalpy represents the total heat content of air (the sum of its sensible and latent energies). Cooling loads can be easily calculated knowing the conditions of both the outdoor ambient and the building’s interior air.
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