The Eplus expert has given you the reason already. I do not think that you can follow what all these files are.
You are not the only one who wanted to use the warmest day data in the weather file for sizing. I do not know who initiated the use of weather file data for sizing simulation. (ASHRAE or EPlus)
The reason why not to use the warmest day in the weather file data is quite simple. The data only occurred once in a year, and it is only based on the temperature of the outdoor air, on a Typical Meteorological Year (TMY).
If you ask the local weather station, or look up the weather Almanac, you will find the warmest day based on the maximum day time temperature. These day will appear on different day of the year, and the maximum temperature is not the same for each year. The data listed in EPlus .epw file is compiled using the data from a month which do not have extreme data range. It may not match any of the real warmest day of the year.
If the equipment is sized to this warmest day of the weather file, it would usually be over sized. The DesignDay value is chosen in such a way that a certain day of the year would have higher temperature range. The object is classified as 0.4%, 1%, and 2%. The meaning of these are explained in the manuals.
If you choose the 99.6% DesignDay Data for Summer, only six days in a year may have higher outdoor temperature in the TMY. In the real situation, only one or two days may have the high outdoor temperature and clear sky together. Therefore, the DesignDay data is a better way to size the equipment. You can increase the DesignDay maximum dry bulb temperature to that of the warmest day to compare or special observations.
In fact, the equipment will not be turn on during the hottest days, because the office, school, factories may have holidays during the warmest months.
The values in the DesignDay object can be adjusted to meet your special need. (cloud conditions, solar angle variation, day/night variation, wet bulb at maximum temperature.) There are a number of schedules that can be used as well in the DesignDay data.
There are many reasons why EPlus was designed to work in the recommended way. If you follow the rules and read the manual, you may understand the process better.
Many user used the whole year data in the epw file for sizing. You may be one of them, because the warmest and coldest days would be included. Why waste time in dong the 365 days simulation, when you can get the same result using 2 days simulation? The answer I got was, "My PC is fast. No noticeable difference in run time.". The common side effect is getting thousands of warning, if there are only one or two real ones, which are repeated.
Many IDF files posted on the forum do not have DesignDay objects in them.
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You are not the only one who wanted to use the warmest day data in the weather file for sizing. I do not know who initiated the use of weather file data for sizing simulation. (ASHRAE or EPlus)
The reason why not to use the warmest day in the weather file data is quite simple. The data only occurred once in a year, and it is only based on the temperature of the outdoor air, on a Typical Meteorological Year (TMY).
If you ask the local weather station, or look up the weather Almanac, you will find the warmest day based on the maximum day time temperature. These day will appear on different day of the year, and the maximum temperature is not the same for each year. The data listed in EPlus .epw file is compiled using the data from a month which do not have extreme data range. It may not match any of the real warmest day of the year.
If the equipment is sized to this warmest day of the weather file, it would usually be over sized. The DesignDay value is chosen in such a way that a certain day of the year would have higher temperature range. The object is classified as 0.4%, 1%, and 2%. The meaning of these are explained in the manuals.
If you choose the 99.6% DesignDay Data for Summer, only six days in a year may have higher outdoor temperature in the TMY. In the real situation, only one or two days may have the high outdoor temperature and clear sky together. Therefore, the DesignDay data is a better way to size the equipment. You can increase the DesignDay maximum dry bulb temperature to that of the warmest day to compare or special observations.
In fact, the equipment will not be turn on during the hottest days, because the office, school, factories may have holidays during the warmest months.
The values in the DesignDay object can be adjusted to meet your special need. (cloud conditions, solar angle variation, day/night variation, wet bulb at maximum temperature.) There are a number of schedules that can be used as well in the DesignDay data.
There are many reasons why EPlus was designed to work in the recommended way. If you follow the rules and read the manual, you may understand the process better.
Many user used the whole year data in the epw file for sizing. You may be one of them, because the warmest and coldest days would be included. Why waste time in dong the 365 days simulation, when you can get the same result using 2 days simulation? The answer I got was, "My PC is fast. No noticeable difference in run time.". The common side effect is getting thousands of warning, if there are only one or two real ones, which are repeated.
Many IDF files posted on the forum do not have DesignDay objects in them.
what is mean that you say dont use it as equipment sizing data?
i need the warmest day in the year to simulate my mechanical system for this day only.
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