If the ASHRAE database is chosen, once Next > is clicked the following dialog will be shown. Here the option is given to use a design weather location different from your site location. This gives some flexibility for calculations. By choosing Select the location for the source of the design weather data can be chosen. The procedure for this is identical to choosing a location for the Location & Site Data, except that this time only locations in the ASHRAE weather database are listed.
If the location data was edited on Page 1 of the wizard the weather dataset will come up blank on this page. However the Select dialog will come up with the nearest ASHRAE location highlighted.
Once a location for the design weather dataset is chosen then the user has the choice to decide upon how the design summer and winter external temperature is derived.
To illustrate, a Percentile for Heating Loads weather of 99.6% defines an external winter weather design condition where the outside temperature is colder than the design value for 0.4 % of the time, and a Percentile for Cooling Loads weather of 0.2% defines an external summer weather design condition where the inside design temperature is exceeded for 0.2% of the time.
There are 2 options, Fundamental and Statistical.
The contents of 3.2.1 Source of Design Weather: ASHRAE Database
