The values for the “Monthly average daily global solar irradiance on a horizontal surface” used by CYPECAD MEP in the analysis of a solar thermal installation for sanitary hot water production, can be assigned automatically by the program depending on the selected location (Job > Location) or can be defined by users together with the rest of the climate data (Job > General data > edit Climatic conditions > select User values > edit “Monthly daily average global solar irradiation on horizontal surface” section and introduce the values for each month of the year). As of the 2014.e version, when users edit the “Average daily global solar irradiance”, the values of the “NASA Langley Research Center Atmospheric Science Data Center” can be imported by clicking on the 
button.
The values that are imported from this database depend on the Latitude and Longitude that are indicated in the “Climatic conditions” dialogue box when user values are introduced. Therefore, highly reliable values can be introduced of the solar irradiance for any place on the planet.
Not all the data within the “Climatic conditions” dialogue box is used in the design process of the solar thermal energy installation for the sanitary hot water production. This data appears because the dialogue box is used in both the “Air Conditioning” and “Thermal analysis” tabs, where it is used to design the air conditioning installations or carry out the required thermal checks. Therefore, the solar irradiance values can also be imported from the NASA database from these two tabs.
As of the 2014.d version, the solar irradiance values of the NASA database are also adopted when the other climate data is imported from the “ASHRAE Weather Data Viewer 4.0” database. This database was implemented in the 2014.d 
. In this case, the monthly solar irradiance values correspond to the weather station selected by users when the climate values are imported from the “ASHRAE Weather Data Viewer 4.0” database.
