This part of ISO 15927 gives the definition and specifies methods of calculation and presentation of themonthly external design climate to be used in determining the design cooling load of buildings and the designof air conditioning systems.Depending on the building type, a range of parameters can be used to define the individual days of hourly orthree-hourly data in each calendar month that impose a cooling load likely to be exceeded on 5 %, 2 % and1 % of days.The parameters that are always used in the selection are dry-bulb temperature and total global solarirradiation (or sunshine hours). The daily swing in dry-bulb temperature, dewpoint temperature and