At the time of writing 'AIRWIND Pro' and 'COLDWIND Pro' programs are unique amongst the world's A/C load calculation programs in being able to cope with rooms having an infinite number of walls, at any angles, placed in an unlimited number of zones and with any mix of construction materials. However for added convenience and even faster operation a facility to instantly select one of two pre-defined room shapes has been added. Simply click on either of these 'self explanatory' buttons - 
Traditionally cold rooms are generally described at the planning stage using external dimensions. This tradition is believed to have come about because cold rooms are usually constructed inside another building shell or envelope. It is thus easier to associate the cold room with the space available to accommodate it. However, this practice does not apply in all countries and even where it does apply it is sometimes more convenient to work with internal dimensions. In either case Mistral's programs cope automatically with the sometimes very complex mathematics involved, particularly in schemes involving multiple and linked rooms of varying shapes and sizes. To switch program operation from external dimensions to internal dimensions, and vice-versa, a pair of simple 'toggle' buttons are provided in 'COLDWIND Pro's' Program Launch Page Selection menu.
Clicking 
button changes the program from external dimension operation to interior operation and clicking the 
button switches it back again to operating with external dimensions.
For security or design integrity, if a program results file is created and subsequently re-opened, then whichever mode of operation the program was set to when the file was created and originally saved will be respected for that re-opened file. Regardless of the current setting.
Switching from external dimensions to internal in 'Coldwind' will result in access to the Refrigerated Container (Lighter) load calculation routine being denied. Describing shipping containers by their internal dimensions is pointless even though 'Coldwind' will compute product capacity etc., based upon internal volume.