Considering your temperature requirements PETG could be used on unheated beds.
High operational temperatures for your products requires filaments with a high glass transition temperature (the point where the plastic becomes soft. A filament with a high glass transition temperature causes filament to shrink considerably when the bed is not heated (as when the bed it heated, the plastic is soft and withstands the shrinkage stresses better). Basically, your requirements are in contradiction. You should be using a heated bed and ABS, or a high temperature resistant filament like a co-polyester.
Example of filament comparison
If a heated bed is no option, PETG is you most likely candidate for printing as many filament manufacturing brands say that a heated bed is optional. My personal experience is that PETG very much likes a heated bed, getting it to stick at lower temperatures is more difficult.