it is a comercial job and they have asked me for a coshh.i didnt really know what they were on about ,but didnt want to look un profesional .
did they ask for any thing else, are you only doing window cleaning, if so you can download the data sheet for fairy liquid/ or whatever you use.
by the way coshh stands care of substances hazourdess to health, I know I spelt that wrong, but if you don't use chemicals just tell them so and suggest they want a risk assessment and method statement, at least that way you will look more professional