Firstly thank you for your kind comments regarding the Replacing the Replacements seminar. You were not alone when you said you found it interesting and radical, others have said that it was a wake up call. We have covered the subject in our latest PVC Windows Report that I would recommend as important reading to any company supplying into the window sector.
Moving onto the point you make about trickle vents, I'm afraid there is no short cut you have to refer to building regulations. You will understand that no two applications are alike, particularly when you add heating appliance implications into the equation. If you get questions asked then it would be handy to have a copy of the Building Regulations available to help your customers to calculate the venting for their specific application.