Sentence Correction

Hi Guys,

I have a question regarding punctuation.

A) I am right on the assumption, that "that" can serve two functions: 1) That as a introductry word for a essential modifier. In this case we do not use any comma. 2) That introducing a subordinate clause.

B) If "that" introduces a subordinate clause, do I have to use a comma then?
E.g. Robert R wood's experimental result, that temperature rise takes place in a glass chamber because of warm air rising and mixing with cool air is the foundation of the greenhouse effect.

Thank you very much in advance... it is really driving me crazy.
Cheers

You are right with number 1, but number 2 is not correct.

Instead of 'that' use 'demonstrating', 'showing', etc...