Nah, I don't think that I could find anything conclusive from this... Your data is sort of all over the place, and there are many factors that affect the relationship in question, many of which are probably functions of one another.

I had thought of doing an engineering analysis of the relationship between several environmental factors, ground temperature, material, etc. as a building systems engineering study. In order to isolate one variable at a time to see the effect on the other variables (and to be consistent with my technology budget of $0.00), a computer analysis is probably the best choice, given that it's the only available method within my means.