The book "Introduction to Architectural Science: The Basis of Sustainable Design" by Steven Szokolay (see Books list on this website) has a section that looks at U-values, thermal mass, admittance and decrement delay. The information was well presented and found to be informative. There are also some useful work sheets at the back that help to pad out the calculation side of things. As an architect I found that it to be a excellent primer (other that energy/comfort the book also looks at other aspects of environmental science including lighting and acoustics).
Finally the book makes reference to CIBSE guidance on calculations, so if your looking for even more technical stuff you could look into the relevant Guides that CIBSE have on offer (Guide A?).