Residential Energy, by John Krigger, is very accessible and is used extensively by raters and home performance professionals, especially as a reference during rater exams. The current edition includes the CD rom version. 

If you are not applying for our rater training class or are not a member of NEHERS, we prefer that you order the book from Saturn Resource Management at www.srmi.biz, as we carry the books mainly for use in our trainings.