This book examines in great detail the D-B and IPD methods, while touching on D-B-B and CM project deliveries. In this vein, the discussion regarding IPD is a variation from ASHRAE Technical Committee TC 7.1, Integrated Building Design (IBD), with the focus herein on by consulting engineers and mechanical contractors. This IPD variation is also described later in the book as a 21st-century version of what was 20th-century D-B project delivery although D-B project delivery is still widely used.