Leaning into IPD: A primer for engineers: definitions
Design-bid-build (D-B-B) is a traditional delivery method in which the owner enters into an agreement with an architecture and engineering (AE) team to design and document the systems required for their building and enters into a separate agreement with a contractor to furnish and install the equipment and materials that comprise those systems. The AE team stamps and seals the basis of design/calculations, plans, and specifications while the contractors bid the documents and subsequently develop submittals followed by furnishing/installing the work (Figure 2).
Design-assist (D-A) is a less traditional, hybrid sort of delivery method that mirrors the D-B-B delivery method except that the contractor takes some design and documentation responsibilities for subsystems and also provides continual feedback on alternatives that can improve value to the owner (Figure 3).
Design-build (D-B) is a less traditional delivery method that has been implemented for the past few decades in which the owner hires a single entity that is responsible for designing, documenting, furnishing, and installing everything necessary for the required systems. In many cases, the owner hires the contractor and the contractor, in turn, hires the AE team. The AE team still stamps and seals the basis of design/calculations, plans, and specifications while the contractors develop submittals followed by furnishing/installing the work. However, the contractors don’t need to bid the documents because they’ve been pricing and buying the work throughout the process (Figure 3).
Integrated project delivery (IPD) is a relatively new delivery method that aims to improve collaboration to increase value by using an incentivized risk-reward form of tri-party agreement. IPD requires that a team be able to move beyond reactive coordination into proactive integration. IPD is not for every project; the benefits of IPD increase as the scale and/or complexity of a renovation or new construction project increases. Like with design-build, the AE team stamps and seals the basis of design/calculations, plans, and specifications. The contractors develop submittals followed by furnishing/installing the work; however, the contractors don’t need to “hard-bid” the documents because they’ve been pricing and buying the work throughout the process. There is a school of thought that suggests owners have demanded this type of incentivized delivery method to move beyond the traditional yet confrontational, wasteful construction process that has typically led to cost overruns, schedule extensions, and unmet owner expectations (Figure 4).
Integrated project delivery (IPD)-light is not a formal delivery method; it is a commonly used term that tends to be synonymous with design-assist (Figure 3).
Value is defined as quality plus performance divided by lifecycle cost plus schedule. Some teams may choose to use first cost instead of lifecycle cost (lifecycle cost tends to be used for owner-occupied facilities that are more complex in their design and operation, such as labs or hospitals).