In a conventional building project the design and execution of the building are carried out in an "assembly-line" style. The architect hands off plans to an engineer, who specifies HVAC (Heating, Ventilation and Air Conditioning) systems, that are installed by a subcontractor who is responsible for that system and nothing else. The same pattern repeats through all other parts of the building - the building shell, plumbing, electrical, etc. are each treated as separate systems. Each professional focuses solely on their aspect of the project without much communication between team members.

In contrast, "green building" differs substantially in this regard. To get high enough building performance to qualify as a green building, the entire building must work as a whole. Windows are not simply to look out of, they help heat and light the building. HVAC works in conjunction with insulation and with the way the roof absorbs or reflects sunlight. Every place heat could be transfered within the structure must be considered and addressed. Every aspect of the design has to be planned with energy efficiency and other environmental factors in mind.

A high performance building can only be produced by an approach to building design called the "Integrated Design Process."

The Integrated Design Process (IDP) uses a team of specialists who work together to make sure that every aspect of the building works as a whole to produce the best possible product, with the best possible energy and cost savings. This team approach means all professionals are involved in the early planning stages as decisions are made about how different parts and systems of the building will function together. Everyone must come to the table to discuss how each specialty area might affect the others. This is the way synergies between the systems can be found and capitalized upon.

Many of the unexpected benefits of green building are actually results of the Integrated Design Process. Because the building is so carefully thought out and planned, there are many improvements in areas of the building outside of the purely green features.

Additional Resources
The Integrated Design Process
Whole Building Design
The Integrated Design Process (including a checklist) (pdf)