The three-tier design approach is an important work-flow for every architect to master. By following this method and thoroughly understanding its importance effort, money, and energy are all properly conserved throughout the design – construction – habitation process. Architects employ different methods related to heating, cooling, and lighting within each tier to most efficiently solve their livability issues. As much progress as possible is made during the basic layout and massing process by focusing on things like the relationship between surface and volume, shading or exposure of surfaces, and the use of thermal mass and insulation (tier 1). Passive techniques are used in tier 2 to further influence livability through more complex interventions that require a more detailed level of analysis by the designer (and more complicated and accurate construction by the contractor). Despite the higher initial costs due this requires, money is often saved in the long-term due to the reduced need for mechanical systems and their associated operation and maintenance costs. This work-flow emphasizes that tier 3 mechanical and electrical equipment should be employed as a last resort solution, when passive techniques are simply too expensive or unsuitable for the situation.
To illustrate the three-tier design approach and its usefulness in design I have created a flowchart (adapted from Lechner) to guide the decision-making process that architects should employ. Additionally, I have indicated instances where choices made in the design process will effect others and whether these relationships will be symbiotic or antagonistic.