By: Duncan Prahl
I attended Scott Sedam's "Lean Design" webinar (view the slides) and was overjoyed to hear him speaking about the same thing we here at IBACOS have been working on with our builder clients for years. I call it the Integrated Design Process (IDP). I firmly believe that the overall operational profitability of a company building high performance homes can be as good as or better than a company building simply to code. One way to help pay for higher performance strategies and get the most bang for the buck is through IDP. Below is one part of a flow chart I created as a generic process map for IDP, which is available for download.
For builders moving toward high performance homes, this process starts to clarify all of the interrelated systems in the home and the tradeoffs that may take place. It also helps to rally everyone around the goal. It is critical for builders to have a set of overall performance criteria or a specific performance metric for the team to achieve. This could be meeting ENERGY STAR® requirements, participating in the Department of Energy's Builders Challenge, following the EEBA Criteria, or selecting the performance criteria from the green building program of your choice. Meeting these requirements will be much easier when everyone involved has a voice in the initial design and agrees on decisions that significantly impact performance (number of windows, home orientation, thermal enclosure options, mechanical system routing, and structure), which are also balanced with aesthetic goals and cost constraints.
An important aspect of IDP is to not assign blame for things in the past and to work collaboratively to achieve the goals for the project. IDP will not work if everyone at the table is unable to be open and honest and can't "Face the Brutal Facts" (as Jim Collins puts it).
Furthermore, it is critical with high performance homes to have specific and detailed sets of plans, as you need to be clear where the rain control, air control, vapor control, and thermal control layers are in the home. All these layers must be understood by the entire team, clearly detailed, and properly executed in the field for the home to actually achieve the desired level of performance.
