Part 2: Outcome-Based Codes Are Our Friends
Posted on May 4, 2018 by Helen Sanders and Mark Silverberg on USGlassmag.com
One of the potential advantages of outcome-based codes (OBCs) is they are likely to change behaviors for the long-term positive benefit for our industry, building occupants and the planet. This month, we expand on these potential benefits and discuss the challenges related to OBCs.
OBCs give greater flexibility for the architect and provide a better way to balance energy efficiency with impacts on human health. Since OBCs don’t artificially prescribe a minimum window area, the designer has the flexibility to design with as much glass as they wish. Of course, this approach requires the as-built energy use to meet the design target, which is achievable with the use of high-performance solutions tuned to the building’s mass and orientation, climate zone and use purpose. In contrast, increasingly prescriptive design-based codes cannot capture the synergies of more holistic designs. As a result, they have the potential of becoming so restrictive regarding, say window to wall ratio, that there is a considerable risk of creating dark buildings, which are incompatible with human health and well-being.
Under OBC scenarios, there will be a greater reticence for value engineering out the high-performance fenestration options. This is because of the risk of not meeting building energy performance targets – not only in the first year, but in the many years of operation and disclosure thereafter. This also suggests that higher performance fenestration products are more likely to be incorporated to deliver both energy efficiency and durability.
We also anticipate an OBC structure will shift the financial conversation away from the current primary focus on the upfront cost of construction to one that considers total lifecycle costs, retained value of real estate and return on investment.