A More-Comprehensive Approach to New Energy Codes
- May 20, 2011
If the multi-housing and commercial building industries have heard a lot more about new energy-efficiency codes recently, it’s because the time has come to pay the piper. And the piper is the American Recovery and Reinvestment Act of 2009 (ARRA). States that accepted ARRA stimulus funds did so with strings attached—including the requirement that they adopt the 2009 International Energy Conservation Code (IECC) and subsequent editions.
ARRA also requires states to develop procedures to verify 90 percent compliance with IECC, and many states already have begun the process for adopting the code. That means that most designers will be affected by the IECC very soon. Moreover, because the IECC references ASHRAE 90.1 as a compliance alternative, that standard also is part of the ARRA mandate. ASHRAE 90.1 sets minimum energy-efficiency requirements for all but low-rise residential construction.
There is also another driver behind the stricter energy-efficiency standards. The Department of Energy, the American Institute of Architects and others have agreed to a goal of improving energy codes by 30 percent over 2004-2006 requirements. This has helped to speed the adoption of much more stringent insulation requirements in the latest editions of both the IECC and ASHRAE 90.1.
As a result of these factors, the course toward more energy-efficient construction is already well charted. And the new energy codes that will guide this construction are poised to have a profound effect on parts of the structural design of multi-housing and commercial buildings.
This may seem counter-intuitive. Historically, the path of the structural engineer seldom has crossed those of other engineering professionals in the normal course of design. Adhering to the American Iron and Steel Institute specifications and/or other standards, the structural engineer focused exclusively on the structural system, while others followed a similar process to develop HVAC, plumbing, lighting and other systems.
But as stricter energy code requirements have begun to take hold over the past year, there are new incentives for structural engineers—especially those engineers using cold-formed steel (CFS) for exterior load-bearing or curtain walls—to go beyond the design of the load-bearing frame and begin to develop solutions that conform to new energy-efficiency requirements.
In fact, if they are to design and construct energy-efficient, steel-framed buildings, structural engineers must get up to speed with today’s new energy codes and standards, and understand how all the other systems in the building integrate with CFS structural components to meet energy-efficiency objectives.
For example, the 2012 IECC contains new insulation requirements that significantly expand the use and thickness of continuous foam insulation on the exterior walls of CFS and other buildings. This presents new challenges for both structural engineers and other members of design teams, who will have to examine how the foam insulation interacts with the lateral resistance of the building, how exterior cladding is attached over the insulation, and many other issues.
In this case, these new energy requirements provide structural engineers with a unique opportunity to expand their role in the design of the thermal envelope and other parts of the energy system in a building. Structural engineers are well versed in performance-based design concepts. A similar path exists for energy code compliance that allows them to look at optimizing the energy components to provide a cost-effective thermal envelope that is compatible with the structural system.
This means that structural engineers, working alongside CFS manufacturers, have the opportunity today to harness relatively inexpensive software solutions to conduct energy design simulations that will not only satisfy the new energy code requirements, but also meet cost and performance objectives.
The foam insulation requirements mentioned earlier are perhaps the best opportunity for a designer to address and create a more cost-effective design. In many climates, the cost of the foam insulation is far greater than any related energy savings and creates significant cladding attachment, fire and other issues. A simple trade-off substituting slightly more efficient air conditioners or furnaces often is enough to minimize the need for the foam insulation while still delivering a building that meets or exceeds code requirements.
With a low-cost investment in some software and a small learning curve, the structural designer could develop an improved structural system that is safer from a fire-safety and structural perspective than the default prescriptive energy code insulation requirements while delivering a more cost-effective design to the builder and the occupant who eventually pays the energy bills.
Stepping outside of our comfort zone is always difficult. However, the latest energy codes will require someone involved in the building’s design to do just that. With steel-framed buildings, the opportunity for an engineer, architect or even the steel supplier to deliver a value-added service that is more inclusive of the energy system design will create a better and more cost-effective building.
Mark Nowak is president of the Washington, D.C.-based Steel Framing Alliance. He recently presented a session on “Energy Codes and Structural Design–Challenges and Opportunities for the Designer” at the Mid-Atlantic Steel Framing Alliance Expo And National CFSEI Annual Conference on May 23 in Annapolis, Md.