As vice president of engineering and research, Thomas Kenney is the NAHB Research Center’s most senior research engineer, and heads up work for the organization in the ANSI National Green Building Standard’s consensus development arena. His experience with a wide range of engineering disciplines and housing product research and his participation in several professional standards committees, including ANSI, ASHRAE and ASTM, as well as the National Green Building Standard ICC 700 (NGBS), provides Kenney with a insider’s perspective on the development of codes and standards, and the obstacles and opportunities we face on the road toward a carbon neutral building industry.
“The first obstacle is defining carbon neutral,” says Kenney. “Until we have a clear definition it won’t be become commercially viable.” Nonetheless, Kenney predicts a bright future for the greening of codes and the construction industry in general. “We did a study for the U.S. Department of Energy titled “The Potential Impact of Zero Energy Homes
,”looking all the way out to 2050, including many factors from household formation, retirement of older homes, the probable adoption rate of new technology in housing, and then applied all of this to the potential impact of net-zero. The results were pretty positive, at worst, energy consumption growth by the residential sector becomes very low and will plateau by the year 2045; another scenario points to a marked reduction in residential consumption along with dramatic drops in carbon emissions.”
Effect of ZEH on Single-Family Home Energy Consumption Under Various Diffusion Scenarios, from “The Potential Impact of Zero Energy Homes”
Although a strong proponent of voluntary green standards, Kenney does not feel discouraged by the agonizingly slow and detailed process of updating standards, or the push and pull of building consensus among green advocates and old-guard industry stakeholders. “There’s a healthy give and take between those that want to make an immediate difference, and those resisting rising costs and regulation. It provides a check-valve that keeps the public from harm, preventing us from taking thoughtless leaps and bounds in untested directions that often result in negative, unintended consequences. Keep in mind that provisions in codes are not necessarily based on scientific fact and logic; they are political documents.
”Kenney points to the example of the International Energy Conservation Code (IECC) providing no performance credit for mechanical equipment efficiency. Buyers in the competitive marketplace respond to “best value,” which typically means performance and features at the lowest price. The current IECC does not permit this best value optimization to take place—where energy performance and cost of construction determine the design.
Kenney offers the following scenario: “You have two design options. Two almost identical homes both use the same amount of energy for heating and cooling, but the first one employs a highly efficient heating and cooling system and less expensive construction material; the second uses a less efficient heating and cooling system allowed by federal regulation, but more expensive building materials. Remember, houses one and two are identical in every respect, including utility bills, but house two is more expensive to build. Which one would you build? Yea, house one, but house one is not code compliant, only house two is code compliant. In other words, for the same energy performance the only option available is the more expensive construction. That’s bad logic,” says Kenney.
But this represents just one example, otherwise Kenney sees an ideal, working balance between voluntary green building standards that provide multiple levels of performance and tend to encourage innovation and model codes that reflect “the best we can do today.”