Many disparate groups are individually addressing energy performance in housing, offering new certifications, new programs. Here, however, experts at the National Resources Defense Council discuss how cross industry collaboration could offer ways to improve the system.
Building a more energy efficient home can employ many different approaches. The builder can use more insulation and better windows, they can install ductless heating and cooling systems, they can orient the house to collect sunshine through the windows in winter and shade them in summer, they can seal leaks in the walls and ceilings and assure healthy indoor air 24/7 by providing reliable mechanical ventilation with energy recovery, they can use cool roofs, and the list goes on...
Traditional building energy codes and efficiency incentives have focused on promoting one or several of these technologies in an inflexible package, requiring specified amounts of insulation in the floor, walls, and roofs, specified heating and cooling efficiency, specified air leakage…. This prescriptive approach succeeds at improving efficiency at low cost, but does not give credit for energy savings from comprehensive or holistic design strategies. Furthermore, the specific measures promoted within codes and incentive program change over time, causing uncertainty in the industry.
Builders therefore tend to resist it because it reduces their flexibility and is more expensive than it needs to be for any given energy efficiency target.
For example, perhaps one of the specified criteria is very expensive to meet for a particular house while another technology that might cost much less could save even more energy.
NRDC has been working with builders and building efficiency suppliers, as well as with nonprofit efficiency advocates, to introduce the combination of more ambitious energy goals and more flexible ways of meeting them into building energy codes and other market-based programs described next. The cornerstone of these methods is the HERS Index, a home energy inspection and rating method developed by RESNET, a nonprofit standard-setting organization that NRDC has supported since its inception. Markets in energy efficiency can only work if buyers and sellers have the information needed to evaluate energy efficiency in dollars. Long-term transformation of efficient construction practices relies on allowing stakeholders across the new construction industry to compete for overall home performance, not just incremental improvements in individual technologies.
The HERS Index is similar to a miles-per-gallon sticker on a car: it projects energy use compared to a baseline. The baseline score of 100 is based on a house that meets the 2006 energy code, while a score of 0 means zero energy use, on net.
More than 20 percent of new homes were rated in 2017, with an average score of 62, which is impressive considering that few entities provide incentives for such ratings. A score of 62 is some 15 percent better than the requirements of the most advanced model energy code in America. How much better could we do with financial incentives for the lowest scores?Read More