A few months back I wrote about the relative stringency of different green building certification programs and the difficulty in comparing them on an apples-to-apples basis. The bottom line is that green building certification programs are structured differently from one another, and the best certification system for a particular building project depends largely on the unique priorities of the key stakeholders. A multinational corporation looking to improve its corporate sustainability record might opt for a different certification program from a large property owner aiming for reduced operating costs across its entire portfolio. Given the varying goals achieved by different certification programs, there has been a trend toward “cross-certification” in the green building sector, or buildings boasting more than one certification or label.

Part of the overlap comes from the tendency of green building certification programs to piggyback off one another from a process standpoint. ENERGY STAR, for example, is used as a prerequisite for several certification programs such as the DOE Builders Challenge for new homes. In other cases, one certification program might be used as an optional “pathway” toward certifying a building, thereby reducing the amount of effort required to apply multiple certification programs to a single building. The same steps a building team would have to take to achieve ENERGY STAR might also help them achieve LEED, too.

In other cases, cross-certification is the best way to accomplish multiple green building goals in a single building. This phenomenon is especially prevalent in Europe, where many countries have their own national-scale building programs. (France leads the national certification program race with no fewer than seven homegrown programs.) While national-scale programs such as BREEAM in the UK and HQE in France may help attract local tenants, the internationally recognized LEED program will provide better differentiation for international tenants than national programs. Many property owners and managers report that they use LEED, a national certification program, and even others such as the EU’s Greenbuilding label on a single building just to cover all the bases.

There are additional benefits to cross-certification, too. While it can be more expensive to use LEED overseas (given the fact that it was originally designed more for the U.S. climate and construction norms), national scale certification programs are often better harmonized with a particular country’s situation on-the-ground and can be cheaper to implement. Moreover, many national-scale certification programs are tied to governmental incentives for green building such as grants for efficient equipment and expedited permitting, which can facilitate the certification process overall.

The chart above demonstrates the high incidence of cross certification in the United States. Many buildings will receive both the ENERGY STAR commercial buildings label as well as LEED certification; over half of green buildings in the U.S. will have more than one certification by 2015. Cross-certification, therefore, is going to be an increasingly important trend to watch as interest in green building mounts.