Treehugger has an article identifying 7 executive orders which Obama should sign to protect the environment.
The one which interested me calls for protecting stronger state laws from weaker federal ones
The next President should [...] should amend the existing Executive Order on Federalism to strengthen provisions setting forth a presumption against preemption; require agencies to provide a written justification for preemption; and require that, when a federal statute allows states to adopt more stringent standards or seek a waiver of statutory preemption (as in EPA's denial of California's Clean Air Act waiver), agencies must provide a written justification to the White House before denying the state's regulatory authority or waiver request. As is the case with the existing Executive Order on Federalism, these recommendations are consistent with the goals of the various statutes under which the environmental, safety, and public health agencies operate, including the National Environmental Policy Act.
The preemption issue has proven to be extremely significant in green building regulatory challenges. In AHRI v. City of Albuquerque, we saw an effective challenge to Albuquerque's green building code based on weaker federal energy standards for HVAC equipment. See my post here for more on the AHRI v. City of Albuquerque case.
However, an executive order will not go very far to prevent federalism challenges to green building regulation. For example, it would not have effected the challenge to Albuquerque's green building code because 1) the City of Albuquerque never applied for a waiver, so the executive order would not have applied in that case, and 2) Congress specifically preempted state regulation of energy efficiency of HVAC equipment.
See related posts on green building law and federalism here