The National Apartment Association is considering joining the legal push against the city of Denver’s green-building rule known as Energize Denver. The national advocacy group is weighing its options, which include potentially filing its own legal challenge against the city and county of Denver, according to an email obtained by Bisnow.

Any action would come on the heels of an April lawsuit in which the plaintiffs claimed the building performance regulations imposed by the state and city of Denver will create “new and unexpected burdens” on an already struggling commercial real estate sector.

In addition to Energize Denver, the suit also challenges the energy performance standards for large buildings that were established last summer by the state’s Air Quality Control Commission. The April suit argues the local rules are in violation of the federal Energy Policy and Conservation Act, which plaintiffs say prohibits state and local regulations stricter than federal law.

The groups involved in the litigation include the Apartment Association of Metro Denver and the Colorado Apartment Association, both NAA affiliates. Plaintiffs also include the Colorado Hotel and Lodging Association and NAIOP Colorado, as well as advocates from Colorado’s hospitality sector.

According to an email written to leaders of AAMD, NAA is contemplating its own, separate challenge under the Energy Policy and Conservation Act against the county and city of Denver.

“In short, we see two distinct legal advantages in filing a separate EPCA challenge and also welcome the opportunity to share the workload if actions are considered,” NAA General Counsel Ayiesha Beverly wrote in the May 30 correspondence. The email further speculates about the benefits of consolidating lawsuits.

“NAA also has a strong interest in being a part of these cases to protect affordability for our members nationwide, and we welcome future collaboration efforts,” Beverly wrote.

A second lawsuit would avoid “any Eleventh Amendment motion to dismiss, since it would be against just the County and City of Denver,” she wrote. The Eleventh Amendment restricts individuals from bringing suit against states in which they are not citizens.

Eleventh Amendment arguments have been an issue in EPCA lawsuit in New York and Washington in recent years.

In a request for additional comments on the email, NAA’s public affairs director said the organization was “not commenting on litigation at this time.” When reached for comment Monday, AAMD deferred to NAA. Beverly did not respond to multiple requests for comment.