The state agency regulating development in Kakaako has acknowledged that its rule governing the opaqueness of glass on new condominium towers may need to be modified to achieve a better balance between reflectiveness and energy use.

The issue came to light earlier this year after it was discovered that the glass being installed on the Symphony Honolulu tower under construction at the corner of Ward Avenue and Kapiolani Boulevard doesn’t comply with a Hawaii Community Development Authority rule.

The glass, the agency informed Symphony developer OliverMcMillan in February, doesn’t let enough light into the condo units.

Construction began on Symphony in late 2013. Glass windows have been installed up to the 35th floor on the 45-story tower.

OliverMcMillan petitioned HCDA to waive or suspend the glass rule, and the agency held an initial public hearing Wednesday at which HCDA’s planning director said it may be appropriate to change the rule.

The agency’s board will continue to accept public testimony at a hearing Thursday at 9 a.m. and is slated to make a decision onAug. 5.

On Wednesday, Symphony’s developer argued that it could not build the tower with glass that met both HCDA’s glass rule and a separate rule that requires a certain level of energy efficiency.

“Our feeling is there is a conflict within the rule,” D. Scott MacKinnon, a local attorney representing OliverMcMillan, told the board, explaining that more light passing through windows generally requires more energy to cool and make living spaces comfortable.

An HCDA staff report disagreed that a conflict exists, and said an analysis by an independent consultant shows that the agency’s energy efficiency and glass transparency rules could be met by Symphony, which can improve energy efficiency in other building components besides windows.

“There is no conflict in the rule,” Deepak Neupane, HCDA director of planning and development, told the board.

However, Neupane added that the way the glass rule is written fails to achieve much of the rule’s intent, which was to reduce reflections of the sun that can heat up neighborhoods in what is known as an urban heat island effect.

The rule requires that tower glass above the ground floor must have visible light transmission, or VLT, of at least 50 percent. Symphony’s glass has a VLT of 28 percent.

Existing towers in Kakaako have VLTs of 37 percent or less, according to OliverMcMillan, and go as low as 9 percent at the Ko‘olani tower on Waimanu Street near Pensacola Street.

HCDA adopted the glass rule in 2011 to replace former rule language that specifically set a reflectiveness limit of 30 percent. HCDA figured that its new VLT standard would limit reflectiveness, but that’s not the case because glass with a high VLT still can be highly reflective.

Neupane said the board may want to reconsider restrictions on glass appearance, including reflectiveness and darkness, that would apply to Symphony and future towers.

John Kobelansky Jr., a resident in the Imperial Plaza tower on Cooke Street, said something needs to be done so that Kakaako doesn’t become a dense forest of mirrored high-rises.

“When I go for a swim at Ala Moana I’m inundated by light rays from everywhere,” he said.

So far, the Symphony project is the only tower to run afoul of HCDA’s rule, though the recently completed 801 South St. Building A may have a similar issue. Other towers under construction, including The Collection, Waiea and Anaha, are part of master plans on land owned by Kamehameha Schools and Howard Hughes Corp. that are grandfathered under HCDA’s old rule that doesn’t specify VLT.