There are no easy answers to draw from Friday’s tragic fire that killed three people at the Marco Polo condominium tower.

There is, however, one necessary answer: Heed the calls to retrofit older buildings with fire sprinkler systems.

This isn’t the first time this controversial issue has been debated. Installing fire sprinklers in older high-rise buildings can be extremely expensive, and mandates have been opposed by those who would bear the cost.

The Kapiolani Boulevard condominium tower of 568 apartment units was built in 1971, four years before the City and County of Honolulu required new buildings to have automatic fire sprinkler systems installed.

The lack of sprinklers was evident. Honolulu residents watched with horror as the blaze scoured the upper reaches of the 36-story tower, as firefighters desperately used high-pressure hoses from adjoining balconies to try to reach the fire. The victims included many injured, as well as those who lost their lives: Jean Dilley, her son Britt Reller and Joann Kuwata.

An earlier fire outbreak in 2013 at the Marco Polo prompted the Marco Polo Condominium Association to commission a report that year on sprinkler systems. The report concluded it would cost an estimated $4.5 million to retrofit the entire building, including the homes and the common areas.

Mayor Kirk Caldwell said he believes the improved safety of Honolulu’s highrises would be worth such an investment. He plans to introduce a bill requiring the retrofitting of buildings more than 75 feet high — the height limit for firefighters on ladders, according to spokesman Jesse Broder Van Dyke. Other details of the legislation would be worked out through the City Council’s series of hearings.

Exactly how this happens, as well as when the new mandate would take effect, will be the subject of hearings with the general public and revisions made through the Council committees. How to pay for it will be critical. The cost to each individual apartment owner at Marco Polo has been estimated at about $8,000 to $9,000 — a hefty sum that some residents no doubt can’t afford. They will need some help. Ideas such as low-cost loans and tax credits, as well as other financing means, have already been floated and should be considered.

The city has a compelling interest in safeguarding its residents and their homes through strong building codes, especially those that would suppress fires in highrises. The safety of the residents, as well as the firefighters who protect them, are worth some sacrifice of tax revenue to enable the upgrade at Oahu’s older highrises.

Regardless of what emerges from Honolulu Hale, there are steps apartment owners’ associations and building management should take now. Building inspections and educating residents on safety procedures can help reduce injuries and fatalities in a rapidly spreading fire.

Of course, residents and frequent visitors to highrises must themselves sharpen their awareness. They should test their smoke detectors monthly to make sure the alarm works. They should make sure the fire door on their floor is properly set to prevent a fire from spreading.

Requiring retrofitting is not an easy call. Most cities across the country have avoided putting this requirement on their books; even so, some, such as Los Angeles, Denver and Philadelphia, have done so. More may be joining their ranks over time, given that these old buildings will only get older, and more vulnerable to fire.

The city should confront this issue now. Its duty to Jean Diller, Britt Reller and Joann Kuwata is to see that Honolulu doesn’t suffer any more such grievous losses.