If Honolulu wants to privatize all of the city's public housing units, there's only one way to do it properly: The city should make sure any sale includes a provision to keep all 1,250 of these units affordable in perpetuity.

Perpetuity, of course, means forever. But that's the required detail needed in any future contract with a potential buyer. In fact, even the meaning of the word "affordable" must be clearly negotiated up front.

A 10-, 15- or 20-year commitment to affordability is not enough.

If any deal falls short of forever, we all should have a real problem with the city getting out of the affordable-housing business.

To date, there have been discussions between the City Council and Carmel Partners, a group that is in the process of buying the privately owned Kukui Gardens, an affordable rental project in Chinatown. Carmel's talks with the city must be taken seriously. Mayor Mufi Hannemann is on record saying he would agree to a sale of the city's 12 affordable housing properties as long as the units stayed affordable and tenants were not kicked out.

Sounds good. But it would all be more reassuring if the city would place even greater emphasis on that all-important detail: perpetuity.

Without that detail, the city puts into question whether it is seeking privatization for the right reasons.

The fact is public housing has been an investment made by the city with taxpayer dollars. The city may feel it should sell these units because it lacks the ability (or will) to maintain and run public housing as a business.

But that doesn't erase the need for affordable public housing in the community. With the need for affordable housing growing throughout all economic sectors in Honolulu, we have more than a compelling reason to make sure the investment the city has already made in public housing is passed on and remains affordable.

A clause in any sales contract that protects affordability in perpetuity would certainly impact the price the city could command, which could make the city think twice about any deal. But without such a clause, any short-term gain for the city's coffers is likely to result in real long-term problems.

Any sale should protect affordability forever. If it's serious about privatizing public housing, the city must demand that level of commitment to the public good from any potential buyer.