Not the city or state's responsibility to give special treatment to older buildings when their are alternatives. City could give some property tax credit.

What you didn't know is the Association can take out the loan to do the sprinkler upgrade, using the building as collateral. A 10 year loan will work.

Next the Association can spread the cost through an increase in the monthly maintenance fees, large enough to pay off the loan, small enough so the owner can handle it.

Association can also give each owner the option to pay "Their Fair Share" of the loan up front, minus the 10 years of interest.

Either way lets get'r done.